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Author Topic: Huge Threading Problem Help  (Read 16095 times)

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Re: Huge Threading Problem Help
« Reply #30 on: October 23, 2010, 11:58:21 PM »
Thanks. Yeah over the years I've done some crazy stuff with my lathe, but it all works out in the end.

BTW Giants GOING TO THE WORLD SERIES>>>>>> SAWEEET...I'm in SF if you didn't know.
Re: Huge Threading Problem Help
« Reply #31 on: October 26, 2010, 02:13:23 PM »
OK, so that didn't work. I tried going to V3.042.040 and the RPMs only said 7 or a low number when the lathe was on, so I went back to 3.042.020. Is there a different version where the threading problem was fixed but that's not .040?

I tried a whole host of other things trying to get this thing threading correctly. I tried 100 RPM, 200 RPM and 400 RPMs and different DOC. The BIGGEST difference was using thread cutting oil, before I was using the Cool Mist solution in a heavy spray.
So in the end I got one good test thread now I'm going to try to reproduce it. My specs were 16 TIP 4.475" OD down to 4.3984, .005 DOC, 400 RPM and brushing on the thread cutting oil. Now hopefully that works with a REAL piece.

Oh, I also am using a carbide insert that's coated, before the ones I used were uncoated.

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Re: Huge Threading Problem Help
« Reply #32 on: October 26, 2010, 02:25:16 PM »
Did you try a different setting for the Index Debounce in 3.042.020?
You should be able to get most other versions on the FTP site, you will find its link on the downloads page.
Hood

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Re: Huge Threading Problem Help
« Reply #33 on: October 26, 2010, 02:37:00 PM »
oh another thing, not sure how your spindle is controlled, if not via Mach you need to have at least a M3 to tell Mach your spndle is started before it will look for the RPM and I think you may also need to enable the relay for spindle on spindle setup, even if you are not using one.
Hood
Re: Huge Threading Problem Help
« Reply #34 on: October 26, 2010, 02:49:05 PM »
Mach controls the spindle through a board from cnc4pc and a vfd. I didn't mess with the debounce, didn't know I needed to. What version do you recommend?

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Re: Huge Threading Problem Help
« Reply #35 on: October 26, 2010, 02:54:41 PM »
Normally you dont need to mess with the Index Debounce but maybe with the threading changes it has affected things and you may need to. Note it is the Index Debounce I am talking about and not the Debounce Interval.
I am afraid I cant recommend any version for threading except to say one from 3.042.32 or newer. Reason I cant say is I use the SmoothStepper so threading is not an issue for me, then again threading was never an issue even with the earlier revisions, probably due to plenty of HP at the spindle.
Hood

Offline RICH

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Re: Huge Threading Problem Help
« Reply #36 on: October 26, 2010, 06:24:02 PM »
Quote
Is there a different version where the threading problem was fixed but that's not .040?

Prior to version .032 threading was not done in real time so to speak. There also was the problem of a goofy X axis move and also loss of snyc with the
spindle index caused by a driver problem such that  you could end up having the Z axis trash the threads. The threading code was then
redone and tightened up to provide for improved pitch control. The compensation ( spindle slow down ) was adjusted during the revisions.
You may epxerince problems if there is a slow down say 15 to 25%, i know you can't have a complete spindle stop anymore in the later versions.
 A lot more went on but that is the gest of it.

You don't want to go back to any version before .032.  ;)

I would strongly suggest that you first do a search for all versions of MACH.sys and Mach exe Sometimes old versions are reinstalled.
Also go into Windows device manager and delete the driver. To reinstall the driver you need only run the driver test and the driver test you run should be from
.032  or whatever later version you installed.

INDEX DEBOUNCE will affect the sensitivity of the index signal. IT basically is how many interrupt periods the signal must be present, or not present before
 a change is rpm  is actually sensed.  SO if set to 2 for example, when the index appears it will be ignored for 2 periods to make sure it isn't noise.
Same with when it disappears. Setting debounce too high will make the index go away altogether, setting it at zero will mean it reads whatever is sensed, even
noise. If the reading time is too short you may not get a reading at higher rpms.

Practicaly speaking, if no rpm showing in DRO  after some rpm, lower the debounce. Try 0 , 10, and see what happens. You should have full rpm reading with
a good  index signal.

You have a VFD, then  manualy set it at a desired rpm, and not have it controlled. You should see that rpm in in the DRO. If the VFD is changing the rpm
 and mach is compensating before the thread cycle they could be fighting each other and not sure what you will end up with.

Do the tests described in the write-up, ie; spindle check out and do a scribe test. If you can't scribe an accurate line around the cyclinder then you will never
thread properly. The spindle and the motor is unloaded when you do that.  ;)

Simply said, the better the rpm reading from the index  with less change to displayed rpm the more accurate the threading will be. If you can scibe it accurately,
and then in practice it dosen't work, it could be a number of things related to motor settings and machining practice,  etc.

Hope this helps,
RICH


« Last Edit: October 26, 2010, 06:26:44 PM by RICH »
Re: Huge Threading Problem Help
« Reply #37 on: October 26, 2010, 08:48:40 PM »
Thanks both of you for the help...I HAVE SUCCESS!!

Nothing was wrong with my setup, but when my spindle slowed down I got that taper thing happening which is what started this whole thing then I was having problems with the stainless.

What I did today was upgrade to V.032 and I threaded 4 perfect parts.

What, I think, made all the difference was using an insert that was TiN coated and using actual Thread Cutting Oil. The difference was amazing.

First I cut a 16 TPI thread 4.475" to 4.3984" .005" DOC 400 RPM 1 Spring Pass, that came out good but wasn't nearly deep enough. I'm using the same parameters as before, maybe it's the new version, doesn't matter it cut fine. Then I redid the threading going deeper this time to 4.38" .01 DOC. Still that wasn't deep enough so I went to 4.37" .01" DOC and that was perfect. Absolutely beautiful crown. I had to brush on, heavily, the Thread Cutting Oil during the entire process and got lots of smoke. But it worked and I got 4 perfect parts.

Again, thanks for all the help.

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Re: Huge Threading Problem Help
« Reply #38 on: October 26, 2010, 08:53:34 PM »
One can say your now on thread ............ ;)
Glad it's working,

RICH
Re: Huge Threading Problem Help
« Reply #39 on: October 26, 2010, 08:57:02 PM »
thanks.