Machine Stutter (video link)

[adam.n]

https://www.youtube.com/watch?v=Ai1-zVYpkZw

Hi,

I work with an old shopbot (48x96", with a V201A chip) that has been doing strange things. Until recently, it was running off an old Windows XP computer (with 512mb ram) which would run out of ram and cause problems ( it would drift in X or Y axis between cuts, during cuts, etc), so now we've switched to a windows 7 computer with 16GB RAM, and new problems have appeared. I've posted 2 videos as examples of this 'stutter'. The machine occasionally will begin stuttering violently as it moves and stops and moves again rapidly, as if the signal is garbled. I have always hit the stop button quickly for fear of it causing damage.

It happens intermittently, I can't figure out any variables that are always present. the first video shows it happen straight from the moment I press go, it's moving up in Z and away from me in X as it heads toward the start of a cut, or trying to at least. The router off so you can hear the machine. Other times it has happened at a specific point during a multi-pass cut, after finishing a cut while returning home, and it's even happened while moving the machine with the arrow keys, not running any cut file.

I've read a bunch of other posts and I'm sure the solution I need is there somewhere, but I'm too new at this to know what's relevant!

Here's what I've tried so far:

- plugged control box into USB 2 hub with nothing else attached
- tried cut files from fusion 360, as well as old files made on part wizard on old computer
- tried grounding the machine a little (single wire connected to X rack, waiting for go ahead to buy wiring, and properly ground)
- re-installed firmware on control box

I've read the pdf on properly grounding the machine which I will do once I get the go ahead, but the machine has been used as is for 5+ years in the same location without being grounded before.

I know this is probably not enough info to diagnose, but I'm hoping someone can lend me some insight and help me narrow down what to be looking for.

Thanks for any help you can offer!

[paul_z]

Make sure you know what type of machine you have (PRT Alpha? without the 7.2:1 upgrade?). Type in "UR" and select your machine type. This will reinstall "factory default" values (including acceleration values) on your computer. They are occasionally corrupted on my machine (once every 18 months or so) and result in similar sounds and jerky movement.

Paul Z

[adam.n]

So this is where I feel silly dealing with this 20 yr old? machine, nobody knows for sure.So how can I know for sure which version to use? The only info I have to go on is the board in the control box, which has the following:

engraved on the top of the board: PRT v4.17 P/N 001740
on a label at the bottom of same board: PRS-S 021508 0634
on the smaller board plugged into larger one: v201A

When UR asks for a file, which one do I choose?

[barrowj]

My recommendation is to call Shopbot as soon as they open up and tech support will be able to advise you pretty quick.

Joe

[paul_z]

Did this get resolved? If so, how?

[jerry_stanek]

That is a PRT standard not an Alpha Alphas steppers are pruple not red

[gcox2]

Adam....I have also had that stutter problem recently. My machine is an 8 year old buddy alpha. I have been with tech support also. they have had me do some of the same things you have tried. None seemed to work until I decided to reboot my older Dell laptop (why I don't know!). I still use the windows xp. Anyway that cleared it up right away. It worked well on the rest of my cut files the rest of the day. I don't turn off my computer between sessions so the next day when I started cutting files, the stutter was back! So I rebooted again and it was gone again. I still don't know why and I need to know so I can find a permanent fix. My only thought is the old antique computer is dying or there is something going on with the controller. Tech support was also perplexed with this. I will continue to watch this post for replies. Sorry I don't have the magic bullet to solve this. Note: this must be a flaw in my character.....my mood and well-being depend on the health of my Buddy!!!

[adam.n]

Well I'm glad to know I'm not the only one baffled by this.

To update, I have been trying to narrow down the variables, and the main thing I've been using as a marker is the Packet_ET # when using command UD (utilities / Diagnostics). With the problem computer, this # increases after each action the machine takes. The # starts at about 15ms, but after running a cut file for 3 mins it will be 50ms, after running several files, each a few mins long, it can reach 170ms. the stuttering seems to starts when this number is around 70-80ms. I've run our machine off my personal laptop (surface pro 2) and the packet Et stayed around 17ms after running 3 different cut files. My company's IT guy tried drivers, or the ordering of the USB slots in windows (I'm not sure exactly) and while he was there everything seemed to work okay after that, but today its' back to it's old ways.

I haven't specifically noticed differences with how long the windows comp has been running, but I will experiment! So maybe the issue is the windows computer not being grounded properly? or some software issue with sending and receiving info through USB...

[adam.n]

gcox2:

See my other reply as well, but try running it from a different computer if you can. I can't see how the control board is at fault if it works on one computer but not another... circuits can't play favorites, at least not yet!