Looking for CNC Mill Part I

[crankorgan]

Hi Gang,
MDF is wood powder and some kind of resin. It took me awhile to accept it. Up until then I was toying with 1/2" PVC. The
house next to me was torn down. The new one in it's place is a monster. The steps and deck are MDF. I got some cutoffs to play with. It hates normal woodscrews. It likes to be pre drilled. Use screws that have the same thickness of threads for the length of the screw. These act like a bolt. So I thought! Why not tap and use a bolt. After you cut MDF it looks rough. A few strokes of a sanding block and it seems to mend itself. I can get 2' X 4' pieces at Home Dupa for about $10. The boards are so flat a vacuum forms when you pull them apart. I was told you can pull air through MDF. I sent two days trying to spray paint a MDF machine. MDF soaks up Krylon faster than it can dry.

Why is MDF so good? Cheap and Straight, a good piece of 3/4 MDF is very flat. Make sure you paint it! One drop of oil and it gets a large stain.

Cranky

[Hopperfly22]

Oh great now you've done it! The first time I read this thread it tickled my brain, but I said na too expensive. Now after looking at that Morph machine I'm going to have fight the urge to splurge. I mean I have a Dremel tool....;)

[crankorgan]

Hopperfly22,
CNC can be dirt cheap if you stay away from that other group. They will have you spend $800 just for the motors
and controller. If you surf the internet you will find machines made out of printer parts. They never talk about those! As long as you are not trying to top someone elses machine, you can make a complete system for under $200. It won't cut steel! Wood and Plasic yes!
I wish my brain was tickled instead of obsessed! Just started work on my 10th machine in two years.

Cranky

[crankorgan]

Hi Gang,
Here is a part made out of 3/4" MDF and 1/2"PVC. It allows the use of two gas pipes as linear rails. The PVC blocks act as four jaw chucks, allowing you to adjust the two rails so they are parallel to each other. These are parts of Scrappy! All parts hand made.


Cranky

[Hopperfly22]

Under $200? See there you go again now I have to make up more excuses lol. Really my only stopping point right now is space in which to put it. How big is the Morph? I mean if you wrap it ina box how much space would I need? 4'x4'? Less?

One of these would be great as I've started working with CAD and have an uncle who does it professionally. I've also got a couple of years of Metal Tech under my belt. As far as milling, lathes, and welding goes.

I'll probably order your plans if I can figure out a place to put it. Maybe in the shed if I can talk my father into sparing some space. As I'm a broke college student living at home lol. Well I guess I'm broke because I spend all my money on this hobby.

[crankorgan]

Hopperfly22,
Morph is 2' X 2' Ha! Ha! Ha! Can be made larger! Made out of MDF-PVC-Roller Blade Bearings-Electrical Conduit and cheap threaded rod. It was built using a scrollsaw-jigsaw-beltsander and hand tools. It was orignally designed to hold a pen to draw kite patterns onto cloth. When I say kites I mean the big money ones. In the back of my mine there is also a blimp lurking. Radio Shack sell a minature RC car. Just right for hacking!



Cranky

[Hopperfly22]

Only 2'x2'? I think I could squeeze that in somewhere. Mainly because I doubt I will ever need to cut out anything longer than 12" or wider than 12" for that matter. Of course I say that now lol.
Ok you sold me lol if nothing else it'll be fun to build it. That and I hate cutting things out with an x-acto knife.

[uscra112]

Cranky - yeah, that't the stuff I use. Never heard it called that before. Very good dimensionally. Perfect for our projects.

Ran across an article on basics of stepper motor application in a trade 'zine that was lurking in my reading room. Forgot to bring it in to work, but one thing I remember from it was that you should NOT oversize your motors. They apparently want to run with a load that uses up 40% to 70% of their rated torque. If you run at too low a load they apparently want to overshoot and GAIN steps. This make sense to you? If it does, then anybody trying to sell you $800 worth of motors is doing you more than a financial disservice! I'll try to remember to post the website for the 'zine -

[crankorgan]

uscra112,
The rotor in the motor acts as a flywheel. Without a load to help it slow down, it will overshoot! If you watch Ebay you
will see a group of stepper motors along with linear rails almost every week. Human nature causes some people to buy expensive linear rails and large motors. They buy the linear rails for accuracy and large motors for power. Then they can't find a spindle motor other than a router. They find out fast linear rails can jam if dirt gets in them. Linear rails for the most part are for positioning of assembles. Most surplus ones are light duty. When I read the conferences it's like watching a road runner cartoon. My favorite question is: Which is better Steppers or Servos? Just like the people who try to own the best computer! Only to jump! jump! shoot! shoot! in a game. I tend to do all hobbies the same way. I build my own gear. Fish tanks-RC transmiters-Computers and audio amps. My dad was the same way. I do buy things! I bought my satellite receiver. The company is giving me back the money as a monthly credit. I built a dish years ago out of a round plastic snow sled some screen and a coffee dish. It only
picked up HBO out of New York. I love building things. I used to build Heathkits. I remember their RC trans and receiver. Their servos used freedback coils instead of pots. Ahhh 1973


Cranky

[uscra112]

Right. Which says that some friction in stepper systems is actually a good thing, especially if it's in the leadscrew nut. It damps the motor and avoids the over-shoot and possibly even vibration.

I've seen this to be true more than a few times in DC servo systems in machine tools. Too little dampening and too high gain in the servo, coupled with maybe a too-flexible structure, and you can get some really scary slide oscillations in big machines. I had one once that snapped off a 3" diameter pinion shaft like a fresh carrot. Hadn't thought about it in the stepper context, though.

The very low friction of your roller-skate-wheel guideways might be subject to this, but I'll bet you still have enough dampening in your threaded-rod leadscrews and plastic nuts to make it all work. Our CMMs all use air bearings because they are virtually zero friction, both static and dynamic, and we seem to be using some very sophisticated motion control accel/decel algorithms to make them work as well as they do. It's one of Zeiss' deep, dark secrets - I've been here 10 years, but they still get all coy if I ask about it.

Also occurs to me that keeping the inertia of the leadcrew low is also a good thing. It's part of the flywheel. I saw this on the big machine tools, too. At about 15 feet length, the screw diameter had to be so large to prevent whipping that it's inertia became more than the inertia of the slide it was driving. Most of the really big machines therefor used rack-and-pinion drives.

