Favorite method of sizing a dado? Accurate Guide

[Alan Tolchinsky]

Hi All, I was just looking at Accurate Guide's web site. This guide fits on your router and helps you get the exact dado width to fit your stock size. What's your favorite method of sizing the dado width to match the material you're putting in it? Anybody own the Accurate Guide? Alan in Md.

[Tom Hintz]

See the link below for photos of a dado guide I use, updated from one an old-time cabinet maker who used to live behind me used for years. When making dados that fit witihin it's range (roughly 24"-long or shorter), the thing works like magic.
For longer dados I use a simple clamp-on fence and good router bits, sized properly for thematerial being used. Infinity makes a set specifically for the common plywood sizes that actually fit and makes those dados far easier for me than multiple passes.

http://www.newwoodworker.com/autodadojigpln.html

[Alan Turner]

I just built one, my "invention" if you will, and was interested to see the one noted above. It appears to be based upon the width of the bit, requiring a separate jig for each bit. Mine does not have that limitation. Mine uses a 1/2" bit, and a 5/8" o.d. bushing guide. You could use others also. It is similar to the one on the web. To set it, take the stock to fit into the dado, and a 1/8" shim, and tighten the sandwich. Remove the spacers, and set the jig to the stock, off by 1/16" I used 12mm BB ply for it, and edged all of it with hard maple. After gluing up I used a shoulder plane to get it dead on at 90 deg. from the base that it registers against.
I think I prefer several passes as a captured bit tends to jump a bit.
With all that siad, it gets its maiden voyage this evening. On a scrap piece, of course. More to follow if I don't get CRS, and a pix if it works (or a deletion if it doesn't).
Shop built jigs are a part of WW that I much enjoy.
Alan

[Chris Padilla]

Alan,

Most of my dado work is in plywood. I found out that all my sheets of 3/4" (really 23/32") were different in thickness which really ticked me off one evening as I was struggling to get a cabinet carcass together.

For plywood it is just set up the dado as close as possible and make several test cuts. In my case, if the dados weren't 23/32", they were large so with my awesome fence (Incra TS-3a), I was able to bump it out a hair to widen dados where necessary.

The accurate guide got a test ride on Woodshopdemos:

http://www.woodshopdemos.com/nprod-2.htm

[Alan Tolchinsky]

Hi Chris, I looked at woodshop demos before and the accurate guide make sense in theory. But I wonder if it's worth it? I prefer to do dados on large pieces with a router and guide. How do you manage large pieces for a cabinet on you ts doing dodos?
I have a dado blade and have yet to use it. Talk about buying things you don't need, at least not yes anyway. Alan in Md.

[Dennis Peacock]

For me....I use a stack dado set from Freud and my TS. I use the TS fence to set the distance to the first dado. Cut and position for the next dado. If it gets beyond the reach of my 50" fence, the I position from the other end and keep going. I do use a miter guage to help guide it through to keep it nice and smooth.

I have used a router at times to make dado's....but it sure takes a lot more time doing it that way. Could be just me though.

Sometimes I feel like I'm woodworking with 4 left hands.!!!

[Alan Tolchinsky]

See the link below for photos of a dado guide I use, updated from one an old-time cabinet maker who used to live behind me used for years. When making dados that fit witihin it's range (roughly 24"-long or shorter), the thing works like magic.
For longer dados I use a simple clamp-on fence and good router bits, sized properly for thematerial being used. Infinity makes a set specifically for the common plywood sizes that actually fit and makes those dados far easier for me than multiple passes.

http://www.newwoodworker.com/autodadojigpln.html

Hi T


Hi Tom, Yep I saw that jig and it looked good. Your idea about the Infinity bits that actually fit the sheet goods sounds great; I have to get some of those. Alan

[Alan Tolchinsky]

For me....I use a stack dado set from Freud and my TS. I use the TS fence to set the distance to the first dado. Cut and position for the next dado. If it gets beyond the reach of my 50" fence, the I position from the other end and keep going. I do use a miter guage to help guide it through to keep it nice and smooth.

I have used a router at times to make dado's....but it sure takes a lot more time doing it that way. Could be just me though.

Sometimes I feel like I'm woodworking with 4 left hands.!!!

Dennis, Thanks for describing your method. I've never done that and I'd like to give it a try. Is it hard to keep a long piece from getting crooked as you cut? I guess that's what the miter guage is for. Alan

[Cecil Arnold]

Alan, I use Dennis' method most of the time and find it to be accuarte for most case work. I also agree with his Freud stack dado, one of the best for the $ IMHO. If you are looking for something to use with your router, you might want to look at Micro-Fence. I've used it to inlay in boxes and you can get additional attachments (circle cutter, elipsis jig). The MF allows you to adjust your bit to + - .001 which is too close for most wood.

[Chris Padilla]

Alan, yep, I use Dennis' method. The key to cutting many dados on a long board (cross-cut) is to make sure you go slowly but #1 is to make sure your table top is clean and smooth so the work glides nearly effortlessly. I have good success with this method...other than plywood not maintaining its thickness!!

[Kurt Aebi]

I built the exact jig that Tom has and use it sometimes.

Sometimes, I use Dennis' method.

More often; though, I use my stacked Dado head in my radial arm saw to to cross-cut dadoes ( I do have the Dado/Moulding head guard & use it!), it gives me a lot of control over the depth of the cut and can see the cut as i is being made. I do, however push the dado stack towards the machine rather than pulling the saw from the rear of the table (keeps the saw from "running" across the board). I always keep one hand on the saw when I turn the power On as using the saw with the saw motor at full extension is NOT the factory recommended use of the machine and care should definitely be taken when using a saw of any kind, wspecially with a dado stack! If the board I an dadoing is too wide for this method, I use the table saw and sliding miter table.

[Alan Turner]

Here are pix of my router jig. I have now used it and it is dead on. The test cuts established a cut in the cross members, and thus permits accurate setting to a knife line. I slide the back cross piece tight to the stock, and this is a bit of a clamp, but I also use aux. clamps. I put the whole package, jig and stock, on sleepers on the bench, which gives room under the jig for clamps. The sandwich is then clamped over the sleepers to the bench.

In building this jig, the critical feature is the squareness of the fixed end to the fixed rail, which I achieved by trimming it with a shoulder plane following glue up.
Alan

[Alan Tolchinsky]

[QUOTE=Alan Turner]Here are pix of my router jig. I have now used it and it is dead on. The test cuts established a cut in the cross members, and thus permits accurate setting to a knife line. I slide the back cross piece tight to the stock, and this is a bit of a clamp, but I also use aux. clamps. I put the whole package, jig and stock, on sleepers on the bench, which gives room under the jig for clamps. The sandwich is then clamped over the sleepers to the bench.




Alan, That's a great looking jig. One question: What do you do for over/under sised plywood? How do you compensate for this? Alan

[Alan Tolchinsky]

[QUOTE=Alan Tolchinsky]

Here are pix of my router jig. I have now used it and it is dead on. The test cuts established a cut in the cross members, and thus permits accurate setting to a knife line. I slide the back cross piece tight to the stock, and this is a bit of a clamp, but I also use aux. clamps. I put the whole package, jig and stock, on sleepers on the bench, which gives room under the jig for clamps. The sandwich is then clamped over the sleepers to the bench.




Alan, That's a great looking jig. One question: What do you do for over/under sised plywood? How do you compensate for this? Alan

Alan, I reread your original post and I think I see how you set it. You're using the actual plywood to set the jig but what are the spacers for?