Looking for CNC Mill Part I

[senna12625]

PanzyPoof...

I just went back to view your photo of your storefront aluminum. It lacks the circular slotted portions of the extrusion that I am using as one of the motor plate mount attach points. See drawing...

Senna

P.S. The drawing should really read... MOTOR PLATE SECONDARY MOUNTING HOLES...:D

[balsaman]

Senna,

Cool drawings. Don't plan the next till ya build the first!:D I like all the parts you posted. They are NIB! Mine were old and worn, but still great for a project like this.

Cranky I borrowed a dial indicator to check the depth thing. I am within .010 in the y direction and .020 in the x. The x is perfect on the ends but the MDF board sags .020 in the middle between the rails. Not sure what to do about it. I put another board over the base and programmed the zillion holes. I need to get the right bit and I will run the program. I may then shim the center .020 but will it sag some more? Maybe 20 thousands isn't worth worrying about?

Eric

[crankorgan]

balsaman,
No problem with the depth thing. I only brought it up so if you do some 3D work, you will know to shim the blank before you start. Only 1% of CNCers get as far as you have.
I like that large Cad_Cam conference! Thousands of members but you never see the good posts like the ones that are here with just a few members. Why is that?


John

[senna12625]

PanzyPoof...

Here's how I'm going to attach my motor mount end plates. I'll be using 1" aluminum angle pop riveted to the storefront extrusion. If the aluminum angle isn't capable of being tapped... I'll back it up with a lockwasher & nut. See drawing...

Senna

[senna12625]

Hey balsaman...

Good advice about not getting ahead of myself. It's just being laid up is exceedingly frustrating!!! :mad: With so much FREE time on my hands... you're seeing the result.

BTW... I went and looked again at your drawings posted back when... it surprised me just how similar the designs are!!! :( You may not believe it but my drawings were done completely ignorant of what you came up with!

Since discovering this group I am feeling a bit more engaged and enthused!!! :D

Senna

[balsaman]

BTW... I went and looked again at your drawings posted back when... it surprised me just how similar the designs are!!! You may not believe it but my drawings were done completely ignorant of what you came up with!

Great minds think alike!:D

I ended up with my x axis brindge strengthening gussets on the inside, to save space. My cnc is over twice the size of it's cutting area! Probably 3 times. Zoltar said a gantry style saves space. I believe him. My first design I drew up had a moving gantry just for that reason. I couldn't figure out how to move the gantry with one motor reliably. I didn't want it on one side. I ended up with the table moving in the y axis. People said (not on this thread) "You should move the cutter in all axis so the load is fixed" I am finding out the load doesn't affect the steppers at all. I could sit on the table and it would move fine. The steppers have lots of push.

I hope you are up and around soon. It looks like your "Brute" is well on the way, and it sounds like your itching to finish it.

Eric

[crankorgan]

balsaman,
The Pipe Dream is an inverted Gantry. By hanging the Y-Z axis it became easier to adjust. Only one drive screw. The Pipe Dream has the largest cutting area of my past designs. The new Scrappy was designed to cut deeper and faster. The Scrappy is larger than the Pipe Dream but I think the Pipe Dream will still have a larger cutting area. The MRI style is easier to build and adjust as you have learned.

John

[senna12625]

John (previously known as Cranky),

In reviewing pg 9 of the ‘BRUTE’ manual I noticed the COUPLER tubing dimensioned as 1-1/4” long X 5/16” ID. I have yet to acquire this tubing but now that I have this particular forum available... I’ll ask my question here before I actually spend the money.

If the plans call for 1/4-20 threaded rod for the LEADSCREW... how is a secure fit achieved with 5/16” ID tubing... tubing 1/16” larger in diameter than the LEADSCREW or motor shafts? Could it be 5/16” OD tubing? That to me would make more sense. You also have the RUBBER DISC dimensioned at 5/16” so maybe it’s not a mistake after all. Without actually having a piece of tubing to test fit... I’m having a difficult time believing a secure fit can be achieved as dimensioned... BUT what do I know! :confused:

Senna

[crankorgan]

senna12625,
Use 5/16" OD auto Vacuum line. You can use clear tubing if you want. Lots of people have built the Brute, you are the first to catch that typo. Should be 5/16" OD! I found if you degrease the motor shaft and screw with alcohol the rubber vacuum line really grabs. The rubber disc can be 1/4" in diameter since the two shafts inlarge the hole. You can leave the disc out with the vacuum line tubing. It is there to prevent the two shafts from touching and causing noise. With the vacuum line it is very hard to compress the trapped air and get the shafts to hit. Use auto vacuum line tubing.

Good Eyes!

Cranky John

[senna12625]

balsaman,

I agree!!! A fixed gantry does eat up more of the real estate! I also have played around with several movable gantry designs. My worry is that if MDF or MDO is used in construction... AND say a 30" X 40" cutting area is desired... we're talking quite a bit of mass in the Y-assembly itself... let alone having the Z-assembly coming along for the ride too! (Pun intended) :( (Tim the TOOL MAN Taylor would be grunting MORE POWER right about now!!!) :D

Baby steps... that'll have to be my mantra for awhile yet. A fixed gantry is just simpler to construct and probably less expensive. Maybe a moving gantry for the 3rd machine...!!! Yeah... that's the ticket...!!! :p

OK... enough with the pipe dreams... back to finishing the BRUTE! Soon I hope!!!

Senna

[crankorgan]

senna12625,
If you find your milled beds have too much resistance riding on the aluminum channel. Cut them in a "H"
shape where only the ends grip the channel. This will mimic my orignal concept. How easy do they slide now, with one finger pushing them?


