Stepper Compatibility

[lars86 42]

Hi guys,

Would this stepper plug and play with the UMO stepper drivers?

http://www.omc-stepperonline.com/gear-ratio-51-planetary-gearbox-high-torque-nema-17-stepper-17hs191684spg5-p-40.html

I'd like to design a new extruder drive around it, or something similar.

Thanks!

[lars86 42]

...and while I'm at it, switching in these for X and Y:

http://us.stepperonline.com/09deg-nema-17-bipolar-stepper-motor-2a-46ncm-17hm192004s-p-122.html

[lars86 42]

Anyone?

The rated current per phase of 1.68A * 2 phases = 3.36A, seems reasonable for the geared stepper.

Is the 2.0A / phase on the other motors too high for the UltiStepper driver?

[gr5 2,230]

I don't know but they look fine. Keep in mind that the speed limits of 300mm/sec are based on how many pulses the arduino can put out so if you increase "steps/mm" in the firmware you need to decrease the max velocity by the same ratio (e.g. 3X as many steps/mm means 100mm/sec is top speed).

I suspect the 2.0A is fine. My understanding is that the stepper driver on the UMO will only put out so much current and if you push harder it just skips a full step. That's what that little adjustment is for. I noticed that when I fight the stepper motors such that they are working harder the machine also draws more current. So steppers don't draw the full specified current if you don't make them work hard.

[lars86 42]

Awesome, thank you for the insight!

So, is that to say the drivers are only safely capable of 300 mm/s * 78.7402 steps/mm = 23622 steps / sec?

I'm guess that after switching X and Y to these 0.9* / step motors, I can switch from 1/16 microstepping to 1/8.

[lars86 42]

On that note, wouldn't doubling the steps / mm, and halving the microstepping be a wash as far as the Arduino is concerned, in steps / sec output?

[gr5 2,230]

On that note, wouldn't doubling the steps / mm, and halving the microstepping be a wash as far as the Arduino is concerned, in steps / sec output?

 

Yes.

That's why I mentioned "steps/mm" instead of talking about microstepping or steps/degree or gearing.

>23622 steps / sec?

I think it can do that for X *and* Y at the same time so 46k steps/sec but it can go a bit faster than that even - there is a little room for E and Z maybe? But yes. That's what I'm saying. I mean that was the original reason 300mm/sec was chosen and I don't think steps/mm has changed from UMO to UM2 to UM2+ (for X axis), right?

[gr5 2,230]

I was looking at the beaglebone a few days ago. Wow. It has a second simpler computer that shares the same memory (actually it has 2 of these) that can do simple logic (somewhat limited) and it can be programmed to do the actual stepping. It's a 200mhz sub processor (the main processor is 1GHZ I think) and it can do all the stepping for you. People who wrote the code say you can do 1 million steps/second no trouble at all. And the "real" cpu is bored typically at 1% utilization while printing.

So the fast computer does all the floating point math and figures out the path (acceleration, decelaration, jerk, max speed, and so on) and puts the path for the next dozen or so points into a table and the sub-processor reads the same table and executes it in real time. The "real" computer typically has linux on it and can do tons of other things with the rest of that 99% cpu available.

[lars86 42]

Droooool

I REALLY want to upgrade the electronics on my printer, and the Replicape/BBB looks like a really powerful combo. My biggest concern with that, is the firmware. I really like Marlin, and am excited about some of the new development work in it for extruder advance.

[gr5 2,230]

and am excited about some of the new development work in it for extruder advance.

What? New development? The advance stuff has been around for years and some printers use it routinely (they need it!) but I haven't heard about any *new* development.

[lars86 42]

 

and am excited about some of the new development work in it for extruder advance.

What?  New development?  The advance stuff has been around for years and some printers use it routinely (they need it!) but I haven't heard about any *new* development.

 

https://github.com/MarlinFirmware/MarlinDev/issues/402

The advance function in Marlin has been broken since I got into printing. Someone has already figured out why it isn't working and fixed it. But we've got a discussion going on creating a better implementation.