TinyG Fan Control

Discussion of tinyG control platform
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pastprimitive
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TinyG Fan Control

Post by pastprimitive » Tue Aug 26, 2014 7:19 pm

So I have my Tiny G in a custom laser cut enclosure I built for it. And I covered all the stepper drivers, and the atmega processor with AL heatsinks. I'm using a 12 volt 40mm fan to cool it, and I notice it's a 3 pin fan port. Yet my fan just seems to run at 100% the entire time. Is there no variable speed control built in?

It sounds like a jet plane taking off at full speed, and I am quite sure it's not necessary all the time. So if there isn't what would I need to do to put in the speed control in the firmware? I've got some thermistors for feed back if needed. Even if it was "dumb" control, and just turned the fan onto full speed only when running a gcode program that would be acceptable as well.

I realize I can just put a resistor inline, or throw on my simple 555 PWM circuit. But I'd rather go the more integrated route first.
ShapeOko 2 6095. Double Y-Axis Nema 23s (140oz/in), X & Z Nema 23 (262oz/in), TinyG, 500W DC Brushless Spindle w/ 48VDC 10A Supply, Acme Lead Screw, 24VDC 10A Supply, Threaded Inserts Table, Auto-tool height setter.

CastIrony
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Re: TinyG Fan Control

Post by CastIrony » Wed Aug 27, 2014 3:06 am

I wonder if you could run the spindle and fan speeds off the same PWM signal.
Shapeoko 3 #192 - Complete! Needs limit switches.

aldenhart
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Re: TinyG Fan Control

Post by aldenhart » Wed Aug 27, 2014 4:55 am

You probably don't need a fan that's so powerful. The stepper drivers need light cooling - and only if you are drawing more than about 2 amps. This usually means NEMA23s - Most NEMA17s don't draw this much. The Xmega should not need any cooling.

I'd remove the heatsinks (at least temporarily) and put in a smaller fan. Then see if you need the heatsinks. Expect the driver chips to run warm - this is normal. But they should not go into thermal shutdown.

One other thing - make sure the motors are not being over-driven. Too much current affects performance as much as too little current.

Have you seen the wiki entries on these topics?
https://github.com/synthetos/TinyG/wiki ... or-current
https://github.com/synthetos/TinyG/wiki ... yG#cooling

pastprimitive
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Re: TinyG Fan Control

Post by pastprimitive » Wed Aug 27, 2014 4:33 pm

Thanks Alden,

I have read through those wiki entries.

I'm actually powering NEMA 23's with it. And my fan is about as small as they come. it's just a 40mm fan. I mean I could put in a 24 volt fan and run it off the 12 volts, or just use the 12 volt fan with a voltage divider, resistor, etc... But I didn't think one 40mm fan was exsesive. Ok the heatsink on the atmega... yeah no point. But I have a ton of them, and just figured i'd rather error on the side of ridiculous caution. But it's ridiculous, agreed. It's not obvious, but the side of the enclosure that isn't visible is the exhaust vent, and it's plenty large. I am going to recheck my fan. I might have inadvertently put a 5 volt fan in there, hence the unusual amount of noise. Also this is all just me being prepared. I haven't even run a job yet. So this was all preventative precautions. I was designing the laser enclosure, and figured I might as well add some active cooling since the fan pins are so convenient.

I haven't done my current adjustments yet, but plan to soon. I've experienced first hand how annoying over currenting the steppers can be with my 40 Watt Chinese laser cutter rebuild. Vibration, weird jitter, etc... So i'll make sure I tune that in. Although what small testing I have done they are running silky smooth, with no vibration, under-torque issues. So they aren't too far off.
IMG_1107.jpg
TinyG enclosure
IMG_1107.jpg (389.47 KiB) Viewed 1754 times
ShapeOko 2 6095. Double Y-Axis Nema 23s (140oz/in), X & Z Nema 23 (262oz/in), TinyG, 500W DC Brushless Spindle w/ 48VDC 10A Supply, Acme Lead Screw, 24VDC 10A Supply, Threaded Inserts Table, Auto-tool height setter.

aldenhart
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Re: TinyG Fan Control

Post by aldenhart » Thu Aug 28, 2014 1:54 am

I like the case. Looks cool. let me know how it goes.

dougal
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Re: TinyG Fan Control

Post by dougal » Fri Aug 29, 2014 2:05 pm

What about a fan with a thermal sensor like: http://bit.ly/VSEU8T this one is 60mm though.

sraney
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Re: TinyG Fan Control

Post by sraney » Fri Aug 29, 2014 7:33 pm

Its an old post, but ill chime in.

I suggest moving to a larger PC case fan. The 40m. and smaller cage fans always are loud due to their tendency to build back pressure across the plane of chop unless you have a horn. Double the sze and apply 12v and it will cool more effentently and be half the Db.
-- sraney
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pastprimitive
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Re: TinyG Fan Control

Post by pastprimitive » Tue Sep 02, 2014 3:11 am

Going up in size would work well. But i'm not excited about cutting out a new case. But agreed I am running my 40 mm to hard. I'm thinking i'm going to put in a voltage divider and just run it at 6-8 volts.
ShapeOko 2 6095. Double Y-Axis Nema 23s (140oz/in), X & Z Nema 23 (262oz/in), TinyG, 500W DC Brushless Spindle w/ 48VDC 10A Supply, Acme Lead Screw, 24VDC 10A Supply, Threaded Inserts Table, Auto-tool height setter.

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