Well, that's all well and good, if all of your pieces are the same size (but
just not all 1/2" or 15/32" or whatever). When you're making a cabinet,
it's really tedious if all your dadoes have to be sized individually.
If you've got different thicknesses of stock - ply or otherwise - the only way
to make good fitting dados is to cut them (or shim them to) slightly different
widths. Even if you have different thicknesses of ply, this little jig will
allow you to cut snug dados - of varying sizes, if necessary - very quickly. Try
doing that with a dado stack or special sized router bit...
I know it would be easier if ply was of consistent thickness, but sometimes it
just isn't. There can be thickness variations within a single sheet!
If you ask nicely, I would bet Leon will send you plans for his jig. Fast,
easy setup, and accommodates various sizes easily.
Pat Warner does the same thing with two pieces of wood and a couple of
I feel your pain... How about putting a rabbet on the edge of the ply
to get it to a consistant thickness as a technique? Not only makes
takes the guesswork out of the dado width, but the shoulders cover up
any little nicks the router might happen to make if you get a little
shaky at the wrong moment.
I also feel your pain. I bought a set of "plywood" bits. Tried the "1/4""
on a scrap. Worked great. On my latest project--I was furious. I assumed
the plywood would fit nice and tight. But no, no, no, loose as hell.
Just make a fricken standard. How hard is that.
For the past few years I've found it necessary to make two trips to the
lumber yard when I buy multiple sheets for a large project. A digital
caliper goes along on the first trip when I pick out the grade, grain, etc,
and even note which stack the plywood I want is in.
Back at the shop I cut a dado in sample FF material based on the caliper
measurement (being sure to make project notes on the number, size, and
position of the cutters and spacers in the dado stack). Then it's back to
the lumber yard, using that sample dado, to check the fit, and select _each_
individual sheet of plywood.
The piece of dadoed FF stays on the dashboard of my truck until the project
A necessary PITA these days if you work to any kind of tolerances where
multiple units must have the same measurement, and things like drawer slides
must fit drawers made long before a cabinet is put together.
No one in the building industry, at least in this area, will guarantee
anything regarding material dimensions these days, and if they did, it has
been my experience that you would do well to verify it yourself in any
Since I am one of those who does FF's first on cabinets, it saves time, not
to mention peace of mind, in the long run to insure that I don't have to
re-cut dadoes in FF's.
I do a good deal of pre-planning, and since I order on a purchase order
before delivery, I generally make two trips in any event. The first to check
color, grade, grain, price, etc, the second to take delivery.
In between is when I take the extra step to cut a dado as a "thickness
guide" for individual sheets when I pick up the order.
Your dado thickness guide is a keeper. I like that. Thank you sir.
I do some metal work. Mostly fabrications out of squate tubing. Although
there is far less size discrepancies in metal than wood, it is an increasing
problem there too. Particularly in the corner shape. Which changes the time
and skill required to do the fabrication.
Like you, I bring samples to the yard to check them against what they give
me. And I submit samples each time I order. Even then, they screw up the
order now and then.
So I have already been doing this. I just did not think to apply it to wood.
On Mon, 25 Apr 2005 09:57:55 -0400, "Lee Michaels"
You're not kidding there- we've got three or four steel suppliers at
work, and every single one of them has a different corner shape.
Doesn't matter all that much to the operations I'm performing, but it
sure does piss off the plasma cutter operators and the welders.
I also ran into this problem with metal 1"x1" square tubing. Even
though all the pieces were 1/16" wall, some had corners that were more
rounded than others. When the pieces were welded, the guy had to
fiddle around with the beads on some of them to get the edge flat and
And it is a problem if appearance is important. I was welding up gym
equipment. And a machine that has different tubing profiles within it looks
like it was put together by a back yard welder with recycled metal. It
doesn't look professional at all.
Another problem. As the wall thickness gets thicker, the corner gets more
rounded. Which means if you want to make part of the machine stronger, you
have to use the heavier gauge tube throughout. Otherwise, it looks crappy.
Which makes the machine much heavier and more expensive.
And talking to your metal supplier gets all kinds of protests that they have
no control over what the manufacturerr sends to them.
We settled on a fix to make the joints look good with the rounded profile.
We just stuck a peice of flat stock in the hole. Then weld as usual. The
flat stock was thick enough to fill the hole. When the weld was applied, it
just melted together with everything else. Not all that elegant, but it
looked good and was strong.
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I'm wondering if you get more consistency with Appleply or real Baltic
birch. You know, the expensive stuff. I'm not surprised it would be a
problem with home center quality materials. But in their defense, these
materials are intended for construction, not precision woodworking.
First, it's my supposition that the BB has a tighter tolerance. As for the
rest of your comment, I believe most of us are talking about hardwood ply
from our local hardwood supplier. At least I was in my case.
It's been my experience with BB that the tolerances are very good.
I just experienced this problem a couple of weekends ago with a birch
veneer core plywood from Menards. I bought 4 sheets of 3/4" plywood
(from a stack that I had them open) and two of the four sheets were
24/32 and two were 23/32. I've never had this issue with BB (5x5 sheets).
You need to consider the source... If you're in the Eau Claire area
(and I have no idea just how far the Menard's epidemic extends,) try
Pigeon Creek Hardwoods on Hwy 12- cheaper than Menard's by at least
150%, and a whole lot higher quality. If you're in the Twin Cities,
Menard's is nothing but trouble.
Aut inveniam viam aut faciam
I figure that the 23/32 was actually 23/64. Excepting that, my
experience is pretty much the same as yours.
Even buying from the same supplier, who is using the same
manufacturer, and where the pieces are coming from the same unit -
doesn't get you all the way home.
The usual solution is to not use a full dado but to create a
dado/groove of 1/4" or 5/16" in width and then machine a tongue that
is sized to fit that width.
This goes pretty quick with a good dado blade.
Tom Watson - WoodDorker
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