Minibot Motor Press Fit

[Chris is me]

I'm trying to press fit "something" to the Tetrix motor with transmission removed. The shaft appears to be 1mm in diameter. What size hole should be drilled / reamed into my part in order to nicely press fit onto the motor shaft?

[MrForbes]

1.00mm diameter? or something else?

Generally a couple thousandths of an inch interference makes a good press fit. But it depends.

[kramarczyk]

I agree with Jim, .001"-.002" per inch of diameter, so your tolerance is pretty small. What material are you pressing on? The softer it is the more press it can tolerate.

[Jared Russell]

1.0mm? Our motor shafts are 2.5mm in diameter... (0.0984 inches)

We were able to press fit a 3/32 inch (0.0938 inch) hole in a 6061 aluminum rod (.25" OD) onto the shaft without difficulty. Just make sure you support the back of the motor where the shaft "nub" is so you don't pop out the other side

[BrianT103]

Jared is right, it is a 2.5mm shaft. Be careful when you're press fitting something on there, I can think of other ways to accomplish what you're trying to ultimately do. Press-fitting may or may not be your best option

[Brandon Holley]

As the others have said...The shafts are 2.5mm. I always try to use a micrometer to measure the exact diameter of each shaft and ensure they are very close to each other. When you are dealing with smaller pieces and press its important to be as accurate as possible.

-Brando

[BJT]

I used a #41 drill bit which measures .0960 inch. my calipers measured the motor shaft at .0980 in. we are most likely pressing the same "something" onto the motor.

[Chris is me]

I just got the 1mm number off of a flawed CAD model. Thanks for the clarification.

[Chris is me]

Originally Posted by BrianT103

Jared is right, it is a 2.5mm shaft. Be careful when you're press fitting something on there, I can think of other ways to accomplish what you're trying to ultimately do. Press-fitting may or may not be your best option

I can't - the shaft seems too small to affix a setscrew to. Is it not?

[DinerKid]

Originally Posted by Chris is me

I can't - the shaft seems too small to affix a setscrew to. Is it not?

Instead of going with a set screw you could use a "clamp on" style thing you want to attach to the shaft.

~DK

[Chris is me]

Originally Posted by DinerKid

Instead of going with a set screw you could use a "clamp on" style thing you want to attach to the shaft.

~DK

I didn't know clamps came small enough to rigidly fix onto a 2.5mm shaft...

[Trent B]

Red loctite can also be used to secure press fits. We have it in a custom gearbox securing a RS775 to a tough box shaft and it has worked great.

[Nirvash]

If you have Loctite 638, then I would recommend that over Red (271) for press fitting something onto a motor.

[Trent B]

I was going to mention that, it is actually made for press fitting two smooth objects together, oddly the local autoparts stores here didn't sell it even though it is often used for bearings in cars. So we settled for red loctite which works in low torque situations (like our lifter)

But similarly, I am not sure 638 is technically allowed on the minibot where-as Loctite designed for thread-locking is.

[topgun]

I would like to introduce you to a wonderful site of utilities for the shop:
http://www.myvirtualnetwork.com/mklotz/#shop

Many, many programs that calculate whatever you need to do in the shop. Your answer should be found with the FITS program.

Go up one level and you will find a bunch of math programs as well.

I have also noticed that the KOP CAD models from PTC have incorrect diameters on the motor shafts.