metal behaviour question...

rafezetter · 23 Mar 2014

Some of you may have read I'm thinking of doing a cosmetic repair on a plane where a bit of the side section has broken off, and what I was considering was simply drill and pinning it using the technique of friction fitting, by drilling the holes, then freezing the pins so they shrink a tiny bit, then as they warm up they make a friction fit.

I'm thinking of this mainly because I don't have a tap set, but I do have a freezer! The plane body is cast iron, but the repair section will be brass (if I can find any that's 5mm thick), so what I need to know is which metal would be safer to make the pins out of? Should I use brass, being softer, my thought is as it expands it should hopefully compress a bit, if it's a tiny bit too big, rather than crack the iron sole, or maybe something softer like an oversized copper rivet?

wizard · 23 Mar 2014

strip it and bin it simples

Richard T · 23 Mar 2014

I would be very cautious about expanding anything, anyhow, in cast iron. Much safer to bite the bullet and get relevant tap, drill and bolts.

I noticed that someone on the other thread asked about filing the bolts flush when in - much easier to cut them to length before they went in I should think.

marcros · 23 Mar 2014

Cast iron should be easy to tap- meaning that the cheap tap sets will do the job.

By the time you have found somewhere to buy, and have bought a drill .1 of a mm smaller than your dowel size it would probably be cheaper to use the cheap tap set.

Spindle · 23 Mar 2014

Hi

The distances you are thinking about are far smaller than can reliably be achieved by drilling, you would need to ream the holes to size, which I'm guessing is an expense you don't wish to consider, (a good reamer will be in the region of £20), and the potential for cracking the cast iron is quite high.
Tap and file post fit with countersunk screws would be my choice if I had to but I'd also be asking is it worth the effort.

Regards Mick