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Author Topic: Odd glitch in movement?  (Read 10737 times)

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Offline Davek0974

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Odd glitch in movement?
« on: April 24, 2014, 07:16:54 AM »
I drew up a part this morning and run it on my plasma table in thin sheet as a trial part.

It contains arcs and straight lines plus one circle, I have attached the dxf file plus a picture.

On the picture I have marked four points where the action goes from straight motion to an arc and there is a visible divot at each point.
However there is no divot at the exit from each arc - it transitions perfectly. The other bigger arrows indicate cut direction.

I can not see anything wrong in the dxf and likewise in sheetcam so it has me guessing now, any ideas???

Offline stirling

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Re: Odd glitch in movement?
« Reply #1 on: April 24, 2014, 12:07:08 PM »
I've got a feeling I've seen this before - but my memory's shot. I seem to remember it was only happening on straight line to clockwise arcs - which looks like what you're seeing. I think this was YEARS ago though. What version are you using?

Offline Davek0974

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Re: Odd glitch in movement?
« Reply #2 on: April 25, 2014, 02:16:00 AM »
This one - Mach3Version3.043.066.exe

Offline stirling

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Re: Odd glitch in movement?
« Reply #3 on: April 25, 2014, 06:20:04 AM »
Never used 3.043.066 but I believe Hood advises not to use it.

Offline Davek0974

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Re: Odd glitch in movement?
« Reply #4 on: April 25, 2014, 06:22:58 AM »
Damn  ::)

Is there a "recommended" plasma version?

Also, is it an easy install or do i have to follow a winding path to get it all working again?

Offline stirling

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Re: Odd glitch in movement?
« Reply #5 on: April 25, 2014, 06:44:16 AM »
Someone woke up Mr. Grumpy this morning then...

re-install is easy - but of course you should always backup first. I do it all the time on my test PC to try different things and have never lost any settings. I do it by un-ticking everything except for the parallel port driver. That way it installs Mach and the PP but no xml, no screensets, etc.

Just a hunch but read this thread - I think it may be related. http://www.machsupport.com/forum/index.php/topic,24350.0.html

Offline Davek0974

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Re: Odd glitch in movement?
« Reply #6 on: April 25, 2014, 07:53:41 AM »
Not sure it was related but interesting anyway.

I have a copy of 062 here, I'll try that.

Offline Davek0974

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Re: Odd glitch in movement?
« Reply #7 on: April 25, 2014, 10:40:12 AM »
062 made no difference.

Something I have just noticed is that on a dumbell shape cut - a bar with a circle on each end, I get a sharp entry into the arc from the straight but on exit from the arc to the straight Mach is cutting the corner and giving some sort of fillet - the two sides do not match.

Picture attached.

the drawing looks like the sharp transitions not the rounded ones.

Is this a mach issue or a settings issue?

Clearly it could not be used like this.

It is better at low speed but still the entry/exit do not match

Offline mc

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Re: Odd glitch in movement?
« Reply #8 on: April 25, 2014, 12:02:47 PM »
Could be a lookahead/CV problem.
How are the arcs being created in the G-code?

Probably worth uploading the G-code you used for that, so people can see if the G-code is good.

Offline Davek0974

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Re: Odd glitch in movement?
« Reply #9 on: April 25, 2014, 01:49:39 PM »
This is the code, I know there is an issue with the odd THC on/off codes but that's not the issue here and is being dealt with elsewhere.

I have learnt that it seems to be connected with CV and acceleration settings so I'm going to retune next week and see if that makes a change.

N0010 (Filename: Test 1.tap)
N0020 (Post processor: Mach3 THC with scriber 2.scpost)
N0030 (Date: 25/04/2014)
N0040 G21 (Units: Metric)
N0050 F1
N0060 G53 G90 G40 G64
N0070 (Part: Test 1)
N0080 (Operation: Outside Offset, 0, T2: 1.5mm Steel, 30A, Std Tip, 103v)
N0090 G00 X41.3478 Y30.1053
N0100 G28.1 Z3.00 F800.0
N0110 G92 Z0.0
N0120 G00 Z3.9000
N0130 G92 Z0.0
N0140 G00 Z3.5000
N0150 M03
N0160 G01 Z1.0000
N0170 M101 (THC Off) (On arcs)
N0180 G03 X50.9478 Y20.5053 I9.6000 J0.0000 F2310.0
N0190 M102 (THC On) (On arcs)
N0200 G01 X72.6444 F3300.0
N0210 M101 (THC Off) (On arcs)
N0220 G02 Y9.4947 I14.3556 J-5.5053 F2310.0
N0230 M102 (THC On) (On arcs)
N0240 G01 X29.3556 F3300.0
N0250 M101 (THC Off) (On arcs)
N0260 G02 X0.5522 Y9.7414 I-14.3556 J5.5053 F2310.0
N0270 M102 (THC On) (On arcs)
N0280 M101 (THC Off) (On arcs)
N0290 X9.7414 Y29.4478 I14.4478 J5.2586
N0300 M102 (THC On) (On arcs)
N0310 M101 (THC Off) (On arcs)
N0320 X29.3556 Y20.5053 I5.2586 J-14.4478
N0330 M102 (THC On) (On arcs)
N0340 G01 X50.9478 F3300.0
N0350 X52.4478
N0360 M05
N0370 G00 Z10.0000
N0380 X0.0000 Y0.0000
N0390 M05 M30