[origamimavin]

I'm building my first CNC, and have a lot of the parts already. The original plan was to use Nema 17's, but I'm thinking about upping it to Nema 23's. I'll be using a SmoothieBoard to drive it, which only has 2A max output for the steppers, but have breakouts for external drivers. The Nema 23's I'm looking at pull 3A.


My build is as follows. My cutting window is 14"x13" with a height of 4.5". I'm using 3/8" 10TPI 1-start ACME threaded rods with anti-backlash nuts. The motors are to be connected to the ACME rods with belts, and I can use this to change the gear ratio if needed. The whole machine is to be made of aluminum sheets. The cutter is a 600W Chinese air-cooled spindle (2k-13k rpm, 24-110VDC). I hope to cut plastics, some wood, PCB's, and hopefully aluminum.

Current motors:
https://www.buildyourcnc.com/Item/el..._motor-62_ozin

Possible upgraded motor (or similar)
NEMA23 282oz/in 1/4? Single Shaft Stepper Motor ( KL23H276-30-4A) | Automation Technology Inc



My questions are, will I see much of an improvement moving from Nema 17's to Nema 23's, and what would be the best stepper driver to use with the SmoothieBoard to run the Nema 23's? Do you see a glaring 'weak link' in this design (3/8" rod, belt between ACME and motor, motor size, etc)? Any other tips?

Attached is a rough screencap of my design. If I'm missing anything or anyone needs any other details of this build, I'll be happy to provide info. If I've posted this in the wrong place, I apologize, please direct me to where it belongs)

[awerby]

Yes, 23-frame motors will probably work better than the 17s, if you give them enough power. But if you're limited to a board that can only handle 2 amps per channel, I don't see how you can run 3 amp motors with it. Unlike the voltage ratings, the amperage ratings on steppers are really what they will need. Also, those motors have fairly high inductance, which means they'll need more voltage to perform well. Gearing the motors down isn't really necessary, since you'll want as much speed as they'll deliver for cutting wood. If you're really set on the "Smoothieboard" Smoothieboard - Smoothie Project, look for motors with a lot less inductance, so they'll get up to speed with the 35v max voltage, and that need less current, so they'll work within the 2 amp limit.

[origamimavin]

Thanks for the response! The SmoothieBoard has breakouts for the ST, DIR and EN to connect to an external stepper driver, so besides the added cost, I shouldn't be limited to the 2A on that board. That's interesting, about upping the voltage with the lower current. Are there any good Nema 23's that would work for this application that can run on 2A? I'm not sure what the max voltage is that the SmoothieBoard can output. I am tied to the SB, though, as that's one of the items I've already purchased.

This all being said, I still wouldn't mind buying some external stepper drivers if it would help performance. Any thoughts on a good driver that isn't too expensive?

[H500]

Auto. Tech. has a version of that motor with a 2 mH inductance. Although you will only get half the rated holding torque when using 2 amps, the machine might actually perform better because the torque is maintained at a higher speed.

[origamimavin]

Auto. Tech. has a version of that motor with a 2 mH inductance. Although you will only get half the rated holding torque when using 2 amps, the machine might actually perform better because the torque is maintained at a higher speed.

If this the one you found with the low inductance?

NEMA23 381oz/in 3.5A Single Shaft Stepper Motor KL23H2100-35-4A | Automation Technology Inc

That uses 3.5A.. Anything with a lower inductance that I can see is unipolar.

I'm still kinda new to the specifics on stepper speed, torque, inductance, and how they're rated. If I went with a motor with higher inductance, you're saying it should still run at a lower current as long as I continue to feed it the right voltage? If i started off by going that route, and wanted to upgrade and get external stepper drivers, what would that do to help? Which external stepper drivers would work well for an application or motor like these?

[H500]

This one: NEMA23 282oz/in 3A Stepper Motor
Use it in the bipolar parallel mode. I am using them for my SX3 mill.

If you want future proof, then this might be good.
NEMA23 570oz/in 5A 3/8? Dual Shaft Stepper Motor (KL23H2100-50-4B) | Automation Technology Inc

Low cost drivers are limited to about 40v. If your motor inductance is too high, you will have no choice but to go with high end drivers costing up to 6x more.

You will likely see the greatest performance increase by upgrading to ball screws.

[origamimavin]

Thanks H500 for the info! It's given me some good stuff to think about. I think I'll start by running a Nema 23 off the 2A provided by the smoothieboard and see how it runs, and if I need some more oomph later on, I'll add to it.

