Settings for fouth axis?

[Pete M]

I tend to do things very slowly on my bot. I bought a motor from shopbot a while ago to make an indexer. Using Brad Winesett as my exemplar, I got a small lathe and some MSC cog wheels and belt. My question is: what settings do I need to adjust to get my JA,90. command to equal 1/4 turn? I have tried VU for the a axis but I get no good results. Help will be appreciated, maybe.

[kubotaman]

Peter, not sure if I can help you but my indexer is on my B axis as per Shopbot. I have their 12" indexer and they could not tell me my number of steps to set the setting at! They had the info for their 6" but that was of no help. So I figured I was on my own. What I did was get a long screw and put it thru a piece of material and taped it to the top of the mount of the indexer. I then put a pencil mark on a piece of masking tape on the chuck itself. I very carefully lined up the screw with the line on the tape. Remember to put a number in the steps for the indexer. I then told the indexer( B axis for me) to turn 360 degrees. When it did turn and stop gave me an indication of where I was as far as steps. With time and patience I was able to get the steps on a nat's ass. Just take your time and you will get it very refined to turn exactely 360 degrees. If I remember correctly you can make the number of steps in thousands of an inch. I have never had any problems with my indexer as far as being correct for degrees. Hope this helps!

[steve_g]

I used Daryl's method with the exception that I told it to go 3600 degrees. That told me with 10X resolution that my number was correct.

Steve

[kubotaman]

I also should have stated when I got the steps with 360 degrees correct I would then turn it to turn say 9000 degrees. That would be 25 turns of the chuck. If it landed on my mark that would tell me my steps were correct!

[kubotaman]

Steve you beat me to it. Age makes one slower!!!

[steve_g]

But your method is 2.5 times better!
I used a larger font in respect of your age!!!

[kubotaman]

You're right! 9000 divided by 3600 = 2.5! Just wish the fonts were bigger!!!

[Pete M]

Thanks All,
My question is not so much how to dial in the accuracy of the indexer, but what setting to adjust. The methods outlined here seem like they would work well, I especially like the multiple rotations.

[blackhawk]

Peter - VU should be the only setting that you need to change. As someone mentioned, be sure that B axis is correct for your setup. You could be on the A axis.

[myxpykalix]

Also be sure that, that axis is set for DEGREES not INCHES. If you need the proper number settings let me knw and i'll run out to my shop and copy down my settings and post here.

[Pete M]

Yes, the VU settings were all I needed. A value of 32.0 gave me accuracy within a pencil line on a 4 inch face plate over 10 revolutions. thanks for the help.
I am on the A axis. Way back when, before I bought my motor, to check if my A output from the controller worked, I connected the Z axis motor, switched to 4 axis, and A commands moved the Z, success. When I finally got my motor(did I mention that I move slowly), I hooked it up this way.
I am sure I can use the bot with A commands, but I agree that B would be the better choice as I am placing the 4th axis parallel to the Y axis.
I just need to figure out how to change it.