[Rickyg]

Hi there.
Hope someone can assist.
Couple of dumb questions.

First I an curious if a 425oz stepper is in effect stronger then a 270oz stepper. In simple terms that is.

Also, I have noticed that some steppers are 1amp 8.6 volts while the next is 6.2 volts at 3.0. I am running a tb6560 board and it works great. The board runs an 8.6 volt 1 amp nema 23 just fine, yet I can't for the life of me figure out how the board knows the voltage of the stepper is 8.6 volts and not 6.3. There is nothing that tells it what type of motor its got attached to it.
The only settings are Current, decay and micro stepping.

Thoughts would be appreciated.

[doorknob]

The TB6560 board uses a "chopper" type drive, which means that rather than applying a constant voltage at the motor's rated "nameplate" voltage and current, it can use a higher voltage and regulate the current to match the motor's requirements by pulsing the power feed to the motor.

The reason that a higher voltage is typically applied to the stepper motor than the 'rated' voltage is that the higher voltage potentially permits a faster top-end motor speed to be reached.

Stepper torque is rated in ounce-inches (oz-in). The rating that is usually given is the "holding torque", which is the torque that it would take to move the rotor away from a stationary position when the rated voltage and current is applied. When you actually start rotating the stepper motor, the available torque will drop off. Generally the manufacturer of the motor would supply a torque vs. speed chart that you could refer to in order to find out the expected torque at any speed within its range. (There are other effects such as resonance that can interfere with the actual torque that may be available at any given speed, but the chart is useful anyway.)

So, the holding torque of a 425 oz-in motor should be greater than the holding torque of the 270 oz-in motor. As for how that might change when the motor is actually turning, refer to the motors' respective torque vs. speed charts.

[Rickyg]

Ok I think I get it then.
I was asking as I notice that the Nema 23 270 oz drive can stall on my device if I try to go over a certain number of inches per minute. Now I know there are a number of things that can contribute to the stall and I am working through them and slowly seeing improvement. But I also was wondering had I gotten a stepper that was perhaps to small for the mass it was tring to move.

Once I started reading the specs for various motors I then became confused over the voltage. So from what I read from your reply the one setting I do need to address is the current setting so that I don't over supply the stepper and I assume damage it.

More reading to do.,


Thanks for your help

[H500]

The motor's voltage rating doesn't matter. A good driver measures and regulates the current.

Instead of using an 8.6v power supply, use 24v-30v. You will get 3 to 4 times the speed you get now. You don't need a stronger motor. The 287 oz-in motor on my mill can lift the 115 lb head upwards at 100 IPM.

[Rickyg]

Hi there
Thanks for the response. I am running a 24 to 30 volt power supply. I thought I was running into a horsepower issue as I was having a jam at 17ipm. Which was very frustrating. While I have lots of time, 17ipm is ridiculous. So I began to think the issue was just plain power. But then I read about resonance. Oh my this looks like the issue. I watched a youtube video and the jam in the video was exactly the same problem I am having. So next is to add a damper.
I have been reading the damper threads and they have been very informative.

I figure, if I am going to learn to do something I might as well start by building a machine and thats what I did. Now I just need to work through the bugs.

Its a blast. My mind reals with the possibilities this type of device provides.

thanks again.

[Rickyg]

In re-reading your post.
Ar eyou suggesting that the input voltage from teh power supply shoould be as high as it can be set at. That this in effect provides the energy needed to move the stepper motor at a higher speed.
I ask this because of th ecomment around lifting 115lb. I can't get my device to move greater then 15ipm today with out stalling or missing steps.
I can watch it turn and the darn motor will skip a steps at anything greater then 12 or 13 ipm. while this would still get the job done.
It really sucks performance wise.

I turned the current down to 50% from 75% which should in my mind be around 1.5 amps against a 1.0 amp motor. 75% I noticed they where getting pretty warm. However I also notice the current change has had no affect on performance. Now I am wondering if I need to crank the voltage up as I think I have it as low as it can be due to my not understanding the implications of voltage on the device. I see a 20 volts against an 8.6 volt motor as a bad thing. But I am still thinking analog.

IS my assumption correct. Crank that puppy up.

[ger21]

What kind of screws are you using? YOU may just be limited by the combination of components you have.

1) your drives are not exactly high performance.
2) An 8.6V 1 amp motor will not spin all that fast, even with high voltage and good drives.
If you're using allthread screws, 15ipm may be all you can get with what you have.

If you can put your hand on the motor, it's not to hot.

I see a 20 volts against an 8.6 volt motor as a bad thing.

To get the most performance possible from a stepper, you typically need to use 15-20 times it's rated voltage.

[H500]

Yes, set the voltage as high as possible, but no higher than about 7v below the rating of the driver, to make sure you don't damage it.

The current setting will usually not have much of an effect on the speed. It only affects the low speed torque. At high speeds, the coil inductance prevents the current from rising to anywhere close to the set value. That is why high voltage is required; to overcome the inductance.

