Frustrated with erratic behavior

We have been experiencing unexplained errors with our ShopBot since we got it. At first we thought we were making mistakes that caused our issues. As we get more comfortable using the software and machine, we are becoming more and more frustrated with what seems to be random and erratic behavior.

1. When resuming a toolpath after pausing, the spindle dives into the table and begins an unexplained move. This has happened when simply pausing and resuming AND after entering a "nudge" value although it does not always happen.
2. When doing a 3D offset, the z raises to 4" (when started from 1") before starting the aircut. This happens every time we do a 3D offset.

Our shopbot PRS alpha has the lastest control software. I have talked with a few support engineers but no one has been able to provide an answer.

Issue #1 is an annoyance and causes problems when using thick material and/or a long bit as the z-axis will top out and error forcing a re-zeroing of Z.

We have snapped a number of bits as a result of issue #2 and tonight we dove right through our spoilboard leaving a gash that will require replacing the entire sheet.

Is anyone else experiencing things like this? Have you been able to find and fix the issue? I should be able to reliably pause and restart a file without risking my bit or my vacuum table.

Please help.

Frustrated,
Greg

What do you have the safe z set at in your cam program.

cant help you with number 1 but my question is what is your safe z or home position set at.

What version of software are you running? Know you say latest, but want to check if it's the latest production version or the beta or ?

Issue 1, I have seen in previous versions but have not encountered it lately. I stop and resume often, but don't much use the nudge feature.

Issue 2, using the 3d offset feature of the FP command is not one I believe very many folks use. Most of us do this in our design software these days. It would help here if you could provide the first hundred lines or so of your program, and what you are entering into the FP fillin sheet for offsets and proportions.

Thanks for the responses.

Control Software Version: 3.6.44
Partworks 3 Software Version: 3.504
Home Position in Partworks 3: X:0 Y:0 Z:0.8
Clearance in Partworks 3: 0.2
Plunge in Partworks 3: 0.2

Partworks 3D Software Version: 1.002
Rapid Clearance Gap: .25

I offer the settings from both partworks and partworks 3D because we have had issue #1 happen with files coming from both. Again, this is an intermittent problem but the bottom line is that I am never comfortable pausing a file anymore.

Ken, regarding issue #2, we instruct our users to do a 3D offset "aircut" before running their file to be sure they have done their tool paths correctly. The only thing we change in the fill in sheet is the option for the offset. I instruct users to move the tool to 0,0,1 before loading the part for the aircut (as long as the cuts they are doing are less than 1" deep).

As an experiment, you might try zeroing your Z above the material for your aircuts instead of using the 3d offset and see if it makes any difference.

For an aircut, I move my z an inch above my material, then do a ZZ, then run the toolpath as normal (no 3d offset).

This might tell us if there is a problem in the Offset portion of the control software.

I know for a fact that issue #2 only happens during a 3D offset. There is a sub-routine that is supposed to check for safe height, then raise to safe height if Z < safe height. For whatever reason it loops the subroutine 3 times in a row before it stops. I'm sure that your idea of doing a ZZ at 1" above the material will bypass the problem but I'd love to see this fixed.

I began digging through the code but frankly found so many odd things that I decided it was a bigger issue that should be addressed by ShopBot.


As for #1: The next time this happens, what can I do to capture the commands that were executed? I can guarantee that this is not a problem with the actual SBP file since folks have run the same file multiple times, having no trouble at all. Then out of the blue, BAM, broken bit, wrecked material, destroyed spoilboard, shattered confidence.

Greg,
ShopBot does not monitor the forum in any official or support capacity. You should send an email to support or call to get your questions resolved from the support staff, as your model ShopBot (E.G. - ATC) may act differently than another tool in a given circumstance.

I have seen anomalous behavior when pausing a file from time to time, and it should be noted that only certain versions of the software seem to do this. As others have pointed out, 3D offset (and the other options on the yellow FP fill-in sheet) is pretty much ignored by about 99.9% of users, so you may have uncovered something that nobody knows about. (Make sure you tell support)

I would also just set the Z up 1" above the material and ZZ it there for part file verification, rather than use the 3D offset option. I know it is a matter of principle, but personally I don't care about that when I have a job that needs to get done - I go with what I know works...not what I think should work - at least for the time being.

