[Flyer66]

Hi All

I've search arround the forum and i've only found a post that says that is ok to power de nema 17 motor with 24v or even 36v (10 up to 20 times the rated voltage)
the TB6560 board that i'm using that is a piece of cr@p states that max voltage for nema 17 is 12v only.

Anyone as experience for this kind of setup combination? TB6560 + Nema 17 + 24 v(or 36v) power supply

the nema 17 is 42BYGH0425 :
(°) (mm) (A) (Ω) (mH) (g.cm ) (No.) (g.cm²) (g.cm ) (Kg)
42BYGH0425 1.8 48 2.5 1.25 1.8 4800 4 68 280 0.34

I'm looking for a use for the 24v power supply that I have and if it will give me more motor torque the better.

Thanks

[doorknob]

While I haven't tried it yet, running my NEMA 17 motors on 24 volts with my TB6560 board is in my plans sometime in the next week or so.

On general principles, I would not believe anything that a Chinese TB6560 board manufacturer claims. NEMA 17 is a physical size description, not an electronic specification. (While the physical size limits may be reflected in some electronic parameter limits, the electrical characteristics of NEMA 17 motors that I have investigated can and do vary over a wide range. So a blanket statement that the max voltage for a NEMA 17 motor is limited to 12 volts likely has no factual basis.)

[Flyer66]

Thans for your reply. I'm aware that the nema xx is a size like description and they vary alot in the specs. the nema 17 size motor that I have when configured to 100% current in the tb6560 get a little hot and have to decrease speed in order not to skip steps. the motor itself is rated 2.8 volts, i guess that using ohms law that the more the voltage the less the current given the same resistance and the effect is to produce more torque.
but the critical question is : will the tb6560 chip hold in 24v with those nema 17 bellow without the risk of burn the motors or the chip.

I'm new in this kind of cnc stuff, I have build a prototype with drawer sliders just to prove the concept, i'm in the middle of making a MDF a little bigger with more strength and some accuracy, and my concern is in did the torque issue. i'm not sure at the moment what is the best combination for the TB 6560 dip switch. the purpose is to build a alluminium structrure like shapeoko or by one.

I guees i'm going to trial and error...

Thx

[doorknob]

the motor itself is rated 2.8 volts, i guess that using ohms law that the more the voltage the less the current given the same resistance and the effect is to produce more torque.
but the critical question is : will the tb6560 chip hold in 24v with those nema 17 bellow without the risk of burn the motors or the chip.

The TB6560 chip has built-in current limiting. So that is why you can run the motors at a higher voltage than the rated voltage without drawing excessive current. You select the desired winding current by a combination of the value(s) of the current-sensing resistor(s) soldered onto the board, and the DIP switch setting (for 100% current or some smaller percentage). The torque from the motor depends on several factors, but perhaps the primary one is the amount of current that is supplied to the windings. Running the motor at a higher voltage lets you achieve better torque at higher speeds than you could get at a lower voltage.

The TB6560 chip is rated for a maximum voltage of 40 volts (IIRC), but you would not want to run it anywhere close to that value. Many people successfully run 24 volts on their TB6560 boards. Note, however, that many people burn up their TB6560 chips regardless of the voltage that they are running at, due to other problems.

It is normal for stepper motors to run hot, even when they are sitting still and not moving. A motor can be too hot to hold in your hand, and yet still be operating within its temperature ratings. So just because a motor gets hot does not mean that you are about to burn it out.

I'm new in this kind of cnc stuff, I have build a prototype with drawer sliders just to prove the concept, i'm in the middle of making a MDF a little bigger with more strength and some accuracy, and my concern is in did the torque issue. i'm not sure at the moment what is the best combination for the TB 6560 dip switch. the purpose is to build a alluminium structrure like shapeoko or by one.

I am building a ShapeOko. Some people use NEMA 23 motors on their ShapeOko CNCs (mounting holes for both NEMA 17 and NEMA 23 motors are provided on the X- and Y-axis supports - but some other arrangement would be needed to run a NEMA 23 motor on the Z-axis).

A lot of ShapeOko users are using Pololu A4988 drivers, which can run at 24 volts, but the driver chips are physically small and need good heat sinks and a fan when running them at more than 1 Amp of current. I have started doing tests with the Pololu drivers - I have started out using a 12 volt power supply because I had one available, but will probably switch to a 24-volt power supply, either with the Pololu drivers or with the TB6560, once I have completed mounting it in a box and wiring it up.

If you look through the ShapeOko forum, I believe that you will find other people who are using TB6560 drivers with 24 volt power supplies. ShapeOko.com ? Index page

[Flyer66]

Hi doorknob thx for your reply
I'll try to connect my nema 17 with a 24v Ps, reduce the current dip setting to 25% and go up from there and see what happens.
About the shapeoko, do you feel that for some heavy duty work it needs a nema 23 or 2x nema 17 will do the work the same way , what is the configuration you are going to choose? 1 x nema 23 on X or 2x nema 17 on X axis?
BTW Are you going to use the (stock) belt drive or going to upgrade to guide racks ?
I'll also look a the Pololu A4988, I'll feel that If I'll have the shapeoko in the future the "weakest link" will be the TB6560...

Thanks,

Thanks

[doorknob]

Hi doorknob thx for your reply
I'll try to connect my nema 17 with a 24v Ps, reduce the current dip setting to 25% and go up from there and see what happens.
About the shapeoko, do you feel that for some heavy duty work it needs a nema 23 or 2x nema 17 will do the work the same way , what is the configuration you are going to choose? 1 x nema 23 on X or 2x nema 17 on X axis?
BTW Are you going to use the (stock) belt drive or going to upgrade to guide racks ?
I'll also look a the Pololu A4988, I'll feel that If I'll have the shapeoko in the future the "weakest link" will be the TB6560...

Thanks,

Thanks

Although I do not yet have it working, my impression is that if you want to do "heavy duty work" then the ShapeOko may not be the right solution - the overall sturdiness and the quality of the bearings and the Z-axis drive are not what I would expect to see in a machine that is designed for heavy duty work. But you may wish to pose that question on the ShapeOko forum where you can get advice from people who are actually using their machines to do real work.

I bought the dual-drive kit, and will be using two NEMA 17 motors with the X axis.

I will also be using the stock drive belts and pulleys.

The Pololu A4988 drivers do not have as high a current rating as the TB6560. They are probably OK for a small machine, but I would be careful if I had motors that draw close to 2 amps or more. As it is, my motors have a 1.68A current rating, and so I will want to keep an eye on the cooling to make sure that I don't exceed the capabilities of the drivers.