My power supply is 40v. My driver can tolerate 80v. That would double my speed. But I don't bother because I don't need it to go any faster. If you're using a tb6560 driver, don't go higher than about 32v.

I'm using ballscrews. If you're using ordinary screws, you should get about 1/4 to 1/2 of what I get. Your x and y should easily do 50ipm at 40v.

I don't even know or care about what the voltage rating of my motor is. All that matters is the maximum current rating and the inductance.

[Rickyg]

thank you both.
First I am working with 10tpi Acme screws.
I noticed a lot of vibration so this evening I began checking out the various components and making adjustments to drive out the noise.
so far so far.
I adjusted the mounting of the steppers and now its a lot quieter.

I am using flex couplers, which I have read isn't a good thing. So I have ordered rigid couplers, they should be hear in a couple weeks.

Tomorrow I grab my volt meter and set the voltage. I was thinking of unplugging the controller and then measuring the highest voltage from the power supply then dialing it back to peak minus 7 volts as suggested.

Then I think I need to look into stepper resonance. I am not looking for 100ipm, but 30 would be nice. thing is these are single shaft steppers so I need to get creative with the damper. but first I need the new coupler.

Any other advice is greatly appreciated. This has been the most fascinating project I have ever built.

cheers

[ger21]

With 1/2-10 single start, and 24V, a 2.5 amp drive and 2.5 amp motors can get about 60ipm. With your motors and drives, I'm guessing 30-40ipm is the absolute best you can expect.
It's extremely important to make sure there's absolutely zero binding, and the screws are well lubed. If you remove the motor, the screws should be able to be turned easily with your fingers.

[H500]

I think you misunderstood my power supply recommendations. You need to set the voltage about 7v below the rating of the stepper board. If you set it too high, you might destroy the board. Do you have specs for the board and motors? Perhaps you can post a photo of your machine.

I suspect that your motor inductance is too high.

[Rickyg]

hi there.
Wow that was fast.
If I pull the motor out I can easily turn the shaft. Even with the motor in the shaft appears to turn fine with my fingers. However I noticed this evening there is a wobble in the coupler. This isn't a good thing in my mind. So ridgid couplers will help there. I saw a video on youtube that showed the same sort of problem I am experiencing now. I hit full speed and grind....grrrrrrrrr. Ah thats not so good.

Which brings me back to my original question. Would going to a 425 oz stepper make a difference. In truth, 15ipm may just be fine. I am not trying to make a buck just learn and build some parts for hobbies.

however my first real part may be a damper of some sort as I still suspect resonance as being a problem

[Rickyg]

Technical Specifications

Part No.: 57BYGH603
Frame Size: NEMA23
Step Angle: 1.8 degree
Voltage: 8.6V
Current: 1.0 A/phase
Resistance: 8.6Ohm/phase
Inductance: 18mH/phase
Holding torque: 14.5Kg-cm
287oz-in (For Bipolar connecting, the holding torque is 287oz-in)
Rotor inertia: 480 g-cm2
Detent torque: 0.68 kg-cm
Number of wire leads: 6
Weight: 2.20lb (1.0 kg)
Length: 78mm

[Rickyg]

Thanks for your help.

As for the photo, I will try to take a couple picks tomorrow.

[Rickyg]

The documentation I think is wrong.
When I set the microstep to 1 8th per the documentation I need 32000 pulses for an inch. If I set it to 1 16th per the documentation I need 16000 pulses.
According to the math, 200 * 8 * 10 = 16000. Spot on. Doc`s wrong.

[H500]

I see what the problem is. The motor inductance (18mH) is far too high. It's 2mH on my motors. There are no low cost drivers capable of getting good performance from them. I recommend new motors.

Do you know the voltage rating of your driver?

[Rickyg]

Are you asking the input voltage range for the driver board.
Thats 12-36 volts.
So I assume by your comment that a 270OZ motor isn`t the problem, its the inductance. So finding a motor with lower inductance is the right direction.

[H500]

Yes, the problem is the inductance. Get new motors. This guy has some good ones: Stepper Motor

I have the KL23H276-30-8B. If you're willing to spend more, you can get a higher torque one, but don't buy anything with an inductance higher than 3mH.

[Rickyg]

I was looking at this motor, what I didn't understand what the amperage.
The max amperage on my driver board is 3.0 amps. So I don`t know if ìt would support this motor. Also the fact its a 6 wire and the controller is 4 wire also makes me wonder. Lots more to read.

Model 23HS8630B

Step angel (°) 1.8

Motor Length L(mm) 78

Rate Voltage (V) 3.0

Rate Current (A) 3.0

Phase Resistance (Ω) 1.0

Phase Inductance (mH) 1.6

Holding Torque (oz.in) 270

Lead Wire (NO.) 6

Rotor Inertia (g.?) 480

[Rickyg]

I am not trying to earn a living so I can afford slow and frankly am not looking to spend a fortune.
So could I ask for a recommendation.
I need the Nema 23 format.
My driver supports 12-36 volts to a max of 3 amps if I read the specs right.
Its 4 wire. so I am struggling with what is the right motor.