Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: lswatson on September 27, 2007, 08:37:38 AM
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I'm a noob and have had a recurring problem. Small test models come out fine. I change step over down to .05-.02 and my models often come out 1+mm too thick. I've eliminated tool shift in the chuck, all Z axis issues (checked before and after models and its dead on), and Lex at Desk Proto has reviewed my G Code and its fine.
So now I've come to find out how I can detect if Mach3 is giving me this problem. I know nothing to suggest it is, except process of elimiantion. Which has taken almost two months of head banging.
The other day I ran three parts on one wax. No tool change. First two 2mm thick as desired. Changed step over in DP, ran the third part (for four hours) and it was 1.2mm too thick. Z checker varified Z was zeroed before and after the run.
Any hints or tips would be grealy appreciated.
Thanks in advance.
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Changed step over in DP
What does this mean? DP?
Brett
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Ooops, sorry.
DeskProto.
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Ok, if you are regenerating your Gcode and then reloading, could be lots of things. Is the home posotion to same for both files? I don't think this is a Mach problem. I think it is in the code or, the way you zero, set work coord., etc. If you have a certain depth set and are using a v-bit, the step over may change your depth. The wider the step over, the deeper the bit will have to go to clean up .
I hope this makes sense.
Brett
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Hi Brett,
Thank you for responding.
I am not setting a particular depth other than cutting to the surface of my model. I import an STL of my model in Desk Proto, and generate the tool paths there. I'm using bits in the .015 to .003 range, with 0 "skin" on the model, one tool cutting the entire model.
The developer of Desk Proto has checked the code and it looks good. Zero for the part is zero for all axis' of the mill. The part is centered (half above, half below) the intersection.
I'm zeroing with an electrical widgit and a special gauge for setting Z. From those settings I can cut test models to within .0003". Which is fine for my jewelry pieces.
I just recently started using the Z gauge. I zeroed it, cut two models in a piece of wax. Both were fine, except for the step over. Changed the step over of the second part, ran it a third time. It was 1.2mm too thick. This had happened time and time again. But not until I got the Z gauge did I have proof the tool was not moving. Z position of the tool was identical after the third part, as it was when I set it prior to running the first part. All indications while I am in Desk Proto is that the model is set up properly. Needless to say, I've checked this many times since having this problem, which is over two months when I started milling.
My wax is put in the rotary axis with tail stock holding the other end. I am performing a two sided milling proceedure with an auto flip between sides. This is set up in Desk Protos N-Sided Wizard. I then load the G Code into my milling computer, open in Mach3 and run it.
Any ideas of what to check are appreciated.
By the way does anybody else have Mach lock up with G Codes approaching 5 million lines? Thats another problem I have had.
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I zeroed it, cut two models in a piece of wax. Both were fine, except for the step over. Changed the step over of the second part, ran it a third time. It was 1.2mm too thick.
Did you zero it again, as you did the first time, before you ran it the third time?
I have sent you a personal message.
Brett
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Hi Brett,
Thanks for the note. I'll follow up.
I did not zero between part #2 and #3.
#1 and #2 were dead on re: thickness (Z height).
So I ran #3 and got the surprise. I checked Z after running #3 and it was .0003, high. Which is well within my needs.
This extra thickness problem happens often. Small parts (10mm and under) with step over more than ..5 to .1 seem fine.
When I go to .03 or .02 stepover, thats when I have the problem.
I appreciate your help.
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What version of MACH are you running??? Are you using stop or rewind during your testing, if so watch the dro for XYZ as you press stop, rewind. Did they change any. You may want to try the latest version (;-) 2.51.
(;-) TP
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Hi Brett and TP,
I'll have to check which version I have. It came with my Taig mill which I got in early June, and was the most current version as of last May.
Last night I may have discovered two "operator errors" to account my my topsy turvy results. I won't waste space explaining, but its akin to putting your hands on the wrong keys on a keyboard and typing away. That one initial error creates endless errors afterward.
It seems Mach3 is in no way responsible for my results.
Although I do have a question about Mach locking up on my 4.9 million line code. I even tried it on my dual core, 4 gig, 64 bit Win XP Pro system and Mach would not load the code. Is there a known limit to the number of lines Mach can load?
With a step over of .02 to .01 and very organic displacement surfaces ( like a cloud texture on a pendant), the G Code gets pretty lengthy.
Thanks again for your responses to my posting.
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Glad to hear you are making progress. I don't think there is a limit to the number of lines of code you can run, not certain though. Maybe someone else will pitch in and help on that one.
Brett
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Might be your toolpath is the problem with the large file, try turning the toolpath off and see if that helps.
Hood
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Excuse my ignorance, but how do I do that?
I'm creating the NC program in DeskProto and opening it in Mach.
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Look on the Diagnostics page, just above the reset button you will see a Toolpath On/Off button.
Hood
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Hi,
I had a similar problem until I turned on an option on the Config->Motor and Pins dialog. The option is had to check was "G21 half step mode". (right hand side on first screen)
Hope it helps...
Conroy
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Thanks. On my screen its right below the Diagnostics button on the Diagnostics page. Which is top center. Reset button is bottom left.
So I can turn toolpaths off and still run my part?
I know, that must be another really dumb question. :-[
Thanks for the tip.
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Just loaded the 4.9 million line file with no problem.
Thank you !!
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You must have an older version but to answer your question, yes all that will happen is the graphics for the toolpath wont load so you will not see anything but your code will run just fine.
Hood
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You posted while I was typing, glad you got it sorted :D
Hood
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Ah, thanks again.
My version looks to be from May, 2007.
But it does have a special interface set up by Taig.
Anyway, now I know where the button is, and my code loads.
Which is a big step forward.
;D
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You can upgrade if you wish to a later version, just backup any custom screens, macro etc that you have just in case they get overwritten.
Hood
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I may upgrade later.
All I do is zero stuff out, jog a bit and load & go.
No major acrobatics within Mach on my part.
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Well as they say "If it aint broke why fix it" :D
Hood
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Thanks again, guys,
Couldn't ask for more helpful and timely support.
And at 6:30 am on a Sunday........