Need to work out voltage for unknown stepper motors

[justinj]

I had been planning to make a CNC for a while and the guy I work for decided to be nice and purchased a table top CNC from an online auction. The only problem is it had no control box (Which had the PSU) and was missing a cable. I've ordered a 4 axis controller but now I need to work out what voltage power supply to buy. The steppers say YOC2012- 5 7 - 7 6 1.8' 3.0a but I can't find these on the internet so I don't know if they're 24v or 36v and don't want to get the wrong PSU. Can anyone help me out with a way to determine voltage or happen to know this particular model?

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[awerby]

Usually the nameplate voltage ratings on these little steppers don't represent a maximum voltage. In practice, you usually get best results running them at about 25 times the nameplate voltage. I doubt 36 volts would harm your motors. The drivers, on the other hand, will be more sensitive to excess voltage than the motors, so you should look at the specs on the new 4-axis controller you bought and see what the maximum recommended voltage is. Generally, steppers perform best towards the top of their voltage range, although you may need to add resistors to limit the amperage they draw.

[justinj]

I have no idea what the nameplate voltage is for these steppers as it has nothing more written on it outside of the photo shown. The controller supports up to 36V. The water pump that came with the machine is 24V so I don't know if it originally used 24V or just had 24V out for the pump.
Is there any way of testing to make sure 36V is safe? I have a lab power supply that'll go up to about 32V and 5A. Can I test it by sending the axis up and down for a while and see if it gets hot? Or should I be looking at something else?

[2e0poz]

I think your motor is one of these 23HS8430 which you can check the spec of it here on page 12. the question is is it a 4 wire (bipolar) or 6 wire (Unipolar)? They tend to get bundled with both 24v and 36v combo (blue) drives you see on the bay. Hope that helps

http://www.svaltera.ua/catalogs/know...er_Motor_E.pdf

[justinj]

Yes it does tick all the boxes of the 23HS8430 (Current, step size, physical dimensions) and is a bipolar motor. There's no mention of voltage on the spec sheet, would it be safe to assume 36V is OK?
Controller is just one of these cheapie ones (Which look like the type that would come with the machine in the first place) 4 Axis TB6560 CNC Stepper Motor Driver Controller Board | eBay

[2e0poz]

All i can say is give it a go, i've run smaller steppers at 36v with no problem at all. The fact they bundle these with 36v boards would give me a tick in the box :-)

[Mzones]

justinj

Ohm's law will tell you what the motors are rated at.
Amps is the important thing.
The driver is what limits the voltage you use.


Mike.

[Jim27]

If the stepper control is a chopper drive that limits current (and all but low end controls should be) then you need to be setting the maximum current not the voltage. As others have said typically steppers get run at many times the name plate voltage. The name plate voltage is what can be used without resistors or current limits but doesn't give good speed performance. A chopper drive will limit the average voltage to a low value when at low speed or stopped but give higher voltage when moving faster. If the motor says 3.0A then you really have all the information you need. Set the control to 3 A and use 24, 36, even 48 volts shouldn't be a problem for the motor. Check the driver for voltage limits of the system. The higher you go in voltage the faster you can run. If you don't have any ratings (voltage or current) start low and gradually increase keeping an eye on motor temperature. And you shouldn't use resistors with chopper drives. It's not needed and just wastes power.

On the other hand, if the drive isn't a chopper drive adding resistors to limit current while boosting the voltage will get better high speed performance. But it's not nearly as efficient or effective as a chopper drive.

[justinj]

Thanks for that info I can't run 48V because the controller isn't rated to that, the controller is a chopper type (Toshiba TB6560AHQ) so I'll probably run at 36V.
You mentioned that a higher voltage runs faster, would that not cause jitter or vibration if it steps too quickly? Also how much slower would you expect it would run at 24V vs 36V? Mainly because the SMPS I'd normally buy (Meanwell SP series) doesn't come in 36V above 320W which means I'd need to go to the HRP series which is more than double the price and then I'd also have to get a DC-DC converter for the water pump (Not that that costs much).

[2e0poz]

Just remember everything comes at a cost, running at high amps and voltages gets converted to heat. Being able to run your steppers at the max 3 amps will what will give you torque. The Tosh chips do not like running too hot especially for prolonged periods of time. The 36v 320w power supply will be plenty for your driver and steppers, always leave some spare or the supply will suffer too much heat as well. I would not get too bogged down in the details as you will understand more as you go along.

[Mzones]

Jim27

The driver is what limits the voltage you use

.


I was referring to the fact that the TB6560 accepts 12-36 volts
for the motors power input.



Mike

[john-100]

Hi justinj


looking at the data sheet for the TB6560
the maximum motor supply voltage in the Operating Range table on page 6 - is 34V (not to be confused by Absolute Maximum Ratings !!!! )
https://www.toshiba.com/taec/compone...E_EN_27885.pdf

more info here -
http://www.cnczone.com/forums/genera...-software.html


John

[justinj]

Hi justinj


looking at the data sheet for the TB6560
in the the maximum operating Operating Range table on page 6 - the motor supply voltage is 34V (not to be confused by Absolute Maximum Ratings !!!! )
https://www.toshiba.com/taec/compone...E_EN_27885.pdf

more info here -
http://www.cnczone.com/forums/genera...-software.html


John

I guess you should never assume that what the Chinese put on their boards is accurate! Thanks for the info John, I'm thinking I'll run it at about 30V (RSP-500-27 adjusted up) as per the 'How I fixed my' link after reading the TB6560 sheet and the link. That link has some good info on it and it looks like it's exactly the same model as mine so I'll look at implementing some of the improvements as I'm not shy with a soldering iron

Now I have to work out the spindle (New thread) and I'll be all set!

[Jim27]

You mentioned that a higher voltage runs faster, would that not cause jitter or vibration if it steps too quickly? Also how much slower would you expect it would run at 24V vs 36V?

I am not sure about the vibration question - don't think that is usually an issue. As for the speed difference it probably isn't an issue unless maximum speed moves are really important. I don't think you will see a lot of difference between 24 and 30V.

[justinj]

So I tested my machine yesterday with the controller set to 100% current and the spindle off, despite the steppers being rated at 3.0A when I tested it with my 'lab' power supply it went from 300mA idle to 1A with a single stepper in use. Does this mean there's something wrong with the controller or motors or is this expected behaviour?

[justinj]

After thinking about it on the drive home today I realise I should probably leave the controller set to 75% as the power supply showing only 700mA with the axis in motion is probably due to PWM dividing the usage and the ammeter not reading it correctly as a result.

[Toinvd]

Your Amp meter is most probably giving about the right value. The higher the input voltage the lower the current from the power supply for the same power ( current ) through the motor at the same freq.
You can test this by lowering the voltage of your lab powersupply while one motor and driver connected. The Amp meter should give higher readings if you lower the voltage.
This is due to the driver giving the same current to the stepper motor by regulating the chopper.
Don't go above the rated voltage of the stepper driver, better stay a safe value below like you said 30 volts is a safe value for the 36 volt rated driver.
And about the motor current, have it running for 15 minutes and check the temperature. If its below 60 degree, it's fine. If to hot, lower the current setting. If to cold you can increase the current and have more torque.
I run mines so that I can touch them, but not hold my fingers to them to long ( I gues about 50 degree centigrade ). which is far on the safe side.