Biscuit Tin Steam Engine. Part3.

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Tony Bird

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Hi,

The bottle empty and cogitation over; the decision reached being that work would continue with the complete cylinder, while thoughts would continue of what to do about the off-set ports of the other cylinder.

Now the previous put off problem, of what to do about the lack of piston clearance in the cylinder needed to be addressed.

As can be seen on the drawing made of the cylinder assembly the shoulders on the cylinder covers are quite thick. (P.020).

020 BTE Cylinder drawings.jpg


So each the cylinder covers shoulders were reduced in height by about 1.5mm (small 1/16”) which added to the previous minimal piston clearance hopefully would be enough for the engine to work well. (P.021).

021 BTE Reducing cylinder shoulder.JPG


The cylinder bore had been accurately bored, so a ‘0’ring was fitted on the piston. (P.022).

022 BTE Piston.JPG


A bracket similar in design and from the same material to the bearing stand was made for the cylinder assembly. (P.23).

023 BTE Cylinder bracket.JPG


A magnet was used to hold the cylinder bracket with the cylinder attached to the engine base plate. With the piston at TDC and later a BDC marks were made on the base plate which showed that there was 4mm (large1/8”) maximum clearance between piston and cylinder covers. The 2mm (large 1/16”) clearance at both ends of the stroke should be enough. The cylinder bracket would be bolted to the base plate half way between the two marks made on the base plate. (P.024).

024 BTE Cylinder on base plate.JPG


Before the cylinder bracket could be bolted to the engine base plate a port block needed to be made. Alas there was no brass in stock thick enough for the job, so two sheets of brass were hard soldered together. To stop the two sheets of brass floating on the melted solder two rods in slightly large holes were used to stop this. One of the sheets of brass was larger than the other to give an edge to feed the solder in. (P.025).

025 BTE Port block for soldering..JPG


When soldered together the port blocks were machined to size using a lathe. (P.026).

026 BTE Port blocks soldered.JPG


The port block was drilled for the cylinder trunnion which allowed the cylinder bracket to be bolted in position on the engine base plate. (P.027).

027 BTE First cylinder fitted.JPG


It was becoming obvious that the engine bed plate needed a base to sit on and some timber off-cuts from making a garage door were used for this. The engine base being glued together. (P.028).

028  BTE Rubber feet.JPG


The base finished with rubber feet and the engine and its base plate fitted. The drilling jig for spotting the steam ports being in place. (029).

029 BTE Port drilling jig.JPG


To be continued……
 
Interesting use of 2 pieces of brass silver soldered together. As this needs to be steam-tight after machining, how did you flux the joint to ensure complete penetration? I was taught how to soft solder wipe a joint when tinning a large surface, then using 2 tinned surfaces together form a joint, but that was with plumbers lead solder, not silver solder.
I need to thicken a plate on an old copper boiler - similar to your thickened plate. But need to be sure my process fully penetrates the joint.
Ta,
K2
 
Hi,

Interesting use of 2 pieces of brass silver soldered together. As this needs to be steam-tight after machining, how did you flux the joint to ensure complete penetration? I was taught how to soft solder wipe a joint when tinning a large surface, then using 2 tinned surfaces together form a joint, but that was with plumbers lead solder, not silver solder.
I need to thicken a plate on an old copper boiler - similar to your thickened plate. But need to be sure my process fully penetrates the joint.


I don't think you can be sure there is complete penetration. To increase the chances of a good penetration,; the mating surfaces were flat and clean and were held in place with two loosely fitting pins. On the hearth the lower plate is larger than the top creating a shoulder all the way around them. The plates and pins are fluxed, the assembly on the hearth is raised so that its rear edge is high, a strip of solder the length of the plates is placed on the raised shoulder of the plates. The plates are heated until the solder flows and with luck? The solder appears along all the shoulders and around the pins. I have used this technique many times with success but I don't think I would use it to stiffen a boiler plate.

Take care Tony.
 

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