Messages

1

General Mach Discussion / Re: Using more than one cutter

« on: June 02, 2009, 12:23:11 AM »

AAAAAARRGH!!!!!  Careful measurement of the part reveals the true problem.  It measures 0.3mm less at the top than at the bottom, so I'm still losing steps and getting a gradual drift of the machine position.  The centre drill is 0.6mm different from side to side (the 0.3mm out of position indicated by the part being smaller at the top).  I'm now completely back to square 1.  Will re-post to a new topic, with the correct question -back to accuracy and step loss.

2

General Mach Discussion / Re: Using more than one cutter

« on: June 01, 2009, 09:13:27 PM »

No, it was all programmed at the same time -from the same datum.  But I've obviously done something that has lost/changed the datum on the machine when changing the tool -I just don't know what yet.

Regards
Kevin

3

General Mach Discussion / Using more than one cutter

« on: June 01, 2009, 05:31:57 PM »

I needed to drill some holes in a part after machining a form on to it.  I just wanted to centre drill the hole positions to pick them up for drilling later on.  Being lazy instead of working out how to use the tool table I just did two separate programs, one for the machining and one for the centre drilling.  It's a manual tool change, so no advantage in having it all in one program anyway.  I ran the machining, then when the program finished I changed the tool, reset the Z to suit the new tool, loaded the next program and ran the centre drilling program.  But the centre drill was out of position by about 1mm in X.  I've obviously missed a crucial step in the way I did this -can anyone tell me what that was?  I did notice that the original form was cut with tool 0, and the centre drill was tool 1 (they were programmed from one cam set up and it just incremented the tool number automatically), would this have made any difference.  I have had accuracy issues in the past, but I'm happy the machine is accurate now, as the form was cut in over 60 passes all of which lined up perfectly -I just centre drilled in the wrong place.  Obviously lost position somehow when changing tool and re-setting the Z.

Regards
Kevin

4

General Mach Discussion / Re: Turning Syntax

« on: May 27, 2009, 01:53:01 AM »

Hi,

Double checked my axis today, and everything seems to be the right way round.  Plus moves away from the job and minus takes me in to the job on both axis, and they travel the same way as the cursor keys whan I jog.  All seems to be going well.

Is there a feed rate overide on turn, I can't see it anywhere.

Regards
kevin

5

General Mach Discussion / Re: Turning Syntax

« on: May 26, 2009, 01:41:27 AM »

Thanks for the advice.  I'm not worried about the X or Z axis settings -I know which way they are going, and it matches the postprocessor settings in the cam.  The important thing was the G90.1 setting, just tried the program with that in and it worked great -no more chamfers instead of arcs.  Is it important to put the G91.1 in at the end?

Regards
Kevin

6

General Mach Discussion / Re: Turning Syntax

« on: May 26, 2009, 12:09:13 AM »

I'm confused about G02/G03 as mine seem to be the other way round -see pic

7

General Mach Discussion / Re: Turning Syntax

« on: May 25, 2009, 11:43:44 PM »

Thanks, I'm missing the G90.1 The start of my code looks like this

N00010 G21 G40 G99
N00020 G97 T0000 S500 M03 G54
N00030 G00 X26.113 Z0.421
N00040 X28.14 Z-0.4
N00050 G94 G01 X25.4 F30

It's programmed in Xturn (part of the XCad, Xmill package that then became Excalibur and then seemed to dissapear).  Is it best to use the G90.1 to set IJ moves to ABS or just change the postprocessor to output them as incrimental (either is easy).

Regards
Kevin

8

General Mach Discussion / Re: Turning Syntax

« on: May 25, 2009, 10:08:08 PM »

DOH!!!! That was the wrong code, I was experimenting with some settings when I did that (I thought I'd deleted it). This was the code I meant to post

N03350 G00 Z-0.4
N03360 G01 X9.
N03370 Z-7.
N03380 X9.2
N03390 X19.8
N03400 G02 X21. Z-8.2 I19.8 K-8.2
N03410 G00 X25.8
N03420 X25.885 Z0.323
N03430 M30

9

General Mach Discussion / Turning Syntax

« on: May 25, 2009, 09:25:04 PM »

I'm running a program to do some simple turning (shown below -just the bit with the arc move in) and all goes fine until it gets to the arc move.  I just end up with a straight line between atart point and end point.  is there something wrong with my code, or do I need to change some mach settings.

Also, if the software is configured in imperial (I have imperial leadscrews) can I get it to default to metric units or do i need to configure the machine in metric (which is dd figures with an imperial leadscrew, but possibe).

Regards
Kevin

N03190 Z-7.
N03200 X9.8
N03210 G00 Z-0.4
N03220 G01 X9.4
N03230 Z-7.
N03240 X9.6
N03250 G00 Z-0.4
N03260 G01 X9.2
N03270 Z-7.
N03280 X9.4
N03290 G00 Z-0.4
N03300 G01 X9.
N03310 Z-7.
N03320 X9.2
N03330 X19.8
N03340 G01 X21. Z-8.2 R1.2
N03350 G00 X25.8
N03360 X25.885 Z0.323
N03370 M30

10

General Mach Discussion / Re: Accuracy Problem

« on: May 13, 2009, 12:12:38 AM »

Thanks for the help and encouragement.  I'm making some progress,  but not there yet.  While thinking about the pulse frequency it reminded me that I'd been limited on microstepping the drives by my frequency.  So I increased it to 35,000 and increased the microstepping on the drives from 8 to 16, which now means 1600 pulses per mm movement.  Step and direction have been moved back to 5 (as the Z axis would not drive correctly with lower settings at 1600 pulses per mm).  Although this hasn't cured the issue yet (butI've still got room to play with the step/direction values over 5) it has decreased the problem.  I think I'm still losing the same number of steps, but because each one now moves the machine by half the amount due to the higher microstepping the problem is reduced.  On a simple 2d program I think that this would be virtually un-noticable now.  It's just complex programs with lots of code that are an issue.

Regards
Kevin