problem with accuracy V carvepro

2408 Views 11 Replies 6 Participants Last post by BalloonEngineer, Jan 30, 2018

mike2700

Discussion Starter · 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

· #2 · Jan 25, 2018 (Edited)

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

Discussion Starter · #3 · 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

· #4 · Jan 25, 2018

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

· #5 · Jan 25, 2018

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

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mike2700

Discussion Starter · #6 · 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

· #7 · Jan 26, 2018

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

Discussion Starter · #8 · Jan 26, 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

· #9 · Jan 26, 2018

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

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mike2700

Discussion Starter · #10 · Jan 29, 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

· #11 · Jan 30, 2018

Welcome to the forum Mike.

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BalloonEngineer

· #12 · Jan 30, 2018

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

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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