Technician Needed in Central Florida - WILL PAY!

[QMI]

I have a PRS Alpha and we are currently experiencing an issue where tool paths on one side of the table are not straight. The lines are wavy and seem to be uniform from program to program.

We have gone back and forth with support at ShopBot for the past few days with no real solution to the problem.

I need someone who has experience with these machines to come and look at it and fix it. If you are interested, please message me.

Thanks.

[srwtlc]

Would like to, but you're quite ways from me.

Have you checked every point of the machine for any slop/looseness. Move the tool to the place where the issue is most noticeably and grab the nose of the spindle and give it a push/pull in each direction, mainly the X +/- direction and feel for any play. Verify that the lower Y car rollers are properly adjusted and not loose, allowing the spindle to move fore/aft. If your PRS is older and has the bolted onto the gantry beam v-rails, verify that these rails are parallel. If they aren't parallel, the Y car can be tight at one side of the table and loose at the other. Check for loose pinions on the motor shaft, mainly the X car pinion on that side. Make sure the motors are adjusted 'up' into the rack properly and then tightened to the end plates (firm hand pressure while tightening the motor plate bolts). If you try to move that end of the gantry, is there any play due to a motor not engaging the rack properly?

Check the rolling hardware to see if any v-rollers are loose or riding off the rail on that side/location of the table.

Just a process of elimination to find any play in the machine first.

[Brian Harnett]

Sounds definitely mechanical, like Scott said move it around and check for play, A few years ago I was cutting small circles they were coming out oval after about 2 hours of checking I found router bearing up by the brushes had gotten loose.

[QMI]

Thank you. We have checked everything mechanical. Replaced all the pinions. Yesterday, we couldn't even get the machine to come on. ShopBot thinks it is 2 chips, which are programmed by them, that have gone bad. So, we will try replacing those, could that be associated to the machine not cutting straight lines?

[BrandanS]

I have a PRS Alpha and we are currently experiencing an issue where tool paths on one side of the table are not straight. The lines are wavy and seem to be uniform from program to program.

We have gone back and forth with support at ShopBot for the past few days with no real solution to the problem.

I need someone who has experience with these machines to come and look at it and fix it. If you are interested, please message me.

Thanks.

QMI,

I wish I was closer as well. I am currently running 4 Shopbots which machine aluminum, and 2 of which are dual spindles. I had a similar issue on my first ShopBot wherein the spindle mount screws became loose. We had to take the spindle assembly off to get to them. As Scott mentioned above, grabbing the nose of the spindle is what indicated it to us. You could also slide the gantry along V-Rails and test for sloppiness. Again, as Scott mentioned, if the rails are no parallel, it will feel tighter on one end then the other. When you say uniform program to program, does that mean the symptoms are apparent no matter what you run? How about where you run the program? Do some "areas" on your table seem to machine better than others?

[srwtlc]

So, we will try replacing those, could that be associated to the machine not cutting straight lines?

It's possible, but I would think it would be all over the table and not just one side. Have them replaced and try again.

[QMI]

QMI,

I wish I was closer as well. I am currently running 4 Shopbots which machine aluminum, and 2 of which are dual spindles. I had a similar issue on my first ShopBot wherein the spindle mount screws became loose. We had to take the spindle assembly off to get to them. As Scott mentioned above, grabbing the nose of the spindle is what indicated it to us. You could also slide the gantry along V-Rails and test for sloppiness. Again, as Scott mentioned, if the rails are no parallel, it will feel tighter on one end then the other. When you say uniform program to program, does that mean the symptoms are apparent no matter what you run? How about where you run the program? Do some "areas" on your table seem to machine better than others?

Everything seems pretty sturdy as far as the spindle and gantry. We are going to replace the PIC chips tomorrow and see if that helps. Yes, the symptoms are apparent no matter what. Even old programs that we have used before and were good have the same issues when we run them now.

We also found a nick in the cable of one of the stepper motors for the x-axis. It is where it plugs in to the machine wire on the motor side. Could that have anything to do with it?

[bleeth]

X-2? If that is running intermittently or not at all due to this (or the chip issue) that could easily make cutting on the high side of y erratic.
While you are at it check the rails on the gantry at high y carefully for alignment.

