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Making split bronze bearings [ silver soldering ]

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David Kenyon 221/03/2019 20:52:16
181 forum posts
143 photos

I need to saw a piece of phosphor bronze round bar in half and then solder it back together before machining to size for the split bearings.

My question is, do I put flux on the mating surfaces before clamping together or leave them clean , clamp together and then just run flux along the join.

When the piece is soldered I will need to turn the diameter down so I presume the solder will need to penetrate the join so it stays in one piece.

roy entwistle21/03/2019 21:21:08
939 forum posts

I wouldn't silver solder. Ordinary soft solder should be OK

Roy

Brian H21/03/2019 22:17:35
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1047 forum posts
83 photos

I agree with Roy, soft solder is best.

Brian

Hopper21/03/2019 22:58:19
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3388 forum posts
65 photos

One way is "tin" the two halves with a thin layer of soft solder than clamp the two halves together and heat until solder melts again.

Paul Lousick22/03/2019 04:51:01
1002 forum posts
467 photos

Soft solder is good enough. Thats how I did the split bushes on my engine. Apply flux to all mating surfaces and heat until hot enough to solder. Touch joins with solder and it flowed to all surfaces.

See my post on MEW at click here

Paul

Speedy Builder522/03/2019 06:42:27
1689 forum posts
114 photos

If the mating surfaces (After boring) are big enough, superglue can sometimes be sufficient.

JasonB22/03/2019 07:32:57
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Moderator
15005 forum posts
1522 photos

I quite often use soft solder paste, apply a little to one face, rub the two together so they are both coated and then heat.

For larger bearings I'll tin (flux heat apply solder and wipe off excess) then put the two tinned surfaces together with some flux and heat again. See this post

vintage engineer22/03/2019 09:13:15
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84 forum posts

The best way is to use solder paste. Machine both halves flat, coat with solder paste, heat up till it melts then wipe off with a piece of leather. This should leave you with a couple of microns of solder on the bearings Now clamp the two halves together and heat up to fuse the two halves together. If you use too much solder you will have to shim the bearing after cleaning up.

Ian S C22/03/2019 10:31:08
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7261 forum posts
227 photos

The way I make con rods with bushed and split big end, bore the hole to take the bronze for the bush, fit the piece of bronze, either a light press fit or Loctite, drill and tap for the big end bolts, now split the bearing and fit the bolts, bore the bearing to size. Usually I drill the bronze before fitting if its been in the lathe to take the OD down to size. Not too practical for main bearings, but one thing is, the bearing can't rotate in the housing, it's oval on the OD.

Ian S C

JA22/03/2019 12:31:32
721 forum posts
38 photos

My attempts at using solder and glues failed so I made a proper fixture to hold the halves. This allowed the ends to be faced in addition to the boring of the bearing.

A little bit of thought and accurate machining is required.

bearing fixture 2.jpg

bearing fixture 1.jpgJA

Andrew Johnston22/03/2019 12:55:12
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4492 forum posts
520 photos
Posted by JA on 22/03/2019 12:31:32:

My attempts at using solder and glues failed so I made a proper fixture to hold the halves.

Same for me; the solder joint either gave way when machining, or the bearings required a serious amount of heat to melt the solder - not easy. Depending upon the bearing I made a simple jig:

Crankshaft Bearings

Or made a jig plus the actual bearing housing:

boring crankshaft bearings.jpg

Andrew

David Kenyon 222/03/2019 14:05:54
181 forum posts
143 photos

Well thanks for the replies, certainly given me something to think about.

I was worried that the solder on the mating surfaces would compromise the final bearing size

but I see this is not the case.

I will get some solder paste and give that ago first , will let you know how it goes.

Brian Oldford22/03/2019 16:55:09
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476 forum posts
4 photos

With any soldering operation cleanliness is next to godliness. Make sure you use sufficient flux to prevent oxidisation of the solder.

roy entwistle23/03/2019 08:33:58
939 forum posts

David After you've bored the hole and turned the outside don't forget to mark the halves before you split them so that the correct halves go back together and the right way round

Roy

Rik Shaw23/03/2019 10:08:19
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1235 forum posts
336 photos

For historical accuracy split brasses are a nice touch but I will make mine differently. I shortly need to make 4x PB journals for the crankshaft on my current Double Tangye in progress. They will be made from solid bar, no splits, no soldering! The feed spigot on the oil cups will stop them rotating.

The only splits found on this model are between the CI standards and journal caps. The completed journals will be slid onto the crankshaft then the standard caps will be fitted holding the crankshaft in position.

Rik

JasonB23/03/2019 10:19:27
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Moderator
15005 forum posts
1522 photos

A lot depends on the layout of the particular engine and crankshaft/pin. With disc cranks and separate pin on the Tangye solid bearings are possible but they won't work if you need one in the middle of a double throw crank or your big end bearing fits between two webs of a solid crank.

What I often do where it is possible to slide the bearings on is to make them as split ones but don't unsolder them, makes it easy when taking the engine apart and reassembling and less chance of mixing things up. The main advantage is if you do get wear or find your fits are a bit slack it you can simply melt them apart at a later date and treat as split ones.

Rik Shaw23/03/2019 11:20:12
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1235 forum posts
336 photos

Quite understand what you are saying Jason and I understand that not all crankshafts are equal. However, and as you point out, the DT design does allow for solid journals. My only other engine also had journals from solid. Maybe I'll try another model in the future with the split variety but until then it will remain a "pleasure" to come.

Rik

clovercrank.jpg

CuP Alloys 124/03/2019 08:41:48
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176 forum posts

Hi David.

Paste is an expensive solution to the problem although the technique is sound.

Use a paint. It is cheaper, easier to apply and you will use less of it.

Readily available from any good supplier.

Regards

Keith

BW24/03/2019 12:24:23
205 forum posts
36 photos

Why do people want to split a bearing and then solder it back together again ? WHat is the improvement that is gained by doing this ?

Bill

JasonB24/03/2019 13:14:43
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Moderator
15005 forum posts
1522 photos

You don't actually make it and solder back together. You solder two pieces of bronze together and then ream or bore the hole before melting them apart. two main reasons:

1. A split bearing can be tightened to take up wear.

2. On a typical one piece crankshaft you would never be able to fit the big end bearings if the bearing was solid with a hole in it. No other way to get something like this

To fit around the middle of this

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