Cranky

[senna12625]

Cranky John,

Thanks for the alcohol tip! Automotive vacuum line tubing it is then! 5/16" OD!!!

I hope it's a simple matter to edit your plan set. Possibly it's on the hard drive and you print plan sets on demand when orders come in. If not I guess changing out a number of pg 9's isn't that big a task! :D

Up until this thing with my foot ... I was having a GREAT time building your machine! :p

Senna

[crankorgan]

senna12625,
Most people change things. They use store bought couplers. Someone told me the clear tubing was stiffer. I tried it for awhile. I like the black rubber auto vacuum line. It sticks to the shafts like glue.

John

[senna12625]

Cranky,

It took me a minute to get your drift... but I understand completely! Since my milled beds have in effect full legnth GUIDEs... that entire contact area contributes to the total drag... correct? So your suggestion is to remove some of the center section... which does not contribute to 'guide' the bed along the channel... yet leaving GUIDE sized sections at the 4 corners. That's doable!!!

As everything stands... things are fitting EXTREMELY well... no slop at all in any of the 3 BEDs. VERY smooth sliding with low force along the channel rails. That's with everything dry... no oil as yet.

Thanks for thinking of me...

Senna

[PanzyPoof]

H cut.
Ok think I got it>see pic

[crankorgan]

Hi Gang,
An "H" like this.


Cranky John

[crankorgan]

Hi All,
Two years ago this Thankgiving the Brute design was born. I was at a repair job. When I got there the place was closed so I hung out at the glass shop next door. They were having a fight with the guy I was waiting for. He would not let them use his grinder. The next time I dropped by I gave the glass guys an old grinder I had. They then offered me any scrap aluminum I wanted. I looked over the shapes and commited them to memory. That night while laying in bed I realized the aluminum store front channel might make a great base for an axis. I spent Thankgiving morning building the new design, cooking pork chops and watching the parade. By the end of the parade there was a new cheap easy to build CNC design. This killed of my first machine! Six months of work, gone!

Cranky

[crankorgan]

PanzyPoof,
Your "H" design would be good if there was no dust. It is important to be able to keep the guides clean and don't forget a little oil!

Cranky John

[uscra112]

Senna - my sympathies - I've got a sinus condition so bad that I can't walk a straight line. Same deal, time on my hands but can't do anything.

Full-size gantry mills are almost always driven on both sides. The typical aerospace gantry has two complete servo systems slaved to one control channel. FAR too expensive for us, so I'm just using two lengths of threaded rod and cogbelt pulleys from the motor. I've got a size 34 stepper for that axis.

Cranky. - I've run across a really cool DC servo motor made by Kollmorgen - the U-Series ServoDisc. They were, according to my source, used in a lot of lens-turning machines that were in all those 1-hour eyeglass places, but are being replaced with something newer and therefor going up for auction on eBay for less the $50 USD typically. 400 in.oz peak torque and 40 oz.in. continuous. U9M4 model is designed for 24 vdc max. Gotta find a source of drive amps and feedback systems to use them.

[PanzyPoof]

Daa what was I thinking?
Ya Ok much better no dust under bed rails. Was thinking about that problem. Will do;)
Stock Gib, Will use existing Beds and modify.
Thanks Cranky!

Whow you guys have Made this into a 5 star thread. :D

[crankorgan]

PanzyPoof,
Things aiways heatup where I go! One guy called me a conversational cancer. Others say I was vaccinated with a phonograph needle. I just like sharing information! It causes others to think and join in! I caused one group to explode. Then someone complained because I was still using perf board and point to point wiring. I was try to explain how I learned how to lay out complex single sided circuit boards. Without me posting there everyday, the place is dead. Every post made causes someone to get a thought. In the end everyone benefits. I like to see how other people approach a problem. I have repaired vacuum cleaners to cockpit aircraft instrments. I have a set design mode based on things I have repaied. What works and what does not. This place is the TOP homemade CNC site on the internet! Lurkers enjoy!


Cranky John

[crankorgan]

uscra112,
I still did not run my steppers with 24volts! Servos are big money even for me. I would also like to make my own circuit.
Have you found a circuit for a servo system? I have a good "H" bridge that I am testing.

John

[uscra112]

John:

Thought maybe you had. I know how electrical servos work, at least in principle. You take AC and turn it to DC thru SCRs or FETs. By modulating the turn-on voltage of the SCRs you can modulate the DC current to the motor. If you're using FETs then you modulate the on-vs-off ratio.

It's generating the control signal to the output devices, be they SCRs or FETs, that's the problem for us. You have to have software that will decide every millisecond or so what signal to apply. This software is looking at the difference between the command position (as defined by the CNC axis-control program) and the feedback device on the axis, plus it is factoring in accel-decel rate limitations, current limits for the motors, and a whole bunch of other stuff. It can get very fierce, which makes these stepper systems look SO much more attractive for hobbyists.

[senna12625]

Cranky's 'H' mod suggestion is most certainly doable. It's on my 'things to do' list. It will reduce uneeded contact surface by about half!!! Substitute the word DRAG for 'uneeded contact surface' in the last sentence. I think I'll start off conserative with the cutout area and go from there. My BEDs slide VERY smoothly and freely as is but without anything to compare it to... the modification could only improve things.

Since I can't get out to the shop just yet to incorporate Cranky's 'H' Mod to the BEDs... I made the modification virtually... in Photoshop! :D

Senna

[uscra112]

Senna:

On top of which, if the drag is coming from contact near the middle, it is degrading the yaw control of the slide. The slide should be contacting ONLY near the corners. Do it for real !

