3D finishing

This forum is for general discussion regarding VCarve Pro
electrictermite
Posts: 11
Joined: Mon Oct 29, 2018 12:44 am
Model of CNC Machine: Carve King

3D finishing

Post by electrictermite »

After the roughing pass and the finishing bit has been put in, do you move Z back to zero or Do you jog Z down to the new surface that the roughing created.

User avatar
Adrian
Vectric Archimage
Posts: 10594
Joined: Thu Nov 23, 2006 2:19 pm
Model of CNC Machine: ShopBot PRS Alpha 96x48
Location: Surrey, UK

Re: 3D finishing

Post by Adrian »

You re-zero to the same level you zeroed the roughing bit at. You can't go back to the original zero as the bits are almost certainly not exactly the same length.

electrictermite
Posts: 11
Joined: Mon Oct 29, 2018 12:44 am
Model of CNC Machine: Carve King

Re: 3D finishing

Post by electrictermite »

so you are saying to go back to original zero which was the surface point before ruffing. but at the same time you are saying you will never get true zero because of bit length. if this is what you are saying then i understand. the finishing file will plunge down to ruffing area just done.

BigC
Vectric Wizard
Posts: 389
Joined: Tue Apr 02, 2019 7:06 pm
Model of CNC Machine: Workbee

Re: 3D finishing

Post by BigC »

Where have you set your XYZ datum point? (hoping you haven't milled this away with the roughing pass)
C

electrictermite
Posts: 11
Joined: Mon Oct 29, 2018 12:44 am
Model of CNC Machine: Carve King

Re: 3D finishing

Post by electrictermite »

X0, Y0, Z0...This will be my first attempt at 3d and hope to learn before taking a run at it.

User avatar
Adrian
Vectric Archimage
Posts: 10594
Joined: Thu Nov 23, 2006 2:19 pm
Model of CNC Machine: ShopBot PRS Alpha 96x48
Location: Surrey, UK

Re: 3D finishing

Post by Adrian »

electrictermite wrote:so you are saying to go back to original zero which was the surface point before ruffing. but at the same time you are saying you will never get true zero because of bit length. if this is what you are saying then i understand. the finishing file will plunge down to ruffing area just done.
Use the original zero point but not the original zero value. When you set the initial z-zero you should use a point that won't be removed by the roughing tool pass. If you've removed all the material at the level that was the original zero point then you've got a problem.

electrictermite
Posts: 11
Joined: Mon Oct 29, 2018 12:44 am
Model of CNC Machine: Carve King

Re: 3D finishing

Post by electrictermite »

I thought you could jog back and watch the X,Y,Z change until the G code sender showed x0, y0, z0 and that would put you at the original pre ruffing start point.

kstrauss
Vectric Craftsman
Posts: 188
Joined: Mon Apr 29, 2013 3:37 am
Model of CNC Machine: Tormach PCNC770
Location: Cobourg, ON, Canada

Re: 3D finishing

Post by kstrauss »

If you've removed all the material at the level that was the original zero point then you've got a problem.
If you are using CNC software (LinuxCNC or Mach3 or PathPilot or...) that uses its tool table to compensate for the length of your tools, removing the material is not an issue.

User avatar
TReischl
Vectric Wizard
Posts: 3642
Joined: Thu Jan 18, 2007 6:04 pm
Model of CNC Machine: 8020 Build 48X36X10 RP 2010 Screenset
Location: Leland NC

Re: 3D finishing

Post by TReischl »

Another way of saying this:

You must use the same plane for setting both tools.
"If you see a good fight, get in it." Dr. Vernon Jones

User avatar
Xxray
Vectric Wizard
Posts: 2147
Joined: Thu Feb 17, 2011 8:47 am
Model of CNC Machine: CAMaster Stinger 1
Location: MI USA

Re: 3D finishing

Post by Xxray »

Always Z on top of original material for all passes, if you Z what has been cut you will be in for an unpleasant surprise of the finishing pass going way too deep, perhaps through the material into the spoilboard.
Doug

User avatar
martin54
Vectric Wizard
Posts: 4954
Joined: Fri Nov 09, 2012 2:12 pm
Model of CNC Machine: Gerber System 48,Denford Triac Modified
Location: Crossgates, Scotland

Re: 3D finishing

Post by martin54 »

electrictermite wrote:I thought you could jog back and watch the X,Y,Z change until the G code sender showed x0, y0, z0 and that would put you at the original pre ruffing start point.
The point people are trying to make is that you will zero your "Z" axis on the material surface with the bit you use for roughing. Once the roughing pass is complete you would then normally change to a different bit for the finish pass. The bit used for the finish pass is unlikely to finish up at exactly the same length below the collet as the roughing bit which would give you a false z zero position unless you had some way to set it. There are ways to do this but a lot of people will just re-set the zero position for the z axis on the material surface the same way they set the z zero position for the roughing bit in the first place :lol: :lol: :lol:

electrictermite
Posts: 11
Joined: Mon Oct 29, 2018 12:44 am
Model of CNC Machine: Carve King

Re: 3D finishing

Post by electrictermite »

That was the answer I was looking for is just jog down Z to new surface and reset Z to zero before running finishing gcode.

User avatar
gkas
Vectric Wizard
Posts: 844
Joined: Sun Jan 01, 2017 3:39 am
Model of CNC Machine: Aspire, Axiom AR8 Pro+, Axiom 4.2W Laser
Location: Southern California

Re: 3D finishing

Post by gkas »

electrictermite wrote:That was the answer I was looking for is just jog down Z to new surface and reset Z to zero before running finishing gcode.
The key is NOT using a NEW surface. You should set your Z to the same spot for ALL of your bits. Pick a spot that won't get machined. If you use 3 different spots, you may be picking 3 different thicknesses of wood.

User avatar
Adrian
Vectric Archimage
Posts: 10594
Joined: Thu Nov 23, 2006 2:19 pm
Model of CNC Machine: ShopBot PRS Alpha 96x48
Location: Surrey, UK

Re: 3D finishing

Post by Adrian »

electrictermite wrote:That was the answer I was looking for is just jog down Z to new surface and reset Z to zero before running finishing gcode.
Wrong. You use the old (uncut) surface not the new surface. Both bits are zeroed at the same level (plane).

Of course we're assuming that you have set the z-zero in VCarve to be the material surface. If it's the table surface then you have to zero to that. Either way you zero to the same level (plane) for both toolpaths.

User avatar
martin54
Vectric Wizard
Posts: 4954
Joined: Fri Nov 09, 2012 2:12 pm
Model of CNC Machine: Gerber System 48,Denford Triac Modified
Location: Crossgates, Scotland

Re: 3D finishing

Post by martin54 »

pick a spot on the material surface that isn't going to be machined by any of your toolpaths & use that spot after any bit change to reset your z zero. I generally put a small pen or pencil mark on the surface so I don't have to try & remember where I first set my z zero position :lol: :lol: :lol:

Post Reply