I'm going to be doing pretty much the same thing shortly Malc and intend to use the existing (worn) shaft and turn it down slightly to fit new Oilite bearings in the original (cast iron) bearing holes – which I will bore out. Turn the shaft just enough to remove the wear and then check for the nearest ID bearing size down (either metric or imperial) and shoot for that.

I will probably lap the shaft (after turning) to get the best fit & finish….

Regards,

IanT

Edited By IanT on 31/08/2020 22:02:23

I would just use silver steel and replace with size oilite bearings to suit the shaft. If you have to bore the casting you can turn the OD of the bush to suit the casting as the inside is the bearing area with lube which shouldn't be machined unless it can't be helped.

David

And note, use "Oilites" guide for hole diameter in casting. When fitting they rely on a compression fit which also squeezes Oilite bore down to nominal size.

Regards Ian (another one)

Old Mart is not being cynical, just realistic.

Whatever you lose will come to light just after you replace it!

Silver steel would be my choice for the shaft. It may well take a long while to wear it badly, as long as the shaft and bushes are kept oiled.

Howard

What diamiter iand length s the shaft and what diamiter is the hole in the casting. Have a look at simply bearings web site they have a good selection.

David

The difficulty in accurately measuring an inside diameter doesn’t help in these cases.

If a measurement is really important, make a very close fitting plug and measure the outside diameter of that.

Hi Malcolm just looked on line and you can get a piece of silver steel from less than £12.00 and a couple of bushes for around £3.50 each just knock out the old bushes and check the diamiter with a micromiter. If you look on the Oilite web site it gives the corect size for hole and if it is OK and matches the bush should just press in with a piece of screwed rod two washers and a couple of nuts. Try the spindle in it should rotate but not loose.

David

I too am restoring an old Kennedy power hacksaw and by luck I stumbled across this thread. I have exactly the same problem of a worn shaft and bushings. On mine, the shaft is unhardened. I intend to fit new Oilite bushes and would like to upgrade to a hardened shaft, which I believe is advisable when running in bronze. I can’t find any commercial source of ¾” hardened and ground steel. So I thought I would have a go at turning down some EN3B, carburising it using an old tin of Kasenit I have and then grinding it to size on the lathe with my toolpost grinder. I’m wondering how much grinding allowance to leave. It needs to be enough to correct any distortion but not enough to grind through the casehardening. The shaft is only 4.3/4” long and I will plunge the shaft vertically when hardening it to minimise distortion. My gut feeling is about 4 thou but I don’t have any feel for how deep the carburising will be. Any advice will be gratefully received.

I doubt dunking your shaft into a tin of Kasenit will achieve much case depth at all.When I did industrial case hardening the parts were soaked for many hours in carbon rich compound.

Tony

You can get surface hardened shafting intended for linear bearings. It can be machined with carbide. Alternatively get the existing shaft hard chrome plated and grind it back to size.

Having said all that I'd just use en8, how much sawing are you going to do in a home workshop

Put in Google images 'carbon steel temper colors', loads of information for you to peruse & make your choice. Shafts aren't normally though hardened but yellow to orange I would say.

Tony