The Fine Woodworking Winter 2013-14 tools and shop issue (#237) had a short article about turning a carver's mallet. While I don't carve, I could really use a larger mallet than my brass head ones or the large square head mallet I have. In fact, at some point in the future I'd like to also make a timber framing mallet. But for now, I'll stick to something for shop use. As a learning exercise, I am going to try to follow the plan as closely as possible.
I selected a reasonably dry piece of hophornbeam that was originally intended for firewood - a neighbour owns a rural woodlot and happily lets me select prime pieces to divert for other purposes. I had intended this piece to produce chisel handles, just as Lie-Nielsen does. It is an irregular split, but I should be able to get a 3.5" cylinder from it. This should be an ideal usage for it, locally it is more commonly referred to as ironwood, but this is a piece of Ostrya Virginiana. They don't tend to grow very large, particularly in this area right at the northern top of their natural range, so lumber is basically impossible to find. But at 1860 on the Janka scale, it is a little harder than hickory. Very few woods in North America are harder, I can think of only live oak, mesquite, and osage orange - none of which grow anywhere near here.
This is the first time turning hornbeam for me, although I have made a few handles in maple now. This will also be one of the larger turning projects I have attempted to date. The piece has just a little bit of spalting, and one area where the wood has died and darkened - perhaps an inclusion of a dead branch. It is unclear how far into the piece the area goes. I am unsure as to whether or not to use that as the handle area and cut it away. However, the other end has a couple of deep drying cracks which might even be more problematic. Since I acquired this wood, I have learned quite a bit about drying wood - in hindsight, it was a mistake to keep it indoors. Either way, I will start by taking it down to round. The piece was quite irregular initially, producing some fairly large vibrations. Sometime in the not too distant future, I need a new lathe stand.
When I cut this out of the log, I learned a little about setting up a bandsaw. The line pattern on the remaining flat side is from light burn marks - cutting this stuff is not quite the same as pine. Unfortunately, the crack in the center of the dark area widens, becoming larger as the diameter of the cylinder got smaller. Once I had a full round, I began to rough in the taper of the head, mainly with the skew chisel. I decided to use the end with the darkened flaw. Firstly, I was not quite confident that I would be able to cut it away completely as the handle. But also, the wood around it is in good shape, whereas the cracks at the other end may go deeper and already extend quite a bit further. I'd rather try to work with the readily visible flaw.
This is where the project began to go sideways. First off, a rough session with the skew. Probably not sharp enough even for the initial rough work, but I think I was just off. Some big ugly catches were the result. The net result is that I may end up having to adjust the dimensions of the head, perhaps reducing the taper, because I may not have enough material left when I smooth down the catch marks to have the originally planned diameter.
My confidence was at a fairly low point by the end of this session. I was surprised at how much more difficult a smooth and consistent taper is than a simple planing finish cut with a skew. Projects like this are frequently recommended as a good lesson, and I can see why.
The other problem that arose was the 'dead' area in the head. It was not a great surprise, given the irregularity of the crack, but a piece has become nearly loose, unsupported on three sides. As I have been cutting the taper, I have definitely been cutting away flawed material, and it is improving on the whole. But if I go any further I am almost certain to tear out a large chunk.
Time to refocus...there are two reasons to do this project. Learn, and have a usable tool in the process. Rather than getting too worried about the flawed wood I am using, I am going to soldier on. At the end of the day, it will get the job done for a time, it doesn't need to be perfect. No need to throw up my hands and start over. At the same time. if the purpose is learning, this is a good opportunity to try something new. I have used cyanoacrylate to fill small gaps, but larger ones supposedly do better with a filler mix. If it doesn't last forever, so be it.
Doc Green, the author of Fixtures and Chucks for Woodturning, has an article on his website about using coffee grounds with epoxy as a filler. Green notes that used coffee grounds have a somewhat finer texture, so I spent a day drying the morning's coffee grounds. I mixed up a small batch of epoxy in a sample cup, then mixed in the coffee. His text sort of suggests that you can put a lot in before it gets at all stiff. Somehow I didn't believe him, yet when I actually applied, it was obvious I could have put quite a bit more of the coffee grounds in. Despite making the smallest batch I though I could manage, I still had lots. Using a glue spatula, I really tried to work it into the crack.
Green uses the 5-minute variety of epoxy, sometimes the 30-minute. I had 5-minute in cumbersome syringes, or some 1 hour set/24-hour cure to choose from. I went with the slow stuff, so I would not have to panic. Not viable in a production environment, but I can move on to another project for the rest of the evening and let it cure.
0 comments :
Post a Comment