4th Axis Indexer and Shopbot Post-Processor

darran · ‎06-30-2018

I'm struggling to get Fusion's CAM+Postprocessor to produce a file that will work with the 4th axis indexer on our MakerLabs' Shopbot PRS. Please bear with me as I lay out the details below.

I've stripped things back to something extremely simple. In the attached FBD, I've modelled up a 4" x 2" x 2" block oriented as shown below.

For CAM, all I'm going to do is use a 1/4" end mill to touch the existing border of each of the long faces. I do a 2D contour on one face at the model height and then pattern it with 4 90-degree rotations. That is, I'm not unwrapping anything, just changing the tool orientation to bring up a new face. With this geometry and toolpaths, we should only see movements with x coordinates of 0, 4 and y,z coordinates of -1,+1.

With the stock OpenSBP post, and with properties set to have rotations about x axis (default) and 4th axis turned on as shown here,

I get the following part file:

' TraceBoxTest
SA
CN, 90
IF %(25)=1 THEN GOTO UNIT_ERROR
&PWMaterial = 2
&PWZorigin = Part Surface

' 2D Contour1 (2)
JZ, 3
JH
J5, , , , , 0
C7
&Tool = 2
TR, 8000
C6
PAUSE 2
J2, 0, 1
J3, 0, 1, 2
J3, 0, 1, 1.5
MS, 0.5556, 0.5556
M3, 0, 1, 1
MS, 1.6667, 1.6667
M3, 4, 1, 1
M3, 4, -1, 1
M3, 0, -1, 1
M3, 0, 1, 1
M3, 0, 1, 1.2
J3, 0, 1, 2

' 2D Contour1 (2)
JZ, 3
JH
J5, , , , , 270
J2, 0, 1
J3, 0, 1, 2
J3, 0, 1, 1.5
MS, 0.5556, 0.5556
M3, 0, 1, 1
MS, 1.6667, 1.6667
M3, 4, 1, 1
M3, 4, -1, 1
M3, 0, -1, 1
M3, 0, 1, 1
M3, 0, 1, 1.2
J3, 0, 1, 2

' 2D Contour1 (2)
JZ, 3
JH
J5, , , , , 180
J2, 0, 1
J3, 0, 1, 2
J3, 0, 1, 1.5
MS, 0.5556, 0.5556
M3, 0, 1, 1
MS, 1.6667, 1.6667
M3, 4, 1, 1
M3, 4, -1, 1
M3, 0, -1, 1
M3, 0, 1, 1
M3, 0, 1, 1.2
J3, 0, 1, 2

' 2D Contour1 (2)
JZ, 3
JH
J5, , , , , 90
J2, 0, 1
J3, 0, 1, 2
J3, 0, 1, 1.5
MS, 0.5556, 0.5556
M3, 0, 1, 1
MS, 1.6667, 1.6667
M3, 4, 1, 1
M3, 4, -1, 1
M3, 0, -1, 1
M3, 0, 1, 1
M3, 0, 1, 1.2
J3, 0, 1, 2
C7
JZ, 3
JH
J5, , , , , 0
END


UNIT_ERROR:
CN, 91
END

At first glance this looks like a reasonable post. Shopbot uses the "B" axis for the indexer so the "J5, , , , , angle" commands would seem to make sense. We also see that the M3 move commands trace the rectangular border as expected (with a terminating retract in z). However, when I load this file into Shopbot's control software, the visual preview of the tool paths don't look correct:

I raised this issue directly with Shopbot and they pointed my at the following PDF, http://www.shopbottools.com/ShopBotDocs/files/WrappingRotaryIndexer.pdf. The title though, "Setting Up a Wrapping File for the ShopBot Rotary Indexer", makes me wonder if they really understood the issue. I'm not trying to unwrap a cylindrical model, rather just add an extra degree of (rotational) freedom and then have full axis to x,y,z movements. What we see above is that the "cutting" toolpaths don't change in Y. After reading the above PDF, I'm starting to wonder if this is a hardware limitation. Here's an excerpt from Page 3:

Thoughts?

