hardened steel / opening out a hole

[Colin Wilson]

This may sound like a dumb question, but i`ve got some hardened steel washers that came with radial bearings i`d like to put in use.

The problem is they`re 25mm and the shaft they need to go on is a little larger (perhaps an inch, but without having a micrometer / calipers to hand I can`t be sure on the exact radius...)

I might, at a push, be able to get someone to try a cone drill to open it out a little (I can forsee problems holding them in place to enable then to be drilled though), and a regular half-round file isn`t touching them (its blunting the file).

Any simple ideas for this one ?

I recently bought a dremel style thing, and I might be able to try to use a grinding wheel on them (which seem to wear at an alarming rate), but apart from that i`m out of ideas :-}

[Mike Dodd]

Considered a reamer?, failing that (or having considered the cost of a new one), have you considered approaching a sheet-metalworking company (whatever they're called)

Other than that (and I can't believe this'd work) - have you tried placing the shaft in the freezer for an hour?

[Dave Plowman (News)]

If they are hardened, then they'll not be kind to any steel cutter. Grinding is the obvious answer, but difficult to do accurately by hand.

If you could find a suitable tapered grindstone that might be good enough.

[Dave Baker]

You won't touch hardened steel with any metal tool. Only grinding will machine it. It's surely easier to just go and buy some 1" washers from a bolt stockist.

[Colin Wilson]

Can`t find any drill bits or reamers big enough to borrow for free from work, and its probably stupidly expensive getting one machined professionally :-}

Sadly this is out of the question - the shaft is part of a "gravity walker" thing the missus has, and the freezer just ain`t big enough :-}

Freezing can indeed work and is used in some applications though (I think they call it interference fit)

The only reason i`m trying to use the bearings is to stop two mating faces at the pivot point squeaking like a bi*ch when its been in use for

10 minutes :-}

[Colin Wilson]

Why the hell didn`t I think of this :-}

Thanks, i`ll see what I can come up with !

[Ian Stirling]

Anneal them. Heat to some 400C, and then cool slowly. If you have a self-cleaning oven, putting them through a self-clean cycle may have good results.

[John Rumm]

Usually with liquid nitrogen rather than a domestic fridge though ;-)

Can you get a carborundum/grit file rather than an ordinary steel one?

[Andy Dingley]

Why ? Because you need washers, or because you need hardened washers?

If you don't need them hard, then find some unhardened washers to deal with. These ones you're going to have to grind out.

As a cheap fix, get a "tile file" (carbide grit on a half round file - any DIY shed for a few quid) and use that.

Cone drills are expensive. Good way to knacker one.

[Dave Plowman (News)]

I'm not convinced. A thrust washer might well be case hardened.

[Ian Stirling]

Might be. Might not be.

[Cicero]

================ You could try a piece of 3/4" wooden dowel wrapped in emery cloth. It might be tedious but it will almost certainly get you there in the end.

Cic.

[Colin Wilson]

Thanks for the replies guys - i`ve got access to emery paper so that`s a possible, but I must admit the "find a bolt stockist" is probably the easiest option :-}

[Mike Dodd]

You'd be surprised - a bloke I used to work with was building a kit-form microlight aircraft (full cockpit, not a hang-you-off-a-kite job), and followed the kit instructions by placing parts of bearing races in a domestic freezer before assembly.

Regards

[Simon]

400C won't anneal . it will just temper and depending on steel, probably won't change the hardness much .. stick them in the BBQ and leave until next day . and you will anneal them .. but then you would have to reharden ..... better to either source new washers .. or just grind them back a bit with the drum sander in the dremel and AlOx sanding drums

[Andy Dingley]

So what ? Case hardening is still just steel - it anneals and re-hardens same as any other medium carbon steel.

And very little is case-hardened these days - it's an expensive process. Lots of extra process steps involved in it, when it's usually cheaper to just use a hardenable steel. For mass production, plasma spraying and nitriding are cheaper to apply than case hardening.

[Jerry Built]

Gee Hugh Henry. Where *do* you get this stuff? I'm sure you have never studied metallurgy. Above: if a thing needs to be case hardened, "using a hardenable steel (?)" is not a useful substitute. Also, "nitriding is cheaper to apply (?) than case hardening" - nitriding flippin' well *is* case hardening!

J.B.

[Dave Plowman (News)]

I'm not aware the OP mentioned the age of the washers.

[Andy Dingley]

I'd assumed that "came with radial bearings" implied they were new.

[Colin Wilson]

For the record, they are :-}

Still half-heartedly trying to find a local nut`n`bolt merchant btw !