Gallery, Projects and General > How do I??
PMR Coke Bottle Engine
rleete:
I've done almost nothing. I ground the worst of the flash off the parting line on the bottom, but didn't do too much. I also sanded the sides of the frame - nothing like starting on the finish work!
Frankly, I realized I was jumping in a bit over my head, and better get some experience before messing it all up. I cut apart some of the iron castings with a hacksaw (my parts are mostly iron), but not much else.
Bernd:
Might I suggest you give the fly wheel and belt wheel a go. That's what I did to build a little confindence on doing castings. The steam chest is also easy to do. In the mean time we can discuss how to do the frame. This will keep you enthusiasm going.
Odd that yours is mostly cast iron. I think I bought mine back in the late 90's early 2000. Their 2002 catalog has them either in bronze or aluminum.
Bernd
Bernd:
Ok Bogs, I've got 6 pics here for you to study.
It's even tough trying to come up with a way to machine it if you do have it in your hand. I won't worry about getting an answer right away since we're both a ways away from maching the frame.
Bernd
bogstandard:
Bernd,
Now I can see the casting more closely, verfies that the second method is the way to go. The top boss looks rather substantial.
Normally, when build instructions come with a set of castings, they usually suggest you file by hand the first datum face, then after the second one is obtained go back and machine the first hand filed one. My first method eliminated the hand filing bit.
With a casting such as this, your pics verify that turning is the way to go as the first operation, by eyeballing the run of the casting to make it look truly vertical. It is very difficult to make sure it is vertical by doing the first op on the mill.
This casting is very similar in shape to a Stuart Turner standard casting, and I machined one many years ago by using the second method to get the base face true, by holding the standard's top boss, eyeballing to get it running true, and taking a skim across the base face. Everything turned out fine first hit, and ST castings are renowned for having no spare meat on the castings to get a second chance.
I know it can be very daunting when coming to machine expensive castings like this, but there are no hard and fast rules to doing it, it is just a matter of gritting your teeth and hope you make the right decision. Only take off as little that is needed to get your first datum, doing it that way gives you a good chance of a second hit if you don't get it quite right first time. Once you get a few more datums from the first one, you can always come back and trim it down to size.
Once you get done with the base face, then it can be mounted onto a small angle plate, or if small enough onto a 3-2-1 block. Then you can get it onto the mill for machining everthing square to each other.
Good advice on using non essential items to learn how to machine the castings, especially as rl's are cast iron. He can learn how to get under the tough outer skin, and grind up some tooling to achieve it.
John
rleete:
--- Quote from: Bernd on December 23, 2008, 08:51:00 PM ---Odd that yours is mostly cast iron. I think I bought mine back in the late 90's early 2000. Their 2002 catalog has them either in bronze or aluminum.
--- End quote ---
Not really. The parts that you often see painted are iron, the rest is still bronze. Why make them of the more expensive material if they're going to be covered up anyway? So, frame is iron, as are the main bearing caps and both head cover and valve chest cover. The rest is bronze. The part underneath the cylinder (bottom cap?) is bronze, too. Go figure.
They no longer carry it in aluminum. Apparently, there was a cheaper one and a better one (which you got), and they consolidated into one model - which I have.
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