Grease Caps

 My next project is to make grease caps for the wheels of the fire truck. We only have 2 and one of them looks like they pumped too much grease into it at one time and deformed it. The original is an aluminum stamping, but since I haven't been able to find any, I want to cast it.

Here are the originals.

I decided to go the Bondo route to add draft and material thickness. After I got all of the paint off and everything degreased, I slapped some bondo on the inside. I then taped off the end and chucked it in the lathe and turned it on slow.  The theory was that centrifugal force would force the bondo to the outside of the part. It kinda worked. It got a little thick on one side and the other side didn't have enough.

It took a few applications of Bondo to get enough on to machine away. I put about 3 degrees draft on both the inside and out side.

Here are the castings.  They turned out pretty good. One has a flaw in it. I'll use that one first to test out the thread cutting on the lathe. I know I'll probably screw it up since I haven't cut threads in over 20 years.

This one has the flaw.  The other one turned out good.

Next.....machining