(don’t miss the video at the bottom!)
I’m currently building a rack for lumber shorts and cutoffs under 3’ in length. I wanted to do a bit more than slap together Home Depot plywood and solids this time, though. One small ‘extra’ will be exposed pegs through the sidewalls to help support the thin ply shelves (they’re also getting #0 biscuits – I like overkill). These pegs will be flush-sawn, sanded, and finished with the rest of the rack, and most importantly, they’ll be walnut, for beauty and contrast. So I needed walnut pegs. I had a 3/4” square rod I’d ripped from a 5’ plank from a separate project, and from about a foot of the end of that, I used my bandsaw to free 32 little ~5/16” “blanks.”
Back in my little machine shop inside, I set up my Sherline 4400 CNC mini lathe to turn the little things on centers, and wrote a blurb of Python to output the g-code to do the work for me of turning each to precisely 0.25” diameter. My lathe isn’t trammed properly, so it added its own taper, which worked out for me, as it’s 0.002” under the mark on one end of each, and the same over on the other. I can drive in the narrow sides, and they’ll tighten up as they go in.
I made a nice little pile of walnut dust as I went:
The 32 little 1/4” pegs came out so perfectly, and now I have the code ready for whenever I need to turn some more in whatever crazy wood I need pegs made out of. I noticed a chunk of the silver birch out front was coming free (someone before I moved in cut it in half, and was a bit sloppy about it), so I pulled it off, sawed it up in the band saw, found it was riddled with tunnels and live, squishy bugs, but managed to get a piece large enough to turn in the lathe, and it made a really nice, usable little birch peg for me. If only I had a robot arm that could feed in blanks, and remove finished pegs, I’d have my own little peg-maker working behind me on the workbench here in my office.
My code exposes some variables to me, so I can change the step amount (how much to shave off) each pass, how long the peg is, so I don’t run past it into the tail stock, and how fast to make the movements. Each peg took about 2:30, though I could probably push it to under 2 minutes. However, between centers, such a tiny piece of wood slips a lot, because I can’t tighten it up too much, or I’ll just split the little blank apart. This means if I cut too aggressively, the peg just free-spins on the centers, jamming in place. This happened a lot until I started tightening up a lot more, then I was able to increase cut passes from 0.002” each pass (which still occasionally jammed) to about 0.02”, dropping the time from 28 minutes to under 2.5 minutes.
Here’s a “blank,” with a finished peg next to it:
I had fun editing together a little video of the process (which you can see much more sharply at YouTube here):
More pics and descriptions in the Flickr set.
-- Gary, Los Angeles, video game animator