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Which Stepper


andrea tasselli
 

Hello everyone,

Having finished my first OnStep and waiting for a clear night to test it in haste, which isn't going to happen anytime soon if forecast are to be believed, I was think abut my next OnStep project. This got to replace the venerable FS-2 on my G-41 so that I can finally have ASCOM goodies on that mount. This in turn brings in the question of which stepper to order. I have previously used LV8279 and happy with them so far. I was wondering whether I should go with one of two choices for SPI driver on a Blue Pill, either TMC2130 or TMC5160. What are the advantages and disadvantages of these with respect to the non SPI ones? And between each other?

Thanks for any advice.

Andrea


Khalid Baheyeldin
 

On Wed, Oct 21, 2020 at 01:38 PM, andrea tasselli wrote:
This in turn brings in the question of which stepper to order. I have previously used LV8279 and happy with them so far. I was wondering whether I should go with one of two choices for SPI driver on a Blue Pill, either TMC2130 or TMC5160. What are the advantages and disadvantages of these with respect to the non SPI ones? And between each other?
First you decide on the motors (based on torque needed, how widely they are used/tested in the community, availability, price, and so on), then you decide on drivers for them. The reason is that some motors require higher current than what certain drivers can provide.

The two most used motors for Onstep are:

400 step, 0.9A, 36Ncm
https://www.omc-stepperonline.com/nema-17-stepper-motor/nema-17-bipolar-0-9deg-36ncm-51oz-in-0-9a-5-4v-42x42x40mm-4-wires.html?

400 step, 1.68A, 44Ncm
https://www.omc-stepperonline.com/nema-17-stepper-motor/Dual-Shaft-Nema-17-Bipolar-09deg-44Ncm-6248ozin-168A-28V-42x42x48mm-4-Wires.html?

I don't know which one would be needed for the GF-1.

For example, the LV8729 and TMC2130 cannot power a motor which is run at, say 1.5A, but the TMC5160 and S09 can.
Moreover, the TMC2130 heat up considerably. The LV8729 and TMC5160 do not heat up.
The TMC5160 is relatively new and has not been used that much in the community as the LV or 2130.


andrea tasselli
 

Thanks Khalid,

At present I was thinking of using the existing bi-polar motors (hybrid, I believe), which have the following specs:

200 step/rev
Tracking Current 0.7 A
Goto current 1.4 A

They are supposedly as old as the mount itself, so 20 years but they have withstood the test of time, so far. And capable of carrying big loads.

However I’m not precluding changing to a new set if I can fit them in the current set-up and they bring obvious advantages.

Based on what you wrote I’d tend to plump for a pair of TMC5160, as not too expensive to source. Is being a SPI stepper driver such a plus, BTW?

Cheers

Andrea


Khalid Baheyeldin
 

On Wed, Oct 21, 2020 at 02:13 PM, andrea tasselli wrote:
At present I was thinking of using the existing bi-polar motors (hybrid, I believe),
If it was me, I would do that too: saves me the hassle of attaching new motors to the mount, motion transfer to the worm gear or friction gear, ...etc.

which have the following specs:

200 step/rev
Tracking Current 0.7 A
Goto current 1.4 A

They are supposedly as old as the mount itself, so 20 years but they have withstood the test of time, so far. And capable of carrying big loads.

However I’m not precluding changing to a new set if I can fit them in the current set-up and they bring obvious advantages.
That is the best strategy in my opinion: don't try to get everything from the first attempt, and don't let perfect be the enemy of good enough. You can always change things later, depending on how actual performance goes.

Based on what you wrote I’d tend to plump for a pair of TMC5160, as not too expensive to source. Is being a SPI stepper driver such a plus, BTW?
Depends on your board: if your board allows mode switching (Blue Pill, Max/Mini), then an S109 is good too, and have been used by some large mounts (including this giant, which was done before the TMC5160 became available).

If the board is a 3D printer one, then only SPI will allow you to do mode switching for faster slewing.

Depending on how much gear is on the mount, you may not even want fast slew speeds, and the giant mount I referred to does that.
I guess start with the TMC5160, since they are versatile (works with all boards, allow mode switching, and runs cool), and then only go for the S109 if you face a problem.


Howard Dutton
 
Edited

On Wed, Oct 21, 2020 at 11:33 AM, Khalid Baheyeldin wrote:
Depending on how much gear is on the mount, you may not even want fast slew speeds, and the giant mount I referred to does that.
I guess start with the TMC5160, since they are versatile (works with all boards, allow mode switching, and runs cool), and then only go for the S109 if you face a problem.
Think that G41 is 432:1 reduction with the steppers directly driving the worms right?

With 200 step that isn't a terribly high resolution per step so I'd use the TMC5160 drivers.  TMC SPI interface driver advantages?  You can set separate standstill, tracking, and goto currents in the configuration file.  You (and OnStep) can get feedback about driver status.  TMC drivers in stealthChop mode (tracking) are essentially silent.  The TMC5160 has a lower heat for a given current than any other StepStick driver and it isn't even close.  The S109 only goes to 32x microstep.  The 5160 is 256x.  It only bad thing about them is the hassle of getting them working (read the Wiki need to cut a pin on it and connect to ground) and the cost.


andrea tasselli
 

Thanks Khalid and Howard,

Advice much appreciated. So the consensus seems to be on TMC5160 drivers. What about these:



I think they were flagged as been acceptable in the Wiki pages, risk wise. 

Cheers

Andrea

P.S. That mount is awesome!


Khalid Baheyeldin
 

On Wed, Oct 21, 2020 at 07:59 PM, andrea tasselli wrote:
I think they were flagged as been acceptable in the Wiki pages, risk wise. 
I don't have first hand experience with them, although I did buy a set, but never gotten around to using them.

So, I can only point you to what the Wiki says on the different models.

https://onstep.groups.io/g/main/wiki/7233


George Cushing
 

Pretty much the same price as AliExpress.