Looking for CNC Mill Part I

[crankorgan]

balsaman,
The cut looks like it is getting the X and Y value without the radius part of the circle. When I tried to get KCam to do a clockwise cut I had the same problem as you. But KCam does ok with G02. Put the Gcode in DeskNC and Flashcut and do a plot. Stick with it! Remember, very few people get as far as you have! Lots of things are being sold that don't work correctly.
Just like Windoze!

John

[crankorgan]

balsaman,
Now you know why I kept the Dremel Multipro over the RotoZip. Several times I contacted Dremel for info about the MultiPro. I asked them about their RotoZip model and I got no info. The Dremel MultiPro has been around a long time. The RotoZip needs some more time out there. I hope the Porter Cable I bought for $99 can cut the mustard and wood also.

John

[balsaman]

Ok this is getting silly. DeskNC also makes the wrong part! Only kcam makes the right part.

Cranky, here is the Gcode:

F10
G00 Z0.000000
G00 X0.500000 Y0.500000
G01 Z-0.500000
G01 X5.105000 Y0.500000 Z-0.500000
G01 X5.105000 Y2.625000 Z-0.500000
G01 X3.446977 Y2.625000 Z-0.500000
G02 X2.158024 Y2.625000 I2.802500 J2.562500
G01 X0.500000 Y2.625000 Z-0.500000
G01 X0.500000 Y0.500000 Z-0.500000
G00 Z0.000000


The G02 line is supposed to make a cw semicircle. It makes an ugly triangle on Turbocnc, Desknc, and CNCPro. Whats wrong with the Gcode?

Maybe I should get off this part and try another from scratch. I will do that tommorow

Eric

[crankorgan]

balsaman,
A circle is made from FOUR lines of code. One for each quadrant. I think the math is called J POLAR

This makes a one inch circle. Each quarter is a 1/4" arc.
Somehow you came up with a way to make a half circle, BUT
some programs want the circle in four parts. KCam chokes on
G2 I thought I remembered G3.


G3 X-.25 Y.25 I-.25 J0.
G3 X-.25 Y-.25 I0. J-.25
G3 X.25 Y-.25 I.25 J0.
G3 X.25 Y.25 I0. J.25


John

[crankorgan]

balsaman,
Did you hardcode that GCode or did it come from a DXF to GCode conversion? If you got it from a DXF, try drawing the Half-Circle as two 1/4 arcs.

John

[balsaman]

I will try that John.

Thanks

Eric

[balsaman]

Here is the new gcode. Two half circles. I drew it up in Acad and converted it with Ace. Looks ok in kcam, I am going upstairs to "dry run" it.

F10
G00 Z0.000000
G00 X0.500000 Y0.500000
G01 Z-0.500000
G01 X5.105000 Y0.500000 Z-0.500000
G01 X5.105000 Y2.625000 Z-0.500000
G01 X3.446977 Y2.625000 Z-0.500000
G02 X2.802500 Y1.915000 I2.802500 J2.562500
G02 X2.158024 Y2.625000 I2.802500 J2.562500
G01 X0.500000 Y2.625000 Z-0.500000
G01 X0.500000 Y0.500000 Z-0.500000
G00 Z0.000000

Eric

[balsaman]

Nope, thats worse. Goes way off the table now.:mad:

Eric

[cbosch_us]

Check out the Dremel Advantage Rotary Saw tool. It is Dremel's competion to the RotoZip tool. I bought one a few months ago for the CNC router I'm planning to build as soon as time allows. As far as power, noise and speed is concerned, I can't comment how it compares to others. The Dremel does have a full variable speed control built in and the handle is readily removable leaving a feature that I think will enable designing a suitable mount for CNC use. I'm sure the smaller Dremel is adequate, but was thinking the larger, Zip sized tool may have an better front end bearing, considering it's intended use.

Just checked Dremel's web site and the Advantage tool speed control range is 10,000 to 35,000 rpm. I made a drawing of this tool in AutoCad, but it must be on my work computer as I can't locate it now. If anyone want's it, I post it.

Rgds,
--Colin--

[balsaman]

I fixed it! It was me all along! As if you guys didn't know that:rolleyes: . In Ace, ya gotta leave those checkmarks in there or it breaks the Gcode! I put them back in and all was fine!

Man am I dumb. At least all is well now.

cboshus,

I looked at that Dremel tool. I did like the variable speed. I would have bought it if it came with a 1/4" collet. I will try my new router first.

Eric

[cbosch_us]

balsaman,

Dremel has a 1/4 inch collet available as an accessory item. I bought one since I have some other router bits and thought I might need the collet eventually. It's a nice mini-router, but I can't say how well it will work for CNC application.

Good luck with your settup. Sounds like you are making great progress and your machine looks great!

Rgds,
--Colin--

[senna12625]

I too am looking at what's available. The Dremel Advantage does look nice. It has a 1/4" collet capacity... but comes standard with the 1/8" collet.

Senna

[balsaman]

I bought this one. Removed the handles and base. 7 Amp, 9,000 to 27,000 rpm, 1.25 HP. 1/4" collet. I need to buy a 1/8" collet now.:rolleyes:

Eric

[senna12625]

Uh-Oh Balsaman...! Performance creep!!! :D Tim the Toolman Taylor would be grunting and shounting 'MORE POWER' after seeing that new router!!! :p

Next thing you'll be telling us is that those WIMPY steppers you have NEED replacing and you're high bidder for some 250 oz in BIG MOTHERS on ebay!!! :D

I look forward to your reporting on the MDF cutting for the tool holder to contain that NEW toy!!! Pictures would be nice too!