I've been reading around some more, and have read a suggestion of this one:

NEMA23 381oz/in 3.5A Dual Shaft Stepper Motor KL23H2100-35-4B | Automation Technology Inc

What do you think of that? Keeping future proof in mind, as well as something I can run with 2A in my current setup? Where can I find or how can I calculate the max voltage that these steppers can handle? The smoothieboard I'm using can handle a power supply up to 24v, so that's likely what I'll be using.

If I were to get the motor I linked in this post or the KL23H276-30-8A that you suggested already, what would be a good stepper controller to keep in mind for the future? Would I need to go the Gecko route (like the 251X), or would a TB6560/TB6600 suffice? I'm planning the design for the CNC now, and I'd like to make sure I leave enough room inside and drill the holes for a controller upgrade down the line.

[awerby]

If you want to read about stepper motors, the short whitepaper on the Geckodrive site is a good place to start: http://www.geckodrive.com/support.html

To figure out the max voltage, you multiply the square root of the inductance by 32, which for the motor above comes to 53.54 volts. Much less than that, and performance will suffer; more than that and it will overheat. (at 24 volts, they will be about half as fast as they should be.) If you want to run your motors with less current, wire them in series, not parallel.

For the motor above, the Gecko G540 would be fine; you don't need the 251X, which will deal with higher voltage. Whatever you do, don't buy the TB6560; it's the subject of about half the "why won't my machine work?" questions we get here. The TB6600 is supposed to be somewhat better, but still not great. If you're asking me, save the Smoothieboard, along with the NEMA 17 motors that go with it, for building a 3D printer. Get the G540 and a 48v power supply that can deliver all the power your motors want. If you don't want to use a computer with a parallel port to run it, get a Smoothstepper, and use USB or ethernet to communicate with it.

[H500]

I prefer the KL23H2100-50-4B because, at least on paper, it has a higher torque and lower inductance. When driven with 2 amps, you should get slightly better performance than the other one.

The tb6560 is out of the question. They spontaneously self destruct due to a bad design. The tb6600 is much better

http://www.cnczone.com/forums/steppe...rive-ebay.html

The originator of that thread sells several good quality diy kits if you are able to solder. Otherwise, the HY-DIV268N-5A on Ebay is a probably an acceptable choice if you can accept the faults listed in that thread, or if you are able to mod it.

[H500]

I forgot to mention, if you are on a tight budget, the drv8825 at 40v might perform well enough initially. 40v will also be good for the tb6600 upgrade.

[James Newton]

Hey! The THB6064AH kit will give you pretty close to gecko-drive performance for $35 if you don't mind building a kit.
massmind.ecomorder.com/techref/ecomprice.asp?p=416074

[origamimavin]

Thanks, everyone, this information has been a big help!

I understand the math a lot better now, and I can see why that 5A would be better than the 3.5A on paper. I think I'll pick up four of the KL23H2100-50-4B steppers after work today (Automation Technologies is about 20 minutes from where I work, hence my decision to go with them). Using awerby's math, it looks like I'll need something that can supply 50VDC and 5A to get the most out of the motor, but less can work with diminishing effects. I think I'll still be using the smoothieboard to drive everything (rather than a smoothstepper) since I have it and it should be capable of driving the motors or other controllers. The question now is do I run them off the smoothie and just plan for another controller in the future, or go for broke and get the controllers now. Either way, I need to have one chosen to leave room in the case and drill mounting holes. The options in my mind right now are as follows.

I found the TB6600 on ebay for about $22, and that tops out at 50VDC and 5A, which is exactly what I need. I know I should probably get something larger so it isn't maxed out, and I know these are on the lower end of the quality spectrum, but the price is nice.
TB6600 CNC Single Axis 0 2 5A Two Phase Hybrid Stepper Motor Driver Controller | eBay

Is this Lucas' kit? it seems a little underpowered for what I'd (optimally) need, topping out at 40VDC and 4A. Yes I can solder, so as long as I have some instructions on what goes where, it'd really just be the exchange of cost for my time, which is no big deal (I like building things, obviously). Am I missing a higher powered driver on his site? Around $32 isn't too bad.
THB6064 drive kit

James mentioned the THB6064AH kit, which looks promising too, even though it tops out at 50VDC and 4A. The price break for three at $32 isn't bad either, but since the above post seems a lot like and ad, I'd like someone else to chime in before I go that route, but 'close to gecko performance' for that price is a bold statement. I'll also have to wait for more to be in stock. The 'special promotion' about documenting it is a nice incentive.
6064: 4AMP Stepper Motor Driver Kit. massmind

Automation Tech sells a driver, the KL-6050, for about $50. It tops out at 60VDC and 5A, so it should handle the steppers well, though it's a bit pricier. Does this price premium buy me anything substantial, or should I just take this option off the table?
KL-6050 Bipolar Stepper Motor Driver,Max. 60VDC,5A | Automation Technology Inc

As of now at least, the Gecko is off the table because of cost and the TB6560 is off the table because I don't want my machine to catch fire.

