Welcome! Log In Create A New Profile

Advanced

Electronic Component Selection

Posted by shortyski13 
Electronic Component Selection
March 30, 2017 11:06AM
I'm designing a CoreXY 3d printer and trying to determine components.One thing I'm tossed between is going with nema 17 or nema 23's.  Either way I would like 400 steps/rev (.9 deg). The reason I'm thinking of going nema 23 is 2 fold: a) my printer is on the large side with a build volume of about 19in x 22in x 26in (still tweaking that though) and b) i can forsee myself strapping a dremel to it, making some mods, and using it as a wood/aluminum cnc machine.
Thus I'm trying to spec out and cost estimate both set-ups but don't really know too much about the electrical components required. AFAIK, I need a power supply, motherboard, controller, and of course the motors. I have a hard time determining what components will work with nema 23 and what will work with nema 17. Can you, great people of this forum, help me out with specing out the electronic side of the system for a printer I have described for both nema 17 motors and nema 23 motors? This would help me a ton and is much appreciated.
Thanks.
Re: Electronic Component Selection
March 30, 2017 01:00PM
Though there are variations, NEMA-17 motors usually have 5 mm diameter shafts and NEMA-23 motors usually have 1/4" shafts. Make sure you know which you have before buying pulleys to fit the motors. NEMA-23 motors can supply a lot more torque than NEMA-17 but they also vibrate more and usually require more current. That means you may need to use external motor drivers because the controller board drivers are usually limited to 2A, max if you get a good controller board that has the drivers soldered to a ground plane. If you go cheap and use a board that uses tiny stepper modules current will be limited to 1.4A.

When you buy motors, you want low voltage, low resistance, low inductance motors. Look for motors rated for <4V.

Better controller boards can handle 24V power supplies without modification. Use a 24V supply because it will help the machine run faster.

That large bed will require a lot of power to heat it up in a reasonable amount of time. Figure 0.4-0.5W/cm^2. You bed will be about 2700 cm^2. That means you'll need >1000W to heat it up in a few minutes. That means you'll want a line powered heater, switched with an SSR driven by the controller board. You might look into available off-the-shelf heaters before you decide on the final bed size. You can get custom heaters, but it takes time and extra $.

For long X and Y like you are planning, don't even consider end supported guide rails. Go right to linear guides. Likewise, forget about 20 x 20 mm t-slot extrusion for the frame - it won't be anywhere near rigid enough. I would not try to use a cantilevered bed that size, either. Plan on lifting it with multiple screws or belts driven by a single motor.

Avoid using printed plastic parts anywhere near heat or under belt tension, especially motor mounts. Time temperature and tension are all conspiring to flex plastic motor mounts, and sooner or later they will win.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Electronic Component Selection
March 30, 2017 03:51PM
Thanks for design tips. I'm hoping that vibrations from the nema 23 will be minimized since I can solidly mount them to the frame and they are not moving. Will it still noticeably and negatively affect print quality?
For the Frame and guides, I was thinking similar thing in not doing guide rails; instead I'm going with V-slots and wheels on the frame itself. Also, currently I'm going with 2040 Al extrusions for most of the frame members and hoping that is big enough; I am still trying to minimize costs where I can. With that being said, I'm also speccing out with metal bracketry, at least until I see what the final costs comes out to, then I may switch some to plastic. As far as the heating bed goes, while I'm unsure of the name, the "line powered heater" sounds like what I'll probably go for. I think I'm going to snake a coil/wire underneath the print bed and let that heat it up. Also for Z movement of the bed, I'm hoping 1 NEMA 23 will work, but really am not sure. I'll belt it up to 3 different points to move it up/down.

Any links to the electronic hardware that would work together? Driver, controller boards, power supplies, etc?

Thanks!

Edited 1 time(s). Last edit at 03/30/2017 04:02PM by shortyski13.
Re: Electronic Component Selection
March 30, 2017 04:35PM
I am a smoothieboard fan, and I like MeanWell LRS-200-24 supplies- no fan, 8A @ 24V- plenty to run a printer.

I had very reliable operation from a BullDog XL printer with an E3D v6 hot-end, and I'm now testing an E3D Titan extruder with a v6 hot-end and getting promising results.

I don't think I'd attempt to make my own 1kW+ heater, but if you figure out a way to do it, great!