Speaking of pictures... I'm a Mac user... and surfing the web for a Mac OS based CAM program (few and FAR between) I came across Seagull Technologies run by a fellow by the name of Neil Gillies. Anyway... here's his MDF machine... (see pic). Pictures always inspire me!

Senna

[balsaman]

I mounted the router. It ended up fitting the best mounted 90*. It's heavy! I had to slow the z travel a tad so it would lift without missing steps. Its now at 10" per minute. I was at 12" with the rotozip. My other two axis are up to 20" per minute after I retapped the delrin. Still no noticeable slop. I may put some counterbalance springs on the Z to help with the weight. It's going to work well I think. I ended up making the mount from aluminum. Just one clamp on the bottom. Seems pretty sturdy. I will try some balsa plane parts tonight.

I registered TurboCNC. I was impressed with the support I got via email. Version 4 beta will be out next week. It looks very good. I DLed an exe of the user interface. I figure the price is going up! Very cheap even as is at $20.00

Eric

[azflyer]

I must say this CNC stuff does look very interesting. I have a couple of questions to start off:

1) Balsaman, where did you buy your motor/controller kit?

2) How clean are the cuts on balsa? Is there any splintering and is there much sanding required after cutting?

This is a great source of CNC information!

Thanks!

[balsaman]

azflyer,

I got my controller and motoers from www.stepperworld.com

Cuts in balsa are fairly clean with a sharp cutter. here is a pic of my very first part that will fly in an airplane! All my other cuts so far have been goofing off/learning. I cut this one tonight with the new router on the slowest speed at 16" per minute. It's hard to see but very little sanding is required. In fact I did not sand it at all. there is a bit of fuzz where the cutter goes across the grain. This part is medium hard balsa as its a motor support.

Actually this part was the begining of the CNC for me! It goes in my latest kit I am designing. I had the prototype laser cut. I decided I wanted to add this former/motor support while I was building. I was feeling lazy and didn't want to cut that inside semicircle with a knife! Then I saw this thread. I decided I would cut the part after I built a cnc. So here it is. First of many parts for prototyping a new kit. No more waiting to have one kit laser cut, build it, then make any changes, and have another cut. I can get it right, then have the laser guy cut the production run!

Eric

www.e-zflight.com

[balsaman]

Here it is in the plane, what a fit!

[balsaman]

bigger shot of the plane.

[balsaman]

The small plunge router is way over-kill. Especially for balsa. I bought it because it was on sale, variable speed, and would fit. It has a 3 year EXCHANGE warrantee too. Just bring it back to the store for 3 years! If there was a cheap variable speed rotozip I may have bought it. The Rotozip Revolution is variable speed but it's $299.00 here in Canada. That's crazy! The router was $79.00 regular $119.00 The Rotozip Rebel I had on there was $149.99. Almost $180.00 after tax. Panzypoof, I bought it at Canadian Tire, on sale this week. It is kinda bulky but I had just enough room for it.

Eric

[azflyer]

Originally posted by balsaman
azflyer,

I got my controller and motoers from www.stepperworld.com

Cuts in balsa are fairly clean with a sharp cutter. here is a pic of my very first part that will fly in an airplane! All my other cuts so far have been goofing off/learning. I cut this one tonight with the new router on the slowest speed at 16" per minute. It's hard to see but very little sanding is required. In fact I did not sand it at all. there is a bit of fuzz where the cutter goes across the grain. This part is medium hard balsa as its a motor support.

Actually this part was the begining of the CNC for me! It goes in my latest kit I am designing. I had the prototype laser cut. I decided I wanted to add this former/motor support while I was building. I was feeling lazy and didn't want to cut that inside semicircle with a knife! Then I saw this thread. I decided I would cut the part after I built a cnc. So here it is. First of many parts for prototyping a new kit. No more waiting to have one kit laser cut, build it, then make any changes, and have another cut. I can get it right, then have the laser guy cut the production run!

Eric

www.e-zflight.com

Eric,
That looks great! Almost as good as laser cut. :) Which kit did you get from StepperWorld? Did you have to get the one with the power supply and all? SP-3/HT?

[balsaman]

I bought the Fet3, and 3 - 100 oz motors. That's all. I didn't like the SP3 HT. too wimpy. It cost me $200.00 USD plus $25.00 shipping. The motors you need to email him about, as they are not listed on his web page. I did not know at the time, but the resistors were included with the motors, and the cable and software are included with the controller. It was a bonus when I opened the box! I had an old powersupply from a computer. Works perfect.

I think there are cheaper controllers out there. Stepper3.com always has a controller for $99.00 on ebay. I think the FET3 was $135.00. I wanted to buy the controller and motors from the same guy, and Stepper3 doesn't sell motors. I was too confused by the motors on ebay...4 wire, 6 wire, 8 wire, 5 volt, 12 volt, 1 volt, oz/in.....lots of auctions but rarely all the info on what your bidding on! I wanted 5 or 6 volt, 6 wire motors and ~100 oz. That's what I got.

