PRS Alpha Missing Steps

[chubb]

Hi Mike,

Dropped the speed down to 5ips and still had the same offset problem. Also tried one test cut at 3ips, and it started offsetting almost immediately so gave up on trying to lower it and stuck with 5ips.

Didn't know that there's no cross-channel comms between axes. Not sure whether the motor is stalling, is there someway to tell definitively tell if it's stalling? It's a very shallow cut with a new 90 deg bit. deepest cut is about 8mm, average cut is about half that. Also, reducing the speed hasn't reduced the amount it offsets by.


Mark

[Nate Zellmer]

Hi Mark,

Sorry to see you're continuing to have problems with this after the trouble-shooting you've done. The grounding and move speeds are certainly good spots to start when dealing with positional issues. I'm trying to work my mind around what led to the offset you pointed out at the end of the file. I've got a couple thoughts for the next step in identifying what would lead to it though.

1) Are you still using the USB hub that came with the tool? If that's going bad it could be a weak link in the communication chain. It's really intended to help older computer maintain adequate data rates, and on your newer computer with up to date software it's not needed.
2) If you have time while doing other tasks, try running an air cut of the file you encountered issues with. Turn off power to the spindle and dust collection systems and see if you're still off at the end of the cut.

Let us know what you see.

Nate Zellmer
ShopBot Tech Support

[chubb]

Hi Nate,

I'm just heading off back to the workshop to try what you've suggested. Should have an update in about an hour.

Mark

[bleeth]

Don't forget to get that grounding system hooked back up right!!

[bleeth]

Just saw your "laundry list" of things below that you have done and that it includes grounding. I have a couple new suggestions now (After you do what Nate wrote).

1. If the operating computer is networked and/or hooked up to the internet, take it off both. Then apply all "black viper" bare bones service modifications. If you have to have network, then carefully survey the steps so you don't disable this ability, but if hooked up to internet, don't ever go anywhere you are not completely sure of, and don't use it for e-mail. Run the network through a router and make sure your router has a proper firewall. Disable all automatic upgrades, screensavers, timed power control, and software update checks. I firmly believe that any computer that is running a Shopbot should be dedicated to that task and not used for other general needs. Any program running in the background can cause issues. Some of the worst are antivirus and update checkers. If your computer is dedicated than you don't need anti-virus, security shields, or updates.
2. If after doing this you are still having issues, try going back to the 3.6xx SB operating software (available from the SB website). Apparently, there were quite a few bugs with all previous 3.8xx and personally, in your position, I wouldn't use anything but a tried and true version and the newest 3.8 hasn't been field tested enough for my liking. I've been doing fine with 3.6 and also have a single head Alpha with spindle. One of the nice things about 3.6 is the easy ability to do a speed check on your comm speed. Make sure you get the right firmware in if you do change your Op software.

[chubb]

Hi all,

Just an update for anyone keeping up with the thread.

So I followed Nates advice and took off the hub and turned off the spindle.......


Didn't have any effect. Same issue occurred with the offsetting.

But once again the weirdness stepped in;

I had split the cut file into four parts. Now taking the first part as an example; it cut fine for two pieces previously then messed up and offset towards the end on the third. When I did the air cut as Nate suggested it actually did the exact same offset error as it did on the third pattern in the exact same place (so that kinda cancelled out the randomness of the error).

After a call to Nate to try get it figured out he suggested actually changing the cut file. I had to find all J3 commands and replace the 'J3' in the command line with 'M3'.

So did that and run air cut again for the first part and it worked absolutely fine

I'm not too sure what the difference made by changing it from a 'Jog' command to a 'Move' command but apparently sometimes the control software can get a bit fuddled if there are consecutive 'J3' commands and changing them to 'M3' seems to solve the offsetting issue.

Also noticed that after it cut the part it usually cuts properly, instead of jumping to the section which it offsets it actually cuts a completely different section correctly and goes through the rest of the cut file accurately. It seems that it skipped a whole section of the cutting file and jumped straight to the offset part towards the end and lost it's relative position during that fuddle. I hadn't noticed the missing cut pattern before, but looking at the third piece cut, it's obvious that there are some missing elements

Also, it slightly lengthens the time it takes to cut the file, but only by about 20%.

So at the moment, I could only test the cut as an air cut with the spindle off because it's 2am here but it seems to be cutting it properly with the switched out commands.

