Messages

1

Show"N"Tell ( What you have made with your CNC machine.) / Re: Brass Clock Gears

« on: February 12, 2009, 06:13:35 PM »

A few more pictures of the progress.  The verge is only a protoype in brass.  I will be machining that out of tool steel soon and hope I don't break to many end mills.  The rack, snail, and verge will be entirely CNC along with a few of the gears.  All of the gear crossings will be CNC.

Best Regards.

Carl

2

Show"N"Tell ( What you have made with your CNC machine.) / Brass Clock Gears

« on: January 15, 2009, 08:31:06 PM »

Thought I would post my recent progress with the CNC mill for cutting gears and crossing out the gears with the new setup.  Since I have a long post with history I'll just provide the URL but towards the end you will see the gears recently cut and they turned out nice.  Certainly would not have been possibel without the help of the Mach team.

http://www.cnczone.com/forums/showthread.php?p=552366#post552366


Best Regards.

Carl

3

General Mach Discussion / Re: CNC Gear Cutting

« on: November 12, 2008, 06:30:48 PM »

Bill,

I already had that set but did go to the shop and try again.  I played with the settings a little and re-read the posts on this subject but no luck.  Not sure what's different but I may have to double check my version and make sure I have the most recent version as I noticed that some posts sugested it was a new or fixed feature.

Best Regards.

Carl

4

General Mach Discussion / Re: CNC Gear Cutting

« on: November 11, 2008, 05:56:06 PM »

Just finished setting up a 4th axis and it seems to be fairly accurate under no load just doing a full 360.  Will need to do some test gear cutting next to make sure I can get the type of accuracy and repeatability I need for gears.

I'm still a little puzzled by how slow it turns even when I set the velocity to 1000 in motor tuning.  I've tried changing the rotational diameter in Settings Alt6 but it still doesn't seem to affect things.  Not sure what I'm missing but will experiment more.

Here's some pics of the setup.  It's an old Caroll Dividing Head.  The mounting plate for the stepper was done with a CNC program I created which was my first real attempt at making something useful.  Kind of cool to see this all come together.  Need to learn more about how to make better finishes on these parts though.

Best Regards.

Carl

5

General Mach Discussion / Re: CNC Gear Cutting

« on: October 07, 2008, 09:53:05 PM »

Thanks for the spreadsheet RICH.  That will come in handy.

I think my mill can handle the accuracy I need.  I've built one grandfather clock already and have made most of the parts for a second one.  What got me into the whole CNC arena was the desire to easily, quickly, and accurately, cosmetically that is, cross out the gears.  I did the first clock gear crossing by hand and don't care to do that again. 

I think thiis CNC stuff is like dope.  I now want to see if I can do the indexing too.  So it appears that it's feasabile but I will need to run some tests as you suggested before getting too far along.  Even if I can't, it will be nice to have around and besides I've already got the program complete for cutting the mounting plate for the 4th axis which is really neat.

I've also cut pinion wire on the mill which turned out nicely and just parted off the length I needed for each arbor.  I was using drill rod for the pinions so that's the hardest stuff I'll cut on the mill at this point.

Thanks again everyone.  This is a great site and Mach has made this all possible for the average hobbiest like me.

Best Regards.

Carl

6

General Mach Discussion / Re: CNC Gear Cutting

« on: October 07, 2008, 06:45:52 PM »

I think you guys got me back on track.  Thanks for the input.

If I'm calculating correctly, the max error at the tip of a 32DP gear with 34 teeth would be 0.000104.  So as previously stated, my machine can't come close to that type of accuracy.  As long as I use absolute mode, I should never see an error greater than that along with the accuracy of the machine itself.

How does Mach handle fractional steps that the driver/stepper can't accomodate?  Does it round or truncate?  For example, if I need to move 360/34 which is approximately 10.588235 degrees and the angular movement at the spindal per step is 0.003 then I would need 3,529.411176 steps.  Clear the driver and stepper can't do the fractional part of the movement so what will Mach do with the it?