Eric

[PanzyPoof]

balsaman
That's a Sharp looking Plane;)
Tree Magnet could do foam cores for it. Now that he's up and running.
He's looking for work I hear:rolleyes:

Got anouther Stepper mount done, Still to mount to Alum Channel.
Slowely nibbling away at this build.
One of many going on here.

[balsaman]

Looking good Panzypoof. Keep at it. I bought some 1/16" carbide endmill cutters today. I have been using 1/8". Are there smaller? Cranky what size cutters do you use?

Eric

[crankorgan]

balsaman,
A 1/4" one with four flutes. The shaft is also 1/4". Bought it for Scrappy! Then I have three 1/8" shaft endmills four flutes. 1/8" - 1/16" - 1/32" for the Dremel. I also have Mechanical Etching Bits 60 degree from Think and Tinker. The 1/8" ones are about $8 each. They are carbide. The 1/4" one cost me $15.

John

[balsaman]

A production run. Anyone need a speed 400 motor mount?:D :D :D

I busted a bit :mad: . Watch out for those clamps!:rolleyes:

Eric

[balsaman]

forgot the pic again. Sorry.

[azflyer]

Those look nice. Darn it, now I have to build one of these things! Did you get a plan, or just wing it?

[balsaman]

Uhmmm...I made my own plan. It's all in the thread......yeah I know...its a long thread.:p

In short, get a plan from www.crankorgan.com He has simple to build cnc's made mostly from hardware store parts.

You should make one...lots of fun. Can be frustrating, but worth it so far.

Eric

[crankorgan]

balsaman,
Build smaller clamps and you redo the beginning
of each GCode so the bit is over the blank before it feeds down
you can save lots of bits. I also run my GCodes at F4 on the first
part. Then let it rip!

Crank

[balsaman]

Cranky,

Stupid me, I put a box around the parts in the DXF file so I knew how to best arrange them. I forgot to delete the box! The cutter was going all the way around the edge plywood.:rolleyes: That's where all the clamps are.

I am learning cranky, I am learning. I am slower than most but I will get there.:rolleyes:

I am gonna get some 10/24 nylon bolts for the clamps too. The cutter will cut right through the next time I have a brain fart! (soon)

Eric

[crankorgan]

Originally posted by balsaman


I am slower than most but I will get there.:rolleyes:


You are not slow! Only 1 percent of CNC hobbyists get as far as you have. Most of them spend weeks debating steppers VS servos. Did you know? Steppers miss steps! So they say!
Let us know when you sell your first part! That will put you in the 1/2 of 1 percent group.

My best crash happened like this. I was milling circuit boads. After the board is milled, the bit goes back and puts a starter hole in each pad. I decided I wanted the starter holes deeper. I used the FIND and REPLACE for the starter holes. The program glitched. Three holes got a different value. When the board was done I found three large holes in the board. I went back and found the GCode had a problem. I also had three holes in my PVC bed and one in a bolt that holds the bed.

Cranky

[DICKEYBIRD]

Originally posted by balsaman
I put a box around the parts in the DXF file so I knew how to best arrange them. I forgot to delete the box!
You know, I thought it was only my computer....looks like yours will only do exactly what you tell it as well!;) :D Just wait 'til you've been cutting parts for a couple years and you no longer make the the stupid mistakes; then the OOPS!'s get exponentially bigger!

[balsaman]

Yeah darn computers anyways. :D

If steppers miss steps then how come I cut half way through a socket cap screw at 12 in per minute before the bit snapped and when I brought it home it was still at the correct 0, 0, place?

Mines working fine.

Eric

[crankorgan]

balsaman,
I was just being funny. On the Yahoo conference if you mention steppers, people start telling you they miss steps.
If you run them too fast, or ramp them wrong they will loose steps. Most of the people on the Yahoo conference only own motors! Reminds me of Junk Yard wars!

Cranky

[balsaman]

Yea I know Cranky...me too...:D

EricI was just being funny.

[balsaman]

Ok guys, you have come through every time so far so I will ask another question. I am looking for the best way to convert text to vector or DXF format. I am using Corel, writing the text, converting to lines, and then saving as a dxf file. This works well, but the resutling text in vector format is the outlines of the original text. Great for cutting out the letters. Now I want to do letters the width of my cutting tool for engraving, so the text has to end up as single lines. I have tried Wintopo Freeware, which takes any Bitmap, thins the lines, then converts the thinned lines to vector format, but my success has been limited with this method. There must be some software out there for this. Any recomendations.


Cranky, It seems that TurboCNC has trouble with CCW circles. They end up as a drilled hole the size of the cutter, just in and out. CW circles are fine. CCW arcs are fine too so I think if the circles are drawn in 90* arcs they would be fine too, as you suggested earlier in the thread. For now I am putting all my circles on a seperate layer and selecting CW for that layer when converting. The other layers I select "doesn"t matter" so the gcode is efficient when doing fillets etc.

You said CNCPro has the same trouble with CCW circles?

I think as time goes on and I figure out some of the software bugs I will be able to cut a part on the first try!:D

Oh.....and you were right, the sound of the steppers running is like music....the sound of the router..well, that's another story. My wife doesn't find it music to her ears either.:p

Eric

[crankorgan]

Balsaman,
The fastest way to make text is with DeskEngrave at:

http://deskam.com/download.html


It's FREE! KCam has problems with CW. CNCPro only has two problems. 1. cost 2. runs in DOS.