[QMI]

X-2? If that is running intermittently or not at all due to this (or the chip issue) that could easily make cutting on the high side of y erratic.
While you are at it check the rails on the gantry at high y carefully for alignment.

Yes, X-2. Thanks, we will check the rails.

[Ken M]

I have the same issues as QMI and have gone through ALL (I think) the steps recommended. For my PRS Alpha the worst chatter is in the X-axis. It is perplexing to say the least. It really showed up after changing the pinion gears on all four motors as part of routine maintenance. Now straight cuts along the X look serrated. Went through square, level, hold down, loose this, tight that. Looks like a sight visit is the next step on the agenda. Shopbot willing to send someone which is helpful but I keep thinking there must be something I'm missing.

[Chuck Keysor]

Sorry for your headaches Ken! But let me be the first to ask that you post some clear, up close photos. Any trouble-shooters will want to see these. Thanks, Chuck

[Ken M]

Serrated edges on all cuts on hdpe. Did not change feed and speeds which have been working fine (some serration of edges but usually only in curves and even then not to this degree). Checked square of table, level of table and rack. Checked how bearings ride on rails as it rides along the X. Tried to troubleshoot as mentioned in other forum posts and from Shopbot files.
Has a blower motor attached for vacuum. Parts hold down well to table. Clamped sheet to make sure. Same result.
According to operator, machine ran really rough one day on a file we had run previously with no issue. Since then we have not been able to eliminate this serration when cutting in the X.
Only change was new pinion gears. Put old ones back on same result. Thought it might be a motor issue so we switched X motor with Y and Z for same result.
32507
32506
PRS Alpha 48 x 96
HSD Spindle
ATC

[coryatjohn]

Be sure you've set the pinion gears tight enough. That's what it looks like to me. Since you're pushing them up to get them set, it can take a lot of force to overcome the weight of the motor and get them situated correctly.

[gundog]

Try contacting Gary Campbell or Brady on here and see if they would be willing to come fix it. You will probably save money in the long run paying one of these guys to come to your shop if they are willing.

[robtown]

One more thought would be to swap the drivers for your x axis steppers and see if the problem moves to the other side of the table?

[jerry_stanek]

I would drop the steppers and run them while I move the wires may be a broken wire

[Ken M]

Set pinions into rack with a scale to make sure we have recommended pressure into rack. What is curious is I only get this serration in the X axis not in the Y.
Ran motors off the rack, checked for run out and they seem fine. There is a minute amount of play in the shaft which lead me to believe the motors could be an issue. Swapped X motors for Y and Z got same result but I did not use scale to set them into rack during that swap. Got a new 6 foot level and made sure level of table and rack is spot on. There was a small amount of adjustment needed there. Still searching...Would be great if there was someone closer than Durham, NC that could help...

[Ken M]

Tried the suggestions but have not come up with a solution to the X-axis chatter issue. :confused:
There is an issue that sticks in my head and makes me think it could be the X motors. I was told by our current machine operator that the former operator (not with the company any longer and not reachable for a conversation) used a bottle jack to engage the pinion into the rack. He said the X motors were really cranked into place. This may have fixed whatever that operator was experiencing at the time but could have been not a good thing for the motors longer term. When I take the motors off there is a small amount of play in the shaft but I thought I was being hypersensitive and looking for anything to explain this chatter I could not fix. A negative to this theory is when I switched the X motors with the Y and Z I still got the chatter but now I questioning whether I ran the experiment under the same conditions.
If any one local to NE Ohio or beyond is up for a site visit to provide a second set of eyes we can certainly negotiate something equitable for all.

[coryatjohn]

You really have to push the X motors into place. A bottle jack, if done to the extreme, could overtax the motors and damage them though. Brady would probably be a good one to comment on the exact amount of force required to correctly set those motors. I used a pressing clamp to set mine. It's made out of plastic and not that powerful but it does exert a constant force and did the trick. The motors are heavy and fight back.

Be sure to grease your rack too. Doing that takes a bit of slop out of the system but certainly not to the level you're seeing now.