Valve rod coupling. Burrell SCC

[alexcookParticipant @alexcook]

Hi, first post here!

Would like to get some thoughts on the machining process for the 4” burrell valve rod coupling. How have people done this?

[Julie AnnParticipant @julieann]

Hydraulic copy unit to get the basic shape, CNC machined pattern to the lower right:

Two engines are being built so one coupling at each end of the stock:

Manual machining to add flats and holes and hydraulic copy unit again to add the rounded end after the couplings were seperated from stock. In situ with the rest of the valve gear and slide valves:

Hope that helps.

Julie

[JasonBModerator @jasonb]

As i don’t have a copy tool I have done similar with form tools for the balls if not too large or a ball turning attachment.

I would start with bar just larger than the diameter of the largest ball so you can hold the work without squashing your balls. Hold it in the lathe to do the ball on one end and the central one. Then saw it off from the parent bar, face to length and do the other ball.

Over to the mill to machine the flats on one side and also do the holes. Flip it over to do the other flats.

Back to the lathe holding the central ball in a collet or split bush and supporting the end with a female revolving ctr I would use the topslide to turn the taper. Flip it end for end and do the other taper.

[Roderick JenkinsParticipant @roderickjenkins93242]

Another method is to use Manual Numerical Control – draw out the plan shape and record coordinate steps in X and Y (technically X and Z but you know what I mean).  Then smooth off the steps with a file or, if your feeling bold, a hand graver.

Rod

[Julie AnnParticipant @julieann]

It is somewhat easier to machine the flats and holes while the coupler is attached to stock:

Then the unfinished end can be machined using a home made split collet:

The finished items:

I can’t remember why the one on the right was scrap, hence the ‘S’.

Julie

[JasonBModerator @jasonb]

My ball turner needs rather more stick out from the chuck/collet if you are not going to crash it so that is why I went with the balls first. Similar with a form tool, you have a better grip of the cylindrical stock which will reduce chatter and and it moving due side force from feeding in a wide tool.

If the tapers are cut first then yes leaving on the bar for milling is the better option. But as I said having the bar a larger diameter means it is easy to hold in a vice to do the milling work prior to turning the tapers

[Chris GunnParticipant @chrisgunn36534]

I think I might have done it the other way round, start with rectanglar bar the right thickness, drill the holes, very easy to hold, and then do the turning.

Chris Gunn

[BazyleParticipant @bazyle]

If more ideas needed search for ‘making ball handles’ or read the Quorn articles/book which is notorious for its balls.

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