It's looking like I'll be needing a 12-24v PSU to drive the smoothieboard and a 48-50v PSU for the drivers, which would be bought to match the driver once it's chosen.

Am I missing any options, or does anyone have any points to add to my options to make the decision any easier? The TB6600 seems the best suited, spec-wise, and the price is nice, but would paying more for better quality and lowered specs be worth the upcharge?

As a side question, how much heat do these drivers put out? My plan right now is to build them into the base of the CNC, which pulls out as a drawer from the back. This would include the smoothieboard, the power supplies, and the stepper controllers. I have a feeling that keeping these in an enclosed space would be a bad idea, and I should include some vent holes or optimally a fan or two to circulate some air (and likely a filter over a fan to reduce dust). If my thinking here correct?

As another side question, I'm going to be connecting the motors to the leadscrews with a toothed pulley. I have the option to gear this, or just make it 1:1. Would there be any benefits to gearing it (like spinning the motor faster per ipm to bring the torque up some more, or for accuracy)? I'm using 10tpi one start lead screws, btw. Also, two of the belt sizes I'm seeing are .2" pitch (XL series) and .375" pitch (L series). Does one have any benefit over the other?

Thank you all for your support, it has been a great help! I plan to document and post my build once construction begins.

[James Newton]

"James's" THB6064AH is Lucas's kit. He designed it and supplies the PCBs. The chip is the same and most of the components are as well. There are small differences to support the simpler cabling of the BOB I provide. There are lots of good customer reviews at:
massmind.ecomorder.com/techref/io/stepper/THB6064/gallery.htm
The best one being Andreys tiny home castle printing 3D printer.

TB6600's are ok, but please don't buy a cheap one from China. It's cheap for a reason. Buy one from Lucas or someone who actually supports their product.

But... notice that they do NOT support 5 amps... unless you consider 100ms bursts "support". They are rated at 4.5 amps. Again, China lies. They usually list the peak rating not the continuous rating. Check the mfgr datasheet:
http://toshiba.semicon-storage.com/i...dName=TB6600HG

The THB6064AH is 4.5 amps peak and 4 amps continuous. I list 4 amps. Because that's what you can actually expect to get.

And Lucas's and my THB6064AH is NOT rated at 40 volts, It's rated at 50 volts continuous. The TB6600 is rated at 50 volts MAX, 42 volts continuous. Again, China lies by quoting the max when that is NOT what you can actually expect to use. Check the datasheet.

So the TB6600 at 42 volts, 4.5 amps CONTINUOUS for 168 watts.

The THB6064AH is 50 volts*, 4 amps CONTINUOUS for 200 watts.

But the lying b.....'s make it sound more powerful when it isn't. I won't lie, so I loose.

*P.S. It would be a really bad idea to use a 50 volt supply with the THB6064AH because it will have little spikes and regulation problems that can over-max the voltage of the driver. I would recommend running 48 volts (4 12 volt batteries) for a more stable supply and a little bit of room. That's still 192 watts.

[H500]

The 6064 and 6600 both has a 50v max rating. I would keep the voltage below 45v. Any higher would be risky because the motors can become generators during deceleration.

I can't comment on the Chinese drivers. The vendors never post information in these forums, so their design are a mystery.

[James Newton]

The 6064 and 6600 both has a 50v max rating.

Please look again at the datasheet. The 6064 specifies a running voltage of 50 volts and that is also the max. The 6600 specifies a 50 volt "absolute maximum" but then goes on to specify a 42 volt "operation range". The 6064 doesn't say anything on the datasheet about needed to operate it as less than 50 volts.

From the 6600 datasheet:

Output withstand voltage: VCC = 8 to 42 V (operation range)
VCC = 50 V (absolute maximum ratings, maximum value)

From the 6064 datasheet

Output withstand voltage: VDSS = 50 V

Nothing about operation vs "absolute maximum"

I've personally operated a 6064 at 55 volts and 4.5 amps for several minutes using a high end CPU cooler to reduce chip heat. I was trying to kill it to see where it would die. I stopped because the motor melted the plastic mount it was in and fell out of the machine. Andrey ran his into NEMA 42 motors at 48 volts and 5 amps. His did ok until a really hot day and repeated cycling caused a spectacular failure which wiped out multiple drivers and a PC. I don't recommend that, of course. As I said, the most I would go is 48 volts and 4 amps. And with a CPU cooler.

[ger21]

As another side question, I'm going to be connecting the motors to the leadscrews with a toothed pulley. I have the option to gear this, or just make it 1:1. Would there be any benefits to gearing it (like spinning the motor faster per ipm to bring the torque up some more, or for accuracy)?

