Appendix 14. How to Make Corner Braces (and other wood prism shapes)
If you build a pin cab from scratch, you have to cut two types of
wooden "wedge" shapes - or to be more precise, triangular prisms.
One is the for the corner braces that sit under the leg bolt brackets:
The other is the cosmetic trim piece at the top of the backbox:
When I first tried to make these for myself, I found them to be
surprisingly challenging. So I thought I'd offer some suggestions
from what I've learned.
Pre-fabricated options
The simple triangular corner brace is the same shape as a type of trim
molding called a chamfer strip. Unfortunately, it's not easy
to buy such a thing. I've looked but haven't been able to find any
retail sources. Apparently there's not enough demand that anyone
wants to sell them.
The backbox trim piece is (surprisingly) easier to find. It roughly
matches the shape of a common piece of floor trim called a 3/4"
reducer molding. You might be able to find these at your local
Home Depot or Lowe's, and they're also available online. The floor
trim usually has a tab that sticks out in back, which you'll have to
cut off, but that should be easier than fabricating the whole thing.
You can probably even do that with hand tools, such as a utility
knife, hand saw, or jigsaw.
How to make them yourself
When I first tried to make these pieces myself, I realized that it
wasn't going to be as easy as feeding a 2x2 into a table saw. In
fact, the more I thought about it, the harder it seemed. So I
consulted the Internet. Which didn't actually help a lot; I found
a lot more questions about the subject than useful answers. But I did
find a few interesting leads. Here's what I came up with:
- Most people asking about how to make pieces like this are trying to do it with a table saw. That's what I intended to use as well. And it is doable with a table saw - it's just not nearly as straightforward as I would have thought. Most of the rest of this section explains the table saw technique that I came up with, which worked well enough for me that I'll at least explain it. I'm not sure I should actually recommend it, because the main thing I learned from my Internet research is that this is a particularly risky kind of cut to make with a table saw. But I came up with some things that I think make it safer, so I'll share my approach so that you can make up your own mind about whether or not to use it.
- I found several comments suggesting that a band saw (with a table and fence)
is the safest way to make this cut. I don't have a band saw myself, so
I can't weigh in with any personal experience, but this does seem to be widely
considered the best and safest tool for ripping narrow boards. Band saws
don't tend to cause "kickback", which is what makes narrow ripping with
table saws so dangerous.
If you have a band saw and want to give this a try, the technique should be straightforward. Set the table to the desired cut angle, set the fence to the correct depth, and feed the board through length-wise. See the sections below on the corner braces and backbox trim for the specific cut angles and dimensions.
- One person (making corner braces for a pinball machine, no less!) reported that he cut a 2x2 in half diagonally with a hand-held oscillating saw. I can't imagine doing this myself - my hand just isn't steady enough. The corner braces don't have to look pretty, but the parts that go under the leg brackets have to be fairly precise if they're going to fit well, and I just can't imagine making a straight enough cut with a hand-held tool. But maybe you can make this work if you're really careful.
- I was partially successful making these with a track saw. The trick is to firmly wedge the work piece (the 2x2 or 1x2) between scrap wood of the same height as the work piece. That forms a platform for the track to sit on (which is important because the track is much wider than a 2x2), and it locks the work piece in place throughout the cut. But I found it difficult to get consistent results this way. I also found that the depth of the cut was challenging for my track saw.
How to make them with a table saw
Warning: Table saws are dangerous tools. Please don't attempt any of
this unless you're experienced enough with your equipment that you can
evaluate the safety of what I'm suggesting. I'm a newbie at this
stuff myself - don't take any of this as expert-approved. (By the
same token, if you know a better way to accomplish these tasks, I'd
love to hear from you.) If anything seems off or you're just
uncomfortable with anything I suggest, trust your instincts and
find another way that you're happier with.
Extra Warning: The big risk with making beveled cuts with a table saw
is "kickback", which means that the blade grabs the work piece and
throws it back at you at high speed. This can cause severe injuries.
Your saw's owner's manual will have safety advice on how to position
your body during a cut to reduce your chances of getting hit if
kickback occurs. Please read that section and follow it carefully.
(My table saw's owner's manual is one of the lengthiest of any tools I
own, but I found it worth the effort to read it all.) Kickback is
always a risk, but it seems especially likely with beveled cuts, so be
extra careful.
Let me start with what not to do - which happens to be the
thing that's most obvious, to me at least. Don't just take a 2x2
and try to feed it into the saw directly.
Don't do this. Ripping a 2x2 in half diagonally with a table
saw, with the blade set to a 45° bevel cut. This is
dangerous for several reasons.
Woodworkers call it "ripping" the board when you're cutting it down
its length like this. Table saws are great for ripping sheets of
plywood. They've even good for ripping narrow boards like this,
if the blade is oriented straight up. But a diagonal "bevel" cut
like this is dangerous with a narrow board. The big problem is that
the top half of the board coming out of the saw blade isn't supported
by anything, so it'll tend to press down against the blade, which can
potentially turn it into a projectile. It's also tricky to control a
narrow board like this, even with a regular vertical cut, because
there's so little room to push the board through between the fence and
the blade. For a 90° cut, you can solve the second problem with a
"tunnel" push block, like a Microjig Grr-ripper. But that doesn't
help with the top-half support problem when cutting at an angle. In
fact, I think it would actually make the top-half support problem
worse, because the push block applies additional downward
pressure on the unsupported half.
