A safe way to go about using nema 34 motors.

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  • September 11, 2013 at 12:20 pm #4511
    JeromyReno
    Member

    When I picked up my tinyg I read that it was posable, I just wanted to see if anyone else has tried or what anyone has experienced.

    I’m building a machine that’s 5’x 5′ and it will be routing 3/4″ ~ 1″ wood with a 1/4″ router bit, 1/2 10 two start acme lead screws. If 34 motors don’t work then I might go with nema 24’s. I would like to do the deepest cuts posable, multiple shallow Cuts tend to wear out bit tips faster.

    Any thoughts?

    September 12, 2013 at 1:15 pm #4520
    JeromyReno
    Member

    I think I’m going to pick up som 1200oz/in motors and run them in series. The data sheet says its only 4.2 amp draw in that configuration. I would guess with proper cooling the tiny g should be able to pull it off fine.

    September 13, 2013 at 7:49 am #4521
    alden
    Member

    Well, maybe, maybe not. The limiting factor is the driver’s current capability. The max you can drive into the motor is limited by the drivers themselves, and is 2.5 amps per winding – possibly a tad more with good cooling.

    We’ve been playing with some big NEMA34 motors and here’s what we’ve found.
    On a NEMA34 rated for 5 amps/winding and 7 Nm (~1000 oz-in) we can drive this fine to about 300-400 oz-in holding torque. More that that and the motor stalls. This is most likely due to the max current that is deliverable being lower than the current that the motor is actually capable of handling.

    So your NEMA34s will probably work, but you won;t be able to get full rated torque from them.

    September 13, 2013 at 1:23 pm #4522
    JeromyReno
    Member

    Oh I see, maybe I’ll run with the nema 24’s. they seem like they are close to the 23’s only with around 450nm. I’m sure it’s more than enough to push my aluminum gantry. I plan on running two motors on the Y anyhow.

    Thanks for the heads up

    It’s a work in progress. Glad this forum is here.

    September 13, 2013 at 3:13 pm #4523
    JeromyReno
    Member

    This 23 has 425nm with 2.5a. That’s pretty good and verry safe

    http://www.automationtechnologiesinc.com/products-page/nema-23/nema-23-bipolar-stepper-motor-425-oz-in-14”-shaft-with-a-flat

    It would be nice if I could get the extra 145nm for an extra 1a.

    NEMA23 570oz/in 5A 3/8” Dual Shaft Stepper Motor (KL23H2100-50-4B)

    September 14, 2013 at 4:28 am #4524
    alden
    Member

    You can drive the larger NEMA24 motors, but you won’t be able to deliver the all current they can handle, so you won’t get the additional torque. So you might as well stick with the 23’s, which are presumably cheaper. We have some 4 amp Lin motors on the Probotix v90. Great setup, but I know there’s more in the motors I am not getting.

    September 14, 2013 at 5:45 am #4525
    JeromyReno
    Member

    Dang I’m really striking out here haha. I just don’t want to under power my machine. If all else fails double the x and y up with 23’s if its not cutting it. The 1/2 10 two start should have some good pushing force though I would think. I really like the smaller fully contained controller idea with the G code interpreter all in a single package. Get a beaglebone black to run it with and the simplicity and portability would be amazing

    But I might have to re weigh my options. If my 5×5 takes 6 passes to cut 3/4″ wood I might have to change my original plans

    September 14, 2013 at 7:02 am #4526
    alden
    Member

    I would think that the 23’s should get the job done. You can probably max out the current then adjust the jerk so you can get the start you want.

    Are you using a high-speed wood router spindle?

    Another option (more $) is to take the step/direction/enable breakout from the v8 and drive external drivers, but now you are probably into Geckos or some other solution north of an additional $70 per axis.

    FYI – we have been working on driving this with the Beaglebone Black and have some of it working now. Needs more work, of course, but over the next few months…

    September 14, 2013 at 1:43 pm #4527
    JeromyReno
    Member

    That’s great to hear. I picked up the beagle bone already but have only messed with it a bit. Love them though! Hm modding it sounds interesting. I’ll try the 23’s but I’m open to investing more into it. It’s something I have wanted to build forever.

    September 14, 2013 at 3:23 pm #4528
    JeromyReno
    Member

    these look like the biggest thing i can find with under 3a per winding. i’ll think i’ll order them tonight and start on some mounts when they come in. it’s kind of nice cause i already have a set of 1/4 flex couplers that are very nice.

    http://www.automationtechnologiesinc.com/products-page/nema-23/nema-23-bipolar-stepper-motor-425-oz-in-14”-shaft-with-a-flat

    yo thanks for all the help too. i usually just drop into things and learn by trial and error. this we expedite that ten fold.

    September 15, 2013 at 10:48 am #4531
    InPhase
    Member

    You can drive unipolar motors with MOSFETs from the TG outputs if necessary. It just adds another wire to your motors. Less than ideal probably, but you can handle far higher currents with a MOSFET than 2.5 A.

    October 22, 2013 at 12:48 pm #4848
    JeromyReno
    Member

    I know you said you have had good outcome with the beaglebone running the system. I was just looking at the udoo, it’s a raspberry pie/arduino hybrid with a quad processor and 1g of ram. And a gbrl shield would mount right too it. I already have the beaglebone black and tinyG so I’ll keep pushing on with it. But that’s a pretty rad option for future builds.

    May 4, 2016 at 11:15 pm #9652
    aekidna
    Member

    @InPhase, Re: using a MOSFET to allow higher currents, what do you mean with “adding another wire to the motors”? Are you referring to the one attached to the MOSFET source pin?
    Could the power supply powering the gshield be powering the MOSFETs too?

    It would be nice to see a little project that address this, with schematics, as “driving a NEMA 34 motor for the Y axis” seems to be a hot topic.

    I’ll do some tests… hope I won’t fry my gshield or arduino due 🙂

    October 4, 2016 at 7:17 pm #9949
    hackware
    Member

    I’ll jump in here with hoping to use NEMA 34 steppers with the TinyG…

    And my view is to use an external driver to handle higher voltages and currents than the TinyG supports natively.

    With a bit of work, a gecko clone board can handle the voltage and current requirements without causing a wiring nightmare.

    I’m looking at using a PS-8N80 – 800W 80V Power Supply

    http://www.antekinc.com/ps-8n80-800w-80v-power-supply/
    The PS-8N80R5R12 has both +5V and +12V regulated at 1A each.
    List price at Antek is $173.

    The +5V will power a PI board, and the +12V will power the TinyG.

    After it is all done, perhaps synthetos could make the driver board for those in need. Otherwise, I’ll just publish the board info wherever…

    william…

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