Crosshead pins etc.

[smfr]

Hi folks!

So I'm at the part of my Muncaster Joys Valve Gear engine build where I have to think about getting all the pins and fasteners done, and have some questions about the pins used in various places.

The crossheads appear to use pins with a round head one one end, and a spring clip and washer on the other:



These pins are riding in bronze bearings, so my questions are:
1. What material should the pins be made from, and should they be hardened?
2. Where I can I get (or how can I make) an appropriate spring clip?

I know I could just put a thread on one end and and have a washer and nut bearing on a shoulder on the pin, but using a spring clip seems more prototypical.

There are also lots of other pins between the various linkage parts, some of which have no clearance for heads, so should these just be a press-fit into the relevant parts? I suppose I should have made a rotating fit hole on the inner link, and a press-fit in in the webs but I didn't think of that at the time  What's the best material for these smaller pins, and should they also be hardened? For fitting, a bit of Loctite would prevent them from moving, but I would like to ensure things are easy to disassemble.

Many thanks!

Simon

[Jo]

Those look like they are fitted together with taper pins running against washers .

Jo

[Jasonb]

Yes have to agree that a split pin is not that likely to have been used on the original engines.

As well as a taper pin against the washer that Jo sugests your pins that don't protrude can be fixed in a similar way with the taper pin in one side of the fork and positioned to just nick the pin so it won't move, I'll put up a photo later on one on my traction engine.

For the amount of use its going to get you could get away with mild steel but unhardened drill rod may be better as its closer to nominal size so should fit your reamed holes with less play.

J

[smfr]

Ooh, taper pin makes sense. I have some taper pin reamers, but I don't seem to get along with them and broke the last one that I tried using  Is there a trick to using them?

Simon

[Jasonb]

If the part you are putting the pin through is quite long you can use more than one size drill to give a stepped hole which lessens the load on the reamer.

Regarding the split pins, several of the ME suppliers here sell them down to 1/32" below that its make them yourself, I have done them down to 0.5mm. Use the round wire that is used to stitch magazines together and file/scrape it to a half round section then just bend it around a suitable item to form the head and nip the two ends tight with pliers.

[Jo]

Simon, I use watchmaker's broaches to fit my taper pins. I have never had any problem with them breaking, but they are nice Swiss made broaches so are very forgiving 

Some of the commercial model making taper pins have a much steeper angle than the ones used by watchmakers.

Jo

[Ian S C]

     I made split pins for the linkages on the Stuart Turner S9 by clamping a bit of steel wire in a fret saw frame, and filed it to half diameter, cut off bits a little over twice the length required, fold it with one leg just longer than the other, all done.  I think it was stainless wire that I used.
                                     Ian S C