In my Internet searching, the best advice I found was to
not try this with a 2x2 at all, but instead to use a wider board, and cut
off just a corner. Let's see how this looks with a 2x6 in place of
a 2x2 in the original setup:
Better: Use a 2x6 instead of a 2x2 to rip a wedge-shaped
piece off one side.
A 2x6 is the same thickness as a 2x2, so it yields
the same result we were trying to get from the 2x2, but this
seems a lot safer. Unlike with the 2x2, the "top" portion remains
well supported throughout the cut - it's not going to tip over
onto the blade. The wider board is also easier to
control, and you have a lot more room between the fence and the blade
to guide the board. The gap between the fence and blade is still
tight enough that you need a push stick or push block, but at least
it's not insanely scary this time. What's more, this setup lets you
work with your saw's blade guard and anti-kickback pawls installed,
which is a major safety improvement.
Note how the saw blade is oriented relative to the fence in the
diagram above: the blade is tilted away from the fence. This
is widely recommended as the safer way to orient the saw for a bevel
cut, because this geometry is less likely to trap the work piece
between the fence and the blade. I think this is true on any table
saw, but just in case your saw has some special design that makes it
different, please read the relevant section in your saw's owner's
manual to make sure that it agrees. You should of course also check
it for any other safety advice it has about beveled cuts.
The downside of using a 2x2 to make a 1" wide strip is that you end up
with a lot of wasted material. You could get one more wedge shape out
of this by flipping the leftover portion of board over and making a
regular 90° straight-up cut just inside the newly beveled portion,
but even then you have 2/3 of the board left over. I don't think you
want to attempt a third cut, since the remainder is getting back to
the point of being dangerously narrow.
This got me thinking about how we could do the same thing without
using such a wide board. I think using a wider board like a 2x6 is
probably the safest option overall, so maybe you should just stop here
and do that, but the alternative I came up with worked pretty well for
me. I built a very simple jig that holds a narrow board at a set
distance from the fence. You move both boards through the saw at
the same time, so that the wider board steers the narrow board
through the cut. We're effectively making a shape like the 2x6
out of two boards, but we're only cutting up the narrow board, so
there's less waste.
The simplest version of this jig is just a 2x6 and some woodworking
tape. Take the 2x6, and attach the narrow board (a 2x2 or even a 1x2)
to one edge, making sure that the bottom of the work piece is flush
with the bottom of the 2x6. Attach it with "woodworking tape", which
is a thin double-sticky tape made for just this kind of temporary
attachment while you're working on a piece of material. Search for
"woodworking tape" on Amazon for numerous options.
As with cutting a 2x6 directly, you should be able to use your saw's
blade guard and anti-kickback pawls with this setup. Be sure that
the work piece is securely attached to the wider board.
Instead of a 2x6, you could use two pieces of 3/4" plywood cut,
stacked one atop the other and glued together, which gives you the
same thickness as a 2-by. I'd use glue, not nails nails or screws, so
that there's nothing metal for the blade to hit if you should ever
accidentally cut through part of the jig.
It's important that the sides of the jig are straight and parallel.
There are several easy ways to do this; do a Web search for "jointing
with a table saw" for videos showing techniques. The basic idea that
you need another board that already has one straight edge that you can
use as a reference against the fence, and then you use that board to
guide the board that you want straightened (the jig, in this case)
through the saw, to take off just enough material from the rough edge
to make it perfectly straight. After you've "jointed" one edge of
the jig this way, you can run the jig through the saw
again, holding the newly straight edge against the fence, to make the
other edge perfectly parallel to it.
It would be possible to elaborate on this jig with something that
holds the narrower board in place without tape, but I'll leave that to
your ingenuity.
Corner braces
Here's the target size for the corner braces:
Unfortunately, this is not the size you get when you cut a
2x2 exactly in half diagonally.
To get the right size, you have to cut the 2x2 a little off-center.
Exactly how far off-center depends on the thickness of your saw blade,
so the easiest thing to do is probably to make a series of test cuts,
and measure and adjust until you hit the right size.
If you want to test the fit against an actual leg bracket, grab a
couple of small pieces of scrap wood, make a corner out of them, and
screw a leg bolt bracket to the inside of the corner. Then slip the
test piece under the bracket to see if it fits. When the size is
right, the test piece should fit snugly.
The diagonal angle is 45°, so set your saw blade at a 45°
bevel tilt.
Lengths: The most critical function of the braces is to fill
the gap under the leg bolt brackets. The brackets are about 5½
inches long, so you can satisfy this function by making all four
corner braces about 6" long. Alternatively, you can make them a bit
longer, so that they provide additional reinforcement along a
greater section of the corner seams:
- At the front, the braces can extend from the cabinet floor to the top of the brackets, which amounts to about 8½". You shouldn't make them extend above the top of the brackets, since they might get in the way of the plunger and front-panel buttons.
- At the back, the braces can extend all the way from the cabinet floor to the top, about 21½".
Backbox top trim
The backbox top trim piece has this profile:
This piece is purely cosmetic, so you don't have to hit those
dimensions perfectly. Those dimensions are just what the WPC machines
use. I don't think anyone would notice the slightest difference if
you had a bit more or a bit less than the 1/4" lip at the front.
You can accomplish this shape by cutting a 1x2 with the blade set at a
20.5° angle. The 1x2 should be oriented the "tall way", and set
up the fence offset so that the bottom edge is cut to 1/4" thick.
(Approximately - again, it doesn't really matter that hit that
size exactly.)
As with the corner braces, the easiest way to get the fence position
set up is to make a test cut, and adjust the fence based on the
results.
