Monday, December 29, 2008
Scribe Fit Trim: With Hatchet, Froe and Drawknife
Next on the house project list was finishing up around the woodstove platform. When I lay the flooring, I left a gap around the platform for two reasons. First, a small gap was needed around all edges of the flooring to allow for expansion. Second, I knew I was going to put some kind of cap or trim around the stones, so I didn't need to be precise with the flooring itself - which explains why the gap is so much larger than needed for the expansion factor.
I decided to make the trim out of the same bamboo as the floor - but narrower. Now the bamboo is hard stuff, plus it is coated with an anti-scratch layer of some sort (aluminum oxide?), and when I ripped this by hand in the past, it really wore out the saw, and me too. This time I decided to work a little smarter and use a different set of tools.
First, I picked my width. The flooring has two shallow grooves on the back, and I used one of these as a handy reference for splitting out, or riving, my trim stock.
I like to start this job with a hatchet rather than going directly to the froe. Hatchets are awesome, and underutilized tools in the shop, but they are scary and need to be respected. Always chop well below the hand that is holding the work. When you are starting at the top, you have to get tricky. Never hold the top of the piece with one hand and chop right next to it. This is a good way to lose fingers. Instead, what I do is hold the work in my left hand and carefully place the hatchet edge where I want to start the split. Then I lift the whole thing off the ground as one unit. As I drop it back to the ground my left hand pulls away, the bottom of the board hits the ground, and the hatchet, which has never separated from the board, drives a short way into the end of the board.
Here's pictures to help illustrate the first two steps - minus my left hand, which is holding the camera. Beginning position:
After the first lift and drop:
Now that the hatchet is into the board, I can repeat the lift and drop with more force, driving the head in deeper:
Time to switch to the froe:
One or two good levers on the froe handle and the waste pops off and the trim is ready for the jack plane to clean it up:
With the stock ready, I could begin the much more precise job of scribing the trim to match the uneven surface of the rocks. Keeping the trim parallel to the flooring, I moved it towards the rocks until it made contact. To keep it in place while I worked, I taped it down with blue painter's tape. Then, using the dividers - point on rocks and pencil on trim, I carefully scribed the contour of the rocks onto the top of the trim. Here's a shot of the setup - the shim is holding a loose rock in place until the trim takes over that job.
Then out to the shop for a little scrub plane and a lot of drawknife action.
Using the scrub plane (after the first piece, I switched to doing the whole job with the drawknife - just plain faster...or is it plane faster...) I created a back bevel on the trim. The pencil lines help me keep track of how close I am getting, and was a step I didn't need after switching to using the drawknife for this part.
Next, with the trim held in the bench vise (for edge work on flat stock, I tend to use the bench vise - most other times I use the shavehorse) and using the drawknife bevel down, I cut down to the scribed line. I do this on an angle, creating another bevel on the face side of the board.
Here's another shot with the piece reversed (front side is showing):
Then I switch to the back side again, and cut the final relief bevel behind the cut edge. This does not need to be very dramatic, a shallow angle works most of the time.
If I did it right, when viewed from dead on, I should see only the scribed edge. In this shot, you can see I have a little more relief work to do over on the far right.
The drawknife is a powerful tool. It is fast, accurate, and if you are using your whole body, it has tons of control. I have done similar jobs using a coping saw, and I will never do that again! This method was so much easier and cleaner too.
One final note about working with drawknives - be careful! They have a lot of exposed blade just inches from your hands. My rule is "Keep both hands on the handles, or keep your eyes on the blade!" The only time I ever cut myself with a drawknife, I had taken my hand off the handle, and then went to put it back without looking at what I was doing. My hand missed the handle and found the blade - ouch! Oh well, now that finger tells me when the weather is going to change...
Here is a shot of what the drawknife is capable of doing:
And that piece in its final home:
Now that the trim is done, I can start working on the fence that will rest on it and will hopefully keep Teague away from the rocks and hot woodstove. Hopefully. He is already starting to show signs of being a climber!