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Author Topic: Milling Is Off Center  (Read 9220 times)

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Milling Is Off Center
« on: November 20, 2015, 03:35:28 AM »
Hi.. I am having a major problem with my machine.. I cut wood signs and use Vcarve with Mach3... 

The Vcarve preview looks perfect, get it to the machine and zero out all the axis's and it always does not center to the work piece.. it runs off center by .25 possibly .5 sometimes...  It ruins every piece of work I do .. I just did a sign with a vcarve border then a .125 offset from the border where it cuts out the sign from the workpiece... The top is fine but the bottom cuts all the way into the vcarve outline and ruins the piece...

Romaxx says it's a programming problem and no one at Vcarve forums have an answer... Where could this problem be in Mach3?

Thanks for any help... I am new to cnc and this problem is ruining all my work...

Offline Tweakie.CNC

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Re: Milling Is Off Center
« Reply #1 on: November 20, 2015, 04:47:46 AM »
Just a couple of suggestions...

Thoroughly check the mechanicals of your machine (loose grub screws, binding or tight spots on linears or screws etc.).

Reduce your Velocity and Acceleration settings for the X and Y axes by 50% in motor tuning and save the changes and see if this cures the problem.

Tweakie.
KEEP SAFE !
Re: Milling Is Off Center
« Reply #2 on: November 20, 2015, 03:19:24 PM »
"Thoroughly check the mechanicals of your machine (loose grub screws, binding or tight spots on linears or screws etc.)"

Thanks for the help...

would the above cause a loss of steps?  I should have also said the mill returns to Zero with no problems...

Thanks for help and suggestions because unfortunately this venture is not working at all for me other then creating fire food at this point...

Offline rdean

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Re: Milling Is Off Center
« Reply #3 on: November 20, 2015, 04:09:57 PM »
" I just did a sign with a vcarve border then a .125 offset from the border where it cuts out the sign from the workpiece.."

If your v-carve border did in fact cut properly and the preview in V-Carve looked correct for the cutout then the problem is not with V-Carve or Mach3 it is your machine.

Did you reduce your speed and acc by 50% as Tweakie said?

Ray
Re: Milling Is Off Center
« Reply #4 on: November 20, 2015, 04:44:51 PM »
Thanks Ray...

Quote
If your v-carve border did in fact cut properly and the preview in V-Carve looked correct for the cutout then the problem is not with V-Carve or Mach3 it is your machine.

Well the sign looks fine up until the actual cutout from the work piece... Like I said, there is a vcarve borber line that round around the sign by .125" that is because I offset the vector to outside .125" and then use that offset outside vector to outside through cut the piece for the sign shape.. Hope that makes sense..

Now that outside through cut looks great on the bottom half, but on the top the bit runs in all the way to the inside vcarve vector and clearly ruins the piece..

That looks like it is the machine?

Again, I have tried many times to center a cutout on a piece of material and it always cuts it off centered.. I have checked this and double checked  many times with the same result... A entered piece in Vcarve coming out offcenter on the workpiece for a basice square through cut...



Quote
Did you reduce your speed and acc by 50% as Tweakie said?

I have not got back to the machine yet but will in a bit and post if it helps..

Thanks for all help!
Re: Milling Is Off Center
« Reply #5 on: November 20, 2015, 11:48:09 PM »
I was  just looking at  one of my centered cutout failures and noticed that one of the corner radius's (I used a .250" bit) is much less then the other 3 radius's ...  This was an inside through cut .. Seems like all 4 corners should have the same radius no?  The one corners is at least half the radius size...

could that give a clue?
Re: Milling Is Off Center
« Reply #6 on: November 23, 2015, 03:41:30 AM »
Quote
Reduce your Velocity and Acceleration settings for the X and Y axes by 50% in motor tuning and save the changes and see if this cures the problem.

Okay, finally got on the machine today to do some tests and Tweakies  fix above seems to have made a difference.. Not perfect but it closed the offset the machine was running a lot and the milling ran much much closer to center of my work piece... still not perfect though.. Do I just tweak these setting until they are perfect?  Was running about .25" off and now about .0625"

Thanks for the help!

Offline Tweakie.CNC

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Re: Milling Is Off Center
« Reply #7 on: November 23, 2015, 04:15:12 AM »
There is a lot of 'trial and error' required to get each axis Velocity and Acceleration to their optimum values.

This is what I would do...

Just one axis at a time - increase Vecocity until the axis stalls on fast jog (shift + arrow key) reduce velocity by 30% and save changes. Do a similar thing with Acceleration.

Tweakie.
KEEP SAFE !
Re: Milling Is Off Center
« Reply #8 on: November 24, 2015, 01:21:24 AM »
well today did not go so well.. was hoping to finish getting this thing working ...

The fast jog used to "bottom out" when I first got the machine but it does not seem to do it anymore even at 100% jog and shift...

I doubled the Velocity and Accel and the jog it would not stall out....

I took last nights setting of cutting the Velocity and Accel in half and took 25% off that since it was close last night.. That produce a horrible result which did not even complete the rectangle...

I brought the settings back to the half mark to do another test cut and wile the X axis remained .0625" off from center the Y Axis was back to .5"  ....

so I am once again lost and not sure what is going on or happening, especially why last nights results at half the setting produced one result and today they produced a totally different result...

Thanks for any help...

Re: Milling Is Off Center
« Reply #9 on: November 24, 2015, 02:21:05 AM »
Duh.. Okay...

I only reduced the setting by half for the Y axis and not the X axis... so that should get me back to where I was last night.. But it is still .0625" off and I cannot get the axis's to stall out through jog...

any ideas of what I can set the velocity and Accel to from here to get me closer?  Like I said, I cut them 25% from the half setting and it was a mess...