Cranky

[balsaman]

Yup, as usual I got the good advice right here on the 'zone! Thanks Cranky that's just what I was looking for! works like a charm.

Eric

[crankorgan]

Originally posted by balsaman
Yup, as usual I got the good advice right here on the 'zone! Thanks Cranky that's just what I was looking for! works like a charm.

Eric

Balsaman,
I just wish you were around to show me a few things in TurboCad. All my booklet drawings are done in Windows paint!
I use TurboCad to do PCBoards. My PADS have 8 sides. I tried using that ARC tool. When the drawing got converted to a GCode
the pads get cut backwards. I then traced the drawing with a new layer. Sometimes I get tired of playing around....I switch right back to what I know works. Lots of new software coming out! Most of it has lots of bugs! Everybody is trying to find a way
to get CNC to work with Windows. Wait till Windows blows them out of the water!

Cranky

[balsaman]

Cranky,

I don't use TurboCad. I only know Autocad. I don't know how similar they are. If I was doing a trace with a pad on the end, I would make my two lines for the trace, then make a circle at the end. I would then use the trim tool and use the two lines as the trim edges and trim the circle between the lines.

Like I said, I don't know TurboCad. Here is a pic anyways.

Eric

[PanzyPoof]

balsaman say you gonna be making routed plastic
two tone Signs for $?
Saw a White under Black(Private),and such. Were $6.95. At the plastic Shop. SomeOne doing it for them & custom also.
Still tinkering away here. Trying to Stick to the Plan best I can. Floating nut next, it's gonna be a tight fit, My Store frount Alum is tall in the centre Spine.

[PanzyPoof]

Anouther View!
O I'm using Lexan on the End caps/mount plates.

[crankorgan]

PanzyPoof,
The Floating Nut prevents alignment problems. You can use a solid block of Delrin-Nylon or cutting block plastic if you get the alignment right. The rubber coupler with allow some movement if you leave a 1/8" gap between the two shafts.

Cranky

[balsaman]

PanzyPoof,

Not for $$, just for personal and for friends and the Flying club etc. Its hard to cut that plastic! It melts if the cutter is too fast and too slow leaves rough edges.

Eric

[balsaman]

PanzyPoof,

That is looking fine! You will be cutting in no time. That would make 3 in Canada:) Lots of work to make all those plastic parts.

I used a solid nut. What I did was assemble the screw in the nut, move the axis to the extreme travel where the bearing is, then drilled the holes for the bearing mount, shims ect. to make sure it was aligned, then moved the axis to the opposite extreme and mounthed/shimed the motor mount so that end was aligned. It worked! My 1/2-10 rod is pretty stiff and it all ended up nice and straight with no binding.

I do get this wacky resonance in the rod on the y axis (over 30 " long) at the highest speed (20 inches per minute) when the axis is at the ends. when the axis is towards the middle it quiets down because the nut acts as a support in the middle of the screw.

Eric

[crankorgan]

balsaman,
Here is how I draw my artwork in TurboCad. After laying out the artwork, I trace it in a new layer. All tracing is done in a CCW direction. A DOT is put in each pad. During the milling operation, the Mechanical Etching bit then makes a starter hole in each pad. Drawing done in Win Paint-converted in paint shop.

Cranky

[crankorgan]

Here is the Drawing!

[balsaman]

Cranky,

So you draw it in paint first then import into turbocad and trace over it? That works, but you need to draw it twice.

I use WinTopo to convert a bitmap to dxf. Have you tried this? It would save a step.

Eric

[crankorgan]

balsaman,
I draw in TurboCad. The drawing I posted was drawn with Windows Paint and converted to a JPG. Someone asked me what I draw my ilustrations with. I find WinPaint to be the fastest to draw an idea.

Cranky

[balsaman]

Well we all use what works best for us! I know If I tried to draw something in paint it would take me a long time and it would not be pretty. You obviously are very good at it. I like your animations on your web page.

Eric

[balsaman]

Let us know when you sell your first part! That will put you in the 1/2 of 1 percent group.

Cranky,

I guess I am in the 1/2 of 1 percent group now. ;) I feel special! :D

Eric

[crankorgan]

balsaman,
I did the frames for my animations in WinPaint also. I draw at the bitdot level. After I get the animation to work in Black&White, I then add color. Each animation takes about 8 hours. The Crankorgan was the hardest one to do.

Cranky

[crankorgan]

balsaman,
Soooo! You sold you first CNC part. That puts you in a very small percentage group. Having built the machine from scratch makes you even rarer! Right now there is a guy sitting with a $6000 machine he wishes he never bought. Sitting next to that is his $800 treadmill and $1000 PC.


Cranky

[uscra112]

Juts a few scraps of info

- the .dxf file format has a dozen or more "flavors". At work I transfer a lot of stuff from AutoCAD via .dxf so I can hack on it in my old Anvil1K CAD program. (I'm too lazy to learn AutoCAD) The .dxf format from AutoCAD R14 is different from AutoCAD R13 is different from AutoCAD R12. Very often I translate something that has short arcs in the AutoCAD database, but they show up as full circles in Anvil after translating.

Another vague memory is that in prehistoric times (1960s) CNC G-codes did not support full-circle interpolation at all. I remember that "full-circle interpolation" was a selling feature of newer CNCs as late as 1977 when I got into the machine tool business.

