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stepper motors

skymaster

Elite member
#1
hello everyone im am trying to build a cnc machine which i can use for needle cutting and alot of other things. but i am not sure of what stepper motors to get. been looking in to the nema 17 76oz. are these good for the job. any info is appreciated thanks .
 

jhitesma

Some guy in the desert
Mentor
#2
I would say pick a machine design first and see what motors are recommended for it. The NEMA number is mounting dimensions, so a machine designed for NEMA 17's won't fit NEMA 24's without modifications and vice versa. Even with the same NEMA size you can get motors in varying torques and again the recommendations of the machine designer are best to start with.

The MPCNC uses NEMA 17's and the designer currently suggests 84oz/in or 76oz/in steppers he sells the 76oz steppers but provides a link to amazon with 84oz steppers - I believe he generally recommends 76oz for his machine since they're plenty strong and bigger motors are just more likely to damage the machine itself if something goes wrong. I'm guessing he links to the 84oz/in because on Amazon they're probably a better deal than 76oz steppers.
 

dkj4linux

Elite member
#3
Needle-cutting, laser, pen-plotting, drag-knifing are all light loads and not a problem... it's the "alot of other things" that could potentially pose problems... depending ;)

I whole-heartedly agree with Jason... pick a machine design, don't just go by motor size.

He mentioned MPCNC... MPCNC is a fantastic machine and certainly worthy of a look-see. It's incredibly versatile, well-engineered/supported and established, and IMHO about as fun/easy and economical a way to break into CNC as exists today.

-- David
 

jhitesma

Some guy in the desert
Mentor
#4
He mentioned MPCNC... MPCNC is a fantastic machine and certainly worthy of a look-see. It's incredibly versatile, well-engineered/supported and established, and IMHO about as fun/easy and economical a way to break into CNC as exists today.
And just got a new update making it even stiffer this week. Which finally makes me glad about how long I've put off doing the last upgrade since now I can skip it and go straight for the new "Burly" revision :D
 

dkj4linux

Elite member
#6
That is the one i have been looking at MPCNC . so which stepper motors do you recommend? and how many.
I'm a bit confused... did you go look at the MPCNC site? All parts and quantities are detailed in the BOM... motors (there are 5 used on MPCNC) are only one of the many parts you'll need and you can do most of your shopping right there on his site. I can assure you that you'll be hard-pressed to source and purchase/ship all those parts for much less than you'll pay for the parts bundles he sells... they really are good deal. I've built/rebuilt at least a half-dozen MPCNCs and, after sourcing my own parts for the first one, realized it was far easier, quicker and cheaper to just purchase the bundles. I've printed all my own parts so have only purchased the hardware bundles.

We can be a helpful bunch if you'll share a bit of detail about your plans and the machine you want to build? -- David
 

skymaster

Elite member
#7
Little bit confused myself. so what i intent on building is a i needle foam cutter. big enough that i can work on a full sheet of foam board, and later on modify it to a milling machine, 3D router, 3D Printer, Laser Cutter, vinyl cutter, CNC plasma cutter. what ever the need. and you are right about trying to look for a better deal on the parts. but being on a budget. i think i just might start with the 3d printed parts that he has. since i don't have a 3d printer yet. he has a nice 3d printing extruder. but for now ill focus on building the frame.
 
#8
I doubt you will be able to do it cheaper or faster, last bit in particular, other than by basing it on the kit parts. Before you have invested in a 3D printer AND learnt how to use it properly, a surprising amount of time will have passed. And the guys printing the kits are specialists at this point, ensuring wellmade accurate parts. Plus you're not going to get much in the shape of a quality 3D printer for the 100$ that is the difference between the finished plastic parts kit and the neccesary filament, anyway. Once the MPCNC is done, however, you can likely get there by adding maybe ~50-70$ worth of printing head + other bits to your MPCNC.

