Saturday, December 22, 2018

Failed Composite Molding Plug

 Applied chavant y2 klay:

Here's where I went wrong. If I understand correctly, I should have made some sheet metal tools to make a better surface on the clay, then applied layer(s) of fiberglass. After that I can use thickened epoxy filler and surface primer both followed by sanding to create a nice surface.

I didn't know any of this. I slopped on some epoxy filler and revisited my life decisions.

Better luck on second attempt!

Banjo Kit

Assembled a banjo kit for myself to play. For the cost of the kit and how easily it went together, I am really happy with it! I thought of building it from scratch, but I've got too much other work right now.

I really like how it sounds with the nylon strings, a bit like a lute. Better for playing in apartment and more suited to the kind of music I like.

The kit is pretty well made (especially for $300) but there was one flaw I found annoying. The neck is secured in its mortise by a single 10-24 screw, and with the placement of the screw hole, the entire force of the strings was placed as shear force on the screw. I moved the hole a few mm and turned a brass washer to fit the enlarged counterbore:

Also added a 5th string capo so I can change keys easily-

They included brass nails to use as string pegs. I wanted something fancier, so I turned some grooves in stainless taper pins and used them as the pegs:

Thursday, October 25, 2018

Pantograph Mill Tracer Pins

After I told a local knifemaker about the lathe I put together, he asked me to make him some tracer pins for his old pantograph mill. He asked how accurate my lathe was, I guessed I could do +/-.0002" diameter on a good day. If I was just a little wiser I'd have said something like .001". The X axis is graduated in .001" (radius), so .0002" diameter is a tenth of that. Nevertheless, I more or less managed to stay true to my word.

The difficulty was compounded by the required concentricity between shank and working end. I thought I might be able to turn the working end, advance the stock in the collet without rotating it, and then turn the shank. No matter how careful I was, this made at least .001" TIR which didn't feel right. So I just stuck the bar out the full length of the finished part, like a tree in a windstorm. T.T

I contemplated making a follow rest, or shimming the headstock to reduce taper. It would have been clever to get 3/8" bar stock to increase rigidity while turning the tip, that's probably how they would do it in a production setting. All of those options would have taken a few extra days- and made my time worth even less. So I just sharpened the heck out of the tool (m42 hss), and kept sharpening it after just about every pin-

The working ends don't have measurable taper, but the shanks have about .0004" over their length. The old router-style collet that holds it shouldn't complain, and the taper is in the favorable direction. Material is 30 RC 1144 steel.

I press-fit magnets into the back so the knifemaker can stick them onto that beautiful old chunk of iron.

Say, I've never posted a picture of my finished lathe because it's always dirty and with an ugly backdrop. So here's a candid shot-

Yes, I do manage to squeeze my ass in there.

Saturday, October 20, 2018

Mountain Bike

Gave my commuter bike an overhaul to make mountain biking a little friendlier. It had fenders and road 28x700c tires before, now it has 40's and knobs and no fenders to tangle with.

To put on the bigger tires, I had to get a new front derailleur and find a way to mount the lights without the fenders. I made little aluminum brackets for the front and rear:

I also got a smaller handlebar bag. I don't know what sort of G-forces a CX bike front end endures on galbraith mountain, but it was enough to really give the bigger handlebar bag a beating. With the smaller one I still don't have to wear a backpack, but I can still carry tube, tools, garlic press, and a few servings of hash browns.

This version of the bike has been named Monty by my sister.

Hurried to go on a ride with her yesterday, and one bar plug short of a full set, I whittled one out of fir in 12.2 seconds.

The bike is still far from a mountain bike, but after riding the 28mm road tires for a year it feels like I can do anything on it :)

Monday, October 15, 2018


Courtney asked for a shelf for her dearest plants, as they were all crammed onto a tiny wire nightstand.

I made some of the pieces in a proper shop, and some in the apartment shop with hand tools. Cutting dadoes is a very different experience on the table saw vs. hand saw/chisel/router plane; half of them were cut by each method. As the front uprights angled inwards towards the top, cutting them by hand was actually desirable in ways. For the back ones, I'd take the table saw any day, but would have instead made them dovetails if I did it by hand.

The shelves are aluminum offcuts from a local metal supplier. I had to trim three of them- you can see the bottom two aren't quite deep enough, but I saved a lot of money by not making them cut up a large sheet.

This is how I carried the wooden pieces back from the big shop- it was rainy and 10pm but overall a peaceful and quiet ride

Here was carrying the aluminum back with my groceries- I'm starting to grow attached to this bike. To me they start as inanimate machines, and gradually become more like animals or friends.

Thursday, October 11, 2018

Weighted Blanket

A therapist/healer hired me to make some weighted blankets. Many people like a soft, heavy weight atop them; they find it calming.

The therapist wanted me to make them because I was local, and I could fill them with tiny glass beads instead of the usual polyethylene plastic pellets. So far I have bought all the fabric in Bellingham. The glass beads are very nice and smooth to the touch. It feels a bit like sand, but since each grain is a smooth sphere they flow more easily.

The first blanket I made had a zippered cover; this one has the same number of layers but is sewn as a single piece. It weighs about 10 lb (4.5 kg) and is 54 x 40 in (140 x 100 cm). If you are interested in buying one, one this size costs about $150. A small one would be closer to $80.

Saturday, October 6, 2018

Sprinkler Stand II

The last sprinkler stand I made is still sprinkling, but dad needed a second one. The turned hubs of the first one have cracked from getting wet and drying out so many times.

I made the new one to be more waterproof-

Made of aluminum, delrin, and stainless steel.

I could have made the delrin inserts a press-fit, but I wanted them to be easily replaceable. They are each secured with a sheet-metal screw.


Thursday, September 13, 2018

5C Lathe Part II: Power Supply and ESC

450 w 12 v server power supply connected to 25 amp ESC. With this arrangement, I get a very compact 1/2 HP variable speed motor for $100 or so. The parts are all pretty high quality too-

I made the aluminum enclosure from .062" aluminum found in the remnants bin at local metal supplier. The top handle and aluminum for knob came from a dumpster, and the pushbutton switch on the top was recycled from my wooden computer case build.

Servo tester with 'mode' switch and potentiometer breakout.