Other motors- what have you tried?

I know the norm is nema17 motors and that some have used nema 14 but what else have people tried? I would like to try nema 23 motors on a prototype I'm working on but I would like to find out what some other options are and what kind of results you had. I'm on a very tight budget so I don't have the means of trying everything out there unless I can borrow equipment.

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I have Nema23's and Nema35's on various CNC Mills here.
The numbers are just the frame size though.
The issue with them for repraps is that in general they are rated from more power than the little poulus will output, so although a poulu will drive them they are grossly under driven and could perform worse than correctly rated Nema17's.

The drivers I use on my Nema 23 cost $300 for 4, the ones on the mill with the Nema 35's are $150 a piece.
The Mill also weighs 1000+lbs, there just isn't the need for anything larger than the Nema17's on the size of printers most here build.

Your other option is closed loop servos, but the position encoders tend to be expensive, as are the drivers, in the CNC space most larger mills go this way.

Thanks for your response polygonhell! I have some robotics/hobby servos I'm going to try out at some point but I was more interested in what would be good for something with twice the build envelope of the current Prusas. I've already ruled out the little Nema 14's because of the lack of torque unless I can make modifications to deal with that sort of thing. I hadn't really considered using the usual pololus for that reason and was going to go with drivers for larger cnc's.

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If you go with "real drivers" you will likely have issues with most reprap firmwares, they generally don't hold the pulse long enough and there is generally not enough time between the change in the direction pulse and when the first output pulse is sent.
Assuming you retain the same motion configuration for something 2x the size of a PRUSA I don't see any reason you couldn't get by with the usual NEMA 17's, even if you increase the mass of the axis significantly, the force to move it (if it's well assembled and using linear bearings) shouldn't be dramatically different, you'd probably end up with less aggressive acceleration settings in the firmware.

I am building a custom reprap with Nema 23s. I will be driving them with Pololu stepper drivers. The Nemas I am using are rated at 1.4 Amps. The Pololus *with proper heat sinking* will drive up to 2 Amps. The difference in performance between driving a Nema 17 that is rated for 1 Amp at 1 Amp versus a Nema 23 that is rated for say, 2 Amps at 1 amp is second order, in my opinion, and gets into the specifics of rotor inertia, stepper inductance and power supply voltage and maximum pulse rates. Also, Nema 23, as pointed out, is a mounted frame size and does not specify how many stacks (1, 2, 3). Bottom line is that it is my opinion that Nema 23s (with a current rating that is consistent with the 2 amp max Pololu driver with heat sink) can be successfully used in typical reprap machines at reasonable speeds.

In another of your (Anthrochick) posts (if memory serves) I believe you were interested in alternatives to the cogged belts, possibly someway of making your own? If so, and depending on why you want to do this (save money? be more consistent with the self-replicating machine philosophy? more easily sourced materials?) you may want to search the reprappers and developers forums for "cable drive". It appears quite possible to use "cable" drive vs. cogged belts with the cable being various high strength fishing line/leader. Not "make you own" but less "high tech" than cogged belts...

Hi,

I have built 2 printers using nema 23's and ramps/arduino to drive it. Works well.

Regards
Jan

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i have yet to test my stock of motors from sanyo denki (nema17), i was thinking of using something from japan

since you are making something big, well let me share with you mine

my build area is currently designed for 650x 850x 880mm approx (XYZ), originally the idea was 1mx1mx1m lol which is pretty crazy and i found out i didnt have much room to build it in my bedroom hahahaha. it is currently still in the making. it is an adaptation of the cartesian, but the table is fixed, the entire head moves XYZ. i am still waiting for belts n pulleys from SDP-SI, i have most of the electronics, guide rails, etc ... i am still pondering on the format of the heater bed which is quite a huge problem it seems, and i have yet to recieve the parts from ebay for it LOL ... so its more wait than build for me here . hope you have good luck in your build

Unless you're printing with only PLA, I sure hope you have a vent fan in your bedroom window!

Edited 1 time(s). Last edit at 09/01/2012 02:47PM by xiando.

yes i will be building a extractor port, and the final machine will be boxed with vented "pathways" intake and extractor ... i sleep in the same room as the machine ... i need to wake up tomorrow hahahahaha !!

Redreprap- 1mx1mx1m? I can understand why you would run out of room. lol. I was originally tempted to build something that big as well but I ran into the same limited space problem. I would love to know your results with the motors since I haven't been having too much luck with functional motors lately.

---

Bringing 3D printing to America's classrooms.

Follow my efforts at TheChicksNest.blogspot.com

this is mine ... nothing much going on so far ... my pulleys and belts are "lost" from SDP-SI ... cant get any replies from them on email either ... *sad* ... [www.facebook.com]

and i had a medical emergency in the house so .... i guess i wont be moving forward as fast on the buildup

printer that big, 1meter x 1 meter x 1 meter, will you have a forklift to unload 200 lb spools of filament? How else will you keep from running out of filament?

lol yea

on that ... i do have to reduce the size

currently i am trying to finalize some pulleys n belts ordering, so the finalized size should be smaller. build size is approx about 650x750x900

skm Wrote:
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> printer that big, 1meter x 1 meter x 1 meter, will
> you have a forklift to unload 200 lb spools of
> filament? How else will you keep from running out
> of filament?