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Author Topic: Parts are not correct size!  (Read 9866 times)

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Re: Parts are not correct size!
« Reply #20 on: April 07, 2009, 06:30:56 PM »
Hi Sage

I cant upload the toolpaths as they are proprietry .. however they have been run on this machine under TurboCNC and work fine - hardware is not an issue. I have also sent them to Graham via email and he is looking into it.

Yes you are right - I should have kept the second problem for another post... I'll elaborate further on that particular issue once this one is sorted. Pls ignore post #16
« Last Edit: April 07, 2009, 06:33:39 PM by PROMiCA »
PROMiCA - CNCKits
Melbourne Australia

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Re: Parts are not correct size!
« Reply #21 on: April 07, 2009, 07:25:14 PM »
It would help IF you created a test file that duplicated the results you see so we could see and run the file and test for the same results as you.

(;-) TP

Offline Sage

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Re: Parts are not correct size!
« Reply #22 on: April 07, 2009, 08:13:02 PM »
Well, all I can say is your examples have been confusing, such as this one from above (edited for brevity):

Using a 10mm cutter I manually drove the tool about to make a 40.5mm square
Finished part sizing from Mach3 (MDI & g-code)

MDI       - X40.02 Y39.95
Same three parts done under TurboCNC3
MDI       - X40.00 Y39.99


Looks to me like neither of these (including TurboCNC) is making the square to the propoer size of 40.5mm so I remain confused how you figure TurboCNC is doing any better than MACH3.

Sorry I can't help you more. I still recommend (as others) making a simple program to demonstrate the problem that others can use to help you out.


Sage
Re: Parts are not correct size!
« Reply #23 on: April 07, 2009, 10:05:52 PM »
Hi again Sage.


At the risk of sounding a bit defensive you need to read and comprehend ... the text you edited out of my post said that I then took 0.5mm OFF as a FINISHING cut which would make it 40.0mm !!

The purpose of the exercise was to see what differences there were between TCNC3 and Mach3. Each test consisted of three actions - manually driving the tool by MDI, then doing the same but from a gcode file and finaly one was to see if radiusing the corners had any bearing on the outcome as the part I was working on when I found this issue has radiused corners. Pretty simple really and I'm sorry if it confusses you. :)

TCNC3 had the parts to within 0.02mm (0.0005") whereas Mach3 was up to 0.11mm (0.004") out - by my calculations that's 8 times 'worse'. You need to remember that I usually work in metric and 0.01mm is roughly 0.00025". To people who usually work in imperial 0.02 looks like allot - but it's not!!

And again as already stated Graham has the code and is doing his own testing.

If I get the chance later today I will make some test files and post them here.
PROMiCA - CNCKits
Melbourne Australia

Offline Sage

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Re: Parts are not correct size!
« Reply #24 on: April 08, 2009, 08:07:34 AM »
Sorry, I stand corrected. I missed that additional action of taking off the extra 0.5mm.

Sage
Re: Parts are not correct size!
« Reply #25 on: April 15, 2009, 06:25:24 PM »
Sorry for the delay in updating this ...been busy !!

From what I have been told this is a bug that they have been trying to find for a while now ... apparently it only ‘pops up’ now and then and may involve code which utilises G28.1, G92, subroutines and offsets (all in the same code file).

A couple of days after starting that post I ran another job which uses all of the codes in the one file – it ran perfectly... as have others since. There seems to be no logic to which code it will effect which makes it very difficult to work around ... at least if it always did the same thing to each and every file you could code around it or take it into consideration when first designing your part.

Apparently the driver section of the new Version 4 is totally re-written and should have no issues.
PROMiCA - CNCKits
Melbourne Australia