View Full Version : Bipolar Stepper Motor: 2 Axle Qs

07-19-2009, 10:15 AM
I'm interested in getting the bipolar stepper motor and the bipolar stepper motor controller board, but I have a space issue, and I wanted to find out:

1. Is it easy to saw about 1/4" off the top of the axle (you know, the thing that rotates), or is this some super-strong steel alloy?

2. Is the axle notched (that is, is one side flat), or is it totally round such that it requires the attached wheel to be bolted on with some kind of Allen nut or something?

Thanks for your fine products. I hope my questions make sense. I'm happy to elaborate if necessary. I don't know most of the correct technical terms to use in asking these questions!

07-19-2009, 10:42 AM
Most motor axles are made of silver steel. It's quite hard, but a decent hacksaw can cut through it.
Put some masking tape over the axle to prevent the blade from slipping, put the part you want to cut off in a bench vice, support your motor!!! to prevent the axle from bending and/or wearing out your bearings, and it should work a treat.

07-19-2009, 11:17 AM
I've used a hacksaw and a dremel cutoff wheel for the Banebots motors. If you're going to use a cutoff wheel, USE COOLANT! Don't want to cook that grease out of there. And as ScuD noted, clamp the shaft in a vice as close to the vice as practical. I clamp mine in at an angle, and the cut outside on the opposing angle.

07-21-2009, 04:35 PM
Thanks for the replies. It sounds like it would be a real pain in the neck for me to trim it. I have a Dremel but no vise (I guess I should get one of those...), and I'm quite ignorant. A couple of follow-up questions:

- "Coolant"? Do you mean a spray bottle of something, or is there a grease that one rubs on surfaces one is sawing through?
- Does anyone know if the rod is notched or in any way not perfectly round?
- I didn't see the diameter of the rod in the specs. Anyone know what it is? I might not *need* to cut it...
- In the two replies, one person seems to say that the motor should be supported, while the other person says that it should be at the free end of the rod while the other end is in the vise... I'm not criticizing, I guess, because of my inexperience, I'm not sure ... wouldn't NOT supporting the motor prevent it from experiencing too much force? In other words, if I have the vise as one side of a bridge, and the motor supported on a brick as the other side of a bridge, and my hacksaw is sawing through the rod, which is the middle of the bridge, doesn't that put more pressure on the motor end of the bridge than if I were simply pressing down on the rod and it was the resistance to bending inherent in the steel that provided its own support? I hope my question makes sense.

Thanks, y'all! You rock!

07-21-2009, 05:13 PM
You're supporting the bearings. Bearings are not meant to take off-axis forces. If you clamp the shaft and cut the unsupported end off the shaft, then the bearings are only supporting the weight of the motor off-axis (and not even that if it's clamped at an angle with the motor resting on the vice) rather than the forces involved in cutting the shaft. Viewed from that perspective, I think your analogy is flawed. We don't care about the bridge, we're planning to hack it in half anyway, we care about the bridge supports.

Coolant: http://en.wikipedia.org/wiki/Cutting_fluid

I use this: http://www.crcindustries.com/auto/content/prod_detail.aspx?PN=03410&S=Y for cutting generally. You can pick it up in a blue can at Harbor Freight.

Any time you're cutting, grinding, or drilling anything hard you should be cooling it. It's especially important when there's low-temp grease on bearings touching that shaft - that grease is going to cook-off leaving dry bearings which is going to rather shorten the life of the device...

07-22-2009, 07:42 AM
Oh, okay, I think I understand what you mean -- I could clamp the shaft with the corner of the vise, so that the motor is above the vise and the end of the shaft is sticking out (say) to the left of the vise, and that would allow the motor to be completely left out of the equation?

I totally get what you mean re: the importance of coolant for something like that. I've already discovered by accident how quickly you can produce heat and even smoke with a Dremel tool! :p

Thanks very much for your help!