Making the crankcase castings for the BECO 2.0

OK! Here are the new castings! I made a set of castings with the old pattern and discovered that the inside of the casting didn't match up with the outside. So, I had to make another pattern. I didn't see the problem untill I started to machine the castings. The cylinder didn't line up with the journal on the crankshaft.(I had made four castings already). The pattern has now been re-designed and a casting has been made. Hopefully when this is machined it will be in an acceptable tolerance.

Shown here is the crankcase pattern (here is a preliminary drawing) used to make the casting. The pattern is for half of the crankcase. The same pattern will make both halves (the left and right). I didn't plan it this way, but it sure makes it easy by not having to make another pattern.

You can also see that I have added a logo to the pattern. I wanted something to mark and identify the casting in a unique way and the logo does that well.

Here is a picture of the cope mold ready to pour. Also a pic of the cores.The cores define the shape of the inside of the casting. The white seen on the mold is parting dust (I use baby powder with the Petro Bond sand, but it doesn't work to well with green sand).

Each core is made in a core mold (see below). The core mold is a 2 piece mold because of the complexity of the core. It will not slide out of the mold if it is in one piece. The core is then placed in the drag (the lower part of the main mold) and secured in place with a straight pin (from my wife's sewing kit) in each side. This keeps the core in place while pouring or if the mold gets bumped.

Here is a casting, (all I have done is cut the gates from it) I am going to wait about 2 weeks before doing any machining on the castings. I know from past experiance that a new casting is sort of gummy when you start machining on it. You can 'artifically age' it, but I don't have the oven needed for that. I have found that if you wait a while (let it age naturally) there is a significant difference.

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