Will do a full test cut tomorrow after amending all 4 split parts of the cut file and see how it goes.

Will be sure to keep the thread update on how it goes.

Thanks so much to all who put in their 2 cents and helped eliminate a whole host of possible problems. It really helped, irrespective of whether it solved the problem or not.

Nate, thanks so much for all your help in solving the issue.

Just saw your "laundry list" of things below that you have done and that it includes grounding. I have a couple new suggestions now (After you do what Nate wrote).

1. If the operating computer is networked and/or hooked up to the internet, take it off both. Then apply all "black viper" bare bones service modifications. If you have to have network, then carefully survey the steps so you don't disable this ability, but if hooked up to internet, don't ever go anywhere you are not completely sure of, and don't use it for e-mail. Run the network through a router and make sure your router has a proper firewall. Disable all automatic upgrades, screensavers, timed power control, and software update checks. I firmly believe that any computer that is running a Shopbot should be dedicated to that task and not used for other general needs. Any program running in the background can cause issues. Some of the worst are antivirus and update checkers. If your computer is dedicated than you don't need anti-virus, security shields, or updates.
2. If after doing this you are still having issues, try going back to the 3.6xx SB operating software (available from the SB website). Apparently, there were quite a few bugs with all previous 3.8xx and personally, in your position, I wouldn't use anything but a tried and true version and the newest 3.8 hasn't been field tested enough for my liking. I've been doing fine with 3.6 and also have a single head Alpha with spindle. One of the nice things about 3.6 is the easy ability to do a speed check on your comm speed. Make sure you get the right firmware in if you do change your Op software.

Hi Dave,

All our machines run by computer are strictly off any network whatsoever (security e.t.c)

I was an inch away from downgrading the control software and firmware if I hadn't gotten the issue resolved soon. At the moment with the file tweaks it seems to run fine, but thats as an aircut with the spindle off. Tomorrow will be the real test when I amend all the files and do a complete test run in material.

Thanks Dave for helping and chiming in with suggestions. Learnt quite a bit of detailed stuff just from all the suggestions people gave and really appreciated all the feeback. It also helped narrow down what the problem could be and get it solved faster. I'm sure I'll now recognise any grounding or ramping issues in the future

Yes.

Ramping will take care of many situations, but you cannot defy the laws of physics. This is like trying to make your car go 0-100 to 0 in the grocery store parking lot. Just ugly.

You may find this article helpful.

-B

Thanks Brady,

Will definitely give the article a thorough read just to get more familiar with ramping. Thanks for pointing it out.

Will keep thread updated with how it goes tomorrow.

Once again thank you all.


Mark

[Nate Zellmer]

While I'm not certain it's quite "problem solved" yet, I'm glad we've found a reasonable workaround to get you cutting. I look forward to hearing your results today.

[chubb]

Hi all,

Well, amended all the cut files to remove all 'J3' commands and replace with 'M3' for all four part files.

Did all my usual prep and started cutting the border pattern........ran through the cutting file without a single hiccup whatsoever. no issue. It cut accurately and with absolutely no offsets whatsoever. Cut four more border patterns without any issues. The only change was the time it took, which was an extra 20 minutes, well worth it for perfectly cut patterns.

Got a little brave and combined all the four file parts to run as a single file with the 'J3' command switched out, and it still ran through the cut file flawlessly.

Had some spare time at the end of the day so went back to the patterns that had previously given me the same issue with offsetting. Gave them the J3->M3 treatment and air cut them. They also went through without a problem.

Still can;t figure out why particular files were having this offset issue as I have cut files that are way more complex, take way more time with similar feed and plunge rates, and heavier cuts that didn't have the offset issues.

Would really like to try figure out what exactly was the problem and how the machine translated the cut file that resulted in offsets. Just for future reference and maybe prevention.

Thanks so much for everyones input.

While I'm not certain it's quite "problem solved" yet, I'm glad we've found a reasonable workaround to get you cutting. I look forward to hearing your results today.

True, this really was more than a workaround rather than a solution. But as long as I'm cutting, I'm happy

But, do we have any permanent solutions for this issue?

Thanks Nate.


Regards,


Mark

[jerry_stanek]

What is your jog speed set at?

[chubb]

What is your jog speed set at?

Hi Jerry,

Have my jog speed at 300mm/s (around 12ips).




Mark