Of course, we're apparently only moving 12 inches per minute, not 400 or more like the big aircraft-part profilers do.

[Hopperfly22]

Well looks like I've got my chance to give one of these a shot now. I hit it good at the Casino the other night, and basically doubled my paycheck this month.

[balsaman]

Hey,

Share the wealth!

Eric:D

[PanzyPoof]

Hopperfly22
There ya go! no excuse now.
Kit by Zoltar shure looks pretty Hmmm.:cool:
Or go scratch build as I'm doing.
Cranky's plans are very good!
I'm having fun building and learning.
You're call:)

Off to get some 4/40 screws.
That plastic I have taps ok just gotta back out a few times.

[crankorgan]

PanzyPoof,
Did you find 1/4" PVC? PVC taps nicely if you back out a few times. A hole that does not go through is the worst, there is no place for the chips to go! The plastic taps very easily until you try to back out! I used to design with alot of 2-56 screws. I now use more 4-40 ones.

Cranky

[balsaman]

In making my Delrin nuts I found I needed to run the tap in and out quite a few times so they wouldn't be so tight on the rod. I have no experience with the steppers so I don't know how tight is too tight (or too loose) I have them spinning pretty freely but still cant feel any slop so I guess i'll go with it. I can always make more if I need to.

Cranky, do the delrin nuts stay fairly tight (slop free) under repeated use? How long should they last?

Thanks

Eric

[crankorgan]

balsaman,
A good quality Delrin will last a long time! Keep the
threaded rod lightly oiled and clean. I cycled my machines several
thousand times with no wear. The PVC I used worked well also.
Balsa puts next to no backpressure on the nut if the bit is sharp.
I have the most experence milling circuit boards. There I have to cut copper. There is more back pressure into the nut.

Watch out for alignment problems. It is important that the threaded hole goes through the nut at a right angle. Put the Delrin in a vise. Use a drill press to hold the tap. UNPLUG the drill press. Pull the drill press down. Turn the chuck by hand. Tap the nut a few threads. Then loosen the chuck and tap and block of Delrin. Finish tapping the nut out of the vise and drill press.

Cranky

[balsaman]

Watch out for alignment problems. It is important that the threaded hole goes through the nut at a right angle. Put the Delrin in a vise. Use a drill press to hold the tap. UNPLUG the drill press. Pull the drill press down. Turn the chuck by hand. Tap the nut a few threads. Then loosen the chuck and tap and block of Delrin. Finish tapping the nut out of the vise and drill press.

Cranky,

Thant's exactly how I did it. :D I also made delrin blocks for the bearings opposite the steppers to support the rod. I inserted a bronze bushing into the delrin. I was going to use a solid coupling at the motor end and use the motor bearings as support at that end. I wonder about backlash here though. I don't have the motors yet so dont know if there is backlash/play in the shaft. I will figure that out when I get the steppers. How do you deal with this cranky?

Thanks

Eric

[uscra112]

Balsaman you may want to have a little tension in the screws themselves. Not that the rotation speed is going to be all that fast, but without a bit of tension they will tend to wobble, and the backlash from the screw's thrust bearings will be less. Not too much tension, though, or you'll bend your supports.

[balsaman]

ok, but will the bearings in the stepper motor be sufficient? I could put a thrust bearing on the screw at the support end but I am wondering about the stepper end.

Eric

[crankorgan]

Hi Gang,
The threaded rod is held to the motor with a piece of rubber vacuum line tubing for a car. The piece is 1 to 1/4" long.
Make sure there is no oil or grease on the leadscrew or motor
shaft. Screw the tubing onto threaded rod. Then push the tubing onto the motor. Leave a tiny gap between the two shafts. The
free end goes through a bearing that is mounted in a plate. There is a 1/4-20 nut on both sides of the bearing. The nuts get tightened against each other traping the hub of the bearing. This bearing handles all the pressure, not the one in the motor. The one in the motor will work for just cutting balsa and driving a pen.
Harder materials will cause the wavey washer in the motor to compress.

Cranky

[crankorgan]

Oh Yea!,
The threaded rod has copper wire wound on it in the threads. This makes it 1/4" thick so it fits tight in the bearing.


Cranky

[uscra112]

All the thrust generated by the screw should be taken up in the screw's bearings. The motor bearings should not and as cranky says probably will not handle it. Standard machine tool design practice always was to heavily tension the screw, so thrust is taken at both ends, but for these low-speed devices taking all the thrust at one end would probably be OK, as long as you're taking it in both directions. Doesn't much matter which end. I like Cranky's idea of using rubber tube as a coupling to the motor !

[crankorgan]

uscra112,
The black rubber tubing does more than join the two shafts. It prevents binding and it reduces noise! What noise? A
stepper can sound like a siren when it is doing a circle. When you have three motors running at once the wood acts like a soundboard. See Pic of what I am working on!


Talking and Building

Cranky

[balsaman]

What would we do without you Cranky. Thanks for all the tips.

If the steppers are so noisy, would it be worth it to soft mount them? I have some of those rubber isolating "nuts" ie. rubber cylinder with brass threaded inserts on each end. They use them on fan motors etc.

I have read that you need to mount the steppers on a heatsink material (aluminum etc.) or they can overheat. Do you agree?

Eric

[crankorgan]

balsaman,
Steppers are suppose to get hot! I have seen heatsink fins on the body. I mount my motors to plastic or MDF endplates. I never had a motor overheat. The Z axis is the one that gets the hotest. It moves the least of the three motors. You can use some rubber under the motor. The motor makes all kinds of frequencys as it runs. You may stop a few, but the rest will come through. If I were you I would worry more about the Dremel or Router. A Dremel makes X amount of noise. Bolt it to a frame and it gets even louder. At some point I am going with a AC motor with pulleys driving a flex shaft tool. When you finish a machine you don't hear the noise. The joy of seeing it work hides the noise. Then after running it for several hours you notice your ears ringing.

