Video of what motors start doing.

[williams_architectural]

https://www.filemail.com/d/bzpoznbrhfanoxh

In the video the motors start just fine but once a load is applied it just stops and vibrates. I've been having issues with one or the other sounding like they were binding/lagging/grinding. Carriage was rolling smoothly, home positioning was good. Once I started a program, either in jog or cutting, I began randomly hearing these sounds. A couple of months ago I read a post regarding other PRSstandard owners jogging at 4 to 5 ips and over with no problems. I started jogging at 4 to 5 ips with no problems until recently. Started once or twice and then became consistent and started losing position during cutting even though I was only cutting between 1.5 to 2.5 ips.
Anyone else have this issue? I have the Gecko 202 drivers. Scott has been helping and also Frank from Shopbot has been helping me solve the problem but I would like another opinion before buying the wrong parts.

Thanks and please share,

William Moore

[srwtlc]

William,

Good video of the issue. My experience with the older gecko drive systems is limited, so hopefully those that know more will jump in here too. So, it does the same thing when jogging slower and also at slower cutting speeds under load. Did Frank mention anything about the possibility of a bad/weak power supply for the geckos?

[williams_architectural]

William,

Good video of the issue. My experience with the older gecko drive systems is limited, so hopefully those that know more will jump in here too. So, it does the same thing when jogging slower and also at slower cutting speeds under load. Did Frank mention anything about the possibility of a bad/weak power supply for the geckos?

Thanks. Yes Frank did. I checked the voltage and it was 52V so I cranked it down to 48V. Well I don't cut more than 2.75 ips on any material but I did slow it down to 1.25 ips on the cutting. Now that you mentioned it, I'll have to check Monday and see if I slowed the jog speed down or not.

William

[srwtlc]

I would think that more voltage (within limits) would be better. I believe that the geckos are rated for more than 52v, but again, there are others on here that are more knowledgeable on the gecko drives. Does the same thing happen with the Y and Z axis? Drop each of those motors off and give them the same test. If they don't, you could swap those drivers to the X channels and try again.

[williams_architectural]

I would think that more voltage (within limits) would be better. I believe that the geckos are rated for more than 52v, but again, there are others on here that are more knowledgeable on the gecko drives. Does the same thing happen with the Y and Z axis? Drop each of those motors off and give them the same test. If they don't, you could swap those drivers to the X channels and try again.

No I haven't tried that and that would be a good idea to do that. Just checked the voltage for the Gecko 202's and it states as follows:

G202 TERMINAL WIRING

POWER SUPPLY HOOKUP

(TERM. 1) POWER GND Connect the power supply ground to term.1
(TERM. 2) 24 - 80 VDC Connect the power supply “+” to this terminal

CAUTION! Never put a switch on the DC side of the power supply! This will damage, if not destroy, your drive!

The power supply voltage must be between 24 VDC and 80 VDC. The maximum power supply current required is 67% of the
motor’s rated phase current. An unregulated power supply may be used as long as the voltage stays between the limits; keep the
ripple voltage to 10% or less for best results. The drive has a 2 second power-on reset time before the motor is energized.

CAUTION! Power supply voltage in excess of 80 VDC will damage the G202.

[donek]

I have 4 CNC machines. Every single one will do this. It's what happens when you stall a stepper. It is possible your problem is with the electronics as I can't tell how much force is required to stall these motors, it could be something else too. I have only worked on one PRT machine (I think that's what these are from). It was stalling in the x-direction consistently. The problem was with the spring tension. They were way under tensioned. The tighter we made the springs, the less likely the stall. The machine was more likely to stall when moving in one direction rather than the other as well.

[williams_architectural]

I have 4 CNC machines. Every single one will do this. It's what happens when you stall a stepper. It is possible your problem is with the electronics as I can't tell how much force is required to stall these motors, it could be something else too. I have only worked on one PRT machine (I think that's what these are from). It was stalling in the x-direction consistently. The problem was with the spring tension. They were way under tensioned. The tighter we made the springs, the less likely the stall. The machine was more likely to stall when moving in one direction rather than the other as well.

Thanks for the response.
So how do you tighten the spring tension and where is it located?

William

[srwtlc]

As you have a PRS machine, this doesn't apply to you. Also, you can stop them by hand, and that shouldn't be. I'm guessing something is wrong with your controller, be it the board, geckos, or power.

Are you in contact with SBHQ?

[richards]

Stepper motors need to receive one pulse per step. Those pulses must arrive at the stepper driver within the expected time. Also, a stepper motor needs to accelerate from standstill to full speed in a controlled ramp. If the motor encounters a load greater than expected, it will stop and it will ignore any further pulses because the interval between those pulses will be too short for a stopped motor.

Each driver and motor must be tuned so that the ramp rate selected is within the ability of the motor and driver to function properly.

I have used the G202 stepper driver extensively with various motors. Some motors, with low inductance, perform very well at 35vdc. Other motors with high inductance perform poorly even at 80vdc.

With a G202, motors can be wired bipolar serial, half-coil or bipolar parallel (if the motor has 8 leads). Half-coil or parallel work best for me. Series looses torque too rapidly for my applications.

Try modifying the ramp rate (to a longer or slower rate).