Big Nema 23s and Tiny G

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SniperTeamTango
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Big Nema 23s and Tiny G

Post by SniperTeamTango » Sun Jun 22, 2014 4:13 pm

Morning Gents,

I've been steadily designing a decent sized shapeoko modification, and my electrical knowledge has been continually insufficient.

I was wonder if a TinyG with a 24VDC 10A PSU would be proper to handle these motors

https://www.inventables.com/technologie ... or-nema-23 (The 262 ounce ones.)

Inventables support has told me it *should* be fine, I need a bit more than that before I commit to a build I'm sure you guys understand.

Grateful for any help.
~STT

jacob32123
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Re: Big Nema 23s and Tiny G

Post by jacob32123 » Sun Jun 22, 2014 6:09 pm

SniperTeamTango wrote:Morning Gents,

I've been steadily designing a decent sized shapeoko modification, and my electrical knowledge has been continually insufficient.

I was wonder if a TinyG with a 24VDC 10A PSU would be proper to handle these motors

https://www.inventables.com/technologie ... or-nema-23 (The 262 ounce ones.)

Inventables support has told me it *should* be fine, I need a bit more than that before I commit to a build I'm sure you guys understand.

Grateful for any help.
~STT
The TinyG max current per output is 2.5 amps (per: https://www.synthetos.com/topics/tinyg- ... #post-5236), so with 4 motors, that's 10 amps. That doesn't account for efficiency (the drivers get really hot), and powering other things (like the fan output on the TinyG).

cvoinescu
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Re: Big Nema 23s and Tiny G

Post by cvoinescu » Sun Jun 22, 2014 8:53 pm

The power supply is sufficient. The TinyG is not capable of driving the rated current of those motors, but it can get close, so you'll get most of that torque -- which is excessive for a machine of Shapeoko class anyway. So you're good.

It's not as simple as jacob32123 says, though -- that's 2.5 A per coil, so a simplistic calculation would yield 20 A for four motors (two coils each). However, both coils aren't driven at the same time at the maximum current (it varies between 2.5 A in one coil and nothing in the other, to 1.75 A each (70% of 2.5 A) through both coils). What's more, the drivers chop the current, so they can take a relatively low-current, high-voltage supply and output a higher current at a lower voltage into the load. The supply current depends on several factors that make it difficult to calculate, and varies with motor speed and load, but I'd say 10 A was more than enough.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

SniperTeamTango
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Re: Big Nema 23s and Tiny G

Post by SniperTeamTango » Sun Jun 22, 2014 11:26 pm

Thanks guys, got a pipe dream of cutting aluminium and other light metals (tin) with this. Also speeds.

Designing a watercooling systems for the drivers already, unless a single 24v fan will be enough, which I'm doubtful of (got a lot of overclocking experience where air just won't cut it.)

Is it worth getting the 262 oz motors or will I lose so much that the 140's will be enough. Again, really want as much oomf as possible in this machine :)

Thanks very much guys.

cvoinescu
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Re: Big Nema 23s and Tiny G

Post by cvoinescu » Mon Jun 23, 2014 12:41 pm

Please remember that this is a machine with relatively lightweight aluminium rails, and with plastic V-wheels. Putting huge motors on it won't make it more rigid.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

SniperTeamTango
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Re: Big Nema 23s and Tiny G

Post by SniperTeamTango » Mon Jun 23, 2014 1:59 pm

Okay fair enough. Gonna save the money. Thanks for the help!

WillAdams
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Re: Big Nema 23s and Tiny G

Post by WillAdams » Mon Jun 23, 2014 2:07 pm

SniperTeamTango wrote:pipe dream of cutting aluminium and other light metals (tin) with this.
Not a pipe dream --- even a stock SO2 will cut aluminum quite handily:

http://blog.inventables.com/2013/11/mil ... oko-2.html
Also speeds.
For that, you want NEMA23 --- but you have to balance the motor size against the weight/mass of the gantry, or you get into the hot rod mentality of adding a larger engine w/ 10 more HP to move the additional 100 pounds of engine as fast as the machine was before.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

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