Balsaman, you'll eventually be able to read G-code like a comic book. Only then can you get your CNC master merit badge.

I knew a couple of old guys at Fairchild who claimed they could even read the 8-bit punched tape that CNC programs used to be stored on and read from.

[crankorgan]

uscra112,
Paper tape readers is where I first ran into steppers. I was put on a job because the repairs were 6 months months behind. The guy on the job was taking the main stepper out of the unit and oiling the bearings. When he put the motor back in he did not know the punched holes in the tape were supposed to line up with the sensor. After reading the manual, I was able to fix 200 tape readers in two days. I still have the driver boards for the stepper. I use the same circuit on my Piker.
I used to be able to read the tape! We also had mylar tapes
towards the end. There is nothing like entering in a 32 number bootstrap and praying the paper tape reader runs after switching the run/idle switch and hitting step. I think the computer was a SPC16. Magnetic donut memory!


Cranky

[uscra112]

By diggity! It never occurred to me that the index on those tape readers was a stepper, but it sure makes sense now!

How many people know that the whole 8-bits-per-byte thing came out of the code that was developed originally for the tape that teletype machines used, and wwhich was adopted for the early CNCs? I once even wrote programs ON A TELETYPE, one G-code at a time. It was awful. That's how I committed my worst-ever crash. Edited a program and missed keying in one Z-move to a clearance plane before a rapid traverse across the part.

Ever hear of a Moog pneumatic CNC system? I saw one once. Nothing electric on it, not even the spindle motor. Had a pneumatic tape reader, hydraulic motors on the screws, and some sort of fluidic computer that translated the tape commands to the motor servo-valves. They even had pneumatic feedback from the machine tool slides! I wonder if there's also a pneumatic analog to a stepper?

I've recently begun to wonder if the fire-control systems on WW2 ships used steppers. Director up in the crows nest could slave the guns to some sort of aiming telescope he had. A stepper link to a hydraulic servo in the turrets would do it, and could have been done in those days. Is there a history of the stepper anywhere?

[crankorgan]

uscra112,
I also worked with aircraft syncros. A 400 cycle signal is sent into the rotor through slip rings. Depending on the position of the rotor. Three phases come off the Transmitter syncro that goes to the receiver syncro. Both rotors are wired in parallel. The receiver syncro follows the movement of the transmitter. They used these on airplanes. The Transmitter syncros are on the flaps-rudder etc. In the cockpit the instruments have syncro receivers in them. Some syncro receivers had centering springs in them. They worked like meter movements. No tubes or transistor required!!! Just a 400 cycle 24 volt source. The 400 cycle power came from a altenator-DC motor set or the engine of the plane.
And yes this system was also used to relay position of guns on ships.

Cranky

[crankorgan]

uscra112,
I worked at T.A.E. In West Orange fixing DC motors-syncros and cockpit instruments. Here is my security badge. I am
20 years old. With my hippy hair and almost beard.

LOL

Cranky

[uscra112]

John:
Yah, I had a handful of synchros once, too. Surplus stuff my then-boss and mentor had lying around, and he explained them to me. His were about 3/4 inch diameter and 1.5 inches long, as I remember. PIC's buisness seemed to be centered arond selling all sorts of hardware for mounting them, gearing them, coupling them, etc. Neat and real reliable system for feeding rotation information to a remote indicator or whatever.

The so-called resolvers that were common in the '50s as machine-tool feedback worked on the same principle, I think. You fed a 400 Hz. signal onto the stator, and the rotor fed the signal back with a phase shift as the rotor turned. Compare the phase differential and you knew the angle. The Farrand Inductosyn was just a resolver laid out flat.

The synchros I had couldn't generate much torque, though. But I suppose if you built them bigger they could run a servo-valve well enough. I'm still assuming the gun elevation/traverse mechanisms were hydraulic. By WW2 the hydraulic tracer valve was being used on machine tools, and applying that to a gun-aiming mechanism would have been child's play. I really oughta go see one of these old relics they have as museums and find out for sure. The Massachusetts sits in Fall River, and I used to drive by it every day when I was commuting, (in 1985), but I never went into it.

When were you at Edison? From '77 to '84 I worked for a machine tool company in Middletown NY, and traipsed thru NJ all the time. Used to go to Curtiss Wright, rebuilt a giant planer-mill at Worthington Pump, did a two-year stint getting some spar mills and a Lucas NC (not CNC) profiler working at Fairchild. . . Learned an awful lot of now-useless junk, (like how resolvers and hydraulic servos worked).

[crankorgan]

uscra112,
I worked for Edison 1972-74. They sent me to Florida for three months. A group of us learned the jobs there and brought the avionics division back to West Orange. We were in the building where Voicewriter was suppose to go. The cassette
recorder blew the Edison recorders out of the water. By the time the Edison company had a cassette recorder it was too late. Rather than leave the avionics in Florida, they found a way to move it to West Orange. A big tax write off!!! All along they knew they were going to sell it. I worked 70 hour weeks for two years and then they let me go! I went to work for RCA in Harrison and then to TRW in Fairfield. In RCA I did life-testings. TRW I repaired everything to the component level. I have thousands of worthless skills. I retired at age 37. I am now 50 and I sell plans
for a living.

