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Discussion Starter · #1 ·
Hi folks new guy here, looking forward to sharing and learning new things, that being said can anyone help me with a problem I am having with my CNC?

all of a sudden the accuracy on my machine went whacky, I went through my machine and everything seems to be tight, so I am thinking its sofware I have Vcarepro I did a test cut on 3/4 mdf I did a 3" hole and a 3 plug and it came out a little over an 1/8" sloppy. both the hole and the plug were spot on as far as square edges and roundness goes, just too small?? any help woul be greatly appreciated

Mike
 

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Did you doublecheck that the measured bit diameter matches what was specified in VCarve? Using a 3/16 bit when you specified 1/4 could cause this, for instance.

Also, in VCarve, you have choice of cutting inside, outside, or along a vector. You need to choose the appropriate one.
 

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Discussion Starter · #3 ·
yes thats the first thing I checked, I just did a second test and the results are the same, I thought maybe I had the ''offset'' box checked but that was not it
 

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Can you give us a little more info about your machine and controller software?

If you install a v-bit and line it up with an accurate ruler and then, via your mdi command a move (I.e. g1 x12.0). Does the axis move the correct distance? If not, it is your “steps per inch” (or mm) setting that is probably off for that axis.
 

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Discussion Starter · #6 ·
It is a 4X4 cnc from cncrouterparts I bought as a kit and put togrther myself nema 23 motors rack and pinion drive software is Vcarve pro, had it about 5 years never had a problem

till now been an awesome machine I will try what you say in the morning, how do I chang steps per inch? thanks guys

and joe yes it was inside for hole and outside for plug with a 1/4 end mill
 

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Discussion Starter · #8 ·
Hi David,there are no offset's set on the program I am going to try what Richard suggested about the steps per inch and see if that's it
 

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Mike
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One more thing, make sure you are using the right post processor when you save your gcode files.
 

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Discussion Starter · #10 ·
accuracy problem

Hi guys, I found my problem, it was in the mach 3 software

under motor tuning, the two tabs there were set at 2

but they should have been set at 0. I reset them and retested

and the part came out perfect. But the question remains as to

how they could have changed from 0 to 2? I remember a short while back

I had to do a force shut down could that have caused this?

anyway I am back in business and thanks to all those who tried to help!!:smile:
 

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Ross
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Welcome to the forum Mike.
 

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Hi guys, I found my problem, it was in the mach 3 software

under motor tuning, the two tabs there were set at 2

but they should have been set at 0. I reset them and retested

and the part came out perfect.
What settings were off? Normally all of the settings do get saved during a normal exit from Mach, so any abnormal shutdown could have corrupted the settings file.
 
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