Cranky

[balsaman]

I won't hear the noise, you are correct......but my wife, she will get no joy from seeing it run ;) and she will hear the noise :D. I am sure you are correct, the router will be the noisiest part. You just had me worried when you said the MDF becomes a sound board....I was planning on solid couplings from the motor to the shaft, with no other support at the motor end, and supporting the other end in a bearing with nuts per your recomendation. I suppose I could always go to a soft coupling later if I cant stand it. :rolleyes:

Eric

[crankorgan]

balsaman,
www. Meci.com sells cheap 1/4" to 1/4" couplers that use a rubber center. The rubber is there to allow the motor and the leadscrew to be slightly out of alignment. 1/4-20 threaded rod has some flex. This flex along with the rubber tubing will hide most alignment problems. I also show people how to make a floating nut. First time builders have so much to watch out for, I
created a system to fix these problems.

Cranky

[DICKEYBIRD]

Originally posted by balsaman
I could always go to a soft coupling later if I cant stand it.
Eric
Trust me, the steppers can make an almost musical sound as they go merrily about their given task; music to my ears anyway. Now the ROUTER; that's another story. You better plan on a pair of shooter's earmuffs to cut out that 'orrible racket! I'm trying to find a pair of audio headphones that REALLY block outside sound so I can hook up to the headphone jack on my shop TV or radio. I can't hear my hero Norm Abrams when I'm cutting parts on a saturday morning.;)

[balsaman]

I like crankies idea of an AC motor on a flex shaft with pulleys to increase the spindle speed. Something to consider later....

Eric

[PanzyPoof]

Cranky
Got the Controler board;)
Anouther piece of the puzzle.

[crankorgan]

PanzyPoof,
Watch out! If you spin the motors before you finish the machine, the odds will be 1000 to 1 you won't finish. There is a ACME 10 turn per inch leadscrew with a nut on Ebay. I looked at the guys past auctions. He sold his controllers a week or so ago!
I bought some more roller blade bearings. $11.97 for 16 bearings. I walked 6 miles round trip to get them. Saw a guy at the store trying to get a treadmill into his car. I see them all the time in the garbage. The dust is always on one side. People always put them out when it is dark or raining. CNC goes the same way for most people. I like the Taig and Sherlines on Ebay!
Small ding in bed! Oh Yea!


Cranky

[balsaman]

Originally posted by crankorgan
PanzyPoof,
Watch out! If you spin the motors before you finish the machine, the odds will be 1000 to 1 you won't finish.

Cranky

But ya gotta test the board don't ya? I ordered mine last week....I will try not to spin em when I get em.....it will be tough.

Eric

[DICKEYBIRD]

Originally posted by crankorgan
Saw a guy at the store trying to get a treadmill into his car. I see them all the time in the garbage.

Hey Cranky, stop & pick up that treadmill for me!;) They have great motors and variable speed controllers in 'em and other bits & pieces to make a spindle motor for a CNC mill!:D

[crankorgan]

balsaman,
People think the motor system is the hard part. The two hard parts are the machine and the DXF/GCode. Lots of people buy a Taig or Sherline. Then they start asking for test GCodes. You try to explain to them that a GCode needs to be offset for the machine it is on. They think the machine knows where the blank of material is. I have delt with some real scarry people. You get the GCode right and the bit crashes into the clamp holding the work.

By the way....don't forget, the motors might miss steps without a load.

Cranky

[crankorgan]

DICKEYBIRD,
I got myself to the point where I can walk past anything out for garbage. I still look at computers. I walk every morning to the post office. I go through two garbage zones, so I see stuff out everyday. You can't believe what I see! What cured me is having to help several friends clean out their parents house after they die. I had to throw my parents stuff out! Fifty years of worthless junk. If you use a treadmill motor for a servo you will need a optical sensor and an expensive controller to drive it. Big Big money. I will stick with the cheap stuff!


Cranky

[uscra112]

Cranky, et.al.: Right about steppers making noise. We had a stepper controlled spar around here 5 years ago for a demo for a laser measurement system. Was great for trade shows because it would attract attention from people 20 yards away.

Pack any and all hollow spaces in your structures with sand, preferably mixed with thick oil. An acoustics engineer I knew years ago taught me that trick. I figure he knew what he was talking about, the company he worked for was Bolt, Beranek & Newman. He himself did acoustic analyses of nuclear reactors, and BB&N had a lot to do with submarine prop design, too.

OK, OK, seal the insides with polyurethane first. And if your structures don't have any hollow spaces, create some. It'll work! You can also get effective sound-damping by gluing a sheet of firm foam rubber 1/2" or so thick to the the panel that's vibrating, then gluing a second stiff and preferably heavy panel to the foam. The resulting sandwich will hardly resonate at all.

[balsaman]

Cranky,

I agree the Gcode will be tough. I noticed when I take a cad drawing and convert it to Gcode it will make every line but not very efficiently! Its hopping all over! I guess I have to learn to draw in a way that the CAD converts to an efficient Gcode file. Also, there is no positioning feedback on a home made mill, so not only does the machine not know where the wood is on the table, it doesn't even know where the router is! Do you manually jog it "home" before you start? Also, do you have handles on your shafts so you can crank the axis around by hand to get th positioning just right? I am considering putting them on mine.

I would think you may want to do a "dry run" with no tool in the router before you go to test a gcode file?

Eric

[crankorgan]

balsaman,
There are HOME switches. The machine starts from
the HOME postion. The BLANK sits somewhere on the table. The
bottom left of the BLANK is X 0 Y 0 after the machine moves out to it. You can issue a reset. Or you can have the machine move out to where the part really is. A fixture is nice so everytime you use a certain size blank the numbers are the same. With BALSA you just use a large piece. The trouble starts with the Z axis. How far down does it go to cut through? Is the Z a negative or positive Z cur. How far is the bit in the chuck? This is where the ding in the bed comes from. Excited people never use a board under the part. Just as you think to yourself: Why is it doing that?
Half bit is shooting somewhere in the room!

You can also use a GCODE that has a certain cutting Z distance. Down -Z.125 Up Z.125 With this you jog the machine
out over the balsa. Reset the machine and start your GCODE, You
know the Z will only go 1/8" deep! So you start it just above the
balsa. Watch out for those clamps!