Cranky

[uscra112]

That sounds right. It hasn't changed any either - we burn our good service/repair guys to a crisp out here to this very day. (I'm in coordinate measuring machines, mainly for the Big 3 now. . .) The better you are, the hotter you burn. At one point we were launching the line to make the blocks for the new GM "Gen 3" V-8 that's in all the trucks & SUVs, and I did New Year's to mid May with not one day off and not one day less than 16 hours. You only survive that once. Good that you've found a niche like you have. You may live to collect SSI.

[DICKEYBIRD]

Originally posted by uscra112
I did New Year's to mid May with not one day off and not one day less than 16 hours.
:D ....sounds like a perfect conditioning program to get yourself into shape for that bodacious 4 engine, once in a lifetime model airplane project!;)

[PanzyPoof]

So desided on a colour.
Was at Crappy Tire and Found this Krylon Stone texture paint. Soo It's now Mediterranean Green marble.
Looks real kool like it was stone. (Pretty)
High Hide primer WT was first coat.
Was thinking to make my floating nuts and base from lexan. It's a nice fit with low backlash.
Is it a good material for this. It's 1/2"

TreeMagnet posted some pics of his operational Foam Cutter (one thread over) Nice weights.

[crankorgan]

PanzyPoof,
You can use the Lexan for all the parts. If you can tap it. it will work. Don't forget you can use plastic cutting board material for the floating nut.


John

[balsaman]

Panzypoof,

Looks good! Marble!:D Mines as heavy as marble! Just got to assemble it all now?

I think the lexan would work for a nut, but there will be a bit more backlash than with a softer plastic like delrin/nylon etc. Then again, what do I know, I have only tried Delrin. I do know that the delrin makes for a Zero baclash nut, just as Cranky said it would.

Eric

[balsaman]

Hey cranky,

I found three old electic typewriters at work in a heap by some old office furniture. They have two steppers each. They are 4 wire ~3.5 volt at ~1.5 amps each (50 oz?). I asked for them. I will scavange the steppers. Are they worth it? How do you drive a 4 wire stepper? My board only does 5-8 wire steppers. I could sell the steppers on ebay.

Eric

[senna12625]

Balsaman...

I realize you directed your question to Cranky... but what you have are bi-polar steppers vs the uni-polar steppers your new machine is operating with. Bi-polar controllers are out there... slightly different animals. Cranky might be able to expound on the difference much better than I... or not...

1. Stepping motors come in 4, 5, 6, and 8 lead configurations. The
vast majority are the two phase type (a few firms make five phase
steppers, but these are fairly specialized and non-standard).

2. The property of unipolarity or bipolarity is really an attribute of
the drive, and relates to whether the current can flow in one (unipolar)
or two (bipolar) directions. A unipolar drive has six leads to connect
to a motor, while a bipolar drive has four. Simply counting the number
of motor outputs clinches the drive type.

3. A four lead motor doesn't have enough leads to work with a unipolar
drive, and is hence restricted to a bipolar drive. Electrically, it
looks like two independent coils.

Did I forget anything...?

Hope this helps...

Senna

[crankorgan]

Originally posted by balsaman
Hey cranky,

I found three old electic typewriters at work in a heap by some old office furniture. They have two steppers each. They are 4 wire ~3.5 volt at ~1.5 amps each (50 oz?). I asked for them. I will scavange the steppers. Are they worth it? How do you drive a 4 wire stepper? My board only does 5-8 wire steppers. I could sell the steppers on ebay.

Eric

balsaman,
The driver boards that run 4 wire BiPolar motors cost more. A Unipolar board has 4 output transistor or 4 FETS per motor. A Bipolar has two "H" bridges or 8 transistors or 8 FETS per motor. The L298 IC has these parts built in! The L298 is driven in most cases by a L297 IC. The L297 handles the step/direction and it has a chopper circuit built in. Using the chopper and a higher voltage supply will make a 4 wire motor sing! The problem is cost! The motors are worth $15-20 on Ebay. The same size unipolar motor goes for more! Why? It can be run as a BiPolar or a UniPolar.

Cranky

[balsaman]

I will grab them and put them on ebay. Or....I can try and find a bipolar controller board kit to build. We will see.

Thanks!

Eric

[crankorgan]

Balsaman,
Dan at Camtronics sells a kit for $125 plus $6 shipping. He also sells a bare board. The board uses the L297/L298 chips.

http://www.seanet.com/~dmauch/


I have a board designed that uses output transistors instead of an IC. I worked on it when sources for UniPolar motors seemed to dry up. Then a ton of them showed up on Ebay. Every month a new driver board appears! I am sticking with my UniPolar Piker design for now.


Cranky

[balsaman]

That looks like a nice kit. It's a chopper board so it doesn't need a dropping resistor on the motors if I understand correctly. More efficient especially if you use a 24 volt supply. I looked into 24 volt supply for mine and I need 40 watt resistors! I could fry an egg on the heatsink. I may still try that one day for fun. I need to get to a supply house for the 10ohm - 40 w. resistors. Some day. I have a working machine so no hurry. I will grab those steppers and sell them on ebay. I could put the money towards the chopper board and use it on my existing cnc and wire my 100 oz. motors bipolar. I should be able to go even faster then?

I could even then sell my Stepperworld driver on ebay and still be ahead!

Like I said, my machine works better than expected, so no hurry. I have all winter to tinker.

