Dado shim placement

[Johnny Barr]

Most of the instruction manuals for dado blades advise that you spread your shims throughout the stack, which makes sense, and yet I've read posts saying to place the shims between the last chipper and the outside blade, that way you only have to remove one blade to add or subtract shims.That also makes sense. Some have qualified this by saying that if their shims add up to more than 0.03" then they spread them. Then I thought about how Freud's SD 608 stack works. It still uses normal chippers but no shims with an adjustable wheel on the outside blade that increases or decreases (by an audible click) the width by 0.004" which in reality is equivalent to adding shims between the last chipper and the outside blade on a typical stack.

I realise that too many shims between a chipper and the next blade might mean scoring/grooves on the flat part of the cut and possible shim damage etc but I really like the idea of only having to remove the outside blade to access the shims, particularly if I'm only using one or two shims. BTW I just purchased the Freud SD 508.

How many of you do exactly that? If so, have you used more than 2 shims?

[Jim Becker]

I would use the "easier" method when it wouldn't result in any compromise to the cut for the reason you stated...it's a lot easier to make adjustments when you don't have to totally "de-stack" the set to get to the shims.

[Johnny Barr]

Do you have a dado stack Jim? Is that what you do? Which brand?

I'm not new to woodwork but am for dado stacks. I've generally done them at the router table but that won't work when you groove is a long way (2 feet) from the fence. That's why I made my recent purchase.

[Paul Girouard]

I stack them equally thru out the stack, it’s not that big a deal to remove them to adjust the width , generally a couple maybe three try’s gets the result desired.

I have a Freud Dado 8”.

[John Ziebron]

I will go up to .030 in shims between the last chipper and the outside blade. Any more than that and I space them out. But I keep a 1/2 bolt, nut and a couple of washers with my dado set. Put the bolt head with one washer in my vise, add the dado set with shims you think you'll need, then add the second washer and snug the nut up by hand. I use dial calipers to measure total width of cut. If you need to add or subtract shims you should now know exactly what you need before transferring the stack to the saw arbor. Much easier for me with my big hands that have a hard time getting at the arbor.

[Jim Becker]

Do you have a dado stack Jim? Is that what you do? Which brand?

Not currently since I upgraded to a slider years ago, but when I did, it was a Forrest Dado King. If I decide to go back to owning one, it will be the same or one of the higher end Freud stacks.

interestingly enough, while I was doing some shop renovation recently, I found the envelope with the shims... :D :D :D ...so I do have those!

[Johnny Barr]

I have made the jig in this video and it works well. ( https://www.youtube.com/watch?v=M1UQj8iudxk ). Using the jig I found that the timber has to be "just" (couple of thou.) above the stack as the blade(s) width and kerf width aren't exactly the same and they often aren't. So I have no trouble working out what combination of chippers and shims but removing and installing blades isn't super easy on my table saw with my large hands. So placing shims between the last chipper and the outside blade makes it much easier but I wasn't sure, being new to all of this, whether I'd wreck my cuts or shims or create another problem doing this way. Thanks for the confirmation, John. I'll sleep better tonight. :)

[Mike Cutler]

Johnny

As long as the cutters are still over lapping each other, it shouldn't matter.

Generally, unless I know I need a gross shim,I just stack all the cutters, make one test cut, measure it with a dial caliper and install the correct shim(s). It's a one and done method for me. You could do the same with that jig in that video, but you would need to be able to tighten everything up and measure the difference with a dial indicator.

Don't feel as if you're only limited to the shims that came with your set. Shim stock sheet is sold everywhere, and you can easily make your own whenever needed.;)

[glenn bradley]

I run a few stacks. All are outer plate and chipper format. I abandoned shims and set the stack for a bit under the final width. I then make two passes to get the width I am after with a lot less fuss. For production runs this would be unreasonable but, for my 'one piece at a time' method of making furniture it is fine.

[Alan Schwabacher]

If you use shims near the outside of the stack, make sure to keep them from slipping down into the arbor threads. If they do, tightening the stack can shear off a bit, hurting precision and making the stack more difficult to remove. I generally use magnetic shims, and if I use thinner non-magnetic ones for fine tuning, they go on just after the first blade on the unthreaded part of the arbor. That way I never need to worry about shim placement.

I simply measure the stock I want to fit into a groove with calipers, consult a little table I made in digital inches to see which chippers I need, and subtract to get the shims to use. It's never off by more than a couple of thousandths, so I don't need to change the shims after installation.

[Johnny Barr]

Alan, I have just ordered a set of magnetic shims. They sound really good and easy to install but the thinnest is .010". Do they make any thinner than that? Google couldn't help!

[Alan Schwabacher]

The magnetic shims are very nice, but their limitation is that the thinnest I have is .010". That's why I sometimes use the brass shims, placing them on the unthreaded part of the arbor. I don't know if thinner magnetic shims are available.

[Brian Lefort]

Amana Tool 658040 Carbide Tipped Dado 8 Inch D x 46T ATB/FT -5 Deg, 5/8 Bore, Dado Set
I use this stack. I like it a lot. very clean cuts with the 46 tooth design. I spread the shims out.
This one comes with paper shims, so I purchased a set of brass shims.