Hi. In this video, I'm gonna make some zero clearance
table saw inserts.
So, I have several inserts already. This one I use with bedo blades.
This one with 7 1/4 inch blades.
This one I use most of the time.
But I still use this one for bevel cuts.
And that's a bit of a problem.
So, if I need to make a 30 degree bevel cut even if I have
a flat part on the end here.
The hole in the factory insert is so large that if I want to cut this piece like so
there's actually no ledge left at all to support the work piece.
So, especially for a short work piece that's not terribly safe
or accurate. So, I want to make and extra insert
that I can just use for bevel cuts and I won't care about
chewing it up a little bit. So the common wisdom seems to be
to take one of these inserts.
Glue it onto a piece of wood with some carpet tape
and then use one of these pattern following bits to copy the shape.
I'm not a particular fan of that because, when you look at one of these inserts
it doesn't actually fit that tightly to begin with.
So, I'd rather not copy that shape. I'd rather my insert be
a little more precise than the factory made one.
So, I've cut these two strips to be the exact same width as the slot in here.
And the ends of the slot are just a semi-circle
So, all I need to work out is What's the size
of that circle? And how far are they apart?
Well, the radius for this is actually fairly easy.
'cause it's just half the width. Because it lines up like that.
And for the length
we know that we've got the radius here and we've got the radius here.
So, I can just take from here to here.
Minus twice the radius. And that gives me the distance between the two centers
for the semi-circles.
So, the width of this slot is 9.6 centimeters.
And the length
is 34. So, 34 minus 9.6, which is twice my radius
is 24.4. And the radius is 4.8
So, I've already marked a 4.8 radius on here.
Here's the center for it. And so I'm putting the 10
on here instead of a zero because that's easier to line up.
So, now I go to 34.4.
So, one thing that's risky is with an insert made of solid wood, like this
is when the blade is all the way up, there really isn't that much here.
And so there's a risk that the insert might split
and that would cause the rest of it to collapse into the slot.
And, that could lead to accidents. So, what I always do
is I put some reinforcing splines at the end
of it so it's sort of like plywood there.
You could make the whole insert out of plywood
but I want this part to be out of solid wood
so that it's nice and strong and doesn't sag.
So, I'm just gonna cut some slots in the end of those pieces
just like my quick-set Tenon Jig.
So now I need to cut some splines that fit exactly into this gap here.
So, I'm just checking that with the calipers.
It's the same as the saw curve.
And now checking that setting the fence the right distance from the blade.
If you have a zero clearance insert. You can't cut these with a fence like that
because there's still material here to support the work piece.
There is a good chance that the work piece is gonna shoot out, like this
once it's cut. But it's very light and you just stay out of the way.
Now, what typically happens when I cut a spline. It's just a little too tight.
And it won't go all the way in.
And that'll be even harder with the glue.
So, I think that I'm gonna take about 5 thou off of that shim
just by moving the fence.
That's about 5 thou on the dial indicator.
So, that's a decent fit. I don't want it too tight
or it's too hard to get in there with the glue in.
So, now just gluing those splines in there. I'm sure to put blue
in both the slot and on the work piece.
Now, there's a little bit of flex in here so just to make sure
everything really bonds. I'd like to put some clamps on the end of this slot.
So, now I just have to wait for the glue to dry.
People sometimes ask what kind of glue I use.
Well, I just use ordinary yellow glue.
It doesn't really matter what brand it is. This one's Lepage
This one is from Home Hardware.
It's all the same stuff. It's stronger than the wood.
It's sort of like what soap do you use. Well, if it does the job
it doesn't matter.
So, it doesn't quite fit. So, I'm just gonna mark
where I need to sand some stuff away to make that slide in a bit better.
Now, to cut the actual slot the thing to do is to raise the spinning blade
through the insert.
Except the blade doesn't actually go down deep enough
for me to put the insert in here so
what I've done in the past is put the insert in here.
And then fix this exactly over the insert and then rave it into it.
But that doesn't work for a bevel cut.
So, this time around I'm gonna take the blade out.
And put a different set of saw blades in. A much smaller set.
And those ones can retract far enough
so that I can raise the spinning blade through the insert while it's in place.
I'm using these smaller 7 1/4 inch blades to give me enough clearance
But these blades are actually thinner than the regular saw blades.
So, I actually stacked two of them to make sure
that I get a curve that's as least as thick as my regular saw blade will make.
Now, before I do the bevel cut.
I want to make sure this is exactly flush with the surface.
Because the bevel cut of course, is effected by that.
In the past, I'd leveled my inserts just by making them thick enough.
And then, cutting away at it until it rested on these things just right.
But, what I find is there's always a bit of sawdust accumulating on these.
So, it's actually much better to just put some screws in the bottom
to bring that insert up to the right height.
And then, a little bit of sawdust on there won't throw off the accuracy.
So, I pre-drilled the holes for the screws and put a little indentation here
to allow the head to get down far enough.
That's flush now.
So, because I could lower the small blade far enough
I could just cut these slots without worrying about the rest of the insert.
And now I've got enough room to put a bigger blade in there.
And to enlarge that slot when I need to.
Now, there's one more important safety thing.
If I push on the front that insert tends to rock up in the back.
And that can be dangerous.
On the insert that came with the saw there's a pin that sticks out the back.
Which prevents it from rocking up in the back.
And so I'm going to put a pin in the back here, to do the same thing with this one.
Let's just measure how thick the table is back there.
And I'm just gonna use that and mark on here.
Where the pin needs to go.
So, I pre-drilled a hole and I'm gonna use a cut-off nail
and just drive it in there.
And a coat of varnish always helps the insert
slide a little bit better and last longer.
It helps to do both sides and that makes warpage less likely.