Rebuilt Crosti 9f

Osgood

Western Thunderer
Mike,

For moving parts like the anchor link, which is forked, I use small screws inserted from the back. I just run a tapping size drill through both parts and tap a thread all the way through. For valve gear it is 12BA that I use, tapping size 1.1 mm.
The screw put in from the rear locks both sides of the fork but still lets the trapped rod move. ......
This sounds like a really neat solution. :thumbs:
Its key advantage is that it removes all play.
With any linkage it is the inherent play (clearance) that has a major influence on rate of wear - remove that clearance and wear is minimised.
Whilst loading here is minimal wear will still occur due to play.

In this instance not only is play minimised but bearing surface is significantly increased by the greater surface area afforded by the thread profile.
 

spikey faz

Western Thunderer
Mike,

For moving parts like the anchor link, which is forked, I use small screws inserted from the back. I just run a tapping size drill through both parts and tap a thread all the way through. For valve gear it is 12BA that I use, tapping size 1.1 mm.
The screw put in from the rear locks both sides of the fork but still lets the trapped rod move. If needed the screw head can be turned down and thickness reduced after final fitting, or use countersunk heads if there is enough meat to take them. The angular movement is very small, loading light and wear very unlikely.
I use the same method for little end pins in the crossheads. Sometimes screwed in from the outside as there are usually clearance issues behind. The retaining nut is soldered to a bit of screwed rod. This photo of my WD shows how it looks.

Ian.
View attachment 187758
Hi Ian

I'm assuming there needs to be a bit of thickness to the metal for the thread to be effective. I'm relying on a single thickness etching which I suspect is too thin to take a proper thread.

I must say though that you've made a super job of the valve-gear on your WD. :cool:

Mike
 

Ian@StEnochs

Western Thunderer
Mike,

Remember you will be passing the thread through both sides of the link so effectively two thicknesses of etch. 12BA has a pitch of 0.011” so if your etch is 0.018 that is more than enough.

I tap through both pieces at the same time with a taper tap but don’t go right through the forked part leaving the thread tight. The moving bit is run right through while out of the forks.

As Tony says running the rod on a thread effectively cuts out the ‘flop’ you sometimes get in the gear with pins. The floppiness has in the past been a source of intermittent binds as rods clash.

Ian
 

spikey faz

Western Thunderer
Mike,

Remember you will be passing the thread through both sides of the link so effectively two thicknesses of etch. 12BA has a pitch of 0.011” so if your etch is 0.018 that is more than enough.

I tap through both pieces at the same time with a taper tap but don’t go right through the forked part leaving the thread tight. The moving bit is run right through while out of the forks.

As Tony says running the rod on a thread effectively cuts out the ‘flop’ you sometimes get in the gear with pins. The floppiness has in the past been a source of intermittent binds as rods clash.

Ian
I've just tried what you suggested, but unfortunately the holes are just a little too big to get a deep enough thread cut. Shame, as it looked like it was going to work at first.

Mike
 

Ian@StEnochs

Western Thunderer
I've just tried what you suggested, but unfortunately the holes are just a little too big to get a deep enough thread cut. Shame, as it looked like it was going to work at first.

Mike
Mike,

If the holes are too big you could possibly bush them with a bit of brass or nickel silver tube. Solder in and cut out the centre then re-drill and tap.

Ian
 

spikey faz

Western Thunderer
I decided to bite the bullet and do as Ian suggested.
20230530_194014.jpg
Bit of 1.4mm od brass tube.
Bushed out union link and combination lever.

Tapped.
20230530_201021.jpg
Trial run with a bolt.
20230530_201330.jpg
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Seems to work! :)

Clearly I'll need to reduce the size of the bolt head. I've got some countersunk bolts somewhere which may work. Failing that I'm tempted to Loctite the bolt to both sides of the union link and then snip the bolt head off altogether. So long as the Loctite does its job then no reason why that shouldn't work.

Thanks Ian for your suggestion. :cool:

Mike
 

spikey faz

Western Thunderer
I couldn't locate my countersunk bolts, so I lopped off the head of the cheese head bolt and applied some Loctite to the outer parts of the threads. It all seems to work with nothing coming undone. I intentionally left the bolt a bit longer than necessary in case I needed something to grip onto should I need to undo it all. I'll shorten it later.
20230531_144243.jpg
20230531_144316.jpg
I'm assuming the same method can be applied to the other end where the union link attaches to the crosshead? Temporary pin in place in pics above.

Mike
 

spikey faz

Western Thunderer
Today I bushed out the other end of the union link with the same 1.4mm tube. Tapped as before and temporary bolt in place.

20230606_142513.jpg
I can confirm that this produces an assembly that's pretty much free of any slack movement. I think once it's run in a bit with some oil it'll be spot on. Just hope the other side goes as well.

Mike
 
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spikey faz

Western Thunderer
The final pieces of the puzzle with the lifting link in place (ish). I've also popped the lubricator rods roughly in place to see if everything lines up. All appears to be OK. The lubricator rods are from Ragstone.
20230607_202929.jpg
20230607_203209.jpg
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20230607_203523.jpg
At some point I'll need to add the pipes to the actual lubricator. There are many! So possibly some sort of compromise may be necessary to save my sanity!!

Mike
 
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