Actually, gearing it would probably have the opposite effect.
The faster a stepper spins, the less torque it has, so gearing the motor to spin faster can often result in less power, and less speed.
If anything, you'd be better off gearing it 1:2, so the screws spin twice as fast as the motors. This keeps the motor at lower rpm's, where it will have much more torque.

Going back to your first post, and seeing the size of the machine and the 3/8-10 leadscrews, I would say that 570oz motors are far too big, and will probably decrease performance.
In most cases, the bigger the motor, the slower it'll spin. With 10TPI screws, you want a smaller motor that will spin fast.

I'd agree with H500 and look at the 282 oz motor.

[origamimavin]

Ok James, you've convinced me on the THB6064AH! I know Chinese parts are cheap, but it's nice to see some of the math and specs to back it up and know that there's extra support here if something goes wrong. If I have the link correct, it looks like some more are in stock, I may as well just go ahead and get them now instead of messing with lower power to start and needing to upgrade later. Is this the link, where I should buy the $35 kit?
Slowing 69.16.243.61&c=1&t=42097.3095960648

Gerry, so back to the KL23H276-30-8A, then? I think the thing that keeps turning me off from that one is that it's 8 wires and I'll be doubling them up, but I guess it really doesn't matter in the end. It turned out Auto Tech closed at the same time I got off work, so I didn't get anything yet and will have to go tomorrow. Guess it's a good thing! What you said about larger ones moving slower makes a lot of sense. I think keeping in mind that I can change the gearing could be a good way to tweak performance if things don't work as well as I want. When I was picking the leadscrews, I was thinking more about precision than I was about speed, but I guess doubling that up won't affect precision much. In setting up the gearing, should I use 1:2 for all 3 axis, or just X and Y? I don't imagine Z would need to move quite as fast, I'll only have 4.5" of total travel, and because of the weight of the Z, I'm guessing 1:1 would be better for holding everything in place?

So now in looking at that motor, it bring my max voltage up to about 47 and current to 4.2, which sounds a bit more manageable, and it sounds like the THB6064AH will work well. I guess the next step is looking for a good 48v psu. When it comes to steppers, do I need to find a supply that can handle all the motors at full load, so a ~17+A supply? Or would they never all hit that peak at the same time, where I could go with something smaller like ~12A? I'll be using 4 motors and 4 drivers for 3 axis (2 motors on Y).

Thanks again everyone, this really continues to be a great learning experience.

[origamimavin]

Just ordered 4 of the THB6064AH drivers. I'll soon be heading to Auto Tech to pick up the KL23H276-30-8A steppers. Right now I'm thinking of these gearbelt pulleys:

POWER DRIVE GearbeltPulley,XL,28 Grooves - Synchronous Drive Gearbelt Pulleys - 6FFT4'|'28XLB037-6FA - Grainger Industrial Supply
POWER DRIVE GearbeltPulley,XL,14 Grooves - Synchronous Drive Gearbelt Pulleys - 6FFR6'|'14XLB037-6FA - Grainger Industrial Supply

Ger21 and H500, if you don't mind checking these out, I'd be quite appreciative. Right now I'm thinking the 28-toothed gears would go on the X and Y steppers and the 14-toothed gears would go on the Z stepper and all of the ACME threaded rods. Does this sound about right?

[H500]

Please look again at the datasheet. The 6064 specifies a running voltage of 50 volts and that is also the max. The 6600 specifies a 50 volt "absolute maximum" but then goes on to specify a 42 volt "operation range". The 6064 doesn't say anything on the datasheet about needed to operate it as less than 50 volts.

The 6064ah datasheet I have, shows the operating range as 4.5 to 42v. However, that doesn't really matter because both chips uses Toshiba's "BiCD" 50v process.

In any case, I think origamimavin would be better off with your kit, because he can be confident that the design was properly done. The Chinese boards has multiple known design shortcomings and were designed for cost rather than reliability. Also, since you are standing behind 48v, he can try it with confidence. =)

[H500]

Just ordered 4 of the THB6064AH drivers. I'll soon be heading to Auto Tech to pick up the KL23H276-30-8A steppers. Right now I'm thinking of these gearbelt pulleys:

The XL belts have inferior torque capacity compared to the HTD series. Check the torque chart to make sure they can handle your motor. The Gates GT series is suppose to be even better, with low backlash. Alternatively, you can direct drive with Oldham couplings.

I prefer the high torque motor, especially because you are using inefficient acme rods.

Why not use ballscrews? The rolled versions are not too expensive on Ebay. You will get two to 4 times the performance.