-B

Thanks, Brady. I totally get where you are coming from. If this were my personal shop, I would just work around these problems and leave it at that.

The shop I work for, The Mill, is part of a growing trend of community workshops (makerspaces, DIY shops) where we train people in the proper use of this equipment and sell memberships to access these tools. Retraining our members would be time consuming.
As a proponent of shared resources and tools, I am also a fan of shared fixes to problems as opposed to an "it works for me" attitude. My efforts here are both to find a solution for us and anyone else experiencing the same problems.

Greg...
RE: your #1...
If you are using a long bit, and/or thick material, your bit may be retracting past its physical limits when pausing. No matter what is set in the design software, the bit should retract to the SYSTEM safe Z. You can set this value in the "Cutter" tab of SB3 OR by typing [V][C] from the console.

RE: your #2...
Are you using a Z offset? How about a proportion applied to the Z? Many of these create unexpected results to the user, but when the math is applied make perfect sense.


A [SpaceBar] pause during a file is not 100% reliable on many computers, especially those light on RAM. They (pauses) get less reliable when 2D, 3D or "VO" (temp) offsets are applied. Even less relaible if [SpaceBar] is pressed during a vertical move or jog. I train users to NOT use the feature unless to prevent material damage. I also train them to [QUIT] and rezero all axes and restart the file from its beginning.

Gary
#1
We are not topping out on the z axis. Last night we were using a 2" bit and 3/4" mdf. The safe z-height in the cutter tab is set to 1.00".

#2
We are not editing any of the fill-in sheet options when running the actual cut. We run with no offset and no proportions for any axis. I train users to set their x/y zero location with a C3 (zero x/y with prox switches) and then Z2 to their desired location if needed before they do anything else. Then I train them to zero Z (C2) to the material or table depending on the job.
Regarding the spacebar, that's interesting. What do you consider "light on RAM"? Is clicking the "Stop" button with the mouse any less problematic? I will train future users to never restart a file but I imagine that will be a very unpopular solution especially when running long files.

Greg..
I am confused, your answer to 2 appears to conflict with the #2 in the original post.

I consider 2GB to be sufficient for 2D work and 4GB to enable large or 3D files to be run

No difference on the method. A pause is a pause, is a pause. Unpopular, maybe, but as unpopular as starting over with new materials? I also dont recommend being out of sight/earshot of the tool when active. There are many posts on here showing objects cut that took over 12 hrs to cut.

Gary,
Sorry for the confusion.
When we do the actual cut, we are not doing any offsets.
When we do an aircut, we use the 3D offset in the fill-in sheet. The problem of topping out in Z after the repeated lifts only shows up when we do a 3D offset.

Greg...
I prefer to move the Z to .5 or 1" and zero the Z there for an aircut. To have proper control over the depth, I recommend this method. Especially if you are teaching others.

When you check the 3D offset in the fillin sheet, you will effectively set the ZZero to the current position. Apparently your current position, plus your max Z lift causes the Z to max out.

Quote:

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Originally Posted by garyc

Greg...
I prefer to move the Z to .5 or 1" and zero the Z there for an aircut. To have proper control over the depth, I recommend this method. Especially if you are teaching others.

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I concur. It is much easier to convey the idea of zeroing the Z up high than it is to mess with 3D offset - which is a lot more confusing for a new user to grasp. They have enough to learn without using 3D Offset...

I instruct users to ignore the FP fill in sheet until they understand what it does.

-B

On top of that, if you happen to run one 3D offset after another without moving back down, the 3D offsets will compound so eventually you will top out.

Greg...
To expand on what Scott says.....

Inexperienced users may run a file with 3D offset more than once without lowering the Z. Each time the file is run using the 3D offset option the Z height will increase by the amount of the safe Z. Also, if X & Y axes are not returned to 0,0 prior to each file run an offset (temp) is applied to those axes also, even if inadvertent. Best to use Brady's advice. Ignore the fill in sheet until you are sure what each option does.