@Dave: What's the diametral pitch on the motor pinion? That's the critical info missing. And in the photo on the Paralllax website, I count 16 teeth, not 17. Can you double check that?
@fltcmdr: That brass gear on the motor can be easily removed and you can install any other pinion as well.
Erco, I have some steppers and DC motors I salvaged out of a printer. I'd like to swap the belt gear on the DC motor over to the stepper, but I wasn't sure how to take the gears off.
You mentioned they are easy to take off. I don't see a set screw, so what's the trick? Are they just held on with a lot of friction?
Yes, they are usually a press fit, especially brass gears on a splined steel shaft. It's easy to mangle them off, you can "carefully" crush the brass gear off in a vise. Brass is softer than steel, so it will shear off and leave the steel motor shaft in good shape. To preserve the gear you want to remove is a bit trickier, you need to support the gear edges (2 plates atop a vise, straddling the motor shaft works) and tap on the motor shaft with a center punch to drive it out.
Thanks for the info on the gears. Its a great help. Micromark sells a gear puller that should easily remove the gear intact. I have one on order in case I cant find suitable gears for my turrets. Again thanks. and there are 17 teeth
MC
OK I went to the Mcmaster site and they said the pitch is the no. of teeth divided by the pitch diameter. Which by thier drawing looked to be about halfway up the tooth. using the gear diameter and depth you gave me I estimated it to be about .342. that equates to an estimated pitch of about 49. None of their gears are even close to 49. 32 is the largest.
Am I doing something wrong or are their gears just not suitable???
MC
48 pitch is standard for US gears, that's darn close and probably it! Metric is also a possibility, which is sort of the reciprocal of DP. DP is teeth per inch of diameter, whereas module is the metric width of a single tooth.
Uh ok well ya lost me on that. It says its made in china but it dusnt mean they didnt use a US gear. Plastruct sells a gearset that just mite fit the shaft. but Id rather buy steel for the turrets They will be tougher.
Most of the gears that I have looked at are 20degree. I dont know if they would work or not because no serious specifications were supplied with the stepper. Obviously it meshes with "something" but it slows the project down considerably trying to figure out what. I figured this would already be worked out by now.
MC
I would think a 20 degree pressure angle to be pretty well standard for a commercial brass pinion gear. Check the pitch diameter for meshing to another gear.
Comments
The diameter of the gear is .369"
The depth of the gear is .316
There are 17 splines on the gear. You can check with McMaster-Carr at:
www.mcmaster.com
Dave
@fltcmdr: That brass gear on the motor can be easily removed and you can install any other pinion as well.
and the pitch angle... (less critical, but important)
http://en.wikipedia.org/wiki/Pressure_angle
You mentioned they are easy to take off. I don't see a set screw, so what's the trick? Are they just held on with a lot of friction?
MC
Am I doing something wrong or are their gears just not suitable???
MC
MC
MC