If I'm driving 3 steppers at 2.5A will the board need any sort of cooling or heat sinks?
What do you reccommend?
Also - what are shipping costs to UK likely to be?
cheers
Mike
heatsink?
Mike, you will find most of you answers on the wiki.
https://www.synthetos.com/wiki/index.php?title=Projects:grblShield
See here: and look for cooling.
https://www.synthetos.com/wiki/index.php?title=Using_the_grblShield
We ship USPS flat rate internationally, so I think that's about $12. If you place an order or at least take the shopping cart that far it should tell you the exact amount. - Alden
I have a similar question. I'm going to try to drive three 1.4A motors, and expect that it's going to generate some heat. I have read the cooling section on the page linked above.
I saw the images of the massive heatsink for the mini-g that attaches to the bottom of the board. It looks like I could machine a modest heatsink that could attach to the bottom of the board in the space between the Arduino and the grblshield. I could make a bigger heatsink by standing up the grblshield with a set of shield stacking headers. I could make a pretty big heatsink that contacts the driver cases on the top of the board where there is lots of space, but i imagine heat transfer through the epoxy case won't be as good as if the sink was on the bottom. Whatever I end up with, it's easy enough to mount a fan to keep air moving over it.
What do you recommend?
Thanks!
-John
John, You should have no problem with 1.4A motors - I have driven much larger with and without heatsinks. We are putting some heatsinks on the site soon. We found some copper heatsinks used for RAM cooling by case modders. These work pretty well.
We also looked at underside mounted solutions, but there's not much room between the boards - especially with the ISP programming header sticking up off the Arduino.
If you have any issues with heat you will know it - as the driver chips will cycle on and off due to thermal shutdown - or even stutter in extreme cases. In most cases this means you have your current set too high and are overdriving the motors. Back it off until the stuttering stops, then check your torque. You should still have plenty. The chips may run hot, but this is expected.
The most effective cooling is to use a fan. Blow some air across the board and through the gap between the Arduino and the board. This actually makes much more difference than any heatsinks we've tried - including the monster on the TInyG board. However, at 1.4 amps you should not need this.
Also (ironically) the motors run cooler with higher voltages as the power electronics spend less time in switching. So running at 24v will provide better motor operation and cooler chips than running at 12v.
Alden
Thank you. I should have my motors in a week or so and will report back.
Got my motors. They're actually 1.7A/phase. They are very torquey and run smoothly. I'm running them from a 20v power supply, but intend to switch to a 27v 11A supply soon. I haven't run them for a long time yet, maybe 40 second runs. The chips get warm, but aren't shutting down, and this is with no cooling at all. Looking good.
These TI chips are pretty nice. And with all the extra copper that alden added to the PCB... It really makes the board pretty tough.
Riley
Back to grblShield Support or the forum archive.