[senna12625]

uscra112... balsaman...

Thanks eariler for your 'empathic' considerations regarding the foot.

uscra112... I hope your sinus problem clears up soon too! I hope you're not getting dizzy!!! I hate being dizzy!!! :(

I'll have to disassemble all three of the BEDs to make the 'H' modification but as you point out that material does nothing to contribute to the functionality of the machine... it just DRAGS it down! :D

I can actually get started on the disassembly now. This foot situation won't prevent me from turning a screwdriver. That should keep me busy for the next hour or so... then I'm back to bothering you guys!!! :D :D :D

Senna

[crankorgan]

uscra112,
You can get steppers to move a machine at 20" per minute. In order to cut that fast you need a spindle motor with power. There are plans out there for expensive machine already. I am hoping to come up with a design that crosses over from a hobby mill. Before moving to servos I want to come up with a machine that equals what a stepper will do very cheaply! Around $125.00 I am very close now!

Cranky

[uscra112]

Only advantage I can see for servos is higher thrust levels, which we don't need, extreme accel/decel rates and speed, which we also don't need, and closed position loops, which we would like but not at those prices. I know that closed-loop CAN be done with steppers, and I'd say tha's the way to go.

I just want an excuse to do something with this lovely Kollmorgen motor. I'd use it for a generator in a wind turbine, but I'd hate to think of it languishing out in the cold and rain.

[crankorgan]

uscra112,
I keep thinking cheap! I don't think I could own an expensive servo system unless I had a real use for it! A friend of mine is taking me to Home Dupa tomorrow to get a 4' X 8' piece of 3/4" MDF. Then I can finally mount and setup Scrappy! I was able to fit 2' X4' pieces of MDF in my neighbors caddy before he left for Florida. He wanted to rope a 4'x8' piece to his roof. The car is brand new! I did not need the stress. Another friend blew his trans on his truck. He just got it back today. What a year! Everbody is hurting one way or another. I got parts everywhere. I don't look forward to cutting more MDF. I hope the weather is nice, I will cut it outside.

John

[uscra112]

Right, John.

Better get that cutting done soon, snow ruins that stuff.

Won't Home Despot cut it for you on their big panel saw?

THAT'S what you need to build! A CNC panel saw but with a router instead! Imagine, 4x8 sheets cut into parts kits for your designs!

I once worked on a big industrial router that took 2 4x8s on the table at once. Know what they were making? Clipboards!

Try "finishing" MDF with linseed oil.

Makes it look a little like cheap Philippine mahogany.

If you squint.

[DICKEYBIRD]

Originally posted by crankorgan
Then I can finally mount and setup Scrappy!
Hey Cranky....Now that you're almost finished with your latest machine, you need to be thinking about your next one: "The Frugal Foamy" (or whatever) A cheap CNC foam wing cutting machine using easily obtainable parts that can be built by anyone....even me!:) :)

[crankorgan]

DICKEYBIRD,
I found a design on the net. The two mechanisms
clamp to any table. It's made out of nothing! Have you seen it?
I will locate it if you have not. One of the pics shows the guy carrying the assembly.

Cranky

[DICKEYBIRD]

Yup, is this the one? I've been loosely following these machines for a while now and they look very simple and frugal. In reading the posts about them here & there, I just can't convince myself that I can make the French control software work....I have enough problems with English!;) Now, if we could just get a software guru over here on our side to write up a cheap program that would control Dave Rigotti's 4 axis controller kit and also control the wire heat power supply; plus run on G-Code so our CAD drawn .dxf's could be converted easily....we'd be cuttin' some fabulous stuff!:D

Maybe Santa will bring it to me for Christmas, eh?

[senna12625]

DICKEYBIRD,

Try this address for an 'off the shelf', easy to construct CNC foam cutter.

www.8linx.com/cnc/cnc.htm

I've looked this design over several times and almost started building one. Wouldn't take much as almost everything is supposedly at Home Depot. I had trouble locating the square steel table legs and the Simpson post flange. The machine uses a 6" size and my local HD only had the 4". That's the only reason I didn't start my CNC adventures with a foam cutter.

Senna

[crankorgan]

DickeyBird,

Here are a few foam cutter.


http://www.teaser.fr/~abrea/cncnet/table/tables.phtml


Cranky

[crankorgan]

DickeyBird,
Here are the plans I was talking about. In PDF format
no less.

http://gm.cnc.free.fr/gilles.muller10/CNC/rusticaplan_v6_en.pdf


It is very hard to compete in a saturated field. I try not to re-invent the wheel. Software seems to be the big problem in CNC. Three program are needed just to cut out a circle. Hopefully it will change. I suspect that French software is very good judging by how many people built a machine.

John

[Tree_Magnet]

Wahooo the cnc foam cutter works now all i have to do is build me a table and start cut N.

Tom

[PanzyPoof]

Tree_Magnet
Congrats :cool: Luts have a look.
And tell us about it.

[balsaman]

Tree magnet thats great news! Let's see the pictures!

I bought a rotozip. The biggest one I could find. It's 5 amps, two speed. I didn't like any of the trim routers that are available in my town. The rotozip takes a 1/8" and 1/4" collet. It's noisy! Here is a pic of it drilling the 325 holes for blind nuts. It's busy drilling as I type this. The drill program is the first I have run on turbocnc. I am getting used to the software. I almost like it now! I run faster with more confidence in DOS. The drill program is running at 10 inches a minute. It will still take over an hour. The tape is because I mounted the rotozip, then I was worried the thing would vibrate out, so I taped it while the program was running for insurance.:o I will make an extra mount for it before long.

