Always start at 0-0-0??

Discussion/questions about software used with your CNC Shark and programming issues

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wood_fly
Posts: 4
Joined: Sun Dec 25, 2011 12:53 am

Always start at 0-0-0??

Post by wood_fly »

Greetings,
I am machining a two-sided 1" thick project. For the front side, I am indexing in the middle of the project on the TOP of the project. I cut the dowel holes, and remove the material.
I put a sacrificial board on the bed and clamp it down. I then register 0-0-0 x-y-z on the middle of the sacrificial board and cut the matching, mirrored dowel holes.

Then I install my project board upside-down. I am still using the sacrificial board as my Z-0, and telling Aspire to set the home-start position at 0-0-1.2.

When the project starts however, the bit runs right to 0-0-0 and IGNORES the command to home of 0-0-1.2. The front of the G-code looks like this:
( 2 Back-Ruf-Z )
( File created: Sunday, December 15, 2013 - 11:08 AM)
( for CNC Shark from Vectric )
( Material Size)
( X= 6.000, Y= 21.000, Z= 1.000)
( Z Origin for Material = Table Surface)
( XY Origin for Material = Center)
( XY Origin Position = X:0.000, Y:0.000)
( Home Position)
( X = X0.0000 Y = Y0.0000 Z = Z1.2010)
( Safe Z = 1.200)
(. IMPORTANT: Before outputting any toolpaths you)
(should carefully check all sizes and the material)
(setup to make sure they are appropraite for your)
(actual material and CNC. You should also check and)
(re-calculate all toolpaths with safe and approprate )
(settings for your material, machine and tooling.)
(Terms of Use: This Project and artwork is provided )
(on the understanding that it will only be used with )
(Vectric software programs. You may use the )
(designs to carve parts for sale but the Files )
(and/or Vectors, Components or Toolpaths)
(within them {or any derivatives} may not be sold )
(to, or shared with anyone else. This project is )
(Copyright 2013 - Vectric Ltd.)
(Toolpaths used in this file:)
(2 Back-Ruf-Z)
(Tools used in this file: )
(1 = End Mill {0.25 inch})
(End Mill {0.25 inch})
(|---------------------------------------)
(| Toolpath:- '2 Back-Ruf-Z' )
(|---------------------------------------)
G90
G20
F100.0
G64 P.01
S 2000
M3
G0 Z1.2010

Does the CNC shark control panel ALWAYS issue a GOTO 0-0-0? I tried to slow down the software (25%) was the lowest and it looks like it stops on line 2 while sending the bit into the material seeking 0-0-0. I have ruined this project and won't try again until I can figure this out. HELP!

Thanks

4DThinker
Posts: 951
Joined: Wed Jun 27, 2012 9:00 am

Re: Always start at 0-0-0??

Post by 4DThinker »

As far as I can tell, the Shark always insists to go to 0,0,0 when starting, even if the first toolpath is as far away as possible. Vcarve does the same when it is used on the Multicam CNC we have at work as well. If there is a danger of the bit damaging the project when doing that, we set Z=0 to be above the board by a known amount, then set all the tool paths to start the same distance below 0. Safe Z is how high the bit moves to when travelling between tool paths and/or done.

rungemach
Posts: 460
Joined: Mon Aug 02, 2010 8:24 am
Location: Sarasota, Florida

Re: Always start at 0-0-0??

Post by rungemach »

You are correct in that the move to 0,0,0 is not in the g-code but is a "feature" of the controller, and I believe it is unique to the Shark system, and can not be defeated.
That makes it harder to zero on the lower surface of a part, or on a surface that will be cut away in roughing cuts before a bit change to a finishing bit.

The workaround is to offset your zero point of our project ( in the Vectric software) to an area off of the part, where the move to 0,0,0 will not harm the workpiece. Lets say 1" to the left ( -1 in the X) of the left surface of the workpiece. This sometimes requires some creativity in fixturing your work.

You can however, cut some locating grooves on your spoil board as a separate tool-path in your design. You set your new offset zero, then machine the locating groves or holes for locating pins as part of your project. Subsequent tool zeroing, happens at your offset zero point, and all plunges to 0,0,0 happen safely there, off the side of your part. This does not easily lend itself to having the xy zero point in the center of the part though.

wood_fly
Posts: 4
Joined: Sun Dec 25, 2011 12:53 am

Re: Always start at 0-0-0??

Post by wood_fly »

Thank you. I was afraid it was a "feature". The concept of an offset to start though is BRILLIANT!!! I will give that a shot. Thank you.
Tim

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