Makeshift Lathe

Now that I have a mill, naturally, one starts to think he needs a lathe to complete the set. Being cheap like I am, I can't bring myself to pay new price for a Chinese mini-lathe. Plus, it just wouldn't be right to accompany my vintage, American made mill with a new lathe made with plastic parts (unless it came cheap enough!)

I've been watching eBay for an old Craftsman or Atlas lathe to clean up like my Benchmaster. In the mean time, I decided that my horizontal mill is practically a lathe anyway, all it needs is a toolpost and chuck. I picked up a (yes, Chinese) 4", 3-jaw chuck off eBay along with a couple taper adapters. The adapters go from a #2 Morse taper to fit my mill spindle to a J3 drill chuck taper. Then the adventure began...

Leveraging some early experiments with casting aluminum onto/around steel bolts, work began. I ground some grooves into the Jacob's taper of one of the adapters, to help lock it into the aluminum. I used my CNC router to cut out a disk, about 4.25" in diameter by 1.5" thick with a tapered hole in the center to fit the taper adapter. I ran a 3/8" bolt into the drawbar hole in the adapter to protect the threads, pushed it into the foam pattern, and glued on a sprue.

To mount a homemade toolpost (milled slot through a 3/4" bolt, tapped a 1/4" hole through the head for a setscrew), I cut a "T" shaped piece of 2" foam. It was 5" wide at the base, 2" square at the top. Trying to be clever, and lacking a 3/4" tap at the time, I screwed a spare bolt into the top with the plan to let it form threads into the casting. This would prove to be a bad idea.

On the first calm day, I packed the foam parts in sand and fired up the foundry. 1/2 hour later, I poured the two castings with a mix of about 50/50 cast aluminum mower deck and old extruded aluminum. I poured the chuck adapter first, all went well. I just about poured the toolpost base without my pouring cup, but caught myself...almost. That casting seemed to go ok, but I was a little worried about it. Upon removal from the sand, I found that the chuck adapter turned out nearly perfect. The toolpost base, on the other hand, did not. When I almost poured it initially, a drop of aluminum must have dripped from the crucible, burning a "wormhole" right through the entire height of the pattern. That, of course then filled in with sand before I actually poured, so the final casting had a strange "wormhole" through it. Next, it appeared that I didn't keep up with the pour properly, and the 5" long base of the part didn't fill in completely. Then, when I tried to remove the 3/4" bolt, it wouldn't budge...at all....ever. In hindsight, I realized that it was a zinc plated bolt, and that the aluminum melted into and alloyed with the plating, permanently bonding the bolt into the casting. Oh well, I just cut the bolt off with the chop saw and moved on, which meant buying a tap.

Before and after pouring the aluminum.

The chuck adapater casting, fresh from the sand. The heat discolored the steel taper.

Physics wins again. That screw is not coming out of there! Notice the weird wormhole in the casting?

The next step was to do some machining...

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