Eric

P.S. You guys sure post a lot while I am at work!

[crankorgan]

balsaman,
Did you draw a dot in each location on your DXF and then use the drill cycle command. It might be nice to explain how you came up with a GCode to drill your holes.

Cranky

[senna12625]

balsaman,

At least you used 'PRETTY' red tape instead of that drab gray stuff!!! :D

I see what looks to be a PC power supply and aluminum housed power resistors at the extreme left of your last pic. What's the voltage and amp ratings on your steppers? What are you running for stepper voltage and what are the resistors rated at? I assume you're over voltaging your steppers and dropping back the current with the resistors. I'm assuming UNIPOLAR steppers...did you wire for full coil or half winding? I'm also impressed with that BIG RED Emergency Stop Button!!! Handy location!

Seems you've taken to this CNC stuff like a duck to water...! Keep up the GREAAAAT work!

Senna

[balsaman]

Originally posted by crankorgan
balsaman,
Did you draw a dot in each location on your DXF and then use the drill cycle command. It might be nice to explain how you came up with a GCode to drill your holes.

Cranky

Cranky,

I drew a point in autocad at 0,0 then used the array command to put the point every inch from 0,0 out to 12, 24, so there ended up a point every square inch. I used ace to convert it to gcode. I don't think it used a drill command, it just moved the z down an inch at every point. I ran the cutter .25 over the board. It took 2h 40m to complete! When it was all done i sent the cutter back to zero zero and it ended up right over the hole! I was happy.

Senna,

I am using 12 volts to run the steppers with a 2.5 ohm resistor. Unipolar yes. One resistor for each motor. It was the recommended setup from the guy who sold me the controller and motors. www.stepperworld.com

I have used the estop already..lol. Then I figured out the esc key works better. Still, the estop is the safest. It shuts the powersupply down.

I will post some more pics later.

Eric

[crankorgan]

balsaman,
Good worK. I only know how make a dot at each location and then set the depth. This causes each hole to be drilled. I then edit the GCode with a slower feedrate for each hole. I have also programed pecking line by line. CNCPro has G80-G81-G83 for drilling. You can set it so it does pecking. I have never played with the command. Most of my crashes have been during drilling.

Got my MDF today! A buddy drove me over to get it. He
has roof racks. Took the two of us to lift the 4' x 8' onto the dolly in the store. I had the guy cut the board in half. I gives me two pieces to chose from. Home Dupa! had the MDF in the molding and shelf section!!! One Dupa was out of MDF when I was there the other day so I went to the second store. Let the snow come!


Crank

[balsaman]

John,

Build away. Can't wait to see the scrappy go! Are you using 1/4-20 rod again? 12 V supply?

Hey I have a question. I convert with Ace, then use find and replace to fix my z axis travel etc. The problem I am having is what sets the feed rate? With turbocnc it seems to go at the fastest speed the cnc is set for in the setup? I want to set the table up for max speed and use the gcode to set the feed rate. Is it F10 to set the feed rate to 10 inches per minute? If so where does it go? At the beginning of the code? Also, with turbocnc it says you can adjust the feed rate on the fly with the < and > keys, but the feed rate stays the same when I have tried it. Oh and that reminds me, don't try and cut metal at 10 inches per minute. You are correct John, you find out there is slop in the system when you cut metal. The machine flexes.

Thanks!

Eric

Here is a pic of a plaque I made for a friend from that laminated plastic for labels etc.

[senna12625]

balsaman,

The reason I was asking about your steppers rated voltage and amperage, the power supply voltage and the resistors is that I have a couple of equations that I wanted to confirm as valid for sizing power resistors in an over voltaging situation. I figured I could plug in your values and see if the guys at STEPPERWORLD, knowing a LOT more than I about this stuff, sized the supplied resistors in your package according to these equations.

Maybe I'll just post the equations up and see if brighter minds on this thread can validate them...

Sizing... volts supplied - motor volts / motor amps = resistor ohms

Dissipation... motor amps^2 * ohms = watts

Example:
Sizing... 12 V - 1.7 V / 2.4 A = 4.29 ohms
Dissipation... 2.4 A ^2 * 4.29 = 24.7 watts

In the above example if I was over voltaging my 1.7 volt, 2.4 amp steppers with 12 volts I would require a current limiting power resistor of 4.29 ohms at 24.7 watts. Is this correct?

Senna

[crankorgan]

Balsaman,
You start the GCode with lets say a F8 for eight inches per minute. A G00 in the code makes the machine run rapids at the machines fastest speed. Using your FIND REPLACE you can change G1 Z-1.5 to G1 Z-1.5 F4 But then you have to change G1 Z1.5 to G! Z1.5 F8 That slows the plunge cut to
to four inches a minute. Then you have to reset the machine bach to F8.

Crank

[balsaman]

G1 Z-1.5 F4 would change all the G1 moves to 4" per min or just the z moves? I want my g1's (tool down cut speed) to all be at let say 4 inches and my g0's (tool up, rapid) to be at 18 inches per minute (max speed set in Turbocnc)

Maybe I should just try it.

I will be back

Eric

[balsaman]

Senna,

if the steppers are 1.7 volt 2.4 amps the the windings are 1.7/2.4=0.7 ohms

2.4 amps at 12 volts =5 ohms total

your resistors should be 5 - 0.7=4.3 ohms

watts = amps squared x resistance

2.4 x 2.4 x 4.3 = ~25 watts

Yep, you had it right, if you are using a controller with FET's. If not, I beleive you use 11 volts as the voltlage from a 12 volt supply.

