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Newbie problem with Mach3 Turn
« on: November 30, 2009, 05:30:20 PM »
Hi, I wonder if I could tap the collective wisdom on a problem I'm having?  I've got the mechanical conversion of my Super-7 done and built the electronics and everything seems to work fine in "manual" - it jogs properly and accurately and all seems OK.

Then I started to try actual CNC turning and have met a problem.  I started with a piece of 1" bar, to turn down to a shoulder a 10mm long spigot 20mm diameter.  I set the tool origin to Z=0 at the end face of the bar; and X=25.4 diameter on the diameter.  I set the rough cutting to 0.25mm depth and 15 mm speed; and the finish cut to 0.1mm and 5mm; clearance was set to 1mm.

When I set the spindle running and fire off the cycle, it takes the first cut fine; but when it gets to the end it feeds the tool firmly INTO the work and quickly returns the Z axis taking off some very thick swarf in the process!  At that point I pressed the estop in a panic.  It has happened a couple of times...

Could anyone give any pointers as to what I'm doing wrong please?

I should say that I've been really impressed by loading and setting up Mach3, it's a great piece of work and I can see that I'll be spending a lot of time re-learning the lathe!

Thanks, John.

Offline Hood

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Re: Newbie problem with Mach3 Turn
« Reply #1 on: November 30, 2009, 05:39:45 PM »
Where are you getting the code from?

Hood
Re: Newbie problem with Mach3 Turn
« Reply #2 on: November 30, 2009, 05:41:17 PM »
Ah, sorry, I'm using the wizard - radiused shoulder (but with radius = 0).

John.

Offline Hood

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Re: Newbie problem with Mach3 Turn
« Reply #3 on: November 30, 2009, 05:51:01 PM »
Can you attach the code you get, may be a problem withthe wizard.
Hood
Re: Newbie problem with Mach3 Turn
« Reply #4 on: November 30, 2009, 06:18:19 PM »
You say "it has happened a couple of times".
Does that mean that some times it's OK?
If you run without a part or just look at the graphics are things OK after the move into the part?

Offline RICH

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Re: Newbie problem with Mach3 Turn
« Reply #5 on: November 30, 2009, 07:22:39 PM »
John,
I would check your axis for backlash. When it's done with the finish pass it should pull back that 1mm , clear the stock, and then move back in Z completely clear of the stock. Additionaly you may wnat to make sure your work is rigid, since there could be some spring.  Post the code , but, i don't think it is the code, but rather your lathe.
RICH
Re: Newbie problem with Mach3 Turn
« Reply #6 on: December 01, 2009, 05:01:04 PM »
Thanks for all the input.  Just for the record, tonight I did some testing with a DTI instead of the tool and a 3/4 test bar in the taper socket, so I could monitor the actual moves.  There was no sign of the problem, everything went as expected, actual tool moves made exactly as the on-screen monitor showed.  No sign of rigidity problems (this is a S7, and it cuts perfectly normally under manual control), backlash within expected limits.

This test was done with the spindle stationary; then I tried again with the motor running but clutch disengaged; and again with spindle rotating - everything still as expected. 

I decided to try again with a tool and cutting a bit of stock (not my test bar!).  One thing I did was to change from "Tool 0" to tool 1 - don't know if that's significant.  Anyway, this time it worked exactly as expected, no sign of the previous problem.  What was going on I don't know, but it seems to be fixed!

Thanks for the suggestions, sorry this was maybe a red herring, but they made me go back and check everything so for me it was useful.

So a milestone (for me) - lathe/computer combo has made its first unaided successful cut!

John.

Offline Hood

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Re: Newbie problem with Mach3 Turn
« Reply #7 on: December 01, 2009, 05:04:26 PM »
Could have been that you had Tool Zero  chosen, not sure what that would do as I have never tried LOL

Good to hear you have it cutting now :)

Hood