Query - Bearing Materials

In message , Arthur Griffin writes

No point re-inventing the wheel Arthur, you are quite right to seek our collective advice.

I have been down both roads - cast and machined whitemetal for my Wolseley WD2, and made bronze mains for my Ruston-Hornsby AP (originals were whitemetal).

Both approaches appear to be successful in my hands, but I would add a few notes.

I'd use leaded bronze in preference to phosphor bronze - it is softer, therefore kinder to mild steel shafts - PB is best for hardened shafts and gudgeon pins. Leaded also machines more easily - buy it as hollow tube and throw less away as swarf.

If the bearing is split and you cut bronze tube in half then solder together and bore out, bore a bit oversize as when the halves are separated the bore turns out to be undersize, and much scraping is required.

I have an article on casting whitemetal in silicone rubber moulds on my web site - follow the Wolseley page. Using gravity casting, the cooled casting will not be dimensionally accurate due to contraction, so machining all over is necessary to get all dimensions correct.

The set up costs (pattern, mould rubber, etc) for the Wolseley mains were about 30 pounds before I had even cast a single bearing. The mould can however be used many times, though I haven't discovered a huge market waiting to be tapped for WD and Ruston PT bearings.

Good luck............

Phos Bronze has the advantage of being able to carry higher loads at higher temperatures. However, the main advantages of whitemetal (which to me means a tin-based alloy, preferably lead-free) v. bronze are: Conformability - it will accept some misalignment and sloppiness in the mechanism. Embedability - It will allow small particles of debris to sink in and avoid scoring the shaft. Journals need not be hardened.

If the oilite is cheaper and easier, I would say go for it provided you are comfortable that the shaft is hard enough not to be worn by the bronze and that making the main bearing 'precision' will not throw additional stresses on the rest of the engine.

Phil Dando

a>Hi Chaps, I've been a bit busy lately, hay harvesting and sheep shearing when

not at work, so not much engine playing or posting;

main-bearing on a Bamford 3hp horizontal. A replacement

making a mould and machining the bearing, then

tube form which would save wasting time and material

and alllows the grease in.

acheivable for me.

Metal and whether there are any problems with this

Arthur, Would be interested as to how you get on as I have to make a new big end bearing for my 2.25 Bradford enclosed crank.

Martin P

Oilite is a sintered metal, while solid PB comes in extruded or cast types.

The feature of Oilite bushes is their retention of oil in the pores as you rightly say, and using anything but a very sharp tool or reamer will tend to smear the surface causing the pores to close up.

I have a leaning towards Oilite or extruded PB, but others may have their own preferences.

Peter

-- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:

"CHARLES HAMILTON SNR" wrote I had a big end done there

Could I be rude and enquire the cost? Off list if you like ;o))

Your earth might be more expensive than mine!

Regards,

Kim Siddorn.

Hmm, very interesting Charles, you're tempting me.

If you could give me an idea of the cost offline (and a list of your BSW taps, dies etc) and the company name I could well be tempted. I delved further last night, removing the piston and valves, to find that the crank journal was well scored, despite there being no slop in the big end. So I'm thinking the crank needs grinding.

The amount of coke around the head are was impressive and took a lot of removing, as did the exhaust valve cage, which was glued in with coke. Hammering it from the crank end with a wooden drift shifted it in the end, and of course the valve needs refacing, but I can cope with that easily enough.

Aren't engines with a non-detachable head a real sod to decoke?

Regards, Arthur G

You are not supposed to scrape or ream oilite as it closes the pores as you say.Turning with a single point tool is approved.Don`t suppose it matters if the application has its own oil supply. regards,Mark.

Being a gentleman Phil does not mention that he works for Hoyt's. I buy and use his product (No. 11R) and have now made about a dozen bearings. You can use the rod/cap as the mould with an Alu-former inner and an angle plate with fire cement for luting.. Arthur- Rather than me boring the pants off everyone, (and expose my self;-) talk to me off-group if you want details. My limited experience with Bamfords suggests they are as soft as Petter cranks. I would not dream of using P-B on a Petter and every such use I have seen has been a disaster regards

when not at work, so not much engine playing or posting;

main-bearing on a Bamford 3hp horizontal. A replacement

about making a mould and machining the bearing, then

in tube form which would save wasting time and material

turning and alllows the grease in.

more acheivable for me.

White Metal and whether there are any problems with this