Personally, I'm scratch building a different design intended for the same purpose, but it will end up getting to be about twice the price of a MPCNC kit. In my particular case, living in Denmark, shipping and especially customs and other taxes would make the MPCNC kit cost me nearly the same as my solution, and I have other reasons to pick this alternative design. But since you're living in the US, I don't think I know of a better priced alternative.
AND: I've been going at this project for over a year now, finding out where to get the bit and pieces at the right price tag, figuring out different solutions, manufacturing parts as well as aquiring the neccesary tools for this, having to put the project aside a number of times for other more important things etc. Had I bought a MPCNC kit, it probably would have been operative in a week or so, as it is assembly work only. Add a another couple of weeks to figure out cutting tools etc. And we're ready to go.
Do I regret my choice? Only partly, as I've already learned a lot by building mine from scratch, which is part of the fun for me. But I can't argue against that it would have been nice to be able to be making models with it by now.

One thing: Don't expect the MPCNC to be able to handle plasma cutting, though. It's not so much the mechanical parts, they'll probably handle it, allthough arc spray metal will fuse to your different parts and sooner or later block the movement - should be fixable in most cases, though. But the simple standard arduino based electronics are simply not electrically robust enough to withstand the transient disturbances from turning the plasma cutter arc on and off. You need fairly proffesional gear with shielding on electronics and cables (and/or use of optical cables) and purpose built filters and protection components inserted everywhere. Same goes if you'd want to try doing 3D metal printing with, say, a MIG welder or something. The standard Arduino based control solutions are completely OK for most hobby stuff (In fact they are downright amazing for the pricelevel), but they are not particularly well protected against the electrical noise you will find in an industrial environment. Not enough, anyway.
 
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Hai-Lee

Old and Bold RC PILOT
#9
Little bit confused myself. so what i intent on building is a i needle foam cutter. big enough that i can work on a full sheet of foam board, and later on modify it to a milling machine, 3D router, 3D Printer, Laser Cutter, vinyl cutter, CNC plasma cutter. what ever the need. and you are right about trying to look for a better deal on the parts. but being on a budget. i think i just might start with the 3d printed parts that he has. since i don't have a 3d printer yet. he has a nice 3d printing extruder. but for now ill focus on building the frame.
Your aim is very close to the requirement I am trying to fulfill but I live half a world away.

My path or at least the path I am travelling was to first get to know the whole CNC mechanisms and to also help my design and building of RC planes. I risked $200AUD on a 3D printer to print plane bits, any CNC machine parts I might require, as well as teaching myself the processes.

My 3D printer was/is to be disassembled and reassembled/extended for use as a cnc cutter especially as it already has an arduino compatible controller board and display module. As an experiment I first extended my printing bed and found that such changes are trivial in effort and accuracy effect and so effectively there is no real limit on the potential working area.

At this time I am in the process of designing my cnc cutter machine, organising any additional parts and even purchasing a new 3D printer as the printer has a long list of jobs before it.

I still have a large number of gaps in my knowledge but I am confident that those will get smaller and even close as I proceed towards an automated workshop.

Have fun, (I am!).
 
#10
Hai-Lee and DKchris , if I may, I'd suggest indeed to keep at least one 3D printer (or nearly) usable at any given time. This way, if you have some part wrong or not totally up to spec, you'll be able to reprint it if needed...
 

Hai-Lee

Old and Bold RC PILOT
#11
Hai-Lee and DKchris , if I may, I'd suggest indeed to keep at least one 3D printer (or nearly) usable at any given time. This way, if you have some part wrong or not totally up to spec, you'll be able to reprint it if needed...
First 3D printer is still operational and has been upgraded a considerable amount. It has also been checked out for scrapping to make the CNC cutter in the near future. I intend to order a new printer before I disassemble the first one for parts!

It also means that I will gain a 3D printer head for the CNC machine in the final form or spares for the new machine!

Have fun!
 
#12
Hai-Lee and DKchris , if I may, I'd suggest indeed to keep at least one 3D printer (or nearly) usable at any given time. This way, if you have some part wrong or not totally up to spec, you'll be able to reprint it if needed...
The CNC design I'm using is all steel, no 3D printed parts at all. That was one of the main reasons i picked it. No need for learning 3D printing to be able to build it. That it itself can be installed with an extruder later on is a different story.