# problem with accuracy V carvepro



## mike2700 (Jan 25, 2018)

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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## BalloonEngineer (Mar 27, 2009)

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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## mike2700 (Jan 25, 2018)

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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## BalloonEngineer (Mar 27, 2009)

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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## Pro4824 (Oct 17, 2015)

Inside for hole and outside for the plug? Just to double check.


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## mike2700 (Jan 25, 2018)

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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## difalkner (Jan 3, 2012)

Welcome to the forum, Mike! I don't use VCarve Pro but are there any offsets applied to the cuts? If so, that would throw off the actual cut from the dimension as given in the software.

David


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## mike2700 (Jan 25, 2018)

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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## MEBCWD (Jan 14, 2012)

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


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## mike2700 (Jan 25, 2018)

*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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## old55 (Aug 11, 2013)

Welcome to the forum Mike.


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## BalloonEngineer (Mar 27, 2009)

mike2700 said:


> Hi guys, I found my problem, it was in the mach 3 software
> 
> under motor tuning, the two tabs there were set at 2
> 
> ...


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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