Cranky

[uscra112]

Hmmm. The G-Code generator starts with what, a .dxf file? Never thought about that, but a CAD program doesn't care what order the entities get painted on the screen, I suppose. And a .dxf file will surely just take them in whatever order they are found in the CAD data file. If the G-code generator follows the .dxf file's order, that's what you'd get. I create and edit .dxf files using MS Excel. ( I made a macro that converts the airfoil coordinate files I get off the net so I can get them into my CAD. ) Each entity gets a block of code, and it's easy to see the format if you study them a bit. Re-shuffling the blocks could be done with cut-and-paste if there aren't too many of them . . . Egad, what'll I see if I look at an airfoil profile that I turned into a spline? A .dxf of that will be a zillion little line segments! :(

[crankorgan]

balsaman,
Here is trick NUMBER 1. Very few people notice this. When you draw in CAD the GCODE cuts in the same order you drew the lines. This is called THE TRAVELING SALESMAN SYNDROME. The ACE converter fixes the bad moves. Here is how I do it a different way. After you draw your part. Start a new layer in a new color. Trace the part in an efficent manor. Save the file in a new name. Delete the old layer. Now put the trace through your converter. You should see only a few travel lines.
Some GCodes spend more time moving than cutting. You should see my circuit boards mill. After the first one took 3 hours I learned how to fix the GCode so it is pure magic. A simple trace
of the DXF fixed the problem.

Cranky

[DICKEYBIRD]

Originally posted by crankorgan
If you use a treadmill motor for a servo you will need a optical sensor and an expensive controller to drive it.
Nope, I was talking about using the treadmill drive motor to run a spindle & chuck for turning a cutting bit, not for a servo for motion control. I don't know anything about servos and encoders!

I hear that the treadmill motors are available in the surplus market along with their speed control circuit boards pretty cheap. They can be utilized as a variable speed drive motor for drill presses, homemade mills and the like.:)

[crankorgan]

DICKEYBIRD,
I reread your message. Motors are easy to find. A
good cheap spindle does not exist. I tried to talk a few people into making and selling one. Seems like people buy a Sherline one for about $85. This is one of those CNC dead ends. People convert a X-Y table to CNC only to find they can't find a matching spindle motor cheap. That's why I stick with a Dremel tool. There
is also a Die grinder. Looks like a Dremel on steroids. You can use a router, but a nice multi speed spindle is not out there. Maybe someone here has an idea. For balsa even a tiny DC motor can be used.

Cranky

[uscra112]

Cranky-
Do you find that extreme high RPM ( OK, SFPM ) is good for balsa? I've never tach'd a Dremel, but I have yet to find a cutter that works really well in balsa with my flex-shaft Dremel. I've been assuming it goes too slowly, but maybe I'm not using the best cutter geometry. For routing balsa and relatively thin ply, why would we need a variable speed anyway? I would have thought the faster the better. And no, I don't know of any really cheap spindle we can use, and I've had my eyes open for one for years.

[crankorgan]

uscra112,
A Dremel Multipro has a top end of 30,000 rpms. I
think the slow end is 5,000. The Dremel can run for hours without a problem. My only complaint is the noise. Some routers
can only handle intermittent duty. I did some experiments with an RC car motor. I built a spindle assemble. It seemed quiet until I bolted it to the machine. The Dremel is still the best way to go for cutting balsa. My next experiment is a flexshaft driven by a nice cheap quiet AC motor with pulleys that step up the speed. Most flexshafts can run at 15,000 rpms continuously. My only concern is can the final pulley bearing handle 15,000 rpms. The
Dremel is very hard to beat. Lots of expensive CNC machines use a motor tool that looks like a big Dremel.

Cranky

[balsaman]

Cranky,

Tracing the lines in the dxf file is a good idea! Especially for parts with lots of straight lines. It won't be easy on the curves though. I guess you could trace as many lines as posible and then use Ace Converter to convert the drawing. I DL'ed Ace Converter but have not tried it yet. I tried Kcan3 so far only. I will try Kcam3 with a traced dxf file.

So much to learn. I am happy you started this thread PanzyPoof. It's also great that you offer so much experience Crankorgan and Uscra112.

Eric

www.e-zflight.com

[crankorgan]

balsaman,
Also try FLASHCUT. The demo stops running the motors
but it will still do DXF to GCode with plot to screen. I set Kcam to the size of my machine. I can see where it is going cut. KCam also lets me edit GCode. Does offset and Find-Replace. I use CNCPro to run my motors. TurboCNC works great on older computers.
It is best however to learn how to write a GCode using WORDPAD. Seems slow, but it helps you learn how to spot and fix a bad GCode. Its like learning DOS and then Windows. Knowing DOS helps with some Windows problems.

Cranky

[PanzyPoof]

Cranky
I'm working page 16 here! have a ?.
The guides what does <Del> stand for (Delrin)?
No thickness I gonna assume 1/4"

And the Gib I gonna elimanate the Gib beam and notch the Gib with the table saw. Sound OK

Heads Up! there's a typo on Parts Placement Page suplement for the Controler board.
you show IC 7486 on the diagram yet list IC 7484 below. Main Plans Show 7486, my money is on this as correct.

[PanzyPoof]

I plan to use my Dremel 732 RPM is 22000 1/5HP
The Large tool in pic will be mounted.
Simple 1"tool post should be a snap to build.
I have 4 Dremels laying around so it won't be missed. And if i need it a simple tug on the cable and off it comes. Will clean and regrease flex shaft that's old stuff in there.

[PanzyPoof]

Kinda late this round, could have used a CNC machine here:(
These Ribs will be cut out by hand. At least I
have nice templates, Provided by my Stika cutter.
These are for my PBY-2.
So no rush and the CNC will get the next one.
Get the Bandaids out:confused:

[Tree_Magnet]

well i now have my controller for my cnc foam cutter running now i just have to finish the mechanical end of it. the controller is from the french site i used mm2001 and it worked the first time with no problems. i will use the same controller for my cnc router and probably my lathe/mill. (just means changing it from bipolar to uni polar motors:) .

Tom

[Zoltar]

Hello CNC-Group,

I wonder what I've been doing wrong all this time.......

Since about two years I've been fiddling arround with this hobby,
CNC stuff but I did not see a G-code in sight.......I did learn them once at school a time ago.............

And aslong as I am routing parts 2.5 D I leave the G-code alone and use HPGL.
This is the Hewlett Packard language to talk to their plotters. HPGL contains the 2D coordinates and the other half D is pen up / down (mill up mill down) and pen down.

Its really simple and works in combination with a file optimizer very well!

If you go to 3D, G-code or ISO is the language. As I am testing at
the moment some CNC work on 3D body's now G-code is needed. But still I did not find the need to alter G-code.