Eric

[crankorgan]

balsaman,
Higher Torq motors don't always spin as fast as smaller motors. Ineritia of the rotor is the problem. You are correct, a chopper removes the need for resistors. 24volts and resistors still hits the motor with 24 volts. Run a 6volt motor at 6volts. Top speed is 1 to 2 revs per second. That is 60rpms to 120 rpms. Increase the voltage from 6volts to 12volts. Add resistors to limit the current. The motor's top speed almost doubles. The chopper does eliminate the resistors BUT you will only get a little more speed. Most high end controllers use 60volts with a chopper. If your controller could handle 60 volts you would also see more speed. BUT you would need a stronger machine with a different spindle motor in order to benefit.

You can make your machine faster by making a more efficient GCode. Have your GCode cut parts in a counter clockwise direction. As the parts are cut.....have the parts cut in
a CCW direction. When the last part is cut. The bit is back near home, ready for the next part.

Cranky

[balsaman]

Cranky,

You are right about efficient gcode. That makes a big difference. My machine already jogs faster then I dare cut. I have been cutting 1/16 aircraft ply at 12" I have not tried faster. Some time when I have time to make some scrap I will try. I don't think my spindle is a limiting factor. It's way overkill. The rapid travel moves are at the software limit of 20". I was running at 22, but my garage is cold! It missed steps on cold days.:D 20 seems very reliable with no missed steps. I feel very lucky to get 20. I am just rambling....and trying to learn about all the options. I may want to build a small lathe some day:D When I get my grubby hands on those bipolar motors I will post a pic. Maybe I can do a science fair project with them with my son. He is 12. Robot wars anyone?:D That parallel cable may get in the way. I could just mount the laptop to the robot..lol

Eric

[crankorgan]

balsaman,
If you just want to play with with a BiPolar motor, you can run it with a UniPolar controller using large pull-up resistors. This wastes lots of power, but it does work.

Cranky

[balsaman]

eh, I won't mess with my current controller. I need it to run my cnc. Thanks for the advice on the bipolars. Time will tell what I do with em.

Eric

[PanzyPoof]

Hmmm! Space is kinda tight under those beds.
How tall is the centre section of the store frount Alum you use Cranky? Mine is 7/8" could be big diff!
See pic I'm gonna try it less a floating nut and hope it works. Line up of 1/4x20 rod and system is close. It takes a bit of torque to spin the system.
Moves OK seems smooth in travel under Drill power.

[crankorgan]

PanzyPoof,
The hump in the channel I use is smaller. Just make sure the Drive Nut does not hit the hump! Can you turn the stepper with just your thumb and index finger? If so that is good. Make sure the wires on the stepper are not hitting each other. If they touch the motor will BRAKE electrically. The Floating Nuts are not needed if the 1/4-20 rod is long. The rod does flex. Your parts look well made. I put the Floating Nuts in so sloppy builders will still be successful.


Cranky

[balsaman]

PanzyPoof,

That looks good. How's the backlash? Just curious how the lexan works for a nut. If the backlash is ok, then there is probably less compression of the nut when it's pushing hard like when your cutting aluminum etc. I am amazed how much mine can flex when I cut brass. I can hardly flex it by hand but it will flex when cutting the hard stuff.

Take a file and file a wee off that lexan.

I ran mine with a drill too. Fun to see that axis move eh?:D

Eric

[PanzyPoof]

The Lexan has been trimmed back and don't drag the beam now.
It's still a little tight to spin by hand and the slide is dry. Thinking to add a cross beam each side drive beam to
take up the side forces on those 2 4/40 mount screws. Hmmm but it's quite strong good footprint as it's a 1/2 wide.
Backlash is zero at this time.
Tapping it was not bad. Those threw shaft motors allow a pretty good aligment window,Push a long bit threw or a Laser.
Motors I'm waiting on TreeMagnet, he's got spares that he's wiring for connectors > board.
I'll swap them and add flats to drive shaft. 4/40 set screws. I really put that tap to work here. Cost me $6can.
Now to steal back the P2/360 PC from my 7year old.
She's gonna get a new one for Xmas maybe a MAC.:D

[crankorgan]

PanzyPoof,
What controller are you going to use? Let me know if you need any help. I bought 10 of those through shaft motors from Canada. They are very nice! Remember! You can put a small knob on that back shaft. Don't use a crank!

Cranky

[PanzyPoof]

CRANKY, Controler is from You! Should have it built ready to test by Weekend. Arranging the room it's new home.
Will sit it on a Rubber Pad on my old first Desk.

[crankorgan]

PanzyPoof.
Using the double shaft motors 6 volt 1.2 amp 5ohm
per winding motors. You can use 4.7 to 5 ohm 10 to 20 watt resistors. 20 watt will run cooler. I used two 10ohm 10watt resistors in parallel from Radio Shack. It is cheaper to just buy the resistors you need. I show 8ohm resistors on the circuit. They work good also.

John

[PanzyPoof]

Already Done TreeMagnet instructed me and I
got him the 10watt 10ohm ones.
Actualy he just called and is dropping by with some stuff?

[crankorgan]

Originally posted by PanzyPoof
Already Done TreeMagnet instructed me and I
got him the 10watt 10ohm ones.
Actualy he just called and is dropping by with some stuff?


So we are talking 12 resistors, four per motor. Two 10ohm 10watt = 5 ohm 20 watt.

