Update from older software version

[LeChuck]

OK, I tried something on a hunch and reduced the speed to 400rpm. The thread was much cleaner this time but not perfect. The other thing is...it did a 1.25 pitch even though I'm specifying 1.0 in the program. That being said, I started off by customizing a library entry that was 1.25, so it looks like it might have retained that somewhere.

I should be able to thread plastic at more than 400rpm, right?? The carriage has no problem going at a much higher speed but it looks like maybe it's losing some synch with the spindle encoder?

[martyscncgarage]

Post the intercon file it created as well.

[LeChuck]

OK, I'll go look for it. I actually just tried again after deleting the thread cycle and creating a new one from scratch. It seems to work really well for a while, then it looses it and chews up the thread. The first time it did it right on the last pass, so I removed that and tried again, and it did it somewhere in the middle. Before that happened, the threads looked clean.

[LeChuck]

Test files. Also, even though the thread is still bad, after I redid that threading cycle, the last 2 tries, the cutoff was straight.........

[LeChuck]

I found this video posted by someone else. This is what it does for me, works well for a while, then goes completely wrong.

[LeChuck]

I went to check out the encoder output. I turned by hand until I got the little asterisk for the pulse then put a piece of tape and a pencil mark.

Started at 38105808 then it goes by 10000 each time. Except the first one where it had a 05 at the end, but then when going back it was an 8. Maybe a little glitch or misread. It seems consistent at 10k count at each turn.

[cnc_smith]

OK, I tried something on a hunch and reduced the speed to 400rpm. The thread was much cleaner this time but not perfect. The other thing is...it did a 1.25 pitch even though I'm specifying 1.0 in the program. That being said, I started off by customizing a library entry that was 1.25, so it looks like it might have retained that somewhere.

I should be able to thread plastic at more than 400rpm, right?? The carriage has no problem going at a much higher speed but it looks like maybe it's losing some synch with the spindle encoder?

1) You did not state if you were having to reset Z after running the thread? This is usually a sign that it losing position. You stated you changed down to 400 RPM and it improved but still was not cutting correctly. Try dropping down to 200 RPM and see if it will cut correctly at that RPM. For making turning cuts in plastic you can cut at higher RPMs but your feed per revolution is slower. With the 10MM dia x 1m thread you feed is 1 mm per revolutions (.0394 inches per rev). Threading is feeding per rev a lot higher than what you would be doing with a normal turning cut. So with threading if the drive and motors are not large enough you have to lower the RPMs so you do not loose position for threading because of the high feed per revolution.

2) For the cutoff you stated in an earlier post "Another strange thing is that the cutoff tool creates a convex surface on the back of the piece. Then you posted it is cutting correctly now. If you get where it is not cutting flat on the cutoff the following listed items could be the problem. Cutoff tool is dull, feeding too fast for the angle that is on the cutoff tool, the cutoff blade is sticking out to far, or not on center that is causing the tool to flex and lead off.

[LeChuck]

I'm not sure about resetting Z. I first zero out the main tool after pulling and touching the stock to it, then do that again the next time. It doesn't seem to be losing position.

It did do a better thread when I lowered the RPMs but then the second time it mangled it, so that seems random. I'll do a few more tests like that later to see if I can get it consistent and lower the speed. Even at the higher speed, it seems to have no problem for several passes. This thing seems to be able to move really fast. And then it just goes wrong on one pass and cross threads it.

[LeChuck]

It doesn't look like it's a speed issue. 200rpm looks just as bad as 1200.

[martyscncgarage]

It doesn't look like it's a speed issue. 200rpm looks just as bad as 1200.

You are going to have to dig in and check that the machine is repeating position. Check the Encoder, belt/drive etc. Don't know what make model encoder was installed on the machine or how it was installed. On those Emcoturn 120's, I simply removed the existing Emco optical encoder, turned the shaft down for a standard quality encoder.

Doing the thread from Intercon is the right thing to do. You know the program is correctly written.
Do post a FRESH report unless nothing has changed from the recent one you posted.

Marty