Messages

41

General Mach Discussion / Re: Continually incorrect thread pitch

« on: August 12, 2009, 09:46:03 AM »

Well I'm running 1250 steppers on a 12X36 lathe. I just input 86 RPM in the wizard and am now getting 20 threads per inch. I don't understand why I have to enter any rpm in the wizard or need it if the threading movement is synch'd with the spindle index pulse.

42

General Mach Discussion / Re: Continually incorrect thread pitch

« on: August 12, 2009, 09:10:46 AM »

After checking my electronic system again and testing the mechanics coupling, I find the machine is rotating at the speed indicated by the electronics. It starts off about 20% fast at slow speeds and changes to about 10% at higher speeds. Since this is the case, should the threading still be correct since I have the threading movement synch'd with the feedback?

The cheap chinese lathe has been retrofitted with good ballscrews and adequate mounting and motor coupling. There is no measurable backlash greater that .001. I believe the gears in the lathe are crap and don't indicate what they should be but the electronic gearing should solve that.

It is a new cheap chinese lathe. :-)

43

General Mach Discussion / Re: Now What! Jog says mm - Gcode say G21 - machine moving in inches

« on: August 12, 2009, 08:46:13 AM »

I do appreciate your help and I know this is the best value I have found in many years of hobby (or professional) cnc.

44

General Mach Discussion / Re: Continually incorrect thread pitch

« on: August 12, 2009, 08:16:41 AM »

Under config plugins it is there and I have it green checked but under plugins it isn't there.

Nevermind. I needed to reboot. It's there now.

I just checked with the scope again and it looks good. Strong 5V signal about 2mS every rpm.

When I run threading I get 86.28 rpm. Threading in effect. Rpm variation running from 0 to .04. Highest variation .06.

That's kind of strange since the spindle is suppose to be running at 70 rpm. That's my 20% variation.

45

General Mach Discussion / Now What! Jog says mm - Gcode say G21 - machine moving in inches

« on: August 12, 2009, 08:13:56 AM »

I'm about to start questioning my intelligence. My units are mm? The jog display says mm. I have g21 in the code. So what magic switch did I forget to throw?

 
G80 G21
G0 Z0.26
G0 X-0.26
F25
G0 X0.25
G1 Z-14.95 <-- tries to move to -15" here!
G0 X-0.01 Z-14.74
G0 Z0.26
G0 X0.5
G1 Z-14.95
G0 X0.24 Z-14.74
G0 Z0.26
...

46

General Mach Discussion / Re: Continually incorrect thread pitch

« on: August 11, 2009, 08:00:36 PM »

No the threads don't look that clean. More of a U than a V. I thought that was from the tool bit. I don't have a threading plugin. I have Version R3.042.020. I am using synch with spindle speed averaging.

47

General Mach Discussion / Continually incorrect thread pitch

« on: August 11, 2009, 10:21:48 AM »

Everytime I setup .05 pitch for 20/inch I continually get 24/inch. I haven't checked any other pitch but I have check my screw specs and pulses per inch and they are correct. 20% off would certainly show up even with my measurements. I slowed the rpm's to 70 and have tried 3 other settings. The actual spindle dro is saying 203 at 200 and nothing at 70 but the pulses are showing up correctly on the scope. The automatic setting in pins settings still show the spindle index is correct at 70 rpms too.

Come on guys. It doesn't have to be right. Just guess, I won't say anything. I'm out of ideas.

48

General Mach Discussion / Re: Machturn threading problem

« on: August 11, 2009, 10:17:13 AM »

Thank you that was it.

49

General Mach Discussion / Machturn threading problem

« on: August 11, 2009, 08:58:23 AM »

When I use the threading wizard I get one move starting 80" away from the chuck moving towards it. I can't figure out why or how to get rid of it.


result:
G0 G40 G18 G80 G50 G90
G00 G53 X2 Z1
T202M6
G00  X1.025
G00 Z0.1
G00 X1
M03 S360
G76 X0.95 Z2 Q2 P0.05 J0.01 L45 H0.01 I29 C0.025 B0.001 T0
M9
M5
M30

50

General Mach Discussion / Change motor direction in MachTurn

« on: August 10, 2009, 12:24:46 PM »

How do I change the motor direction in Machturn. I have the z axis going in the wrong direction and don't want to take it apart.

Also, does anyone have a trick about getting swarf out of a tube while boring? I keep getting lousy finish because the swarf gets caught in the following cuts.