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Forum topic by BenDupre posted 03-14-2017 03:03 PM 520 views 0 times favorited 10 replies Add to Favorites Watch
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BenDupre

531 posts in 328 days


03-14-2017 03:03 PM

Does it matter where i put the shims in my stack? I usually put one or more next to each inner/outer blade but does it matter. Recently fine tuning a dado for plywood i found myself pulling all the chippers back out to change a shim. Seems like i could just put a couple shims under the iutside blade and be done.

Also, when i sized the dado to the plywood, my test pieces fit but the actual shelf wouldnt go. Pretty sure this was because of a slight bow in the full piece. I recut the dado at a full 3/4 and fit fine. So what do you all do? Does it pay to be precise matching the plywood to the 1/64th of inch? Or does the glue just make up the difference anyway?

Thanks for advice!

-- The problem with communication is the illusion that it has occurred. – George Bernard Shaw


10 replies so far

View Fred Hargis's profile

Fred Hargis

4766 posts in 2333 days


#1 posted 03-14-2017 03:27 PM

I just put them between the chippers and the outside blade. Sometimes the shelf won’t fit because the test piece was cut with the veneer grain, and the shelves are cut across the veneer grain. The shelves will have a little roughness at the edge of the cut preventing them from fitting nicely. I try to get it as close as possible, and if I have a slight bow i can usually get that into the dado and let the dado straighten it. One other trick that might work for you: instead of fitting the dado to the shelf, you could cut it to a close dimension, say 11/16” (or even 5/8”) for a 3/4” shelf. Then rabbit the bottom edge of the shelf to fit the dado.

-- Our village hasn't lost it's idiot, he was elected to congress.

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pottz

2243 posts in 824 days


#2 posted 03-14-2017 03:29 PM

well i always put the shim on the outside blade just for ease of changing,but i dont think it really matters.as far as being precise thats up to you,the more precise the better in my opinion.i dont like seeing gaps myself,looks like poor workmanship.

-- sawdust the bigger the pile the bigger my smile-larry,so cal.

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BenDupre

531 posts in 328 days


#3 posted 03-14-2017 03:43 PM

Pottz

Thanks. I would not be happy with a gap either. I suppose for a shop cabinet a little bow in the plywood is inconsequential. Context matters. I am not super experienced so i was just looking for a rule of thumb. Might be a while before i cut my next 22 inch long dado.

Ben

-- The problem with communication is the illusion that it has occurred. – George Bernard Shaw

View Kurt T. Kneller's profile

Kurt T. Kneller

126 posts in 1204 days


#4 posted 03-14-2017 03:46 PM

They do make shims that are slotted. With those you do not have to completely disassemble your dado. Just loosen the arbor nut and use tweezers to remove/add shims. Works pretty well.
They have them at Lee Valley

-- Start with ten, end with ten.......

View marc_rosen's profile

marc_rosen

127 posts in 3021 days


#5 posted 03-14-2017 03:53 PM

Hello Ben,
When I used shims I would place them closer to the inner cutter only if I knew I’d be undercutting my test piece and then any additional shim(s) would go inside the outer cutter. I never had any significant left over ridges due to wide gaps from the added shims. So like you I did not want to remove chippers to make my adjustments.

Funny you should type this now, I saw Woodpeckers has a dado stack set up jig. I used to test my stacks on a 5/8 inch wood dowel with a flange but found that to be too time consuming. I know some dado stacks come with a guide sheet that tells you which chippers to use to achieve your desired width.

Anyway, if you only add shims next to the outer cutter and you do see a ridge it should be easily knocked down with a chisel or similar tool.

From my experiences with plywood construction I tried to get precise fits if the project/joint would show. If it was structural only, like shelving in a closet or deep inside a cabinet I let glue and a screw or two take care of any looseness.

By the way, you have a lot of great looking projects. That chess set looks very nice It must have been fun turning all of the pieces. Marc

-- Windsurfing, Woodworking, Weaving, and Woodducks. "Most woodworkers are usually boring holes"

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BenDupre

531 posts in 328 days


#6 posted 03-14-2017 04:10 PM

Marc Thank You!

I saw that dado setup from Woodpecker this morning. Woodpecker makes good and useful stuff but i havent seen anything from them yet that couldnt be done another way without spending $169 on thier jig. That could get me a new plane.

I still have the card that came with my Freud stack that tells what combination to use. It was helpful. But i had to mic out the shims and write the dimensions on them. I was proud of myself for being so precise but in the end i took all the shims out and put in all four 1/8 chippers for a 3/4 inch dado and my cabinet went together just fine.

Ben

-- The problem with communication is the illusion that it has occurred. – George Bernard Shaw

View Iamjacob's profile

Iamjacob

48 posts in 2466 days


#7 posted 03-14-2017 04:24 PM

I put my shims between the inside blade and chippers where the arbor is still un-threaded. This way the shims don’t fall in between the treads and get bent. Both of my .005 shims have been crushed when they fell into the threads and I tightened the arbor nut without noticing.

I would love to find a set of magnetic shims that stick to the blades so they don’t move.

I have the same issue with Woodpeckers stuff. They have very cool ideas and they are executed very well but man is their stuff expensive.

View pottz's profile

pottz

2243 posts in 824 days


#8 posted 03-14-2017 04:49 PM

actually what i use now is the freud dial a width dado set,no shims needed just turn the dial for precise adustments.

-- sawdust the bigger the pile the bigger my smile-larry,so cal.

View xeddog's profile

xeddog

173 posts in 2847 days


#9 posted 03-14-2017 04:53 PM

I have started placing shims between the outermost chipper and the outside blade. I used to put them in earlier, like someone else said, by the inside blade where the arbor was still un-threaded. But that got to be a real pain when adjusting the fit.

As for test pieces, when I was building my router table, I got some maple veneer plywood for the bulk of it. I got all of my pieces cut to size and then set up for dadoes. Using a cutoff from the same sheet, I got a nice fitting test piece. After using that setup to cut all of the dadoes in the actual workpieces, NONE OF THEM FIT. My test piece had the thinnest dimension of all of two sheets of maple ply. It took a long time tyo work with all of the dadoes to widen them out 20 or 30 thousandths of an inch.

Someone else mentioned magnetic shims. My Forrest Dado King came with magnetic shims. I’m sure they would sell you a set.

Wayne

View Fred Hargis's profile

Fred Hargis

4766 posts in 2333 days


#10 posted 03-14-2017 05:08 PM

I would love to find a set of magnetic shims that stick to the blades so they don t move.

- Iamjacob

Here you go….I’m sure you can get them elsewhere as well. http://www.highlandwoodworking.com/magneticdadoshims.aspx

-- Our village hasn't lost it's idiot, he was elected to congress.

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