Saturday, February 27, 2010

The first pic is the pump, installed and ready to go minus the fan belt. I ordered one from Grainger and need to go pick it up Monday. I filled the system with water and there are no leaks so far. We'll see later on when it's pressurized. All the water in the pic is from my sloppy filling job with a funnel and a coffee can. I'll paint the copper fittings flat black so they "go away" visually. I also installed a petcock at the bottom of the pump to allow easy drainage of the cooling system. Eagle eyed viewers will note that the pic in the previous post shows a chrome 90 degree fitting where the petcock is. I found that when I installed the pump. I had miscalculated and the fitting sat too low. I solved that minor problem by drilling and tapping 3/4" NPT threads on the side of the bump, above the hole on the bottom and used that as the inlet. Not exactly as planned, but at least I didn't have to scrap another pump housing. The light is hanging loose right now because I needed to remove it to install the radiator. The other pic is of the Masonite mounting bracket template/pattern.

Sunday, February 21, 2010

Here is the new pump, pretty much done and ready to mount on the bike. The lower fitting goes to the radiator and the upper feeds the engine. The studs holding it together are extra long because they will also go through the mounting bracket. As you can see, I also cast and machined the pulley. It was a regular deal, no need to elaborate. I got all set up to cut out the bracket and realized I was out of acetylene. After a trip to the welding supply I will get with it. I hope to have it all done and pumping by the end of this week.

Friday, February 12, 2010

Persistance Is It's Own Reward

Yesterday I poured , yet, another housing. I am happy with the result. As you can see, it is a bit different from the original one. I added a bump out on the back for the inlet instead of the flat back. This seemed to be a good idea, but it introduced a few new problems. The first was the issue of shrink defects. I actually poured another one a few days ago and it had a moderate divot on the rear bump. It was a usable casting as is. The defect was more visual than anything else. It upset my eyes to look at it, so I decided to make another. The biggest problem was that the bump made it, nearly, impossible to chuck it in the lathe. It needs to spin on center in both the horizontal and vertical planes to properly finish it. A huge PITA. My solution to both problems was to drill the back of the pattern and use a removable dowel for a sprue. This allows extra metal in the area that is prone to shrink and, since I drilled it on center and perpendicular to the mounting face, the sprue can be used to chuck the housing in the lathe. It worked out just fine and the machining process was a snap. My big problem now is to find the proper bit to drill for the 3/4 NPT fittings. You don't just go to The Borg and pick up a 29/32" blister packed, Chinese cheepo bit off of the pegboard. I think I will try to bore it out. We'll see.
Well, as usual, I screwed up and ruined my beautiful casting. I tried to bore it out and something went awry. The hole ended up egg shaped and too large at the same time. So much for experimentation. I went straight to Ebay and ordered the proper 29/32" bit. I should have it by the middle of next week. At least I have the casting process down to a science. I'm busy tomorrow, so maybe Sunday I will give it another shot. I think I will go ahead and pour a couple of housings, while I'm waiting for my bit to arrive, so I can have a spare. I'm normally not a very patient person so maintaining my cool has been a challenge. So far there has been little cursing and no thrown tools/parts. I can last for only so long, though. I've lost track of the number of pours that I've made.
Today is Sunday. I poured another housing today and it came out very nice. Probably the best, so far. Maybe I'm getting better or luckier. I'll take it however I can get it. I faced it off, bored the cavity out and generally cleaned it up. I will resist any urges to try to drill the inlet and outlet openings until my drill bit arrives. I can ram up and pour one of these things in about 2 hours, but I'm not anxious to do it again. I still have to make the pulley and a mounting bracket. The pulley will be cast aluminum and I will probably cut the bracket out of 1/4 or 3/8 CRS.
The first pic is of the sprue being trued up so I can turn the casting around and chuck up the resulting protrusion and face the housing and bore it to size. The next pic is of the semi finished pump. I just have to drill and tap for the 4 studs that will hold it together and the inlet and outlet. The sprue will be cut off since I no longer need it.

Thursday, February 4, 2010

Introspective Thoughts and Self Flagellation

I've thought about all of the failures that I've experienced while trying to cast the pump housing. Each one was different....sand too wet, melt too cool, core shift, sprue too close to edge causing fall out, etc. I feel that I've educated myself and the next pour will be a good one. Part of the problem was that my flask was too small and I couldn't ram the sand properly or keep the sprue holes far enough from the outside of the sand. Today I built a larger flask, re tempered my sand and, generally, got ready for tomorrow. It's supposed to rain, so it will be a good day too fire up the furnace and pour some metal.