Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: dainel40 on April 17, 2013, 07:34:27 PM

Title: Related to GDT
Post by: dainel40 on April 17, 2013, 07:34:27 PM

A roller bearing is to be pressed into a wheel hub. The nominal outer diameter of the bearing
and the inner diameter of the hub is 58 mm. What should be the tolerances for the outer
diameter of the bearing and the inner diameter of the hub if a shaft basis medium drive fit is
desired? Do not switch to a preferred size.

I have no clue on how to find this

Title: Re: Related to GDT
Post by: waltr on April 17, 2013, 08:33:00 PM

I would start by seeing what the bearing manufacturer recommends. They usually spec the fit.

As for google search terms try:
bearing fit
interference fit
bearing interference fit chart
bearing interference fit tolerance
roller bearing interference fit tolerance

Lots of info under each of these.

Title: Re: Related to GDT
Post by: dainel40 on April 17, 2013, 09:06:29 PM

http://my.safaribooksonline.com/book/illustration-and-graphics/9781118078884/appendix-b-ansi-preferred-metric-limits-and-fits/navpoint-111 (http://my.safaribooksonline.com/book/illustration-and-graphics/9781118078884/appendix-b-ansi-preferred-metric-limits-and-fits/navpoint-111)

I have that but i cant find the right measurement, do i just round it to 60mm?

Title: Re: Related to GDT
Post by: mallster on April 19, 2013, 04:39:02 AM

 As a rule of thumb.... you should be probably aim for a maximum of .02mm interference per 25mm diameter increase in diameter (tolrance -.01mm, +0mm.)

So in your case I'd say the od of the roller bearing will be close 58.00mm so the hub should be bored to 57.96mm (+.02mm, -0mm)

This will have zero effect on the inner bore diameter of the roller bearing.

Will help to heat or warm the hub somewhat before installing bearing.

Title: Re: Related to GDT
Post by: jwatte on April 22, 2013, 03:05:59 PM

It also depends on what tools you have available, and whether you need the bearing to be the main lateral force carrier.
If you don't have a press of any kind, then an interference fit may be too hard for you, and you may need to take a file or some sand paper to your inner diameter, until you can actually fit it.
Shaft collars can help position/fix things laterally if you're not using an interference fit for the entire assembly.