Cheers,

Darran

P.S. In a vain attempt to fix this issue, I tried upgrading to the Version 42035 OpenSBP post-processor. Unfortunately that won't even work on the attached FDB, generating the following output:

Information: Configuration: ShopBot OpenSBP (Experimental)
Information: Vendor: ShopBot Tools
Information: Posting intermediate data to '/Users/darran/Fusion 360 CAM/nc/TraceBoxTestExperimental'
Error: Failed to post process. See below for details.
...
Start time: Sun Jul  1 01:40:47 2018
Post processor engine: 4.2.1 41970
Configuration path: /Users/darran/Library/Application Support/Autodesk/Autodesk Fusion 360/CEWDMG9Z9PGW/W.login/M/D20180507130870481/CAMPosts/18F30-Shopbot.cps
Include paths: /Users/darran/Library/Application Support/Autodesk/Autodesk Fusion 360/CEWDMG9Z9PGW/W.login/M/D20180507130870481/CAMPosts
Configuration modification date: Sun Jul  1 01:27:12 2018
Output path: /Users/darran/Fusion 360 CAM/nc/TraceBoxTestExperimental
Checksum of intermediate NC data: 2c1da62b181704bf931fb898ee16d3d6
Checksum of configuration: 21b4718ad3471690e3486296be02232b
Vendor url: http://www.shopbottools.com
Legal: Copyright (C) 2012-2018 by Autodesk, Inc.
Generated by: Fusion 360 CAM 2.0.4279
...
Error: Failed to invoke function 'onSection'.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: Failed to invoke 'onSection' in the post configuration.
Error: Failed to execute configuration.
Stop time: Sun Jul  1 01:40:47 2018
Post processing failed.

Note that I edited the title to include "(Experimental)" just so I didn't confuse it with the stock post.

daniel_lyall · ‎07-01-2018

you have the model set up for along the X axis, Also the WCS is not set in the setup you do it here not the first toolpath unless it is on a different orientation, but since you are useing a pattern the setup is the correct spot.

The default open sbp post works fine with the 4th axis prepost set to yes in the pre post dialog it is at the bottom.

darran · ‎07-01-2018

Hi Daniel, sorry but I don't understand what you've written:

"you have the model set up for along the X axis": Yes, this is on purpose. If you look at the post-processor dialog screenshot, "I've got B axis rotates around X" selected. On the Shopbot, the indexer is denoted B.
"Also the WCS is not set in the setup you do it here ...": The WCS is defined in the set up as "model orientation" and "model origin". This is correct for the first run through the pattern.
"The default open sbp post works fine with the 4th axis prepost set to yes in the pre post dialog it is at the bottom": I don't understand this statement as I do have 4th axis set to yes in the properties of the pre-post. You can see it checked in the configuration dialog screenshot above.
Also, what do you mean by "works fine"? Have you actually loaded it into the shopbot control software? If so, do you get a different preview than I show?

daniel_lyall · ‎07-01-2018

@darran wrote:

Hi Daniel, sorry but I don't understand what you've written:

"you have the model set up for along the X axis": Yes, this is on purpose. If you look at the post-processor dialog screenshot, "I've got B axis rotates around X" selected. On the Shopbot, the indexer is denoted B. so you do my bad

"Also the WCS is not set in the setup you do it here ...": The WCS is defined in the set up as "model orientation" and "model origin". This is correct for the first run through the pattern. I was told you set it in the setup and select the axis and only do it in the toolpath if it is different from the setup.

"The default open sbp post works fine with the 4th axis prepost set to yes in the pre post dialog it is at the bottom": I don't understand this statement as I do have 4th axis set to yes in the properties of the pre-post. You can see it checked in the configuration dialog screenshot above. Are you are useing apple or a old shopbot post and I was wrong again.

Also, what do you mean by "works fine"? Have you actually loaded it into the shopbot control software? If so, do you get a different preview than I show? as in what is posted out look good

what is in the post looks good

Have you tried a Air test to see if it is just the control not showing the toolpath correctly. the toolpath looks like it is missing 3 sides of the cut.

Joshua.Aigen · ‎02-05-2019

Hi Darran, I'm in the process of trying to do something similar to you. I wouldn't call it 4 axis more like 3 plus one. Basically, I'm doing two setups 180 degrees from one another then post that out and edit my code with a JB, 0 at the beginning and a JB, 180 after the first side. This way I use the standard Fusion360 SBP post and push the rotary around. That being said I've only done it one and it only came out okay. (still working)

Joshua Aigen
Workshop Supervisor