I've been casting aluminum for a while, but haven't made a whole lot of actually useful things. Recently, Chief Tard asked if I could copy a latch handle from his snow machine, but put a hex opening where his has a splined opening. This allows him to use the latch pieces from a different year to repair his machine.
The handle was cast using my new oil-bonded sand. It came out awesome. It even has the original part numbers on it! I just taped up the splined hole when I made the mold, so it was completely solid with no hole when I cast it.
Making the hex hole was the difficult part. I don't have a rotary broach, so I made a hand tool to do the job.
I made the tool from W-1 drill rod, using my CNC machine to create the hex shape. Then I used a ball end mill to "cup" the center of the tool. This puts enough of an edge on the corners that they will cut. Then I heated it red hot and quenched it in water to harden it.
I drilled a small hole all the way through the handle, then a larger 5/16" hole (the hex is 5/16" across flats) most of the way through. Then I used a hammer and tapped the tool into the hole. The above photo is just after I started and it shows how the tool only cuts the sharp corners; the chips are visible.
Here is the finished hex hole. This fits on a hex shaft and there is a screw that goes on the other side of the handle to hold it in place.
Here's a photo of the handle and the tool. The handle was cleaned up with a grinder and wire wheel, and should fit nicely on the snow machine.