2.5 D -> Cad 2D->export to DXF->optimizer conversion to HPGL(Bonc)->PCNC(dos)->milling 2.5D

3 D -> Cad 3d->export to STL/3D dxf ->conversion (deskproto)into ISO/G-code->PCNC(dos)->milling 3D

Bonc is a fine working file-optimizer distributed free over the Web. Whitin this program you can do whatever is needed to prepare a file for routing parts.
PCNC(2,5/3D) is buyware, but at about 100 dollar its more then worth the investment. As this is a DOS program you can use a inexpensive PC
Deskproto is a expensive program, however distributed as a 30 day full working version. Time enough for some 3D experiment.....

Here a pic from a bottle with a simulation of milling paths arround it in Deskproto. The milling paths are written in G-code by the program. The setup takes place in Deskproto.

Greetings to all!

Chris

(www.rcmodels.net)

[crankorgan]

PanzyPoof,
The ICs are 7486. No body else spotted that! You can use the tablesaw to form a GIB or GUIDE. I went for a handmade machine. Feel free to change things. Del is DElrin 1/4" or thicker. You can get the 8ohm 20 watt resistors for the motor at Radio Shack. You can also put two 10ohms in parallel to make a 5ohm 20watt. Let me know what motors you have, current and voltage.

Cranky

[crankorgan]

Zoltar,
PLT files and GCode are both CNC. Feel free to use either. I run my machines in DOS mode. Lots of people want Windows. What ever gets the job done! Over here in the US very few people in CNC know what a PLT file is. They always want the latest even though they have no idea what they are doing.

Cranky

[DICKEYBIRD]

Originally posted by balsaman
I DL'ed Ace Converter but have not tried it yet.
I use Ace exclusively...try it you'll like it! I have drawn a "virtual worktable" in CAD that is exactly the same size as my work space. Once the CAD plan is finished, I copy/paste all the individual sheet parts I decide to CNC cut onto the "worktable" & move them around for best stock utilization. If there's a bunch of parts all cut from the same thickness stock, I glue 3" or 4" wide sheets together to make up 12"x12" blanks. This makes very efficient use of your stock and who cares if a rib or bulkhead has a glueline on it? You do have to watch grain/joint direction however.

Once all the parts are positioned, I assign each part a separate layer in the order that they are to be cut, making sure that any lightening cutouts have their own layer so that they are cut before the part outline is cut so they don't move around on you. Ace allows you to assign each layer a "Priority" number which is the order in which the parts are cut. You then set the Z-depth and release height (where the Z releases to between cuts) I use zero as my cutting depth, having preset the tool to just touch my sacrificial 14" foamboard worktable overlay, and 1/4" release height for most of my stock. You then click the "Convert" button and ZAAAP! You got yourself a beautiful G-Code. Unless I screw up the CAD work, it works EVERY time, and is FREE! (Hee, Hee!)

HTH,
Milton

[balsaman]

Ok, looking at ace converter I see it does a much better job doing the conversion then Kcam. I used Ace to convert a test drawing and used Kcam to view the resulting Gcode. The Gcode file looks good. Very useful program. Looking at the Gcode file I start to see how Gcode works. I can follow the colored lines based on the Gcode, altho I am not ready to write anything using just Gcode. I see that G01 is a straight cut move G00 is a straight tool up move, and G03 is an arc and the numbers following those are the coordinates that the moves end up at.

Where does tool offset come into play? Do I need to do that at the CAD stage? ie. draw the drawing with the offset built in? Is there a way to tell the software to do it automatically? Also, some tool offsets would need to be on the outside of a part, and others on the inside (eg. for weight relief).

Thanks again.

Oh and I forgot to include DICKEYBIRD and Zoltar whan I said thanks for sharing all your experience.

Eric

www.e-zflight.com

[crankorgan]

balsaman,
G00 calls up the fastest speed of your mill is set to in the software. This is where you can loose steps. If you jog your mill at 14 inches per minute you might not see a missed step. Putting F6 in the GCode will slow the mill to 6 inches per minute during cutting. But when a G00 comes along the mill jumps back to 14" for one move. G00s are put in when you convert from DXF to GCode. They are when the cutter moves to a new location. I change all G00 to G01. Some CNC programs run full out unless you put F numbers in the GCode.

Cranky

[DICKEYBIRD]

Originally posted by balsaman
Where does tool offset come into play? Do I need to do that at the CAD stage? ie. draw the drawing with the offset built in? Is there a way to tell the software to do it automatically?
My MaxNC control software doesn't support tool diameter compensation so I draw in the CNC path on a separate layer & color that's offset 1/2 the tool dia. to the inside or outside of the finished part as required.

I'm pretty sure that all tool dia. compensation is a feature included in the actual software that controls your machine, some do, some don't depending on the $$$. The actual command to activate it is added into your G-Code. Call me crazy but I get some kind of perverse pleasure from drawing it in myself. Of course if I decide to change the tool dia., I'd have to redraw all the paths again.:(

[crankorgan]

DICKEYBIRD,
Your not crazy! Being able to add amounts to a drawing in your head while you draw keeps your mind active. In programs like Kcam you can rescale a drawing. This can be used to make the part larger or smaller. For circuit boards, I figured out how big to make the pads and traces. The tool provides the width between the traces. I also draw the path so the tool goes around and overlaps where it starts. This get rid of nasty little burr shorts. Doing something the hard way usually has a reward somewhere.
Cranky

[balsaman]

Originally posted by crankorgan
balsaman,
G00 calls up the fastest speed of your mill is set to in the software. This is where you can loose steps. If you jog your mill at 14 inches per minute you might not see a missed step. Putting F6 in the GCode will slow the mill to 6 inches per minute during cutting. But when a G00 comes along the mill jumps back to 14" for one move. G00s are put in when you convert from DXF to GCode. They are when the cutter moves to a new location. I change all G00 to G01. Some CNC programs run full out unless you put F numbers in the GCode.

Cranky

So just set the max speed and the cut speed to a low enough number so it won't miss steps regardless of whether its cutting or jogging. Lots to learn. What would we do without the ezone!