Motor vibration isn't likely to affect print quality but it will make the machine pretty noisy. My last printer was so noisy my wife kept complaining about it so I finally moved it to the makerspace. That led to building a quieter coreXY machine that is only recently complete enough to start printing.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Electronic Component Selection
March 30, 2017 05:06PM
Quote
shortyski13
Any links to the electronic hardware that would work together? Driver, controller boards, power supplies, etc?

Following thermal tests, we're about to increase the maximum allowed motor current of the Duet WiFi [www.duet3d.com] and Duet Ethernet electronics to 2.4A, with higher to follow when we've implemented better monitoring of driver temperatures. This makes the Duet boards more suitable for driving Nema 23 motors directly than any other board on the market. These Duets also give you the benefit of up to 256x microstepping, which makes the motors much quieter.

I purchased these 2.8A Nema 23 motors to use with the Duet WiFi: [uk.stepperonline.com]. The spindles are 1/4" and the torque is 1.26Nm. I calculate that at 2.4A current and 24V drive, the torque will be maintained up to about 5 revs/sec, which will give 200mm/sec travel speed using 20-tooth GT2 pulleys.

As for power supplies, I second digital dentist's suggestion of 24V Meanwell.

If you need a custom bed heater, this company [www.aliexpress.com] offers them at very reasonable prices. I have one of their custom bed heaters on my delta printer.

Edited 6 time(s). Last edit at 03/31/2017 09:47AM by dc42.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Electronic Component Selection
March 31, 2017 07:32AM
Someone should tell you.

Don't build a printer thinking you may later turn it into a CNC cutter. If anything do it the other way round but even that will be a compromise of a print head cobbled onto a sluggish overspec'd router frame.

Large build volumes do not justify big motors. You're just moving the same thing over a bigger distance.

Nema 17 and Nema 23 are meaningless words in terms of how much speed/ torque they produce. It's a frame size. Some Nema 17's have more of both than some Nema 23's

Use the search box at the top of this page. Read the wiki. All your questions have been asked and answered many many times.

Good luck with it
Re: Electronic Component Selection
March 31, 2017 08:18AM
If the guy wants to try machining with his printer, it is probably a good idea to have more torque available. Of course there are other considerations, but if you don't have the torque to push a cutter through the work piece, the other considerations don't matter. While it's true that there are small NEMA-23 motors that have similar torque to large NEMA-17 motors, NEMA-17 motors top out at about 100 oz-in. If you need more than that, NEMA-23 motors will provide the next level up to about 500 oz-in.

The OP may be using NEMA-23 motors he already has on hand. If you got 'em, you can save $ by using them.

Large build volumes, do justify higher torque motors. As the spans get larger the moving masses get larger. Higher torque motors can help to keep that moving mass under control. The bed obviously gets heavier with increasing size, and you may need much more motor torque depending on how you lift it.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Electronic Component Selection
March 31, 2017 09:55AM
Spose so. I'll change my advice.

If you are new to 3D printing you would be better to buy a cheap kit printer and have a play about with it to understand the process and the forces and the equipment.
Set against the time, effort and price you will pay to design and build a usable 2 foot square printer/ milling machine the cost will be negligible.
Re: Electronic Component Selection
March 31, 2017 12:19PM
Quote
shortyski13
Can you, great people of this forum, help me out with specing out the electronic side of the system for a printer I have described for both nema 17 motors and nema 23 motors? This would help me a ton and is much appreciated.
Thanks.

It depends on how big the Nema23's are, but you can certainly run small Nema23 with a standard Mega/RAMPS setup. I used to run a Rapman like that, there is a similar setup here [www.youtube.com]. If you do need more powerful drivers, that is a relatively easy upgrade later.

CNC and 3D printing have never mixed very well, although they seem to be similar there are sufficient differences to make it difficult to combine the two. CNC are best slow and stiff (heavy frame, screws) whereas 3DP can be fast and light (lighter frame, belts). Plus there is the issue of small bits of metal and dust getting everywhere.

Sorry to say that reprap.org used to be a good source of information, but is now overrun with FUD from salesmen trying to flog you a $200 controller + extras. If you ignore that, you can make progress at reasonable cost.