I want to try a 24 volt supply some time. I need 10 ohm resistors @50 watts......I need speed! Plus, I will be able to fry an egg!


Eric

[balsaman]

Ok,

From what I can tell the F command changes the feed rate in any G1 command untill its changed again.

So. If you put a F8 in the first G1 line of code, it will do all the cutting at 8 inches a minute for the rest of the job. The G0 or rapid travel will still be at the software max setting.

Hey i see that if you put the drawing in autocad at a z axis of -1 (or whatever depth you cut) you don't have to fix the g-code after you convert. It's already at -1 for the cut depth. I do see however that for some reason ace puts the z at 3" for tool up position. I set it so tool up is at 0 and cut is at - 1 (or whatever). I just chage my Z3.000 to Z0.0000.

So much learning my brain hurts!

Eric

[crankorgan]

balsaman,

(cut box)


G01 Z-1.5 F4 (Plunge cut)
G01 X1 F8 (start of box)
G01 Y1
G01 X-1
G01 Y-1
G01 Z1.5 (end of cutting)

(drill holes)

G01 X1 F8 (move right one inch)
G01 Z-1.5 F4 (Drill hole)
G01 Z1.5 F8 (move out of the hole and restore speed)
G01 X1 (move to next hole)
G01 Z-1.5 F4 (Drill hole)
G01 Z1.5 F8 (move out of hole)

Some DXF to GCode converters let you define the Z rate. The Feedrates are put in during conversion. I like to edit my
GCodes using KCam or Notepad.

John

[senna12625]

balsaman,

Thanks for the confirmation on the math...! I'm having to go waaaay baaaack in the memory department... to high school shop class for what little I know about electronics! Over 30 something years...! It's comforting to know that at least some of that stuff is still rattling around up there! :p

What did you finally opt for with regard to the controller from Stepperworld... the SP-3 or the higher current FET3? I see they have a 4-axis board now too! I'm planning on the FET3 board for my second machine. I'm going to get one of Cranky's PIKER boards and populate it myself for the BRUTE machine controller. A bit more educational doing it that way. Easier on the wallet too. Of course that's assuming I get it right and not fry too many things in the process! :D

OK... the Estop is less desirable because you lose your place... whereas the Pause is resumable...???

Senna

[balsaman]

I got the FET3. My motors are 5.2 V, 1.4 A and I am running them at 1.8A. The FET's were not even warm after the 2h40m drilling job they did. The motors and resistors were toasty:D I could still hold the motors so I was not worried (much).

The e-stop stops the machine, the software has no idea, so it just counts away. It messes up my 0, 0, 0, since I don't use switches. I bought some switches, and I will install them soon. I got them at Princess Auto for $1.00 each. I picked up 10. 6 for over travel, 3 for home, one for spillage. :D

The esc key stops the process. I don't think it's resumable, unless I just have not figured out how in TurboCNC, but you can just send it home and start again from there.

Eric

[crankorgan]

balsaman,
Cutting balsa only requires one feedrate like F8 at the beginning of the GCode. G00 will be the top speed of the machine for moves between cuts. Cutting other materials like plexi-glass require a slower Z speed. (plunge) A four fluted milling bit can be plunged 1/3 its diameter at a time. You must allow the chips to get out! You can tell by ear after awhile. I like milling PVC parts! Some Plexi is nice also. Engraving is done with a special bit. Look up engraving bit to see what they look like.

John

[crankorgan]

balsaman,
Take the lever off those micro-switches. Just use the buttons of the micro switch.


John

[balsaman]

Cranky,

Yes, I will remove the lever.

I made my own engraver bit from a peice of 1/8 hardened dowel pin ground as shown. I used it on the JANSSEN's sign. It melted the plastic a bit... I think my rotozip's too fast. I will look to see what they are supposed to look like on the web.

Eric

[senna12625]

balsaman,

How about an aftermarket router speed control to get variable speed on that RotoZip?

www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/speedcon.html

Senna

[crankorgan]

Balsaman,
Go to this website, click on Drill to Cutter, bottom lefthand side.

http://home.hccnet.nl/m.de.roode/


John

[crankorgan]

senna12625,
Those controllers work great! I wish they made a noise reducer. The Porter Cable trim router I bought is a little louder than the Dremel with lots more power. I can see I will need a speed reducer. I don't know if my Motorman can handle the Porter Cable.

John

[balsaman]

I was thinking of using something like that speed control. I will look into it. My rotozip has two speeds, but the slowest is 25, 000 rpm:rolleyes: .

Eric

Cranky, thanks for the cutter link.

[uscra112]

Rule for E-Stop in the real world ( i.e. OSHA ) is that it must cause all systems to go to a zero energy state. It's a good rule. E-Stop is what you hit when something's going wrong but you don't know what it is. Therefor you stop everything. We also have a "cycle stop" button that just stops the axis motions, and you can restart motion by hitting "cycle start" or "continue". But if the workpiece has come loose on the table, or a spindle running at 20,000 RPM is coming apart, or you've cut into a clamp and it's about to throw parts at you, you want an E-Stop. Balsaman has done the right thing.

[senna12625]

Absolutely no question about an estop being the right thing. Balsaman's BIG RED ESTOP is not only placed in a good location... it's ergonomically angled to boot!!! :D

Senna

[crankorgan]

Hi Gang,
I cut the MDF base, painted it and mounted the rails. Now I will cleanup before putting it to gether. Can't wait to see what does not work!!!