Eric

www.e-zflight.com

[crankorgan]

balsaman,
In the software there is a Ramp Up and Ramp Down setting. This slowly starts and stops the motor. If this is set wrong you can also loose steps even if you run slow. Running a mill under Windows does not work well with the cheaper software. I won't name names. Drop Windows to DOS level and use TurboCNC for a starter. For $20 it works very well. There is also a conference for it! TurboCad-ACE-TurboCNC is a very cheap easy way to go. TurboCAD is FREE and so is ACE. TurboCNC asks for a $20 fee. It costs about $200 to complete a small CNC system for cutting wood parts. It would be nice to have a simple CAD-CAM program for cutting out parts. Mabe someday! I like this conference, there is no one here hawking their motor controllers and software.

Cranky

[balsaman]

Hey Cranky thanks for the Turbo CNC tip. I dl'ed it and it looks great! My laptop I am going to use is just a 486 so the Dos TurboCNC will be perfect! I was worried about whether the laptop would run the windows software. I think I will use Ace to convert, Kcam to get the WYSIWYG view of the resulting Gcode, and when all looks good, use TurboCNC to control the mill.

Now I just gotta build the darn thing. Got a lot of the tough parts made. I need to make room on my bench and start cutting some MDF.

Here are the bearing blocks and threaded nuts I made.

[crankorgan]

balsaman,
Looking good! You must have a good saw. I have a three wheel Black & Decker bandsaw with a dull blade in it a table saw that is a joke. My favorite tool is a Delta scrollsaw. The other tool I use is a bench mounted belt sander. I rebuilt my sears AA109 lathe, but so far I have had no use for it. I own a $89 drill press that the chuck come off if I put a large bit in it. Most of my parts are handmade. The rest are hardware store hardware. Not having or using expensive tools paid off!!! I found simple easy ways to make expensive CNC machines. What would NORM say? I like laying out a part and filing and sanding it in! I find it very relaxing.

Cranky

[balsaman]

The little lips you see on the parts was on the scraps of delrin I found at work, so I left them there. I just needed to cut them out and drill, tap etc. with a drill press. Your tools sound like my tools! I have nothing fancy. I do have access to a full machine shop and licenced machinists who love to help me at work. I like to make as many parts as I can myself as I don't like to keep asking them to make simple parts for me. I will have one of them make the threaded rod parts for me and some aluminum disks for the free end that I will make into manual cranks for the axis'. My design will use that 1/2-10 ACME rod which I will get turned down on the ends for motor couplings and disk/crank handles. I am very lucky to have access to the machine shop for the fancier parts. I know Cranky that they are not required for a mill, and that you have worked hard to make a design to be built with regular tools. Since I have access to the shop, I may as well use it.

Eric

[Zoltar]

Hello you all,

Personally I feel for 2.5D jobs, as we are mostly doing, why make it more complicated as the PLT languages can do the job without a problem, without having to learn G-Codes?

Are you using in the US -G-codes- only programs to drive your machines?

Greetingz

Chris

[balsaman]

So...does my driver board from Stepperworld.com understand a plt file? Do I just downlaod a HP plotter driver or how does it work? I could not find Bonc on the net...do you have a link?

Eric

[crankorgan]

balsaman,
The stepperworld board is a step direction board. Plotters use older phase control. How are you going to get your
Z axis to do a PenUp PenDown? A Penup or PenDown is not a
step/direction signal. Check out the link below. It is where the plotter people get their info. Talking plotters and CNC is like talking electric and gas motors. Same results different methods

http://www.luberth.com/plotter/plotter.htm


Cranky

[balsaman]

As always, thanks for the info Cranky. Maybe tomorrow I will buy some MDF.

Eric

[Zoltar]

Originally posted by crankorgan
balsaman,
The stepperworld board is a step direction board. Plotters use older phase control. How are you going to get your
Z axis to do a PenUp PenDown? A Penup or PenDown is not a
step/direction signal. Check out the link below. It is where the plotter people get their info. Talking plotters and CNC is like talking electric and gas motors. Same results different methods

http://www.luberth.com/plotter/plotter.htm


Cranky

There is a little catch to this......

I believe this can also depend on the software maybe for a certain stepper card.

As I am using HPGL (pen up/down) in the setup within the program stands for a certain height is defined for up and for down also.

So the software knows what to do with a certain PU- PD command
and drives the steppers.
Otherwise it would not work ....

So I've got a gas driven CNC machine or a electric plotter :)

By the way Luberth wrote a nice "plotter" program -C-step- wich is good for CNC also. (if you got the right steppercard).

Balsaman, Bonc can be found on my website on the software section under optimizer.

Greetings ......


Chris

[crankorgan]

Zoltar,
I like both plotters and CNC machines. My Morph design is a plotter that will hold a pen or a Dremel tool. CNC milling machines have limited use, so I set out to create new markets. I own plotters! I also own CNC machines and I own a Morph. Your kit is great! I almost went that route with the Brute. The problem is the ideas keep coming. I was bored to death redoing the Piker so I could have someone else make them. Stocking parts and making up kits is not my cup of tea. I like electric motors in planes, they are nice and quiet! They don't pollute.

Cranky

[DICKEYBIRD]

OK, time to post some actual work from my CNC machine.

Daughter: Rachel, not CNC cut, 12 yrs. old, red haired, feisty little critter. Not very stable, won't go where I point her.

Plane: Dave Robelen GWSport, scratch built from his plans, GWS LiteStick motor, GWS R-4P Rx, GWS 5A ESC, 7 cell 280 mah NiMH batt., Doculam covering, 228 sq. in, 7.4 oz. CNC cut ribs, wing tips, fuse bulkheads, V/stab, H/stab ribs, tips & elevator. Flies great, very stable, goes right where I point her or will fly on her own. Rachel can now take off, fly around with very little help, even made 3 "talked down" arrivals. I'm one proud poppa!:)

[PanzyPoof]

Nice rib work. What % of that model is direct result of the CNC machine?
Ya Pretty Daughter:) Mine is 7 and she's a
treasure! enjoy em now cause they say:confused:

[DICKEYBIRD]

Well, lemme think, 16 wing ribs, 4 wing tip pieces, 3 fuse bulkheads, 4 pieces v/stab & sub rudder, 8 h/stab ribs, 2 stab tips, 2 pieces elevator . Total of 39 pieces. CAD time to draw the stuff up, incl. copying the parts then correcting the draftsman's errors, redesigning a couple of areas as well, creating the cut sheets and converting to G-Code, cutting the parts. Jaysus, no wonder it took me 2 months of spare time to build a bleedin' park flyer!;) I coulda done it in a couple weeks with an exacto, but it wouldn't have been near as much fun!

