Pistons & Crossheads

This section has lots and lots of parts that needed to be made: 17 little ones plus 14 additional small Pins used to connect all these parts ... 31 for one side and another 31 for the other side ... 62 total pieces ... well almost, another dozen or so parts used for jigs or fixtures.

All were machined from 303 Stainless Steel except for the Valve, Link Block and Bushing which are Phosphor Bronze and the Valve Nut which is Brass. Most of these parts were CNCed last February/March 2010 when I had access to the machines. Even when machining these parts using a CNC there is still lots of work that needs to done before the parts are usable ... getting it out of the flat stock, side cuts, slot cutting and finishing to dimensions. Additionally, when all the parts are assembled ... filing, filing and more filing so that parts would move together smoothly. Lots of little tweaking here and there ...

Each picture below is a thumbnail so it can be enlarged to get a better view ... back arrow to return.

There is a 52 second Video at the end of the page ... it may start before you are ready ... if so just restart. Enjoy!


	Link Block ... Soft soldered a slice of Bronze on a Brass plate, mounted that on a plate of aluminum for strength. Then CNCed the Block. Hard to see, but there is a radius on the top and bottom.		936 Bronze for the Valve.

	Machining out the bottom rectangle of the Valve using a 1/8" Carbide end mill. I did lay it out first but used the DRO for the final cutting.		Top side of the Valve using an adjustable Angle Block.

	Valve Nut ... again soft soldered the Brass, milled the height then milled the perimeter, unsoldered and sanded to final dimensions.		Union Link being milled to final thickness. Here I cut a slot in the soft aluminum and pressed in the Link. Just enough holding force to mill using small cuts.

	Side cutting the Combination Lever ... fairly easy, the slot was not as easy ... just had to be extra careful.		Radius Rod ... cutting the slot using a very small end mill. Slow and easy... gave good results.

	Trunnion Plates ... and other parts.		Milling out the Trunnion Plates... the first cuts are to get the thickness close to .125" say about .135" or so. Then cut the perimeter so that it almost drops out.

	Milling to the final thickness .125"		Put it together, drill the hole using the one side as a drill jig then ream.

	The Link Bracket ... set the adjustable angle block to get the hole vertical.		Link Bracket side being milled using the aluminum as a fixture ... note that it is bolted on the edge.

	The Trunnion pin is being turned down using a grooving insert. Taking small cuts is the key ... good control and easy to get to the final diameter ... in this case .1235" to .1240".		Part of the running gear ...
			See photo on left ...Notice that I have not finished the Eccentric Rod yet. I'll get to it on my next CNC run.
	All assembled and ready to run on AIR!

	The video below requires Windows Media Player plug in. I have been having problems with it starting. The file starts loading when the page is activated, rather than on command. If anyone knows how to do it the right way or if there is a better way of playing the video ... let me know!


	Valve Spindle Yoke ... that's a 3/8" thick 303 just right for 3 pieces ... one spare!		Link Bracket (Left) and Return Crank ... on 1/4" plate. The 3 drilled holes will be matched to the 3 that are not drill then drilled/reamed together. I do need to get better at material use. There is a lot of waste here.

	Union Link and Link Bracket with spare parts and more waste.		Expansion Link ... no spare parts here. Will have to be careful when removing these.