crosshead question

[noggin]

Need some advice please folks,Im building a 5inch gauge manor and ive got the crosshead castings from polly models for their grange,It is a nice detailed casting,my slidebars are b m s do you think these two materials run together as ive always used gunmetal or bronze before,or do you think i shoud case harden the slide bars or chop the crossheds and silver solder bronze to them or leave as is, any advise i would be very gratefull. thanks garry (noggin)

[noggin]

Forgot to say the crossheads are made of stainless steel.

[houstonceng]

That' a wierd choice of materail for a casting !

Personally, I'd line the crosshead with bronze slippers which an be replaced when worn. Did this on a BMS crosshead running on BMS slide-bars. Fellow club membver did the same on a GWR 25XX and he runs it every public running (every other Sunday from April to October) 3hrs each time. No probs.

[GWRdriver]

Aug 8, 2011 16:35:29 GMT houstonceng said:

That's a wierd choice of materail for a casting !

I'm not surprised . . . I can't say what the state of the industry is in the UK but in the US there are now as many investment casters in stainless as in any other metal which results in competitive prices and reliable production. It's been decades since I could say the same thing about cast iron in my area.

I would certainly install bronze or cast iron slippers, otherwise I would expect galling.

[44767]

GWRdriver it correct about the galling. You must line it with a bearing metal such as iron or bronze. The clue as to why it is stainless steel is in the statement that it is a"nice detailed casting". The reason it has been cast in stainless steel is that it flows much better than steel and therefore will give very detailed castings. Quite a few lost wax castings are cast in stainless for this very reason. Cast iron in a casting that small would probably be chilled and become very hard.

Mike

[noggin]

Thanks for that guys,I had a feeling that the crosshead needed a bronze slipper, I was secretly hoping that i could use it as is,but i think i will chop it and just use the stainless middle part,thanks once again.Garry

[Jim Woods]

Hello there,

why not just machine it a little bigger in the slideways, say .020 to .040 thou and line it with white metal as they do in full size. I've done this and it works a treat. my engines now 11 years old and only now showing signs of wear, still get another 3 years running yet before I need to re-metal

regards

Jim

[noggin]

Cheers bud, im gonna look at it tonight and see what way to go, thanks garry

[pault]

Hi All
My first thought was the same as Jim’s to use white metal, my only reservation would be how well the white metal would take to the stainless. I guess with the right flux it should be fine.
Regards
Paul

[Jim Woods]

what i did was this, machine it "roughly" so there is plenty of surface area, so machining marks are good or a rub with a father-less file . Tin it where you want it to stick with solder. I then filled the cavity left with white metal, make sure the part is hot. let it cool down slow. machine it up with about .004 clearance all round and put in your oil holes. being a soft metal it will run quite quiet and soon find it beds in nicely. hope this was of interest to you

Jim

[PeteT]

These castings were designed for Penrhos Grange by Neville Evans and he advocated a minimum clean up of the casting (to make sure it was straight and square) and use of a loose PB shim strip, tabbed at the ends to stop it moving.

PeteT

[noggin]

Hi all, Thanks for the replys I know of the rbonze strip idea, buti still did not like the idea of the stainless rubbing the sides of the slidebars,so what ive done so far is mill the crosshead slots as thin as i could then i silver soldered a bronze strip into this then i will mill this out to size later, this will give it about .040" all round i will be happy with that but it is a lot of work(nice casting thou) as for the whitemetal ive no experience with this so i shyed away from it but thankyou all the same. thanks again garry.