This was building someone else's plan (which I rarely do) You don't wanna know how long it takes me to dream one up, draw the CAD plan, CNC cut the parts and finally put it all together!

But I love it!:D

ps: Anybody else got somethin' for CNC show & tell?

[balsaman]

Rachel is sweet. I have an 11 year old daughter, and boys 12, and 8. They grow fast!

Nice plane. Great job.

I hope to use mine for more than just balsa. I would like to use it for fibreglass, plastic, wood, and I hope the odd bit of aluminum (slowly). Time will tell. I hope it will be straight and rigid enough. If not, like cranky says, learn from it and build another later.

Eric

www.e-zflight.com

[DICKEYBIRD]

Originally posted by balsaman
I hope to use mine for more than just balsa.
I have performed some simple engraving operations with mine on brass, aluminum & plexiglass and it worked fine other than the flexibility in my drawer slide X/Y table that causes Z cutting depth inaccuracies.

I also have used mine in my other passion, Cox 1/2A engines. I have used it to grind out the little bridge between the "twin slit" exhaust ports in the more recent .049's. I use a homemade fixture to hold the cyl. and a Dremel abrasive disc chucked in my router after rotating it 90 degrees on the Z axis. I wrote a simple code that cuts out the bridge very accurately.

Funny thing, with CNC control and a conservative amount of stock removal per pass, the little abrasive discs that used to either shatter all the time or wear down quickly when using them by hand seem to last forever now!

ps: You got those boys building & covering yet? Keeps 'em off the streets!;)

[balsaman]

12 year old thinks it's boring. Nintendo is "funner" There is still hope for the 8 year old. :D

Eric

[Zoltar]

Hey Group,

Here's my CNC story.....

As I found myself cutting parts for the PBY - Catalina I thought there must be a better way. I Saw an ad from Step Four (who makes machines for hobbyuse overhere in Europe). Starting at 2000 dollar it was not a real option. I had a look around and found it could be done differently than the conventional machine buildups, and choose to design the machine based on a lasercut 3mm sheetmetal with slot assembly. No welding would be needed as the parts can be glued togetherwith Loctite 330 .
The machine had to be capable to do plywood and also some softer metals. So then the Zoltar-machine was born.

Now I am designing modelparts mostly in lite plywood instead of balsa. Cutting out most internal material you endup with a stronger construction almost as light as you would make it out of balsa.

Here a example of the redesign of a C.Goldberg Tiger II wing in ply with one carbon strip 15x3 mm. The strip can be shifted trough the wingribs and locked with some ZAP. The wing builds up rather quick and no building board is needed as the C-strip takes care of the allignment perfectly.

For more about this see my website under cnc - result.

[Zoltar]

and an other one..

[DICKEYBIRD]

Hi Zoltar,

GREAT work!:D

How do you keep your parts from shifting around and being damaged as the cut nears the end of each part. STRONG vacuum table?

[PanzyPoof]

Real nice. And well planned design ME like!!
So how long would the machine take to do such a sheet O Ribs?
And is the machine feed speed adjusted for Ply/Balsa/Plastics?
Just Wonderful Stuff!!

Controler Board all Built Thanks to (Tree Magnet)
I got Mossie Plans to trade him for his work:D
What a Pal Eh! BTW he noticed the TYPO. ;)

[Hopperfly22]

Well I've been in a building frenzy with my models because I need to clear a space before I can build a CNC router. But looking around and thinking I was bored and got a crazy idea that kinda got me trouble. My mother is a hobbiest too but her hobby is sewing. So I took a sewing machine needle, and dremeled about 2/3 of the end off. Then I cut a groove in an exacto and soldered it to the needle. Put it in the sewing machine, and removed the little thread spool. Draw the part on the balsa, step on the pedal and steer it lol. It actually works pretty darn good. Kinda got busted though as I didn't clean up the mess. Well not all of it anyway, but still cool. Wasn't cutting anything specific just experimenting with a funny idea. Cool thing is it worked and you can control the speed with the pedal although it will only do small pieces. :D

[Zoltar]

Well as you see I just use two pairs of spring clamps on each side....so I do not use a vacuum.

The trick is within the Bonc optimizer software (beside insert the compansation radius of the mill) you can insert small bridges. This means that the mill will go up at a certain point , move a few mm and goes down and continue milling again. As you can define the cutting order it is possible to cut out the holes first and then the contour. So the outside contour is supported by little notches, it wil stay on hanging inside the wooden blank (as with most pro-building kits). Of course you have to cut off these notches when ready. But thats easy done.

Normal working speeds in lite-ply are at about 8 mm a second so at about 0,5 meters a minute. It can go faster with a better, high speed tool, but for us as hobbyists, thats not really needed.
For balsa I can set it to 10/12 mm a second, but 8mm feed give's a nicer cutting - edge.

The tool-speed can be varied by the milling software (PCNC) and can be changed anytime. Anyone interrested in this kind of software look on my site under software, a demo can be downloaded from the supplier. This program accepts also G-Code wich makes it ideal if you plan to do 3D milling in the future too.......:)
The freeware software of Luberth dijkman, www.luberth.com ---> C-step does only do HPGL files, but its free.

As the HPGL (PLT-format) does not contain any information about the tool speed or diameter this can be easy changed, central within the software. Pen up---> mill up speed is set, Pen down, --->mill down speed is set. This is one of the reasons why HPGL is so interresting for 2.5 D CNC routers. Its much easier to control and by this more accesable for beginners in CNC.

Referring to Panzy :
Originally posted by PanzyPoof
Real nice. And well planned design ME like!!

As you draw an airplane design or redesign for a model, you should have the way of production in mind using the advantages.
So by using slots you can make it easier and precise bysticking parts together and saving weight by cutting certain holes.
This means that my TigerII clone does not contain any Balsa anymore. At 10$ for lite plywood and another 10$ carbon and some glue I've got the basic structure for this extremely strong trainer plane.

