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Author Topic: Simple Threading Wizard Problems HELP  (Read 7031 times)

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Simple Threading Wizard Problems HELP
« on: September 09, 2009, 05:54:34 PM »
OK so for most of the threading I do I use the Simple Threading Wizard already in MACH and it works mos of the time perfect. One thing I noticed that has been happening all the time but never really noticed:

When I cut external threads every once in a great while it will do a cut above the threads, I assume that it's timing was a little off so Mach does an ancillary cut to make sure the time is correct, this cut is above the threads. When I do internal threads it does the same ancillary cut to check the timing but it's moving X at a taper and it doesn't clear the threads, it's actually messing them up. So my question is how come it does that taper move but hits the internal threads and ruins the them?

Offline Hood

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Re: Simple Threading Wizard Problems HELP
« Reply #1 on: September 09, 2009, 06:24:02 PM »
Some people seem to see this issue and Art was working through threading a while back to see if the problem could be sorted but have not seen any activity on this for a while.
 It seemed to be more likely to happen if you had a low powered spindle motor or unstable speed control but not always.
 Enable the threading plugin diagnostics and see if that throws any clues.
 Hood
Re: Simple Threading Wizard Problems HELP
« Reply #2 on: September 09, 2009, 07:38:45 PM »
Thanks Hood, but what is the threading plugin diagnostic?

Offline Hood

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Re: Simple Threading Wizard Problems HELP
« Reply #3 on: September 09, 2009, 08:19:29 PM »
Look at Config menu then Plugins and see if you have TurnDiags, if you do enable it then restart Mach then go to Plugin Control menu and click on it, you should then do a thread and see what it comes up with.

 If you dont have the plugin then let me know and I will attach it.
Hood
Re: Simple Threading Wizard Problems HELP
« Reply #4 on: September 10, 2009, 12:21:54 AM »
I got it, I'll try it tomorrow, thanks again. Have a haggis on me :-)

Offline RICH

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Re: Simple Threading Wizard Problems HELP
« Reply #5 on: September 10, 2009, 07:49:05 AM »
CARTIERUSM,
I remember that happening when we were doing thread testing a while ago. Can't recall "exactly" what the condition was that invoked that motion or what threading interation it was in ( we did a whole lot of different threading tests ). It did relate to spindle slow down when cutting and timing. Again it was infrequent and i couldn't duplicate.  

SO i am only going to guess at what i say below:
The best way to describe that x-z move is to relate it to a G60 such that the monitored move is being used as the basis to reaffirm some part of the thread cycle / programming. I remember the X ending location as being away from the outside diameter such that it never clipped the thread. Can't say anything about an internal thread.

SO whatever the condition was when it happened it, ie; spindle slow down / algorithm didn't check / G94 to G95 change / or what ever .......you will not find an answer anywhere that i know of.

Sorry, but that's my experience on it  and can't give you any "exact" advice since  the condition which creates
it is unknown to me.

RICH
 
 
Re: Simple Threading Wizard Problems HELP
« Reply #6 on: September 10, 2009, 08:02:42 PM »
Hood, I ran a 10-32 external thread today and the plugin turn diag. Now it has not done the taper extra air cut on external threads for months only on internal. Anyway, the "highest variation during threading" was 7.69%. I'm not sure if that's the value you were looking for, let me know what I should be looking at to see if anything is going wrong. Thanks.

Offline Hood

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Re: Simple Threading Wizard Problems HELP
« Reply #7 on: September 10, 2009, 08:11:28 PM »
To be honest I dont really know what you should be looking for as I have never used it due to the fact it only works with the PP and I dont have a PP .
7.69% seems quite a variation to me but maybe Rich will come back and say what he thinks as he did a fair amount of testing with the diagnostics I think.
Hood
Re: Simple Threading Wizard Problems HELP
« Reply #8 on: September 10, 2009, 09:23:08 PM »
what's PP?

Offline RICH

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Re: Simple Threading Wizard Problems HELP
« Reply #9 on: September 10, 2009, 10:23:15 PM »
PP is short for the computers parallel port.
 8% is not that bad, well kind of......
My punny Sherlne will drop 4 to 10% and have no problem getting a good thread. I have tested where the spindle was even stopped for a split second and the threading cycle recovered. If memory serves me correctly, you can go down some 20 to 30%  and the threading cycle will recovery from it.

The goal should be very little drop in rpm ( actually its motor torque / power that we are really talking about).

You should play with your small lathe trying different speeds and feeds and see what works for different materials and cut depths, make note of them. Ideally you want no drop in the rpm. Try increasing the spindle speed and use shallower cuts. Aslo you can try a different angle, like 15 degrees instead of 29 or 30 and flank cut the thread.

So, you should be looking to reduce the rpm slow down as much as possible.
RICH