Happy
New Year! I hope 2013 is kind to all of us. The last project I took
on at home in 2012 was gluing up a birch countertop for my shop
cabinets. In the last post, I showed how I got the big planks ready
to run through the planer. In this post, which will be shorter and
easier to understand, I'll show you how to get a good, straight edge
on a workpiece if you don't own a jointer, or I should say, a big
enough jointer.
The jointer I have access to in my home shop is 6”
wide and 42” long. These planks are a bit over 90 inches long,
meaning I would have to somehow push down hard enough on the jointer
bed to balance at least 70” of 8/4 birch, plus hold the wood up
against the fence accurately, in order to prepare my boards for
gluing up. Not likely! If the boards were only 4/4, maybe so. I guess
roller stands fore and aft might work, but I decided to do this job
with the router. I had heard about it being done, but never seen it,
and I was curious. I'm pleased to report it works well. In fact, I'd
be tempted to use this method for planks this size even if I had an
8” jointer in the shop.
The concept is simple: a straightedge is clamped on top of the workpiece, parallel to its edge. A template guide is screwed into the base of the router, and rides against the straightedge so the router moves in a perfectly straight path. A straight bit is chucked in to the router, and cuts the edge of the wood at 90 degrees to its face.
I had
two main concerns going into this process: first, what can I use for
a straightedge, and second, what bit or bits should I use?
The
straightedge is important, because its straightness determines the
quality of my glue joint. The quickest and easiest would be a factory
edge on a sheet of mdf, but I didn't have one around and I didn't
want to bring an entire sheet of that stuff into my shop if I didn't
have to. Then at Home Depot, somewhere between the prefinished
shelving and the millwork, I found the perfect straightedge: primed
mdf boards 10 inches wide by just under ¾ thick. They're 8 feet
long. I would provide a link, but I can't find them on the HD
website.
Why
mdf? Because it's dirt cheap and the manufacturing process leaves it
dead flat and straight. Did I mention it's cheap? Perfect for my task.
The bit
was a concern because I didn't think I had any that would be long
enough to joint the entire 1-7/8” thickness of my birch. I was
afraid I'd have to go as far down the thickness as I could with a
straight bit and a template guide running along my shelving, then
take off the shelving and use a flush-trimming bit without the
template guide to finish the job. Using two different setups like
that is not a good idea when you want accuracy, so I was delighted to
see that my longest 1/2” spiral bit would reach far enough. When I
tried it, though, I found that it could only take a very, very light
cut without vibrating so much it left a choppy surface. I usually use
these bits for mortising, and I guess they're stabilized by being
touched by the wood on both sides of a mortise. Fortunately, at the
back of my bit tray I had a gigantic 1” by 2” carbide bit. I also had a template guide big enough to handle it. The
extra diameter made a huge difference, and the thing cut smoothly
with far less noise and effort than the spiral bit.
The
procedure was simple:
- Take a quick test cut (or measure) to determine the offset between the template guide and the router bit. In this case it's about 1/8”. Clamp the straightedge at both ends of the workpiece in a position that will lead to a full-length cut along the board. Also be sure whatever supports the board (in my case, sawhorses) won't be exposed to the router bit.
- Make light passes, which in this case means lowering the bit between passes. I found it went easiest if I took about 1/2” vertical cut per pass.
- After the first edge is jointed, mark a line parallel to it as a guide for clamping down your straightedge as you joint the second edge. That way your finished board will be a parallelogram instead of an irregular trapezoid. I used my fancy panel gauge because I like it and I don't get to use it very often, but a pencil against the end of an adjustable square is just as good.
- Clamp down your straightedge and joint the second edge.
- Clean up! One disadvantage compared to a jointer is that this spews dust everywhere!
- Test your results with an accurate square, to be sure you'll get a flat glueup. Assuming you generated nice flat faces by following the instructions in the post on how to get flat boards without a wide jointer, you should be fine, but it's foolish not to test your work before you roll on the glue and clamp it up!
This
procedure went much more quickly for me than prepping the stock for
the planer, so I started gluing up the countertop before the sun went
down. These ended up being some of the best glue joints I've made on boards this size, so I'm quite pleased indeed.
Next
up: flattening the countertop!
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