Questions about steppers and drivers

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Questions about steppers and drivers

Postby LeonS » Sun Mar 27, 2011 3:55 am

I was looking at the stepper specification which says the sepper has a 0.9 degree step which would mean 400 steps per revolution. Is this correct?

If that is the case, we only need 1/4 micro-step to get to 1000 steps per inch. Is that the recommended setup? 1/8=2000/in? 1/16=4000/in?

It looks like there won't be anymore KL-4020 drivers, ever. They suggested the KL-4030 which costs a bit more but can handle higher current. Is that a recommended alternative? It's cheap enough but will we need the flexibility of more micro-step options? The KL-4030 has less options for micro-steps.

- Leon
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Re: Questions about steppers and drivers

Postby bdring » Sun Mar 27, 2011 12:46 pm

My original laser motors were 0.9 degrees/step. The new motors, if they ever get here, will be 1.8 degrees/step. FSE likes 1000 step/inch so that would be 1/8 step mode. If you want to try Mach3 engraving you want the ability to go a lot higher than that. Mach3 engraving has a lot a variability to it because short pulses come all the way from the PC parallel port. Each setup may or may not find a sweet spot for that. Therefore I find it nice to have a lot of step options. I have some sample drivers coming with my motors. I will publish information about them later.
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Re: Questions about steppers and drivers

Postby LeonS » Sun Mar 27, 2011 1:39 pm

I guess I am more interested in FSE compatibility than trying to get Mach3 engraving to work.

I have been looking at the Polulu drivers that are getting popular in the RepRap community. They would need some heatsink additions, probably, but have some advantages. They are small, cheap, can do up to 1/32 micro-stepping, they are direct drive, and can handle 3.3 volt inputs. I am not sure about the pulse width specifications for them. I don't know if they would be up to the heavier load of the laser platform compared to that of a reprap platform.

I may get a couple to try since I have plans for making a reprap once the laser is up and running. I'll hook them up to an arduino to test them.

I am looking forward to your recommendations.

- Leon
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Re: Questions about steppers and drivers

Postby bdring » Sun Mar 27, 2011 2:36 pm

I have been tempted to try those Polulu drivers and the new Makerbot A3977 based driver. The laser does not require much current. The motors should only run at about 1.5A, but that probably requires a heatsink. I have made my own version for years based on the A3977. I made a daughter card version several years ago. It was nice, because I made a motherboard and plugged in as many stepper drivers as I needed. I successfully used it on a NEMA 23 setup with thousands of hours in a really dirty environment. These do get warm even with the heatsink and a little airflow at 2.5amp.

The only drawback is the surface mount issues. It is hard to assembly these cheaply in low volume. I have a reflow oven at work I can use for myself, but not buildlog production.

See below.

a3977.JPG
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Re: Questions about steppers and drivers

Postby LeonS » Sun Mar 27, 2011 4:15 pm

Geez, Bart. I stand in awe of the breadth of your knowledge and expertise. I am looking forward to discussing 3D printing with you in the future; maybe a new forum section?

The little daughter boards are pre-built and come with a a little stick on heat sink for $14 bucks. I can't beat that with a stick. I am going to order four and give it a shot. I was mistaken, they only go to 1/16th micro stepping. Should do the trick though.

Regards,
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Re: Questions about steppers and drivers

Postby cpdude » Sun Mar 27, 2011 6:43 pm

Which drivers exactly are you talking about here. The MakerBot ones appear to be $39 and are out of stock. I want to know more. :D

Thanks,
Brian
2.x laser ( Mach3 | SmoothStepper | FSE RetinaEngrave)| DIY CNC Router (EMC2) | Prusa I3 3d printer | Building a Wolfstock deta printer | Rhino v5
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Re: Questions about steppers and drivers

Postby j_siegel » Sun Mar 27, 2011 7:24 pm

I assume you're talking about the Pololu 1201 http://www.pololu.com/catalog/product/1201 modules? Many people use those with MakerBots as they are much quieter and run cooler than the stock (Gen 3) hardware.

In my experience running them on a MakerBot and a Mendel with NEMA 17 motors, they run cooler than stock but still too hot for my taste with the tiny included heatsink. I imagine a small 12 or 24V fan would keep things cool enough for use, though another big factor is tuning the drivers. The potentiometers are convenient to use, but never as precise as popping in a fixed value resistor would be. I doubt they have some of the same hardware protection as the more expensive guys (Keling, Gecko) but for $12.95, how can you complain?

For reference, this is the guy I'm using on my Makerbot: http://www.thingiverse.com/thing:4861
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Re: Questions about steppers and drivers

Postby bdring » Sun Mar 27, 2011 8:04 pm

We could probably make a version of the laser interface board that is a motherboard for 3 Pololu boards. It could have some sort of integrated mount for a fan.
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Re: Questions about steppers and drivers

Postby LeonS » Sun Mar 27, 2011 8:11 pm

That sounds like a great extension of your current board. That would be really great.

I have a 24 volt fan that I will mount over the heat sinks.

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Re: Questions about steppers and drivers

Postby tylerv » Mon Mar 28, 2011 2:05 am

The Pololu 1201drivers are the ones I am planning on using in my laser, mostly because I didn't want to spend $40 apiece for drivers. They should be pretty easy to use with a computer or microcontroller. I'll post when I get to that part and let everyone know how they work.
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