Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: baxter462 on September 16, 2006, 01:57:25 PM
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I am attempting to set up a small CNC mill with my very limited knowledge. I have it running, but am wondering if there is a way to have the stepper motors shut off when they are not moving? I am using a cheap driver-board that does not cut back the current to the motors when they are stopped, so the Z-axis motor gets pretty hot after a few minutes, since it rarely moves. I think the easiest (although I'm sure it's probably not the best) solution would be to have Mach3 turn that motor off when it is not moving (if this is possible). I think that due to the mechanical setup of the machine, it really isn't necessary to keep the Z axis motor energized all the time. Any advice will be greatly appreciated. Thank you.
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Steppers run hot. To hot to touch,hot. They are made to run at these temperatures.
Now that being said if they are REALLY cooking, if you spit on it and it sizzles, you need to make sure that the driver your using doesn't need current limiting resistors in series with the steppers.
You really don't want to de energize the stepper, the only thing keeping your machine from loosing position is that energized coil. You can add some heatsink to the steppers, make sure you don't need resistors, and if all else fails you can find a nice 'chopping' or current limiting 3 axis stepper board for around $115.
Chad
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Thanks Chad. Where can I get the driver board you were talking about, and is it setup for Bipolar stepper motors? Thanks.
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Gecko do a the G201 for about $115 and the G202 for about $135. The G202 has inbuilt capacitor and also it has a protection circuit so it is preferable over the G201.
You will find the drives at www.geckodrive.com
Hood
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Hmmm , Maybe i should have asked more questions before stating the price.
OK the bipolar thing is going to be a problem. I can't find or think of any cheap bipolar drives..
The driver I used when I did my little mill and lathe:
http://www.hobbycnc.com/
This is a kit, for unipolar steppers (what I had laying around) and I am pretty handy with a soldering iron.
Of course this would mean that you would have to buy new steppers. They also sell unipolar steppers at a pretty good price. This part always sucks
The Gecko drives are VERY nice and would work great. They are however $115 each axis.
What kind of mill are you making?
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Xylotex do a 3 axis and 4 axis drive, the 3 axis is $155, you will find them here http://www.xylotex.com/3axBoard.htm
I have no experience of them and dont really know the specs but a friend has them on a small Enco and is happy with them.
Hood
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Thank you all for your advice. The Xylotec drive looks like the way to go for me. It is Bipolar, and allows maximum current control independently on each axis. It is also inexpensive. Thanks again.
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You will be very pleased with the Xylotex driver. They are so smooth when set up
using Mach3 it is amazing. Just be sure they can handle the voltage and amperage
that your stepper motors require. I say this as they are not concidered high voltage
units. Also be sure your power supply is within the specs. for the Xylotx drives. Look
over there web site information very throughly.
Stepper motors do run hot, but I disagree that they are so hot you can't
touch them. Maybe not hold them for long but they sure as hell should not burn you.
Al
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The heat that steppers emit is to do with the voltage you are running them on, I have a large router that has a 90 volt AC power supply and has a ton of power and speed, the steppers get to over 150F, too hot to touch, bad enough that I added water cooling jackets to them, cooled off the spindle cooler. I like the power it has, so don't want to compromise motor life for speed. Yet, my lathe has a 42 volt power supply and the motors on that get barely warm, almost cool to the touch, but it isn't very fast either....