Well done Nigel. Its a great project. 
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O.B. Bolton Marine Triple Expansion Steam Engine using castings by AJ Reeves, drawings by John Bertinat
Well done Nigel. Its a great project.
Thankyou Bryan, it's good fun as I am well out of my comfort zone
Nigel, it's a real beauty and I'm learning a lot. Enjoy your new project! Magic Mike
Thanks Mike, I am trying to go into as much detail as possible without making the log 500 pages long
Bolton part six
After facing the top and bottom of the cylinder blocks to give me the correct thickness of 2" I have turned my attention to bringing them to length. This was accomplished in the mill first with the castings clamped directly to the table (with parallels underneath to get a rough cut. Milling these vertically with a long 18mm cutter gave square ends in relation to the previously machined faces. The pieces were then placed in a machine vice so I could carry out final finishing cuts with the end of the milling cutter.
Both castings have been made shorter than the drawing to allow for 1/64" gaskets at each joint. It is my intention to carry out boring of the cylinders with the cylinders and middle valve chest bolted together and with gaskets installed. This will ensure the centres of the bored cylinders are correct when all is bolted together.
I am a little disappointed by the amount of blow holes/porosity in these castings. this is mainly on the thin webs of the large block but there id one big one right in the area of the high pressure cylinder exhaust passage. Most of this will be removed when machining the passage but I may have to do a local repair with silver solder. I dare say I could try Reeves for replacements but feel I may have the same issue with these. The other blow holes are less of a concern as they can be filled with JB weld prior to painting the blocks.
After facing the top and bottom of the cylinder blocks to give me the correct thickness of 2" I have turned my attention to bringing them to length. This was accomplished in the mill first with the castings clamped directly to the table (with parallels underneath to get a rough cut. Milling these vertically with a long 18mm cutter gave square ends in relation to the previously machined faces. The pieces were then placed in a machine vice so I could carry out final finishing cuts with the end of the milling cutter.
Both castings have been made shorter than the drawing to allow for 1/64" gaskets at each joint. It is my intention to carry out boring of the cylinders with the cylinders and middle valve chest bolted together and with gaskets installed. This will ensure the centres of the bored cylinders are correct when all is bolted together.
I am a little disappointed by the amount of blow holes/porosity in these castings. this is mainly on the thin webs of the large block but there id one big one right in the area of the high pressure cylinder exhaust passage. Most of this will be removed when machining the passage but I may have to do a local repair with silver solder. I dare say I could try Reeves for replacements but feel I may have the same issue with these. The other blow holes are less of a concern as they can be filled with JB weld prior to painting the blocks.
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Hi Shota
There are quite a few examples of this engine in circulation. Unlike model boats, a few pop up in Model Engineering auctions and quality examples demand premium money
Bolton Part seven
This is where I deviate from normal practice and go my own way using what I have learned from the day job.
The valve chests are traditionally machined on the lathe using an elaborate system of faceplate with angle block attached so the valve rod passages can be drilled through top and bottom faces insuring alignment.
Given there is not a blind hole on this engine at the top of each chest as in most Stuart Engines I plan to do most of the work on the mill and use datum faces. An edge finder and the DRO will be used to drill these important holes.
The first step is to take the valve chests to thickness and square top and bottom faces to the same height as the block. The boss for the Valve rod gland is left untouched for now. This will be turned in the lathe in the 4 Jaw chuck as the last operation with the hole used for reference to centre it.
The intermediate Steam valve chest is tapered so this causes an issue as the is no accurate datum face. I have glued a piece of Aluminium to the side of this chest using JB weld. This chest will then be machined as the previous one but I will end up with a square face on the side to reference the edge finder. This aluminium piece will be machined off when the assembled block has it's taper machined.
As a side note, following John's advice, I have ordered a book on this build, some additional drawings along with Bolton's Original drawings for this engine from E and J Winter in NSW, OZ. Postage was quite reasonable and hopefully should land between 6 and 21 working days.
This is where I deviate from normal practice and go my own way using what I have learned from the day job.
The valve chests are traditionally machined on the lathe using an elaborate system of faceplate with angle block attached so the valve rod passages can be drilled through top and bottom faces insuring alignment.
Given there is not a blind hole on this engine at the top of each chest as in most Stuart Engines I plan to do most of the work on the mill and use datum faces. An edge finder and the DRO will be used to drill these important holes.
The first step is to take the valve chests to thickness and square top and bottom faces to the same height as the block. The boss for the Valve rod gland is left untouched for now. This will be turned in the lathe in the 4 Jaw chuck as the last operation with the hole used for reference to centre it.
The intermediate Steam valve chest is tapered so this causes an issue as the is no accurate datum face. I have glued a piece of Aluminium to the side of this chest using JB weld. This chest will then be machined as the previous one but I will end up with a square face on the side to reference the edge finder. This aluminium piece will be machined off when the assembled block has it's taper machined.
As a side note, following John's advice, I have ordered a book on this build, some additional drawings along with Bolton's Original drawings for this engine from E and J Winter in NSW, OZ. Postage was quite reasonable and hopefully should land between 6 and 21 working days.
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