Building up brass component

[AndyStobbs]

Whats the score? How's it done?
I wish to build up this brass fork

thanks

 

[500e]

Have turned the wear out made a shim to bring it back to size, then Silver soldered it to original, or you could fix with countersunk screws if there is enough room to allow for wear

 

[the snooper]

what is it from ?

 

[AndyStobbs]

Friction clutch from fast travel on milling machine. Ended up doing a refurb ha.

 

[AndyStobbs]

So brazing doesn't work well then?

 

[brightspark]

build it up with white metal

 

[the snooper]

So brazing doesn't work well then?

if you was going to use the same parent metal they would both melt at the same temp so your fork would end up a puddle same as your brass rod

 

[Shox Dr]

Can you not machine a new one, you could use phosfor bronce pipe. The selector could be threaded or tolerance fit,

 

[Welderpaul]

Looks like a Doubleboost job to me - cast a new one and machine it to size?!

 

[Wallace]

Are you sure it's not bronze?

 

[AndyStobbs]

Are you sure it's not bronze?

No, In a word I'm not certain.

if you was going to use the same parent metal they would both melt at the same temp so your fork would end up a puddle same as your brass rod

I said this earlier in front of my casual fitter, he , made the excellent and very astute observation that you can build up steel, with steel.

A new one is an option. I have a lump of phosphor bronze large enough to make the entire piece from. The part still works, just fancied doing a proper job.

 

[Wallace]

I would expect a wear item to be bronze dependant on the machine manufacturer, what make is it?

 

[AndyStobbs]

Brown and sharpe, its from the 1940 -1950 years.

 

[Bill Edwards]

So brazing doesn't work well then?

if you was going to use the same parent metal they would both melt at the same temp so your fork would end up a puddle same as your brass rod

No, In a word I'm not certain.

I said this earlier in front of my casual fitter, he , made the excellent and very astute observation that you can build up steel, with steel.

I've brazed brass to steel, which most seem to say can't be done. A few say it's extremely difficult.
I wouldn't expect the same level of control as with steel as it seems to wet and run differently, but I don't see why it couldn't be welded or built up as most weldable metals are.
I'd give it a go, just to find out, if I had a piece of brass available.

 

[Wallace]

I would be erring on the side of bronze given the machine age. Looks to be worn unevenly from the photo, turn it round if the other side is ok?

 

[doubleboost]

It will be bronze not brass
Could be built up with silver solder or
Bronze weld with TIG
Make a pattern & I could cast you one
Bronze weld would be my first try

 

[AndyStobbs]

Yes that's generally my modus operandi, just wire in and learn as I go, but there have been occasions when I've wished I had taken advice in advance.
Any simple test to determine brass or bronze - non destructive?

 

[AndyStobbs]

Other side not as bad but does have some wear too. The part is able to rotate around the centre line of the cylindrical mounting stub, within the confines of the groove in which the fork runs, so it is self aligning effectively.
I think bronze weld looking probable, any particular filler designation to look for?

 

[DAPPH]

Are you sure it's not bronze?

Andy I think it's going to be more like an improved Phosphor bronze alloy ( aka PBA ) mix to give some tensile strength & wear resistance than a simple bronze , or pure brass .
PBA ..... it used to be used for a lot of gear box gear selector forks years ago .

This company website has PDF lists for the uses for many spec's of PBA

leedsbronze.co.uk

I've had a quick look .. it's crossed my mind that you be able to buy the right grade and then get it cast by the likes of " Double Boost " or maybe chose a mix that covers you quest and find out how to sort it out . .

 

[AndyStobbs]

Thanks for the input chaps. The general consensus seemed to be suggesting a new part, so thats what I did.

First machined the 'other part' to make the sides square, the orignal fork had been 0.498", suggesting 0.500" between the edges of the 'hub'. It was so worn, I ended up at 0.570" by the time it was a nice surface. That is properly hard, take the edge of HSS in moments, used my smallest boring bar with carbide insert in the end


Then parted off a disc a little over size from a billet of Phosphur bronze

Machined it this way and that, until I had this



Should last another 70 years...