Turning Archive 2006

Building an extension for General 160

Darrell in Oakville
>Lathe Extension for General 160.

They don't exist. I looked in the catalog and on the General website, and I asked the General rep when he was at an HFMS meeting. No such animal. I can turn about 36 inches between centres on my lathe, which is fine for chair parts, but I have a new project coming up this summer: a four-poster bed for my daughter. Now, I have seen Conover's video on turning for furniture (I think that was the one...) where the guy shows how to cut a tenon on one part and bore a mortice in the other and a bead at the junction so you can get really long turnings on a short lathe. This sounds fine until you put the drill chuck and a forstner bit in the tailstock and discover that the longest piece you can *really* turn is a LOT shorter tha 36 inches. Uh Oh.

Thus, my search for a bed extension. On Saturday afternoon, when everyone else had lit out for other places and their own fun & games, I descended into the shop and started thinking seriously about building an extension bed. I measured the ways on my lathe, drew a quick diagram, and started rummaging through the metal stock out in the garage. I had inherited some angle iron and flat stock from my FIL. Now it was time to put the stuff to use. I regressed back to Kindergarten, sitting on the floor playing with blocks. Here's what I found: some large angle iron, which would serve nicely as the top surface of the extension, some small angle iron, for the lower edge of the ways (for the tailstock to grip), and some 1/4 inch flat stock to just take up space and add mass. Back down to the shop I went, with a handful of iron bars.

The first critical dimension is how long to make the extension. Well, cutting the shortest piece of stock in half yielded two 24 inch pieces, so that was that. I took the hacksaw and started cutting. I needed two pieces of each size of stock. Here's what I ended up with:

I sandwiched the parts together, clamped them, and started drilling some 3/16 inch holes at the post drill. This stuff drills fairly easily. I use 3-in-1 oil as a cutting lube when sawing and drilling mild steel. Once the 3/16 through holes were done, I took the two upper pieces (big angle and flat bar) and drilled them out to 1/4 inch. The small angle was drilled out with a #7 bit.

The #7 is what my tap/drill chart says you start with for a 1/4-20 tap. I tapped the small angle so I would not need nuts underneath. Nuts would get in the way of the mechanism that holds the tool rest & tailstock.

The big angle needed some hefty countersinks for the 1/4-20 flat head machine screws. I chucked a countersink bit in my 12 inch brace to cut these. I stood on a step stool to get up over the brace so I cound really lean on it. Had to stop to hone the bit halfway through the job.

Then I bolted everything together. A couple scraps of 5/8 inch plywood were planed down to fit the slot between the two pieces of angle iron. Then I cut the machine screws off flush with the inside of the assembly and filed them smooth. I also filed the heads of the machine screws to ensure that nothing was sticking up to interfere with the tailstock when sliding down the bed.

Next up, some kind of bas to hold the assembled iron parts. A chunck of 2x6 was just the right width. It was also propeller shaped so I had to face joint it and square up the edges first. I locked the tool rest and tailstock onto the new bed rails to hold them in their proper location and marked out the location of the two grooves. I used my Stanley #45 combination plane to plow the grooves (notice I didn't call them dados, eh?).

I screwed the rails to the plywood strips, and then glued everything together. Lots of clamps and once again the rest base and tailstock were used to ensure that the parts were properly located. So much for Saturday. Now we wait for the glue to dry...

Sunday afternoon I started moving furniture in the shop. I had to get Kathy to help me shift the lathe (man that thing is *heavy*). I also moved the bandsaur over a wee bit. This gave me enough room to mount the extension. I drilled a couple of 1/4 inch holes to bolt a bracket onto the end of the existing lathe bed. Wow, cast iron drills so easily and smoothly. Self lubricating I guess.

I used my straight-enough-edge and an outfeed support stand to align the bed. Once everything was lined up I tightened the bolts and screws on the angle bracket. The outer end of the extension needed some support, so I took another scrap of 2X6 (the cull bin at Home Despot is a great place to buy junk like this) and a couple of pieces of angle iron and screwed everything together.

My lathe can now turn 5 feet between centres. Seems stable enough, but I have yet to try it out. The bed posts should be no problem at all with this. Now it's up the the Ultimate Arbiter of Style and Design to come up with an acceptable profile for the turnings. Those
walnut beams are getting underfoot in the shop and I want to start cutting them up...

now all I need is some green paint, eh?
Wood Hoarder, Blade Sharpener, and Occasional Tool User

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