The men's shed were unable to make a wooden pattern that the casting plant would except. I ended up routing out a wooden pattern using my drill press with a cross slide vice. I tried a couple of different tools, breaking one with a 1/8 shaft. Ended up using a 1/4"cone shaped burr grinder bit, after a lot of minor problems. I have routed thin aluminium in it before, but only up to 5mm. I needed to route out to a depth of 15m,and due to the side thrust encountered the chuck kept on dropping out. When this happened the bit would wander, I tried belting it in with a lump of wood and a hammer, it would cut two grooves straight then would wander as the chuck dropped. I tried smaller multiple cuts no go.
I tried the old talcum powder trick. but eventually solved it by lapping in the chuck with fine valve grinding paste. I thought every thing was fine used a new bit of wood. and managed to cut two or three grooves before it would skew off. the vice table was slowly pivoting under load. I had to put additional leverage onto the bolt that clamps the table and remove all traces of lubricant. I finally managed to route out all the grooves. Under the instructions I received from the casting plant I trimmed of both ends at a slight angle to aid removal of the pattern from the sand.
Last Sunday I dropped of the pattern for approval, and was told to come back on Tuesday if I wanted to see the process. I brought The Ministers camera and took a heap of pictures of the process which I have been unable to shrink with Picresize. I will post at a later date when I can shrink them. The whole process didn't take long, about 45min. They use a different mix of aluminium for different castings, alloy heads pistons and other things depending on requirements. After they broke it out of the sand It was looking good, it will require a bit of a clean up but very true to the original less than 1mm difference. I will start on the clean up and drilling the galleries this week.
Really good guys at the plant I had a good look around this time. There are three sections woodwork, metalwork and the casting plant all run by retirees. While the casting was cooling I was invited into the machine shop. Heaps of equipment, I was in heaven they have two metal lathes a turret mill a small CNC router, and the guy showing me around has a 3D printer and is willing to do projects for members. He had a look at the wood pattern and said he could of saved me a lot of work and run it up in the mill and done it in two pieces and routed out the galleries. He trains guys on how to use it all. I will join in seven months time when I finally fully retire. The yearly cost is a paltry $30.00 Au annually.
Regards Martin.
