New PRS Standard is driving me BONKERS.

[david_gregas]

I just got a new PRS Standard about 5 weeks ago. I am having a problem that I am hoping someone here can help me with. I have explored pretty much anywhere that a problem might occur and I can tell you that the machine is perfectly aligned, X and Y axis' are moving freely, USB communication is around 80%, I have swapped drivers and motors, grounded the heck out of the damn thing and still this problem persists. The issue is that whenever I move the X axis at a speed value of 5 or 6 I get a god awful vibration that is consuming me.
Please help! I need to have confidence in this machine and the way it stands now I can't trust it.
Thanks

[davidp]

David,

I installed 7.2 motors before Christmas and had a similar problem.

Does the vibration only occur when you are doing a move as opposed to doing a jog? ie if you move at say 150 mm per second (6ips) does it make the noise and if you jog at the same speed it doesn't make the noise. If so you need to send an email to support and frank or chris will give you a fix.

Your profile does not mention where you are but I am guessing that you have 220-240 volt power supply and that is causing the problem. If so then the fix is relatively simple but can be tedious and time consuming.

The problem is still apparent on my machine but only on move speeds around 300 mm per second (12ips) and as I very rarely cut at these speeds It is not a problem, It has never been a problem at any speed whilst jogging.

The good part for me was that I pulled my machine to pieces and rebuild it and re calibrated it. The Y axis is now accurate to less than .5 mm over 1200mm and the quality of my cuts is now excellent.

Good luck,

[Brady Watson]

Your communication is choking. Go out & buy a Belkin 4-port PCI USB card from Staples & a USB 2.0 hub. Install the card in any available PCI slot in your computer & then plug the hub into that, and your bot's USB line into the hub. Your USB cable should be no longer than 12 feet.

Run the SpeedTest.exe in the diagnostics folder to find out how good your communication is.

-B

[david_gregas]

By the way guys,I'm running a Standard not an Alfa at 120v and a spindle at 220v. Brady I have run the test and the result is over 80% as stated in my original post, but if you think that this is still a problem then I will get the PCI card and hub. David jogging, moving at SV's of 5 and 6 both produce the same result and I have talked to Frank, Scott and Ryan at ShopBot and not a hint to the cure. Unlike you David, I want and need those speeds in my inventory and feel that they should all work not just 1,2,3,4 then 7,8,9,10,11 and 12. Anyway thanks for the help guy's and any other help would be greatly appreciated.

[richards]

David,
Can you post the actual motor model number of the motors that you're using and the type of Gecko stepper driver that you have (Black = G202 and Red = G203v).

I'm running the math on some possible problems, but I'll need actual model numbers before I can post my theory.

[david_gregas]

Mike I have the black G202 drivers and for motors I have Orientals and for the number I'm not sure at the moment. I,ll guess and say A7421 943ktg??? And by the way Mike I appreciate you taking the time. I'll get back to you with the correct model number for the motors.

[richards]

David,
It looks like you have standard PK296-01AA style motors factory attached to Oriental Motor's 3.6:1 gearboxes. As shipped to Shopbot, those motors have four connecting wires, Black, Green, Red, and Blue. That means that the motor MUST be connected using Bipolar Series wiring, which, for that particular motor is the second best method to use when you want speed - but it is the only method possible.

According to the Oriental Motor torque charts, the PK296-01AA motor, when wired Bipolar Series, is typically used at speeds up to about 150 RPM.

If my facts are correct, the PRS-Standard uses 35-tooth spur gears, meaning that each spur gear revolution moves an axis 3.93 inches (25/20*pi) and with a 3.6:1 gearbox, each revolution of the motor's shaft moves the axis about 1.09 inches.

So, to move the axis 5-inches per second the motor's shaft has to rotate about 4.58 times per second or 275 RPM. The bad news is that motor, using Bipolar Series connections, will have a lot of trouble running that fast. (If the motor had six leads, it could be connected using half-coil wiring and then the motor could easily run at 500 RPM.)