Back to machining the mounting bracket for the dividing head.

Thanks again.

Best Regards.

Carl

7

General Mach Discussion / CNC Gear Cutting

« on: October 06, 2008, 07:16:15 PM »

I'm in the middle of converting one of my manual Carroll Dividing Heads to CNC when it occurred to me I may have a problem with resolution so I was hoping someone may be able to provide some insight.

My dividing head has a 20:1 reduction.  I was planning on mounting a Nema 23 stepper with 1.8 degree steps using a timing belt and pulleys with a 3:1 reduction for a final reduction of 60:1 at the spindal.  When I tried to calculate some of the common tooth cuts I would make I found that some would not fall nicely into the resolution of this setup.  While I could change the gearing which would help in some cases it would eliminate others from what I can tell.

For example, to cut a gear with 34 teeth using my existing 20:1 reduction dividing head I would use a dividing plate with 17 divisions and index 10 positions each time.  This would equate to 10.588235294117647058823529411765 degrees per tooth.

Trying to calculate the steps for the 60:1 reduction CNC dividing head I get 3529.4117647058823529411764705882 micro steps.  It's my understanding that I can not move the stepper the fractional part so I would basically have .4117647058823529411764705882 x 34 = 13.99 steps lost which would be 0.041999 degrees lost.  This would create 1 tooth that is either too fat or too thin if I'm not mistaken which isn't good for time keeping.

Am I totally missing something or do I need to take another approach?

Any feedback would be greatly appreciated.

Best Regards.

Carl

8

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: September 30, 2008, 07:40:10 PM »

One of the tests the group recommended that helped me realize I had some type of interference was to disable one of the axis in Mach but still run a full program in which I had experienced the error before.  To my surprise, the axis that was disabled would occasionally begin moving but very slightly.

Best Regards.

Carl

9

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 29, 2008, 07:48:58 PM »

Rich,

Believe me, I've been trying to bypass the board for quite some time but was not have any luck and didn't want to burn things up.  I finally got Ray's recommendation to use the USB as the 5v source to work.  So with that said, I was able to use pins 2, 3, 4, 5, 6, and 7 direct with no problems.  After 10 full runs without the breakout board, there was no error.  I did not re-zero after each run either!  Just checked the dial indicators and pressed start for the next run.  I realize this was a no load test but at 40IPM I think I can finally declare success!!!!!!!!!

So I'm fairly confident I have a bad breakout board at least when using pins 4 and 5.  While I don't plan to setup a 4th axis immediately, I may eventually convert one of my Carroll Dividing Heads to CNC.  At least I now know how to direct wire if necessary.

I can't thank everyone enough.  Hopefully if I have to post again, it will be a new subject.  Here are a couple of pictures of the setup if interested.

Best Regards.

Carl

10

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 28, 2008, 08:56:43 PM »

Ray,

I'm using shielded cables for the steppers and my limit/home switches and I have a good case ground which uses equipment ground.  My CNC4PC board is the C11 Multifunction Board Rev 3.1.  Not sure if that's good or bad.

I justed completed testing and eliminated pins 4 and 5 on the breakout board.  So X used 2 and 3, Y used 8 and 9, and Z used 6 and 7 where even is step and odd is dir.  After 5 full runs of the program there was no error!!  So it appears that I either have a bad breakout board or a bad parallel cable.  It appears that when both pins 2/3 and and pins 4/5 are connected, there is some type of coupling or cross talk.

I tried to wire direct and am unable to get things to work.  I wired the pins from the parallel cable for step and dir directly to the Gecko driver.  I then tried to use the USB 5V for the common connection on the Gecko driver but no luck.  I even connecting to pin 18 on the parallel cable.  I certainly don't understand how the 5v reference is suppose to be wired in regard to the parallel pins. 

Sage, yes, my troubleshooting skills are lacking in regard to electronics.  Way over my head but I do thank you for the suggestions along with everyone else that has helped.  This has been an invaluable source for me.

Best Regards.

Carl