press fit sizes

Gentlemen,

I am going to make four 2.5" rollers for a friend with .5" axles using silver steel what drill size could I use to get a light press fit or would I need to ream the hole .5"

Martin P

As a rough guide you need the hole .001" per inch undersize. So you need to make the holes .0005" under the size of the silver steel. So measure the silver steel first then set your reamer to cut as above. I would make a test hole first.

You would be very lucky to get an accurate fit by drilling. You would have to ream or accurately bore the holes. Again, you would have to measure the actual diameter of the shaft and from that select the correct reamer 'Fit'. However, most of us probably have the generic H8 reamer and instead of passing the reamer through the hole, just use the bottom end of the reamer (The tapered section) and by trial and error open up the hole to get the push fit you require. Note, not all lengths of silver steel are the same diameter - it is ground within limits.

You could make the holes undersize, then heat the parent metal to allow a sliding fit for alignment

Can you duck the issue with a tapped side hole and a grubscrew?

Its an antique butter churn which my friend drives with a stationary engine, we are replacing the rollers which the drum sits on so I would like it as original as possible so grubscrew wouldn't match the look I have adjustable reamers so I can ream to size, I wasn't sure of the tolerances.

Thank you,

Martin P

Could you turn the roller and axle protrusions out of one piece of 2.5" round material? Would save a lot of work.

Forgot to mention that the roller is made of brass. You have all pointed me to the right way, thank you.

Martin P

Loctite 638 is your friend.

I agree with Chris Evans, Loctite is by far the easiest way to go. You better make sure that the brass is lead free in a food environment.

Ian S C

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Chris/Ian

I am [as you might expect] with you on the matter of Loctite 638

... But I assumed that Martin must have discounted it, on principle.

MichaelG.

Edited By Michael Gilligan on 13/11/2018 10:10:00

MichaelG,

Its a simple task and 638 is a simple solution, there are no serious loads involved and means making the job easier