Hi Guys,
Last night all the red bits had another coat.
This morning everything was dry so went back together with new bolts.
Todays job is to make the slides and slide blocks. The slide blocks are moved up and down the slider. They are moved by the top of the vibrating lever. Because of the movement of the slide and the turning of the return crank the vibrating lever moves the slide valve on the main cylinders to move the pistons.
The design on the plans uses mild steel for the slide and the pin on the slide block. The slide block is phosphor bronze. It is my understanding that this is the worst point on the loco for wear so I have opted for cast iron slides with stainless pins in phosphor bronze blocks.
The first job is to cut a slice of cast iron 2" by 2" by 1" thick. This was then cut in half to give two bits 2" by 1" by 1". The block is actually 2 1/8" so gives spare for cleaning and sizing.
The blocks went into the four jaw chuck on the lathe to be squared and cleaned up. I still left them oversized for later sizing.
Next they are moved to the mill to have a slot milled centrally on one of the long faces. It needs to be 1/2" wide and 3/8" deep
One went a touch too deep but it is not a problem. It will be corrected next.
They went back into the four jaw and were turned to their final sizes. First was the front face with the slot in it. Skimming the front allowed the deeper slot to be corrected. They were then turned and the sides were turned to make the sides 5.5mm from the edge of the slots.
The back and ends of both were then turned to make them match each other. 2" long and 7/8" thick.
A bar of phosphor bronze 5/8" thick had a piece 7/16"" thick sliced off in the band saw.
This slice had two pieces cut off just over 1/2" long. Both were then machined on the mill to a final size of 5/8" by 1/2" by 3/8" to fit the slots on the slides. They were machined very carefully to be a good fit that can slide easily but with no play.
The top face had a millimetre remover in the mill leaving a ridge at the front edge. This will act as a small reservoir for oiling the slides.
The four jaw was used to drill the slide blocks centrally with a 1/4" (6.3mm) drill and slightly counter sunk on the back with an 8mm milling bit. The nut in the picture is to save the ridge on the top being damaged by the jaw.
Next I need two pins to fit these blocks. The end of some stainless rod is turned to be a tight fit in the countersink. It is then turned down to 6.4mm leaving enough distance for the countersink. I left enough of this portion to fit through the block and have a further 5mm to clear the covers. The next bit was further turned down to 5mm diameter. Allowing enough shoulder for the 5mm vibrating lever I tapped the end to M5.
The pin was cut off and the sawcut cleaned and sized to fit into the countersink in the slide. Below should explain it all.
The pins are then ready to be pressed into the slide blocks from the rear countersunk face.
Next I cut some 2mm mild steel plate slightly over size to cover the slotted faces. They went into the mill and had a slot milled 8mm wide and 1 3/4" long. It was cut with a smaller milling cutter and then opened out to final size in several passes as an 8mm cutter will not give an 8mm slot.
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That was all I had time for today so tomorrow I will drill the lids and fit them on with the slide blocks in place. The completed slides can then be fitted to the weigh shaft and the forward reverse lever made to hold them in position.
Cheers
Julian