Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Moonchpa on June 04, 2017, 10:25:38 PM
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Hi.
I have a chinese 6040 machine (new). Previously I have been using a Monmus home made machine which has never given the problem I face now so I am guessing the issue may be the machine not the Vectric file I created.
Simply put, after setting the project coordinates to the top of the workpiece to cut a pocket at 3mm passes, The tool plunges deeply into the wood in a vicious attempt to bury itself.
Anybody got any answers or good suggestions?
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If you zip and post your Gcode file then that can be checked and at least rule out one possibility.
Tweakie.
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Here is my attempt to attach the gcode text.
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As you suspected, there is nothing wrong with your Gcode - it runs just fine here.
Check that your cutter is secure in it's collet and not moving.
When the problem occurs stop the work and check your Z zero position.
If Z zero is now below the work surface a likely cause is loosing steps on the +Z travel - try reducing your Z axis Velocity and Acceleration settings in Motor Tuning by 50%, save the changes. Then, does the problem still exist ?
Tweakie.
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Thanks for that. However, the tool plunges maybe 20mm into the wood although I have not measured that exactly. It is considerable and not marginal which would suggest that is is more than a few steps. The collet is always tight when I undo the buried tool.
This is an extraordinary event in my experience and it keeps doing it even with another file I tried (without the tool).
It's very easy to tell when a tool is supposed to skim the surface of the wood but the Z goes deep sea fishing something is very wrong!
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Hi,
couldn't be as simple as inch vs mm units could it? Try MDIing 1 unit and see how far it actually moves.
Craig
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I set the steps per unit before, using the in-built facility in the settings tab so I know it moves accurately.
I am beginning to think it must be mechanical because I banged the Z into the top of the run a couple of times before I set my home switches properly. I will unscrew some things and see.
I may be wasting your time here because I can't see that it is a Mach 3 issue.
I will also post on the CNC forum and ask there.
Thanks.
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Hi,
are you sure, I know you've set things as before and/or used the built in facility but how do you KNOW it right?
Set the machine couple of inches above the table, zero Z, MDI G1 Z1.....How far does it move? Simple and a sure test of what 1 unit
is on your machine.
Craig
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Thanks Craig
I'll try it tomorrow when I get to my workshop.
Having never used the MDI before can you explain what those commands mean?
G1?
Z1 I presume means it moves one unit... e.g. in my case 1mm?
Peter
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Hi Peter,
G1 means 'co-ordinated linear move at feedrate'.
Being able to read and write simple Gcode fragments is a required skill of CNCing. There are plenty of Gcode tutorials online,
observing the code generated by wizards loaded in Mach3 are valuable learning resources.
'CNC Programming Handbook' by Peter Smid is pretty much the bible as far as we are concerned.
Learning new things is a consequence of and major benefit of our hobby.
Craig
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"Learning new things" is my mantra, hence launching into cnc routing. It has probably been the steepest learning curve I have had in 20 years! I'm a reader so I will look for the book you recommend unless you think it is for advanced cncers.
Peter
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Hi,
yeah CNC is a great hobby for extending your knowledge horizons.
The book is available online, probably free if you scout about. Its a BIG read...
and if your not advanced when you start you will be by the end!
Some of the tutorials are rather more 'accessible' and considerably quicker to get a basic grasp.
Look at the Gcode produced by some of the wizards, rectangular pocketing, circular drill pattern
for instance produce usually fairly simple readable code and worth studying if you wish to write
and therefore read your own code.
Craig
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To all whom it may concern.
My dilemma with the plunging router bit has been solved. It was an error on my part in Vectric software.
In the dialogue panel for toolpaths there is a small dialogue box at the very bottom which sets the axis number on the 3 axis I use. Another setting sets the height for the tool to pass over the work piece which is generally set at about 6mm. Further to this configuration at the bottom of all the settings is this other setting. The X is always set at 0 and so is the Y. But I discovered that the default (?) setting for the Z was very much higher than my machine could manage once I set the work offsets to 0. How it came to this setting I do not know but it obviously has been high ever since I started to use Vectric software. It never made any difference to my previous machine, a home made Momus which had a higher setting for the Z.
My new machine, however, on ready this high setting (41+ mm) was making the Z axis reach for the moon and hit the top. Not being aware of this other than hearing it groan there a bit it would then descend to the work piece and go digging.
I gather that while the Z axis was grinding to go higher than it could, the pulses from the motor was telling it that it was higher than it actually, physically was, hence the desire to go down too far into the wood.
I hope this makes sense. It does to me and now I have my machine working properly... but not quite.
About 3/4 of the way through the gcode Mach3 froze and I could'nt get any axis to work again until I restarted it and lost my place to start again.
Peter :'(