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Messages - mbele

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General Mach Discussion / Re: Is my PC too slow or...?
« on: April 20, 2013, 04:11:11 PM »
Thank you Hood & Ian! I don't know what to say... guys, you're great :)

When I watched Hood's video, I saw the same behavior as in my system: machine slows down/stops three times during execution of one loop - only, on Hoods video it looks smoother than on my machine. I allready wrote the response, thinking that it's normal behaviour and that I'll have to live with that, but then I saw Ian's videos that do not show those 3 glitches :)

Ian, what are your CV settings / lookahead ? Maybe there's a catch...

General Mach Discussion / Re: Is my PC too slow or...?
« on: April 20, 2013, 08:25:05 AM »
Can someone run attached test file @ 8m/min with 0.1G accel ?

I just managed to run it in the air @ 8m/min with 0.3G accel, and the motion is smooth, but these are not safe settings for my machine.
If I lower the acceleration (tried 0.25G, 0.2G, 0.15G and 0.1G) motion is not smooth any more - making slowdowns/speedups between segments more obvious as accel is more decreased :) 

So, my current conclusion is that there are "valid" acceleration and feed rate settings for CV algorithm to work properly, and that they are somewhat proportional (at least on my system/setup, running latest version of Mach3)
Actually, could it be that, because of the lower acceleration, CV is turned off so that cut accuracy wouldn't suffer ?


Others / Rhino: 2D path to g-code
« on: April 19, 2013, 03:53:13 PM »

I've attached few scripts that I use to generate g-code from curves drawn in Rhino. Supported curves are lines, arcs and circles, so before executing scripts, paths should be converted to lines/arcs.

SegmentsIO - import/export paths (evaluation version does not alow but 25 saves)

2DPath2GCode - creates gode from planar lines,arcs and circles. One polycurve (joined lines/arcs) is treated as one continous feature. If you're getting weird paths from polycurves that overlap at subcurve start/end points, try turning off "simplify" option.

Holes2GCode - creates gcode for drilling holes from circles and/or points (other curves will be filtered out after selection)

disclamer: use at your own risk :)

ps. if you find bugs, please post seg files here

General Mach Discussion / Re: Is my PC too slow or...?
« on: April 19, 2013, 03:11:01 PM »
Thank you Ian!!! Not only that program initializes in no time, but the quality of motion is so much better. I'll take out redundant Gs too :)

Now it runs fine at 5m/min with 0.3G accel. For higher feeds I had to lower acceleration to avoid loosing steps. Above 5m/min with 0.1G accel motion is not smooth any more - slowdowns/speedups are noticable, but since accel is relatively low, the machine doesn't vibrate too much. Would higher acceleration make the motion smoother (actually, I tested that and the answer is no, but I cannot be sure since I'm on the limits of available torque) ?

ps. I'm putting rhino script that generates g-code from arcs and lines in downloads section

General Mach Discussion / Is my PC too slow or...?
« on: April 18, 2013, 04:14:35 PM »

I've noticed some time ago that when I increase feed rate via feed rate override in mach3 mill it looks like CV mode turns off (moves are not smooth any more). I'm able to reproduce this behavior now, so I'm posting my g-code and xml file. When program is running at 4000mm/min it runs fine, but when the feed rate is set to 5000mm/min or above (via feed rate override or in g-code program) moves are not smooth any more. What's more interesting is that, at raised feed, the first pass is smoother that the following passes :) I haven't noticed lost steps.

PC is based on AMD Athlon 2400+ 2GHz CPU with 1GB RAM running XP SP3 (Standard PC install). It takes one minute for the attached g-code to initialize (I've always experienced very slow initialization when program is based on arcs).

I get peak power from steppers at ~4000mm/min (~200RPM x 20mm lead direct drive 2.7Nm steppers 1/8 micro-stepping). Kernel runs on 25kHz.

I'd really like to be able to feed faster since my spindle is not very strong and I have to take light cuts.


General Mach Discussion / Re: How to customize keyboard shortcuts
« on: August 06, 2012, 05:04:01 AM »
Thank you Gerry

General Mach Discussion / How to customize keyboard shortcuts
« on: August 05, 2012, 08:48:37 AM »

is there a way to disable all Mach3 keyboard shortcuts, and define smaller set of custom ones ?



I had a similar situation - Z axis would "drift away" after many moves.
Eg. after test case with 500 runs of subroutine that moves 10mm up+down, zero position would consistently be arround 4 mm to low. That makes arround 0.004 error per move (less than one microstep in my setup which is 0.0125mm).
Anyway, after I tried/checked all that was suggested in this thread, finaly changing the kernel speed from 35kHz to 25kHz made it work perfectly.

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