Tetrix Motor

[dodar]

Does anyone know of any schematics for the mounting holes for the Tetrix motor? The motor itself, not the gearbox.

[Teched3]

Originally Posted by dodar

Does anyone know of any schematics for the mounting holes for the Tetrix motor? The motor itself, not the gearbox.

We're going to make you work for it. Put two of the mounting screws used to fasten the adapter plate to the motor housing in any two adjacent holes. Measure one of screws diameter before installing the screws in the motor.

Measure the Outside Diameter chordal distance across those adjacent screws. Measure carefully for the greatest distance, and deduct the diameter of the screw from that distance. This is the radius of the circle the holes are located on. Measure the centering boss on the motor. You will need this to determine what size drill to use to ensure motor centering. Simple trig from there to locate every other, or the six, hole locations. You only need the dimensions for three. PM me with your dimensions.
PS: They are metric screws. We found 2.6 x .45 diameter/pitch work really well. Be careful of length, as too long a screw will hit the magnets or armature inside the motor.

[dodar]

Thanks. About an hour or a little less after posting this thread we actually figured out how to get the hole pattern and punch in some numbers on our mill with the DRO.

[sanddrag]

For future reference, a lot of times you can eyeball it by laying a caliper across it, with the jaws as close as you can get to center of the holes. It works if you have a good eye for it.

[dodar]

Thats pretty much what we ended up doing.

[sanddrag]

Originally Posted by Teched3

We're going to make you work for it. Put two of the mounting screws used to fasten the adapter plate to the motor housing in any two adjacent holes. Measure one of screws diameter before installing the screws in the motor.

Measure the Outside Diameter chordal distance across those adjacent screws. Measure carefully for the greatest distance, and deduct the diameter of the screw from that distance. This is the radius of the circle the holes are located on. Measure the centering boss on the motor. You will need this to determine what size drill to use to ensure motor centering. Simple trig from there to locate every other, or the six, hole locations. You only need the dimensions for three. PM me with your dimensions.
PS: They are metric screws. We found 2.6 x .45 diameter/pitch work really well. Be careful of length, as too long a screw will hit the magnets or armature inside the motor.

This is a good measurement method. Thanks for laying it out. Interesting on the screws. I didn't even know there was such a thing as an M2.6 screw. I just stuck M2.5s in there, and I will say they did seem a tad loose. Hrrmm, learn somethin new every day.

[Teched3]

They can be ordered from McMasters-Carr. Check the clearance depth with a toothpick to get a handle on the length needed, starting with your frame thickness, and checking each hole depth. We ordered nuts as well, so we could chase the threads if we needed to reduce their length. Put a nut on first before cutting. this particular application is very tolerant of spacing, but try to make the center hole an accurate size for the motor centering boss. If I remember correctly, It was a D drill, with minor deburring. test in some scrap first.

[sanddrag]

Originally Posted by Teched3

try to make the center hole an accurate size for the motor centering boss. If I remember correctly, It was a D drill, with minor deburring. test in some scrap first.

I used a 25/64, and there's a tick of free play.

[Teched3]

The free play won't hurt you in this application, but if you're building a transmission/gear train, it will. My philosophy in this competition is to teach students (parents and mentors) how to do it right. It pays many dividends in the long run.

Sanddrag, I really enjoy reading your posts on C/D. they are insightful and informative.

[Teched3]

Originally Posted by Teched3

They can be ordered from McMasters-Carr. Check the clearance depth with a toothpick to get a handle on the length needed, starting with your frame thickness, and checking each hole depth. We ordered nuts as well, so we could chase the threads if we needed to reduce their length. Put a nut on first before cutting. this particular application is very tolerant of spacing, but try to make the center hole an accurate size for the motor centering boss. If I remember correctly, It was a D drill, with minor deburring. test in some scrap first.

Sorry if I misled anyone on the drill size to center the Tetrix motor. Sanddrag is correct - 25/64" is the closest size. Must have had a Senior Moment! We made spacer bushings to go around the boss, so we could drill out the hole large enough to pull the motor/ driveshaft assembly out quickly just in case a motor failed on us. This info might be especially useful to those that pressed a driveshaft over the pinion gear. Not neccessary if your driveshaft diameter is less than .3906 in.

[rahilm]

Originally Posted by Teched3

PS: They are metric screws. We found 2.6 x .45 diameter/pitch work really well. Be careful of length, as too long a screw will hit the magnets or armature inside the motor.

If anyone is having trouble finding Metric screws (we were fairly certain they were metric, but couldn't find any locally), 3-48 screws seem to work fairly well. We were actually going to Ace Hardware in Sacramento on Thursday when we noticed they sold really small screws, and we brought a motor by to check for size; if you're looking for screws quick, Ace has them.