John

[senna12625]

Hey Cranky,

I just read the post about you picking up the MDF at HD yesterday... and now it's not only assembled... it's painted too!!! Amazing!!! :confused: I'm betting the paint wasn't even dry when you took the picture! :D

One questioning observation... with how wide the spacing is between the Y and X shafts (pipes)... it contributes a mechanical advantage to prevent a tendency for the traveling assembly to rack the further the cut moves from the geographic center??? I try to see reasoning behind design... and learn from it.

Scrappy looks GREAT!!!

Senna

[crankorgan]

senna12625,
The trolley is half the size of the length of the rails. So if the trolley were one foot square with wheels in each coner the rails would be one foot apart and two foot long. Since Scrappy is designed to cut out lawn toys and wooden signs I don't think I have a problem with racking. Scrappy's trolley is 15" X 25" the same ratio as the 7th Sojourn. The machine can be made longer. I limited the size because I can't handle a larger machine by myself. I always worry about the Z axis because it overhangs. I test the design by flexing the cutting bit with my hand. I work back from the cutting bit. If the cutting bit only needs to be stiff enough to apply 10 pounds of pressure. Why design a machine with 100 pounds of pressure with no flex? I expect some problems! I know the gas pipe and roller blade bearings work. This design uses my new adjusting blocks. Rather than just update one of my machines with them, I move foward. The gas pipes and flanges take a little more time to setup but you don't have to make them. The adjustment blocks have to be made. Scrappy is almost 100% hardware store.

John

[balsaman]

I like the scrappy John! It will work great!

Eric

[crankorgan]

balsaman,
I think 30" X 40" is the largest base MDF can handle without flexing too much. I used a stong set of legs I had with a top. Took awhile to find a level spot on the cellar floor.

John

[PanzyPoof]

Cranky that was Scarry Quick;)
My Beds are off getting Milled should be at it again Monday, Guess I own Rudi a Beer:D
I gotta get me a proper Mill/Lathe one of these Days this is nice http://www.busybeetools.com/pictures/b2229.jpg

[crankorgan]

PanzyPoof,
I only needed the base board. One of my neighbors drove me last month in his caddy to buy some 2' X 4'. Up until now I have been building machine with 2' X 4' pieces. In order to go 30" X 40" I had to buy a 4' X 8' piece. Heavy! Heavy! I have all the parts for Scrappy done! I have most of the drawings done for the booklet. Building a machine is easy, doing the booklet takes hours. Some drawings take 8 hours each.

John

[senna12625]

I'm chomping at the bit to get back out to the shop... but that won't be for a while yet. Plan B involves spending a lot of time on the computer... usually drawing. So I drew the 'H' mod as suggested by Cranky... the designer of the BRUTE machine I'm building. I think PanzyPoof said something about incorporating this idea into his machine... the 7th SOJOURN.

I also finally figured out how to get my 'avatar' pic going. I'm a nut for sci-fi so some of you may recognize him... a great character from my favorite show!

Senna

[uscra112]

Racking ( skewing, yawing ) will not be a big problem with John's Scrappy because he's got the drive screw centered. Drive device wants to be on line with the combined drag forces and cutting forces opposing it. That's why gantries really have to be driven on both sides. Only workaround if you are forced to have the drive offset from the load is to have a VERY high aspect ratio to the bearing area on the way that does the yaw control.

[crankorgan]

uscra112,
Now I only have to worry if the Z axis from the Morph design will handle the trim router. I got the subassemblies build. I just need one good day to put it together. This is like running a marathon, you have to do the whole thing just to see how it ends up!

John

[crankorgan]

Hi Gang,
The first time I used rollerblade bearings I paid $32 for two tubes (16pcs). Then I bought 16pcs for $24 and the bearings were better. Then I bought 16pcs for $12. The blister
package was cloudy with grease or something coming out from the bearings. I thought no big deaL The bearings are rusting away as you read this. Three possibilities.

1. The package of bearings got wet!

2. Somebody used them in the rain and then returned them.

3. The lube in the bearings is for something else!


John

[uscra112]

John, you are the kind of guy who makes innovation go. I once had an engineer from a big European machine tool company whom we represented in our shop, looking at a major modification we'd done to one of his machines. He was envious - he said he'd been trying for years to get the bureaucracy in his company do do what we'd just done in a month. We had just MADE one to see if it would work. It did. If it hadn't, we'd blown 20 grand, but "engineering" the thing would have cost 50 grand, so who's right? I love an anecdote from Tom Peters' book. He wrote about how they had tried to find out what companies could do to stimulate innovation. They learned that it mattered not how much money was spent, or how many people were assigned, or what the professional qualificiations of the people were, or what kind of facilities were built, etc, etc. The ONLY thing they could correlate to successful innovation was HOW MANY DIFFERENT THINGS WERE TRIED. Keep it up.

[uscra112]

John - Rollerblade bearings are undoubtedly sourced in the cheapest places possible. They may have been packaged in very humid conditions, or the grease used was acidic, or both. For instance, if they had an electroplating setup nearby, there could be acid vapors in the air that got into the grease or onto the parts before they were greased. I once saw a set of forgings for Airbus landing gears ruined by exactly this. In less than an hour they accumulated a uniform coating of rust. They were a high-carbon steel so they could be heat treated, and I still think they should have been scrapped for potential hydrogen embrittlement, but the shop owner cleaned 'em off and machined 'em anyway.

I've gotta get you to try out the poured-epoxy bearing idea sometime. You need pretty smooth guide rails and good alignment, but it sure would be cheap!