Cranky

[PanzyPoof]

So we ended up making a Drive nut same as on treemagnets foam cutter. Whow much better, She rolls along between the fingers and Frame is snug and free it's now 100% Ok one more to go.

[crankorgan]

Originally posted by PanzyPoof
So we ended up making a Drive nut same as on treemagnets foam cutter. Whow much better, She rolls along between the fingers and Frame is snug and free it's now 100% Ok one more to go.

PanzyPoof,
That nut has to be 1/4-20. You will now need more oil if you don't use plastic. If the threaded rod is plated you will see that wearing off also. Just wipe the rod down from time to time and re oil.

Cranky

[balsaman]

Just curious, whats wrong with a crank? I currently don't have either a nob or a crank. Was thnking of a little crank tho.

Eric

[Tree_Magnet]

Cranky I told panzy to get 10 ohm resistors because my drivers for my foam cutter will only handel 2 amps so each motor is drawing about 1 amp/phase now I didn't know what the speck on the drover boa panzy got but if it can handle more then i will drop the resistance if need be to 5 ohms by adding another 10 ohm resistor.
using 12v on these steppers with 10 ohm res. i am unable to stall the motors and seems to work very well with my set up.
i know the router will probably need more power but thats what testing is for:) if you have any suggestions i am all ears :D

Tom

I HATE TREES

[Tree_Magnet]

balsaman i run bipolar (24v) motors on my cnc compact 5 lathe/mill but i am going to put these steppers with the throu shaft and run them in bipolar or unipolar mode i haven't decided yet. i have spent the last while working on my foam cutter. by the way i was the one that found the little gold mine of steppers at sayal in mississauga, the funny thing is that they were $5 so between me panzy 747drv and a couple of other people we must have bought 60 of them now the price is $15 each. sayal jacked up the price (money gougers). i have two controllers 1 for bipolar and 1 for unipolar so i will try both. sorry for ramblin on but its late and i am tired so good night all

Tom

I HATE TREES

[PanzyPoof]

A small crank on all shafts? Ya OK! I wasen't shure what ya ment:rolleyes:

[crankorgan]

Tree_Magnet,
Thev Piker can take 3amps or more if you use heatsinks. With 5 ohm resistors you will be ok with 12 volts. Any more add some aluminum to each transistor.

Cranky

[crankorgan]

PanzyPoof,
That rear shaft is for a optical encoder. If you add a flywheel to it, you can loose steps at high speed. Keep the mass
low. An optical chopper wheel is very light.


Cranky

[PanzyPoof]

Bought this Black $ decker Work Stand, wheels off, $79can.
PC sits nicely inside. Ya Saw horses Work well also. Will have to paint the walls Honey Do:(

[uscra112]

Balsaman - cranks spinning at rapid-traverse speed are good for developing bruised fingers. (On full-scale machine tools they break bones.) Also, a crank has a fair amount of mass at a large radius, increasing the rotating inertia, and potentially causing step errors. That's my take in the question. Cranky?

[crankorgan]

uscra112,
The rear shaft on the stepper gets a light weight aluminum or plastic disk. Very thin with slots in it. There are two optical devices that read the slots. The signal is sent back to the controler as a failsafe signal. Adding FLYWHEELS to the shaft cause inertia of motion. At higher speeds during the cutting of circles everything has to be correct. Adding a crank to the shaft will cause a lost step. It is possible to fix this with the Ramp-up Ramp-down setting. Some software calls this acceleration. A small round knob is a better choice. Depending of the speed of the cut, the problem might not show up during cutting but rather on the G00 moves. (rapid moves between cuts)

Cranky

[PanzyPoof]

So Stole Daughters/my PC and all setup.
Time to download any good Free Usefull Programs.
She's a P2 360mh, 196mb ram, Fresh/formated running Win98. Coral Draw ready, Still need a scanner. later.
Looking to Scan and Cut.
And that program for the Letter Stencle.

[PanzyPoof]

Cranky Found http://deskam.com/download.html
Big Selection! What do I want here? any Worth the Lisence?

[crankorgan]

PanzyPoof,
TurboCNC is only $20 to register. Balsaman is using it! TurboCNC is easier to setup. There is a conference for it also. If you go with TurboCNC you will find more people will be able to answer your questions. And that includes me! I run CNCPro but
it cost $200. TurboCNC is underpriced.


Cranky

[thrmaln]

Hello ALL,

This thread has revived my interest in building my CNC foamcutter. I designed it 2 years ago using Mechanical Desktop 5.0 and due to various things I never got around to building it. Its all ready to go and the parts are detailed waiting to be machined and I hope to get to it sometime this winter when I get slow here at work. I am a linear stage and automated system designer for a small automation company so this is what I do for a living.

Machine specs:
40" x 50" table with a 10" removeable center leaf to make the table 40" x 40" for high taper cutting.
Nema 23 steppers (200 steps/rev)
Thomson Super8 pillowblock bearings running on .4995" SS Precision ground shafting.
1/2-10 Precision rolled leadscrew with antibacklash turcite nuts
HobbyCNC board and timer (I may change to MM2001 board to utilize pc heating of the wire)

Most of these components are a bit overkill but I acquired most of them on ebay and from my previous company when they shut down and I raided the stockroom before it was auctioned off. I got enough parts to build a CNC Balsa mill as well.

Attached is a PDF file with a hidden isometric view. Let me know what you think,

Marc Webster