Machsupport Forum
G-Code, CAD, and CAM => G-Code, CAD, and CAM discussions => Topic started by: ekcourter on January 02, 2019, 06:21:27 PM
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I have a 30 minute plus program and need to re-home my axis about mid point, hands off, using code. I miss enough steps so that the end of the cut is out of position with the beginning. If I slow down for accuracy the time doubles. I need to make about 250 so the time is important. 3 D Carving, using Mach 3 & MeshCam. Thanks for the help, Edward
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Do as you wish, but, what your asking is not the way to take care of missing steps.
Acceleration setting becomes more important on small axis moves to save time. In carving you will have a lot of small axis moves.
Make adjustments in the software ( MeshCam ) to maximize the efficiency of machining relative to a repeatable accuracy level that your machine is capable of. If not satisfied then upgrade the machines capability.
Again, a workaround to an ill defined cause of the problem, is just not the way address the problem.
RICH
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Thanks, The machine is fair to poor but cannot, at this time, be upgraded or replaced. I'm afraid I have to work with the equipment I have, rather than the equipment I wish I had. Edward
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G28.1 ?
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try to get the root cause, not fight against the effects.
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@TPS: Edward knows what the root cause is. If he eliminates it, he doubles the work time.
Sooo... I guess that he contracted a job and is trying to be on schedule (MHO), but the poor machine cant keep the pace.
One of the remedies would be to decrease the acceleration and a little bit G0 speeds.
Rehoming at the middle of the run is not an option as there are errors settled in.
;)
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Its a large wood carving that gets 10/20 thou fladder sanded off after carving. Where I need some help is with the alignment, or parting lines between successive runs. Even these are heavily sanded. What I hope to gain is just some reduced sanding. The machine is very sloppy by metalworking standards but fair for woodworking tolerances. If I could I'd re-home every 15 min. I have been making the same product in the same quantities for 8 years.
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You have what you have!
Don't expect some band aid approach to do machining with a machine run in a manner which is above it's capability.
Can't imagine anyone making recommendations to run your current machine outside of it's capability.
I am thinking, that after 8 years of making the same product, you have done all you can to refine what your doing in MeshCam
to generate a time saving program.
RICH
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BTW,
You can return to home / to some point any time by adding a few lines of the proper gcode to your program.
The problem that you have is that you don't know where / when your actually missing steps, and chances are the missed steps are not repeatable at some location of the program. IE; If you have no head room in your tuning to account for variations in the properties of the wood or whatever you will continue to have reliability problems.
FWIW,
RICH
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I could tell it was beyond it's capabilities from day one. If I replaced It, I probably would use a profile copier with a pattern instead of cnc. The dreaded analog.
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What few lines of code will return the machine to the home limit switches, stop on those limit switch and set the machine zero to the new positions? And then continue on with additional lines of code, hands off? Thanks All Edward
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You could try something like this, NOT tested so be careful
Put a copy of these lines where you think they are needed
M1001 (call macro to record current positions)
G00 Z(Move to save level)
G91 G28.1 X0 Y0 Z0
G00 G90 X#1000 Y#1001
G01 Z#1002 Fffff
continue with code
....
Macro M1001 to be stored as M1001.m1s in current profile macro folder
‘ Get Machine Positions and store into #vars
SetVar(1000,GetABSPosition(0))
SetVar(1001,GetABSPosition(1))
SetVar(1002,GetABSPosition(2))