What is Open Source?
What is Open Source Hardware?
Open Source in a nutshell: the Four Freedoms
CC BY-NC is not an Open Source license
Re: Electronic Component Selection
March 31, 2017 12:33PM
I don't believe in starter printers. Just as we don't all have to reinvent the wheel, there's no need to suffer through trying to make a crappy printer work. Enough people have done that and written posts about it that it is unnecessary to experience it for yourself. You can learn everything a crappy printer can teach you by reading these forums and looking at different designs with a critical eye. A full DIY project on the other hand, will require that you learn a lot of useful things about physics, mechanics, electronics, materials, CAD software, part sources, and fabrication techniques, all of which are applicable to other projects. Oh yeah, you'll learn about 3D printing, too.

There is enough known about what works and what doesn't and the info is readily available for the reading or the asking, that anyone with half a brain, a little money, some patience, and some resourcefulness can successfully design and build a quality printer. The fact that the guy has found this forum to ask questions before starting indicates that he has at least the half-a-brain requirement. It's also a good sign that he didn't immediately start asking about the cheapest available stuff.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Electronic Component Selection
March 31, 2017 02:34PM
I agree with the_digital_Dentist's first paragraph there in that I feel I don't need to start with a crappy one before upgrading; to me it's a waste of money. I'm a mechanical engineer at an aerospace company (sadly we don't make 3d printers so my knowledge here isn't as up to snuff, hence the questions). Because of this, I'm good on the structures, and I think I am putting together a strong enough frame with 2040 extrusions and metal brackets for what I want.
Maybe I should clarify what I am looking for in my potential (but not immediately right away) mods to turn it to a cnc milling machine. At most I'd like to be able to cut Aluminum sheet metal, mostly so I can make sheet metal brackets and sell them (to diy'ers and reprappers) for less than they are currently going for, which in my opinion is too over-priced. Also I'm in to wood working, so I'd like to make some pretty wood pieces with it too. I don't care if it can't cut Aluminum or would super fast and would even settle for "somewhat slow". It's probably just going to be a rotary tool strapped to it, so nothing fancy shmancy. I just want to be able to move it and have it apply forces enough to actually be able to cut/mill a bit at a time. Now my main priority would be the 3d printing side, which is why I don't want to go crazy with Nema 34's, and I don't want to spend that money. I'm hoping 170 oz-in Nema 23's would do it, if I have to go with 23's, but would be willing to go with a bit higher torque one like 267 ozin . Going back to me being a mechanical engineer, I really don't have the breadth of knowledge and understanding of all the electronics, which is why I need some help in that aspect, esp since I can't find much about what to use with the 23's.
Also, again, I was thinking I'd have to go with 23's since I am moving larger masses than smaller machines as well.

Edited 1 time(s). Last edit at 03/31/2017 02:34PM by shortyski13.
Re: Electronic Component Selection
March 31, 2017 04:04PM
The 2.8A motors I linked to in my previous post that are a good match for the modern Duets have 1.6Nm of torque, which in old units is 178 oz in. If you want more torque then you could use these instead [omc-stepperonline.kancart.com] (1.9Nm which is 269 oz in). The inductance is much higher, so you would have to accept that the torque will start to drop off at a lower speed, unless you use external drivers and 48V power. But for CNC and cutting applications, you don't need high speeds anyway.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Electronic Component Selection
April 04, 2017 07:52AM
Good information. So is there a all in one controller or combo board+drivers that is more common for nema23's @ 2.8A. Looks like most things that I find are rated at around 2A instead for drivers.
Also arduinos don't seem to support 24v, which is what u thought I had to run 23s on.

Edited 1 time(s). Last edit at 04/04/2017 08:17AM by shortyski13.
Re: Electronic Component Selection
April 04, 2017 01:46PM
Quote
shortyski13
Good information. So is there a all in one controller or combo board+drivers that is more common for nema23's @ 2.8A. Looks like most things that I find are rated at around 2A instead for drivers.
Also arduinos don't seem to support 24v, which is what u thought I had to run 23s on.

As I mentioned in my earlier reply at [forums.reprap.org], the Duet WiFi and Duet Ethernet have drivers that can handle more than 2A - in theory over 3A, but we're limiting them to 2.4A in the latest firmware, with higher to come in future. Alternatively, you can use external drivers with most controller boards.

It's normal to run stepper motors somewhat below their rated current, because at full rated current they get very hot.

Edited 1 time(s). Last edit at 04/04/2017 01:48PM by dc42.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Sorry, only registered users may post in this forum.

Click here to login