Query - Bearing Materials

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;
just lurk mode.
Sadly, that bearing has not cured itself. I'm referring to a white metal main-bearing on a Bamford 3hp horizontal. A replacement bearing is required. While talking to a friend recently, I was talking about making a mould and machining the bearing, then scraping.
He suggested turning the bearing from oilite phosphor bronze, it comes in tube form which would save wasting time and material boring out solid, and tapping it to put in the little bit that stops it turning and alllows the grease in.
Though not as original, all in all, it seems an attractive option and more acheivable for me.
I wondered what comments the group would have on the merits of PB versus White Metal and whether there are any problems with this approach, which haven't occurred to me.
Thanks in advance,
Arthur G
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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............
--
John Ambler

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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
aOn Thu, 24 Jul 2003 17:15:22 +0100, "Arthur Griffin"

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wrote:

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
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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.
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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 -- Roland Craven nr Exeter Devon, UK snipped-for-privacy@petternut.co.uk http://www.petternut.co.uk
wrote:

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

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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
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Arthur, I may be wrong, but I,m sure that I remember from my dim and distant engineering past that you aren't supposed to machine oilite (?). That's why it comes in so many sizes,it's supposed to be used as is.Our local automotive engineer sends jobs such as yours to a place in Newcastle where they do the whole job at a very reasonable cost. I had a big end done there for a Bradford. I just sent the con rod ,crank and piston and it came back reassembled with new bearings and didn't cost the earth.

shearing
metal
comes
more
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"CHARLES HAMILTON SNR" wrote <snip> 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.
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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

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