The G202 stepper driver can handle motors that have inductance ratings of 1mH to 40mH. Your motor has a Bipolar Series rating of 30.8mH, which is higher than many other stepper motors (and the main reason that the motor performs best at slower speeds), but still within the acceptable range for the G202. (The G203v stepper driver must be modified to properly run a 30.8mH motor.)

On my test bench, I use the PK296A2A-SG3.6 motor, which is the PK296-03AA motor with a gear box. Normally I wire it half-coil and run it up to 1,000 RPM. When I wire it bipolar-series, I've run it at the same speed, but with too much vibration. When wired bipolar series, that particular motor works best at speeds up to about 250 RPM.

I'm afraid that the only suggestion that I have is to change the 25-tooth spur gears to 30-tooth spur gears. That would give you 5-ips at about 230 RPM - which is still too high, but it might buy you some more speed before getting too much vibration.

[david_gregas]

Mike, I think you may have misunderstood me. The problem is only at SV's 5 and 6 while SV's of 7 and up are fine and 4 and down are fine. Also the noise does not happen the full length of the x rails nor does it happen at the same location on the x axis. It's an odd situation I've got here and any insight would be welcome.

Thanks again.

[richards]

David,
At speeds above about 3-ips, that motor, when wired bipolar series, is flat-lined, meaning that its torque is about as low as it can get before stalling. The fact that you're able to run at speeds higher than 6-ips without the vibration seems to show that you've ramped into a speed where the momentum of the axis is making up for the lack of torque from the motor.

Think of it as using the wrong gear in your car. Until you get to a certain speed, the car will shake and shutter and the engine with be on the verging of stalling; however, once you get to a certain speed, things smooth out again. That's kind of what happens with a stepper motor/stepper driver. Because of the torque curve of the motor, it's like having a automatic transmission - until you hit the flat line portion of the torque curve, then, fairly suddenly, it's like being in the wrong gear with a manual transmission - until the speed gets high enough, then things smooth out again.

One way to work around the problem would be to slow down the ramping so that the motor can move more smoothly transition through the rough area; however, be aware that there won't be much available torque at those higher speeds.

[andyb]

David, what kind of computer are you running? This may be off track but if I remember right Wes Mason had the same problem or a similiar problem on his PRSAlpha. It turned out to be at certain model of Dell motherboards.

Andy B.

[ted]

Hi David,

Sorry to be late jumping in. Your ShopBot should not be vibrating at those speeds. To give me a little more info, is it happening in both the X and Y? Does it happen in straight lines or diagonals, or both?

The USB hub suggestion above is good, but is not consistent with your 80% speed report or the absence of vibration at higher speeds.

I've spent a lot of time playing with a new PRSstandard for the last week testing some other new stuff and haven't noticed any vibration issues. But let me specifically go run it for awhile at 5-6 ips.

Meanwhile, we'll ponder this one. If you can call ShopBot tomorrow in the late am after we've discussed it I hope we will have a solution for you.

Ted Hall, ShopBot Tools

[david_gregas]

Ted thanks for jumping in. I'd say that it is just the x axis and it occurs on both straight and diagonal moves, in jog and move mode. This situation has eaten up hours upon hours of my time and patience and I need to resolve it soon. I'm no expert but after all the troubleshooting I have done I believe the problem to be either motherboard or powersupply related because I've pretty much eliminated every thing else that i'm aware of.
Anyway I will call you tomorrow

David

[david_gregas]

!!!!! PROBLEM SOLVED !!!!

I would like to thank everyone at ShopBot especially Ted for the help in getting my problem solved. I'm very happy to know that I have bought a product from a company that supplies a high level of support and stands by their product. Again thank you very much.

David Gregas

[german]

David, let us know how you solve the problem, what you did to get the machine fix?
I'm asking you becouse I have the same problem whit mine.
thank you for your time.

German.

[david_gregas]

German Ted sent me a new control board and drivers and that solved my specific problem. Hope this helps.

David