Stepper motor ampage question

[Fivetide]

Hi guys I have a TB6600 rated at 4 amp and a 4 wire Nema 23 rated at 4.2 amps if I wire up the controller to the motor will it burn it out or do some damage ?
I could buy a TB6600HG (https://www.ebay.co.uk/itm/CNC-Single-Axis-TB6600-0-2-5A-Two-Phase-Hybrid-Stepper-Motor-Driver-Controller/251514331707?epid=1960882522&hash=item3a8f6c223b:g:VbkAAOxyBvZTWWD7:rk:2:pf:0) which is rated at 5 amp just to be safe

[john swift]

If you use a TB6600 stepper driver set to 4A
a stepper motor rated at 4.2 amps will run at the 4A set by the driver so there should be no problem
the motor torque will be reduced to 4/4.2 of the rated torque

having said that I would be inclined to use the TB6600HG so the stepper driver is not run at is limit

John

[Fivetide]

Thanks for the advice John I think Ill go with the 5 amp controller as you said.

[Clive S]

Thanks for the advice John I think Ill go with the 5 amp controller as you said.

Have you taken in account of the voltage to the drives?

[Fivetide]

Have you taken in account of the voltage to the drives?

Hi Clive - I sort of guessed it as I'm no expert but I have a PSU rated at +24v @ 14.6 amp . At the moment I haven't tried just using the 3rd 178 oz Nema 23 it may be ok on the live jobs I 'm going to be doing. and the only difference in fixings is coupling size. The larger 23 I haven't purchased yet but is intended to spin the lathe chuck - in the event 178 needs some more torque at higher feed rates mainly for finishing cuts, although it may be way over the top. The lathe is basically a motorized wood copy lathe, I'm not machining anything that's precise, but if i can get a decent rpm and make a finishing cut of 1 to 0.5 mm without jamming - then it will have done the job intended. :)
First I'm going with a direct drive attempt as its very simple to set up. I also have a 1:2 pulley system I could try if that fails. And if that wont work I'll go for the 425oz.

1. x1
Manufacturer Part Number 23HS45-4204S
Step Angle 1.8°
Holding Torque 3.0Nm(425oz.in)
Rated Current/phase 4.2A
Phase Resistance 0.9ohms
Recommended Voltage 24-48V
Inductance 3.8mH±20%(1KHz)
Weight 1.8kg

2. x3

NEMA 23 MOTOR SPECIFICATIONS:
Holding Torque: 178 oz/inch
Mount : 56.4mm x 56.4mm
Shaft diameter: 6.35mm (1/4inch)
Rated current: 2.8A DC
Recommended Power Supply : 24-48VDC
Step angle: 1.8 degree

[Clive S]

I suppose what I am saying is 24V might be a bit low to do what you are thinking of but the limitation of the drives you have will dictate the max voltage.

[m_c]

For a lather spindle, a stepper really isn't good. The torque will drop of far too fast, and I'd think you'll struggle to get even those shallow depths of cuts.

For cheapness I'd suggest finding a suitable basic DC motor, and combine it with a basic speed controller. Gear it with a suitable poly belt to get spindle speed within a suitable range, and you'll have a far more capable spindle.

[Fivetide]

For a lather spindle, a stepper really isn't good. The torque will drop of far too fast, and I'd think you'll struggle to get even those shallow depths of cuts.

For cheapness I'd suggest finding a suitable basic DC motor, and combine it with a basic speed controller. Gear it with a suitable poly belt to get spindle speed within a suitable range, and you'll have a far more capable spindle.

m_c what about a high-bred I believe they are much better at high rpm in keeping good torque? My mate has the original motor in bits he seems to think it can be salvaged, it may become a combination of DC and stepper motor like you say with a PWM. I want the flexibility of simple spindle work and carving, its all theoretical at the moment until I get it full assembled and tested - I'll let you know the results :)

[m_c]

It depends what you mean by hybrid. Pretty much all stepper motors you buy now are technically hybrid motors (most square motors are hybrid), and they are far better than conventional (typically round) stepper motors.

A quick search of eBay has thrown up the likes of this - https://www.ebay.co.uk/itm/200W-220V-DC-Treadmill-Motor-DIY-Project-Electric-Variable-speed-with-remote/253850778051
And they also sell a 500W version with a basic speed controller - https://www.ebay.co.uk/itm/500W-220V-DC-Treadmill-Motor-DIY-Project-Electric-Variable-speed/253982275690

To give you some reference figures, using the speed torque curve of a leadshine nema 23 motor (http://leadshine.com/productdetail.aspx?type=products&category=stepper-products&producttype=2-phase-stepper-motors&series=57HS&model=57HS22 - one of the first motors I found that has the needed data), at 2000RPM depending on configuration/supply voltage it's only producing 0.4 to 0.7Nm, which works out at 80 to 150W of mechanical power. To get that relies on driving the motor at 68VDC. Drop the voltage, and the torque will drop of far quicker.

At that point costs are verging in to the same as buying a small single phase motor, or even three phase and cheap VFD. A quick ebay search shows a 1/2HP 3 phase motor can be had for £62, and a suitable VFD for £45. It will likely cost you more than that to get a suitable 68VDC power supply and suitable stepper drive.
The only thing with using a standard induction motor, is they are far larger than a similar power DC motor.

[Fivetide]

m_c I ment closed loop stepper sorry

- Closed-loop vector control technology ensures the high torque output, while ensuring that the motor does not lose step.
- With overvoltage, overcurrent, tracking error or over-error, and other protection features.
- Closed-loop driver can significantly improve the high-speed performance of the motor, increasing the effective torque of the motor by more than 30%; Effectively reduce the motor heating and motor vibration, the output current of the driver becomes larger or smaller as the load and speed increase or decrease; It can improve the processing speed and accuracy of the machine and reduce the energy consumption of the machine.

[m_c]

I suspected you really meant closed loop. Yes, they will offer more performance for a given size, and will recover more gracefully depending on settings (I forgot to mention, one big issue with using a stepper for a spindle, is if you do stall it, it will probably remain stalled until you stop/restart it).

If you want to run some comparisons, find the relevant speed/torque curves, then run the figures through the calc here - http://wentec.com/unipower/calculators/power_torque.asp

One thing I should of mentioned in my last post about DC/Induction motors, is the rated power is only at full rated speed. So if it's 200W at 4000RPM, it will only deliver 100W at 2000RPM.
With an AC motor and VFD, you do have the possibility of running the motor above it's rated speed, however you enter a power constant stage. I.e. if the motor produces 1Nm at it's rated speed of 1500RPM (works out to 160W), if you were to double it's speed to 3000RPM, you would only get 0.5Nm (which is still 160W)