Monday, June 11, 2007


Stepper Board Videos!

So, I finally got real live footage of the boards and stepper motors working. Bonus stepper tester video. Check it!

Stepper Motor Action from Zach 'Iowa' Hoeken on Vimeo

waaa... someday i'll have one of those! :D
How hot do the L298's get without a heatsink then ? :)

Vik :v)
I've had L298N's running at full amperage and a bit beyond at 12 volts on a big DC motor without a heat sink.

I measured them at about >150 Celsius. They seemed quite happy to run that hot without problems. The only problem with doing that is that if you mistakenly touch the chip to see if it's warm you burn your fingerprint off.

I blogged that quite some time ago. I may have recorded the temperature then, too.
Make that 175 degrees Celsius. I found the temperature record.
You know what would be really slick. Use the waste heat off the L298N to power the extruder barrel. :-D
175C case temperature is way too hot. Max junction temperature is only 130C. I wouldn't expect them to last long like that.

I generally pick heatsinks to run about 60C. It's quite conservative but I don't like to burn my fingers!

Strangely the data sheet quotes max dissipation as 25W with case at 75C but junction case is 3C/W so that would be 150C junction which is 30C above the junction limit, am I missing something here?
Apart from not being able to subtract 130 from 150!
Hmmm. How long would it take one of these to bring one box, about a foot on a side, up to near the melting point of the plastics? Assuming pretty decent insulation.

Of course, that still leaves the question of what to use for corner brackets, if you're going to meld a reprap with an oven.

What about attaching a CPU coolant fan to one?

What about attaching a CPU water jacket to one? In the latter case, you could run the tubing to the extruder, but you'd still need a heating element...that is unless you want to idle your motors for several minutes before you could start melting plastic.

Also, the tubes would lose some heat, and you'd have to make room for all of them. Two tubes per motor, or perhaps just one axis, (the one that moves most of the time. Maybe x and y) Either two tubes, or all the tubes, for the extruder.

I have a feeling it'd be less effective than complex, however.
Where did you find the step exercise software? I have a windows XP machine and I can't find the software in any packages. I have the stepper board done and the pic programmed, led on and I have a motor ready for testing!
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