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| Machines running Mach Software Discuss your set-up and experiences running your machine using Mach software here. |
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#1
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Another question hopefully you can answer. I use 3D bridges in my toolpaths to hold parts whilst cutting. If the 3D bridge is on a straight cut it works fine, however if the bridge is on a curve the movement becomes jerky etc.. Is there a setting in Mach that may eliminate this?... Normal cutting of curves and circles are no problem, perfect. Any help appreciated. cheers Frans |
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#4
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Hi I can`t confirm this statement but I`ve heard something a while back. Steppers can`t keep up to one another when the axes are moving similtanously. I believe this is even more true when the speed is high. I saw a video by Jeff Davies of homecnc using his servo machine and didn`t notice any jerky movement. From what I saw the motion was very smooth. I too have a stepper system and I see jerky motion when two axes are moving at once. Maybe someone here can jump in and clarify this condition. Barry |
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#5
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| I had the same problem with my Machine Centre with a Fagor 8055 controller. The fix is to put G51 E0.0001 at the beginning of the program. G51 is the Look-Ahead mode which enables the CNC to look ahead up to 50 lines, analyze the tool path and calculate the max feedrate with an max error of 0.0001mm. Don't know if Mach has the equivalant feature. |
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#7
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| Hello Kiwi.. Had a look at the G codes and settings.. couldn't see an equivilent for Mach 2. maybe someone esle will know. I have a feeling it may be a Mach 2 resolution issue?... Bgolash.... Steppers can keep up with Servos etc.. and co-ordinate all axis together.... it is the drivers and controllers that govern how well it works..... cheers Frans |
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#8
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#9
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| Hi Moondog I agree with you that Mach does compensate for different pitches via the setup but whether the pulses out are synchronised is another story. I believe (and I could be very wrong) that when you use circular interpolation (just by using a G02 or G03) that the contoller (Mach) may not synchronise the two axes very well for whatever reason resulting in a 'jerky' movement. I'd fire off an email to Art for his opinion on this. I can't for the life of me remember where I read it. It may even be in the Mach manual. Cheers derekj308 |
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#10
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| If its just a matter of smoothing out those sections of code couldn't you just do a feed rate change to slow down for those sections?
__________________ Halfnutz (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management) |
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#11
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I still think it is a Mach2 resolution problem... |
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#12
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| I do it all the time with a simple F20 at the beginning of the problem and a F40 at the end of the block. Just run the program, and wherever you hit a problem stop the program, open it in the editor, back up a line (or two) add a feed change to the first line of the block and one to the end of the block, and resume cutting at where you stopped. Once you run through the program once you have the problem fixed for good. If its a program you use more than a little, its not a big deal. I use diferent feed rates throughout most of my programs. If Im at the beginning and doing the roughing with little or no Z movement and a simple raster scan I will crank the feed up to 70 or 80 IPM and then slow down to 30-40 for areas with lots of contouring and multi axis movements. I geusse its a pain, but I only have to optimize the program once, and I can take a two hour program down to an hour sometimes. If its a design I like and plan on using over and over its well worth it. I dont know exactly what your doing of course, maybe your talking about a six hour program with a tab every fifty lines, who knows, but its a something to consider.
__________________ Halfnutz (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management) |
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