[rdablo]

Do any of the software packages handle a 4th bank axis on the tool mount? I'd like to use this to do undercuts. This animation illustrates what I mean:Table with 4th Axis (http://www.mindraster.com/mockup.gif)

[crankorgan]

rdablo,
Get out your wallet. You may find 4th axis controller software like CNCPro or TurboCNC. Wait till you buy the CAD
program that does 4th axis. Most people use a forth axis with their 3 axis machine. The Z and the X are used. The Y is disconnected and used to drive the 4th axis. See animation on my
opening screen.

www.crankorgan.com/


Cranky

[uscra112]

rdablo:

My browser chokes on your animation. Can't see it.

4th axis as in twist or tilt of the spindle thru, say 25 degrees? That's going to be hard to build on our budgets. I've been involved with quite a few full-scale 4 and 5-axis profilers like that. They're monsters.

Or do you want to do a full circle of rotation?

4 axis machining centers are usually built around a horizontal spindle axis, with a rotary table in front. Up/down and in/out motions (Y and Z axes) are under the spindle, and the left-right (X-axis) is under the table.

You can use a right-angle attachment on a vertical spindle mill to make the cutter axis horizontal, and add a rotary table, but rigidity is a problem. Your parts have to be more or less cube-shaped, not long and skinny, and fixturing gets a lot more complicated.

Lastly, if you have long skinny parts, you fixture them in an indexer whose axis is horizontal, and use a normal 3-axis vertical-spindle machine. But that config doesn't do cube-shaped parts as well.

[rdablo]

Sorry about the GIF being not working. Any smaller and the detail would be lost.

I wanted up to a 90 degree undercut for edges so I was just going to make a rotating bracket for the tool holder around the Z-axis.

[PanzyPoof]

senna
Ya I having the Hmod done for me No Mill:mad:
Changed one thing , Bed is not milled completely threw. H section is dropped 2 thou.
Same effect more Bed backbone.

[senna12625]

PanzyPoof,

Ahhhh. I get it. Instead of entirely cutting out the unecessary section of the BED that contacts the aluminum channel... you're just relieving the area by .002. Thus you acheive the desired reduction in friction and maintain the full BED outline. That's elegant! Less machining! It's a keeper! :D

That means I get to edit & repost my drawing... :D :D :D


Senna

[balsaman]

I am starting to figure this software out. I see that with Ace you can set the max cut depth, z offset etc. It's handier than I thought. I put the feed rate in the pre priority code and it's working fine. For some reason sometimes Ace puts circles (G03) commands in there for no reason. If I remove them all is well.....:rolleyes:

Also i am getting better at Turbocnc too. I need to install the home switchese on of these days.

I will have to cut an airplane part sometime....:D You were right Dickeybird, whole new hobby.

Panzypoof, I like your idea about relieving the trolley instead of the H mod, but I would go maybe 20 thou or even 30. I think 2 thou is just enough to jet junk in there and hard to clean out.

Eric

[crankorgan]

Originally posted by balsaman

Panzypoof, I like your idea about relieving the trolley instead of the H mod, but I would go maybe 20 thou or even 30. I think 2 thou is just enough to jet junk in there and hard to clean out.

Eric

balsaman,
I was going to say something about this! But this is how people learn. The "H" mod fixed six problems at once. It left two problems. 1.No future adjustments avalible if the part wears. 2.Part can not be made with hand tools.

There are eight reasons why I designed the beds and Guides the way I did. The two top reasons. 1 The aluminum channel varies from batch to batch. My design lets you make the necessary adjustments. 2. Parts can be made with hand tools.

John

[senna12625]

Cranky,

I'm learning! My decision to mill the underside of my Brute BEDS wasn't given a sufficient amount of thought it appears. :( I felt that with the 1/2" thickness of the UHMW plastic... milling a double step bearing surface to accept exactly the storefront channel profile would eliminate ANY possibility of skewing. I now see that with one simple design change a whole host of ramifications have manifested.

1. Increased contact area creates more drag. (Hence your suggestion for the 'H' mod) So instead of simplifying the BED construction... I've made it more complex which requires more complex machining!

2. No GUIDE adjustability for wear. I could retrofit guides when wear problems dictate. This doesn't eliminate the effort to make the adjustable guides... just postpones it!

3. No limit switch PLUNGER. Will have to make stand alone units for all 3 BEDS rather than the integral GUIDE/PLUNGER as designed.

I said eariler in a post that I attempt to see the 'WHY' of design and learn from it. I guess MORE SCHOOLING is needed in my case...!!! :p

I think I'll finish the BRUTE 'as designed' and hopefully learn something I can carry forward for my second machine.

Senna

[balsaman]

I am having a problem with turbocnc. Here are the balsa blanks of a former I cut out for my giles airplane I am designing/building. These two parts were cut from the SAME g-code. On the left, turbocnc, on the right, kcam3. The one on the right is the correct part. I used Kcam to do the converting.

Now the funny part is I tried using Ace to convert the DXF file and when I displayed the part in Kcam, it looked like the part on the left!(wrong shape) I wonder if I used that g-code in turbo, I would have the correct part? Cranky can you explain it? Is there a bug in turbocnc?

Thanks!

Eric

[balsaman]

I forgot the image.

[crankorgan]

senna12625,
The Bute is a newer design of PCBMill which came from NCF2002 which came from NCF2001 which came from NCF2000. So as you can see, lots of work went into the design.
Next week the use of store front aluminum will be two years old.
My suggestion to you is build one axis first. Then keep it as a testbed. That's how I did it. I built over eight versions of the Brute before I was happy with it.
I also considered temperature in my design. Simple designs can be very deceiving.

