Babbit = Pewter ?

I've got a few pewter bits around... so if I need to I can make my own bearing shells.... Right?

Never seen this mentioned before...

Proportions are not really right. for quality bearing so depends how critical it is.

Wondering because pewter can cost buttons on ebay

Some old pewter has lead which may not be what you want and from what I've seen pewter doesn't have as much Cu or Antimony (Sb) as true babbitt...

**LINK**

**LINK**

A good source of pure tin is lead free solder and so you could try your own Sn/Cu mix by melting some tin and chucking in enough copper filings? Antimony is a bit more tricky.

HTH

Jon

babbitt

Antimony

In that case, mix your own alloy (by weight I assume)

Simples

Jon

Not quite that simple - you need to make sure that the various metals all dissolve together, with no 'filings' or other bits left undissolved. This can take time at temperature, and meanwhile oxidation is producing scum or dross, which removes some of the metal (but not in proportion) from the mix.

It can be done, but if it were simple there would be no point in the various off-the-shelf suppliers (who have all gone down the plug-hole of fate, muttering 'bloody lead indium' as they went).

Cheers, Tim

Ady,

It's worth a look through Tiranti's information on 'white metals'

**LINK**

Each of the product pages has a 'More Details'' link, which includes alloy compositions etc.

I'm sure the same detail is available elsewhere, but this is conveniently organised.

MichaelG.

Edited By Michael Gilligan on 25/02/2016 17:32:13

Your point's well made because of the high melting point of the copper (almost 1100 degrees C) and the difference from antimony at 630 and tin at only 230.

...but my guess is that the most deterioration will be to the tin and antimony. So, if you heat a generous amount of tin and antimony with the minimum amount of copper you may get close to a usable alloy for a one-off. All of the metals are fairly stable. But then the mixture needs to get to and stay above 1100 degrees for long enough to melt the copper and get it to mix. The 3 metals all have very similar density 6-8 g/cm^3 and so convection currents in the melt are likely to do the mixing ok with a quick stir.

I think it'd be worth a go for a one-off.

Jon

Edited By Jon Gibbs on 25/02/2016 18:17:42

This extract from "Fitting and Adjusting Bearings", one of "Marshall'sPractical Workshop Series No 3" may be of interest.

No date, but it cost 9d (a copy of Model Engineer cost 4d).

It depends on how critical your application is. With lower speeds and a low load application, coupled with maintaining a good film of lubrication, you may get away when trying to alloy the materials yourself.

The widely varying melting temperatures of each of the alloys in producing the final alloy can very easily lead to a none homogeneous structure of the resultant alloy which will give premature failure.

Probably the two most used tin base alloys used ( in the UK ) are BS3332/A ( preferred for centrifugal casting ) and BS3332/C ( preferred for static casting. Both suitable for high speed and high loading applications. Then BS3332/F for lead based applications.

Cadmium and to some extent silver was used in quite a few alloys to "stiffen" up bearings on high loads but Cadmium has thankfully been  phased out because of its high toxicity.

Edited By MalcB on 25/02/2016 21:26:47

Some interesting information here...

**LINK**

[I'm not sure I'd be drinking the tea after it'd had molten Cadmium alloy teaspoon in it]

...but, it might be better to create two intermediate alloys first - one a 50:50 mix of tin and copper by adding tin to molten copper and a second one a 50:50 mix of tin and antimony by adding tin to molten antimony.

Then, add these in the proportion 1:1 to 3 more parts of molten tin.

Jon

Edited By Jon Gibbs on 25/02/2016 22:28:21

Your point's well made because of the high melting point of the copper (almost 1100 degrees C) and the difference from antimony at 630 and tin at only 230.

I thought it was too good to be true, thanks for the ingots link btw

Thinking about how you can 'dissolve' steel and graphite in cast iron (to make 'synthetc' cast iron) I wonder if you can just stir well-molten 'pewter' with a bunch of copper wire and expect some of it to dissolve?

Neil

Yes, Neil, some copper will dissolve. But you won't know how much - and it won't be any good weighing the copper before and after because the 'pewter' will stick to it.

Cheers, Tim

Edited By Tim Stevens on 26/02/2016 16:40:45

What about a copper compound where the other bit burns off?

Put in some Copper sulphate?

I'm no chemist, lol, just thinking aloud

You could, I suppose, try copper oxide in powder form, and maintain a reducing atmosphere, but I am not sure how hot that would need to be to complete the reaction. But not copper sulphate, Ady1, as the 'other bit' would produce sulphuric acid fumes (or sulphur dioxide and trioxide, just as bad).

Cheers, Tim

So do it at the bottom of the garden... pour in and run away!

As you said, Ady1, you are not a chemist. I was thinking mainly of the effect of concentrated acid fumes on the other metals in the pot, and any other tools which happened to be within fuming distance.

Tim