Friday, October 4, 2013

Wood Turning: The Belaying Pin

As some of you know, I work in my college's theatre department as a carpenter. Previously, this has led me to do interesting and sometimes crazy things. After all, nothing says 'I am really glad to be small chested' like needing to crawl through the 6" gap between the bottom of a slanted stage and the floor so I can screw the platform to the stage.

This semester, one of my classes involves wood turning, which is the process of spearing a block of wood on a machine called a lathe and turning it really, really quickly (to the tune of 2000 revolutions per minute) while holding up a knife and chipping away at the wood with it. Done correctly, you end up with candlesticks, chess pieces, or a belaying pin.*

I had already practiced some beginners' techniques like cutting coves and shoulders on a piece of spruce, which is a softwood. Softwood is bad for wood turning because the grain is large, meaning that it is really easy to chip off chucks of wood that you never intended to cut. It is difficult to work softwood without mistakes, which is why we, the students, were given hardwood for our belaying pin project. Cutting a belaying pin is truly a beginner's wood turning project because it is really easy, especially with a good hardwood.

That's what I was working on last week. Here's the design with the permission of my instructor:



I started with a chuck of maple, a hardwood. While hardwood is good for wood turning, it is difficult to cut on a miter saw or table saw, both of which I had to use to get a piece 2" by 2" by 1'6". There may have been a lot of smoke but the fire alarm did NOT go off, which was the important part. Yes, those are scorch marks. Fun fact, when your instructors/bosses tell you to go slowly, they do not mean to inch along. You need to go fast enough so the friction does not start burning your wood.

Beginning Wood-Turning Project

Easy Wood-Turning Project

If you try turning the block above, you might break your arm. For my class, we need to cut off those corners to form an octagon. Since the base ended up as 2 1/4" by 2 1/4", I measured 1/4 of a side to be 9/16" and set the table saw to 1 11/16" ( 2 1/4" - 9/16") and cranked the bevel to 45 degrees so that the blade cut on a diagonal. I proceeded to cut the block on all four sides.

Wood-Turning - Roughing a cylinder

Maple Hardwood for Wood-Turning

Yes, I know that the piece is not actually symmetrical. The wood kept popping up on the saw.

Anyway, I centered the piece on the lathe and started 'roughing' the cylinder with a gouge, which is a half cylindrical tool meant to remove a lot of excess wood. It produces a lot of big wood chips.**

Wood-Turning - Roughing a Cylinder

After the cylinder was roughed, I smoothed it with a tool called a skew, which is my main tool for detail work.

Wood-Turning - Smoothing a Cylinder

When the cylinder was (roughly) 1-1/2" in diameter (measured with a set of calipers), I measured out the dimensions and drew them with a pencil while the lathe ran at 300 RPM. With penciled guidelines, I started from the right and cut the handle of the pin. That cove (dip) was done with a gouge as well, but with a curving motion instead of a straight cut.

Word Turning - Cutting a shoulder

Word-Turning - Cutting a cove

I cut the rest of the pin (to the left of the cove) with a spear point tool for the shoulder (the place where the pin goes from 1 1/2" to 1" in diameter) and the skew for the rest. I left the left end, the part at the headstock, at 1 1/2" for the time being. At this point, the left half of the pin is almost but not quite 1" in diameter, so I needed to keep shaving wood away.

Wood-turning - Belaying pin

The disks at both ends are my precautions against turning the ends, something that's pretty diffuclt on softwood. I cut the block to 1'-6" instead of 1'-5" (the actual size of the pin)  so that I didn't need to cut all the way to the end. This is not as useful on hardwood as I thought. Later I cut off the disks with a bandsaw.

Wood-turning - Easy project

This is the bottom edge - the pin narrows from 1" to 3/4" in diameter over 1". I did this with the skew.

Wood turning - avoid the edges

After the pin was cut, I kept the lathe running and sanded the piece by holding up a piece of sandpaper like a washrag. When it was sanded smooth, I held up a piece of parafin wax to finish it and then buffed the piece with a scrap of canvas, all with the lathe still going at 2000 RPM.

Wood-turning - Sanding and Waxing

At this point, the pin was very smooth and shiny, abet with the disks still attached. I cut off the disks at the end and sanded down the edges with a belt sander - which turned the edges black. The sanders and I have a very... tumultuous relationship.

Belaying Pin - Finished

No matter. I took the pin to the pin rail and tested that it fit. After about five hours' work, it's ready to turn in.

* In my theater, we have a pin rail which has a lot of holes drilled through it. The point of a pin rail is that if you have scenery that will not move but still needs to be supported by being hung, you run a rope up to a bar near the ceiling and then down to the pin rail. If you stick a belaying pin through one of these holes and loop and tie off the rope around it, the rope and scenery will not move. If the rope needs to quickly be released, you remove the pin by pulling up on the handle and the rope is free. It's useful. 

* Strangely, wood turning does not produce that much mess. It's far easier to clean up wood chips than the sawdust produced by cutting anything on the table saw or miter saw. I know this because I clean the shop and frequently return home covered in sawdust and/or pink foam dust. 

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