Newbie - Issues please help

[TheBulk]

I have a couple of issues now that my machine is built and trying to get it up and running properly.

I am running a G540 with a 48V DC PSU. I have Nema 23's 387 oz-in which are rated to 3.5Amps. I'm not running any resistors between pins 1 & 5.

My questions are.

1. The motors seem to have a high pitched buzz when at holding torque and they get very hot...... is this normal?

2. The g540 manual states that I don't need resistors between 1 & 5 if the motors are rated above 3.5A which they are at but should I put a small resistance in?


-- Can I add that the motors are running fine apart from that. I am able to jog at differing speeds and accelerations
Thanks
Andrew

[CarveOne]

I would say yes, if only to make the current standby mode work.

From the Gecko G540 manual - "If your motor is rated at 3.5A or above you can safely not use a current set resistor; however, your G540 will not go into current standby mode which will result in increased motor heating."

Use the formula in the G540 manual to determine the 1/4 watt resistor value, which is based on the inductance of your particular motors.

CarveOne

[CarveOne]

The buzzing may be coming from not having tuned the little potentiometers for each motor. Look in the G540 manual for instructions.

CarveOne

[TheBulk]

Thanks very much CarveOne.

One more question for you if you don't mind - I'm reading the Mach 3 manual and other sites but for some reason I can't figure out how to jog the motors at a constant velocity so that I can adjust the trimpot.

Thanks again
Andrew

[CarveOne]

Originally Posted by TheBulk Thanks very much CarveOne. One more question for you if you don't mind - I'm reading the Mach 3 manual and other sites but for some reason I can't figure out how to jog the motors at a constant velocity so that I can adjust the trimpot. Thanks again Andrew

If you can reach both at the same time, press the arrow key on your keyboard for the directions you want to tune while adjusting the trimpot with the other hand using a tuning tool or small screwdriver. You may want to put tape over the screwdriver shank so nothing inside the Gecko drive gets shorted out while finding the slot in the trimpot. Just watch out for end of travel crashes. You could create a gcode to run that will help with this also.

My G203V and G540 drives were set close enough from the factory that I haven't bothered to adjust them.

CarveOne

[TheBulk]

I can't find a 3.5K 1/4W resistor. The closest I can get is a 1/2W 3.6K resistor. Would this be acceptable? Or should I scour eBay?

[ssutton]

Yesterday I was wiring up my motors to my G540 and could not find 2.8K 1/4 watt resisters, what I wound up using was a 2.6K ohm resister and a 200 ohm resister in series so the total resistance was 2.8. It is perfectly acceptable to use resisters in series to total up the value desires. Keep in mind that it will be a little more difficult to install the DB9 hood with more than 1 resister. 1/2 watt resisters will be even more difficult to install under the hood.

[TheBulk]

Okay good call. So there is no issue that you know of using 1/2W resistors electronically just the fact that they are bigger and harder to use from a physical perspective?

[ssutton]

No issue at all. I am an electronics tech.

-Scott

[CarveOne]

I would do as ssutton recommends. Any series or parallel combination that gives the desired value is acceptable. If you can fit the 1/2w resistor(s) in the shell that is ok too. Just don't use 1/8w resistors unless you can determine that the rating is high enough. Ahren recommends 1/4w so I would assume that he has done the calculation and 1/8w is not big enough for some conditions.

CarveOne

[TheBulk]

Thanks very much guys.

I appreciate all of your help