John

[crankorgan]

balsaman,
KCam won't do G03 but it does the rest. I always draw my tool paths in a counter clockwise direction so KCam won't choke. I found ACE will remove extra moves but it has other problems. I use KCam to view my GCodes before I run them. The FLASHCUT DEMO will not run the motors, but it will convert DXF to GCODE and display it.

John

[balsaman]

Cranky,

I used kcam to view the tool path and it was fine. I then sent the file to the garage and cut it with turbo. The part on the left is what came out. Kcam was displaying the part on the right. Same gcode! So I fired up windows and used kcam to cut, and I got the part on the right. Same gcode....but now a good part. Very strange.

I do see that ace has some issues. I will try Flashcut demo. Even so...I think that turbo has some issues too. Now I can't trust it with a large project.

Eric

[crankorgan]

balsaman,
I found a bug in CNCPro. It would not do the loop feature. I wanted to run my machine for 1000 cycles and then check for wear. I spent two days trying to figure it out. I sent Doug the GCODE. Then he gave me a new version with a fix. All software has bugs!!! That's why I did not like it when the mob started attacking CNCPro in the CNCPro conference. People who did not own CNCPro were attacking it. They were recommending a different program.
They are all using that Windows CNC program. It has bugs too! and the price is about to go up. CNCPro was $85 at one time. Now that it works great the price went up. TurboCNC is worth alot more than it costs. All software has bugs!!!

The trick is to use Wordpad to check for code you know your software will choke on.

John

[crankorgan]

senna12625,
One of the companies that makes the aluminum channel also makes a plastic inset. One day I got very excited when I saw it. No machining! Just cut it! See Pic!




John

[crankorgan]

balsaman,
Try ACE again! I remember it asking a question about direction of circles. Reverse that option. Check it with KCam.....
I tried to get the guy who sells KCam to just come out with a DXF to GCode converter-plotter for $40.

John

[PanzyPoof]

Cranky that Plastic insert looks like kinda wimpy!
Made to be snapped into place with a mallet.
Maybe if you Beefed it's backbone up by bolting a bed to it?hmmm.
Mods are fun if you have access to proper tools.
And enjoy thinking along the edge.
I did build the beds as per plan and for the Average builder with little tools at hand there fine.
Anouther could do MOD is add a grease nipple to the gap area of the H mod. Keep out the Dirt/lube.
:confused: Ya overkill:cool:

[crankorgan]

PanzyPoof
I WAS excited by the insert. Then I did some testing. I only showed the insert so people can see what roads I have gone down. What kills any insert is every batch of channel is a little different. Once I realized that, I went to an adjustable design.

John

[balsaman]

Well, It seems that g02 and g03 dont work on turbocnc or cncpro for me. Both programs make a funny triangle where a semi circle is supposed to be. It must be my machine or my port setup or ?. Kcam makes the arcs just fine. I am confused. I guess I better email the guy at DAK engineering. I looked at the turbocnc yahoo group with no answers. Turbocnc makes the g01 and g02 commands perfectly. Very odd.

I will let you know.

Eric

[crankorgan]

balsaman,
You mean G02 or G03. I always use capital letters. That might be your problem? You will find the problem if you stick it out. With KCam you can step through the code one line at a time. This is how I find the bugs.

John

[DICKEYBIRD]

Hi guys, been on vacation and away from internet access at work....came in early before shop opening time for a fix! Great posts!

I built a new set of wings for my "Smallest Airplane" entry in the RCU 1/2A forum and cut the ribs & tip plates via CNC. I tried the method mentioned by Cranky of leaving a little uncut spot every few inches to keep the part attached to the sheet. It worked great!

Here's a pic of the "Nano Bipe" 7 5/8" span, 2 channels, Cox TD .010...4 ounces total. Still working on some flight trim issues....a real HANDFUL to say the least.

See ya'll on Wed when I'm back officially!

[crankorgan]

Hi Gang,
In KCam there are three levels for the Z axis. Travel depth-Cutting Depth-Max cutting depth. If you set these first, any DXF that gets imported into KCam is automatically set. The
travel lines are BLUE and the cutting lines are RED. Then all you have to do is offset the GCode and add in feedrates at the top of the GCode.

John

[mynameisAARON]

Hi Gang,

Just finished reading ALL 496 replies to this post:D
only took me 6 hour's saving all the links:rolleyes:

Very Very interesting
thanks, i feel like I just read a book:D

I WILL build one , have to wait after x-mas though
:rolleyes:

Aaron

[balsaman]

Hi all.

Dickeybird thats a funny airplane! Kinda cute. Roll rates are fast huh?

Cranky I am sorry my posts are not clear. I am typing too fast! Lots of typo's. The G01 and G00 are fine, its the G02, and G03 that are trouble. Kcam works fine. Turbocnc and CNCpro make the same bad part! It must be the setup, but I don't know why it cuts the straight lines right. I emailed the guy at DAC engineering, and he is helping me. He asked for the gcode. He says some other customers have had this, but the gcode always works at his house. He is not sure what the trouble is. All I need is a work around for now. I will let you all know.

Eric

[balsaman]

Aaron,

Make one. It's fun! I love mine.

I brought the rotozip back to the store. It was two speeds, but the slow speed broke already. I exchanged it for a small plunge router. Its variable speed, from 10,000 to 30,000. The 10,000 is much quieter! It was also on sale, half the price of the rotozip. I need to mount it to the z axis. That wont be easy. It's an awkward shape, and I need to mount it at 45* angle to make it fit or it will interfere with the gussets that hold up the x axis bridge. I will draw up the parts, and cut them from MDF with my dremel in the CNC. (if I can get the radius's to work).

Check back and see later, now I am going to a rc club meeting.

Eric