I include a screenshot from Quick Cad where the layout has been made to the size of the table:

[Zoltar]

And another from Bonc where you see the breaks in the cutters line (red is the countour of the rib, blue is the cutter-line)

Regards, Chris

[DICKEYBIRD]

Originally posted by Zoltar
The trick is within the Bonc optimizer software (beside insert the compansation radius of the mill) you can insert small bridges.
OK, I understand; that's what Cranky mentioned earlier in this thread. I'll have to try that on my next project. I tried it very early in my learning curve but had great difficulty with the conversion utility I was using at the time....it had to see a joined polyline before successful G-Code conversion.

[Zoltar]

Originally posted by DICKEYBIRD

OK, I understand; that's what Cranky mentioned .......conversion.

Well The Bonc software is not that picky.

G-code is more professional........But can be a real pain in the ....eh head.


Regards, Chris

[balsaman]

Well, I started building the structure. I managed to get the MDF parts cut, glued, screwed, and painted. Here is a picture. I have the Y axis laid out, ready to be bolted together.

Eric

[crankorgan]

balsaman,
MDF always looks better painted! I have been cutting MDF also!

Crankorgan

[balsaman]

Yeah, I hate watching it dry! I figured I better paint right away or i would never paint it! I hate painting.

Eric

[crankorgan]

balsaman,
I use Acrilic-Latex grey deck paint. Dries in about 15 minutes. Three coats (one per hour) does it. Spray paint is fun to watch. Soaks in just slightly faster than it dries. Even Krylon won't work.
How did you like working with the MDF?

Cranky

[balsaman]

I didn't like it! You have to watch the corners when you cut it that they don't crumble off. It seems quite straight and sands ok. Very heavy, which is good I quess. I am happy with it so far, especially since it's painted now. You are right it looks better after paint. I am going to try and tap it as per your suggestion. I will let you know how it works. It seems too weak to tap, but who knows!

i screwed up already. didn't mount my linear bearings right. 9too far apart, which means less y axis travel) Remounting them but now i have extra holes.:(

Back to work.

Eric

[crankorgan]

balsaman,
Drill with a Number 25 bit and tap with a 10-24 tap. Tap the hole once. On holes that go in the ends make sure they are at least 1/2" deep. Use three per board. Two one inch in from the ends and one in the center. Don't over tighten!!!

Crankorgan

[Coder]

balsaman,

Are you building from a published/purchased plan or is it your own design?

[PanzyPoof]

balsaman ya great real pretty now I gotta go and paint mine:mad: Got some Pink left from my daughters room I did last week.;)
Those slides look smooth. Any worry about crap getting in the mount (screw Hole) and slide.
You could mount a paint brush and sweep the track?

[balsaman]

Are you building from a published/purchased plan or is it your own design?

Its my own design.

Those slides look smooth. Any worry about crap getting in the mount (screw Hole) and slide.

They are smooth. The slightly used linear bearings have seals/wipers on them to keep the dust out. I have the plastic caps that go in the screw holes to keep the dust out of those. Actually, I am a bit worried about the slides. Not about dust but with the wipers/seals, there is some drag. No play, but drag from the hard plastic wiper along the steel rail. Add up the drag from 4 and it's a bit to push the axis around. I am guessing 6-10 lbs force to move it around. Removing the wipers results in very little drag, but I dont really want to do that. My steppers are 100 oz. I will try it with the wipers first.

Eric

[balsaman]

Cranky,

I have a #7 drill and 1/4-20 tap. It's for the linear rails. I used glue/wood screws for the wooden structure....it's never coming apart! In modeling, we use thin CA to strengthen tapped holes in hardwood, then retap. I will try it without the CA for now. I can always go with a longer bolt and a nut/washer behind. Kinda ugly tho...lol

Eric

[balsaman]

Panzypoof,

Yours will be pretty too! Put a coat of that pink paint on it. The paint works wonders. Thanks for the inspiration to get me started on this project. I am having a blast! It's due to you starting this thread! Keep the good work up on yours. It's looking good. Post some pictures, and let us know how it's going.

Eric

[crankorgan]

balsaman,
If you tilt the machine 45 degrees will the axis slowly move? Also if you find the linear bearings bind, use two on one side and one on the other side in the middle. If that does not work, there is a guy on the net who sells plans that use gas pipe and roller blade bearings. :)

They sell hardware for building with MDF. Like you said, you can use a nut sitting in a hole.

Cranky

[balsaman]

Cranky,

It doesn't move at 45 degrees. They are tight because of the seals, not because they are binding. I made the rails straight. I loosened all the bolts, and its still tight, so its not binding. If it doesn't work, I will try again.;) I think it will work. I won't have the trouble of it missing steps because its not enough friction.:D If it's too tight, I can remove the seals on the inside under the mdf board. That would make 4 seals sliding instead of 8. the rail would still stay clean because the seals woukld wipe the rails where they are exposed. There are grease nipples on the bearings too. I am running them dry, as I figured thats better for now. I will see. It's fun to try stuff. I can always order plans from a guy on the net if it comes to that.:D I like to learn by trying. If that means making a mistake, or redoing something later, that's ok. You can say "told ya so" later, I don't mind.:p

Eric

[crankorgan]

Balsaman,
I like your attitude! You can also use two bearings on one side and let the second side ride on a rail with just a piece of Delrin as a glide. The linear bearings you are using are accurate to .001 or better. You will be amazed at how much torq your steppers will have, they should be able to move the table.


Cranky

[balsaman]

I put just a couple drops of oil on the rails on each side of the bearings to lube the seals. Much better! At 45 degrees it will slide all the way down if i give it a start. I am confident it will work (at least for a little while.) :D

On to x and z. It will be a couple days before I can get back at it. I am waiting for motors, controller, and my buddy at the shop to reduce the ends of my threaded rod. My x and z parts I want to make from aluminum plate, so I gotta start those too.

You give good advice cranky. Good of you to give it out for free.

Eric

[crankorgan]

Balsaman,
Glad to see it's sliding. I used to use a gram gage to measure how much force was needed to move a bed. Then I came up with the 45 degree test. Most CNC programs can ramp-up and down. This will over come the starting friction. Don't forget the leadscrew has mechanical advantage. It is in fact an inclined plane (ramp)(simple machine)cut into a rod.
No you see what I go through. I also have to design in some bad alignments and sloppy parts in order to simulate building by my customers. If you need any help just ask!


Cranky