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Dado help

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Blog entry by Bighurt1978 posted 09-07-2020 09:51 PM 315 reads 0 times favorited 5 comments Add to Favorites Watch

hello all, I’m using my new dewalt dado blade. In the instructions is dosen’t tell me when to use the shims. When and where do I use them. Thank



5 comments so far

View gdaveg's profile

gdaveg

47 posts in 47 days


#1 posted 09-07-2020 10:09 PM

There should be a card in the blade set with “recipes” for different width of dado cuts. It will say something like two outside blades, two inside blades and two 0.10” shims for your selected width of dado.

There will be two blades that always go on the outside of the dado stack.

The shims go in between the cutting blades. They “do not”go on the outside of the blade set.

I have only done a few dado set ups and am not near the ones I used before. Hopefully other more experienced dado users will give a better description.

And….there is always YouTube.

-- Dave, Vancouver, WA

View gdaveg's profile

gdaveg

47 posts in 47 days


#2 posted 09-07-2020 10:19 PM

View Rich's profile

Rich

5851 posts in 1434 days


#3 posted 09-08-2020 01:23 AM

The shims are for times when the desired thickness is in between two combinations of chippers. Most stacks have two 1/8” outer blades, allowing you to cut 1/8 and 1/4 inch grooves. There will be a set of chippers with them, usually, one 1/4 inch, two 1/8” and a 1/16”. As gdaveg warned, the chippers never go on the outside of the blades.

With those alone, you can set up stacks for cuts ranging from 1/8” to 13/16” (assuming your arbor is long enough) in any increment of 1/16” (but not 3/16”—can’t do just a blade and a chipper). But what if you need something to cut a dado for 1/2” ply, which is nominally 15/32”? There’s no 1/32” chipper to hit that mark, so what you can do is set the stack up for 7/16” (two outer 1/8”, and a 1/8” and 1/16” chipper), and then add shims to increase it by 1/32” (0.03125”).

Your shims should be color coded with a chart showing the thickness of each. If not, just grab some calipers. Add the combination of shims that most closely equals the space you’re trying to fill, in this case 0.031 inches. (Truth be told, 0.03 is close enough). The shims should be distributed between the blades and the chippers to widen the set evenly. The cutters on the chippers are wide enough that you’ll still get a clean, flat cut.

If you really want to nail your dados, rabbets and grooves, invest in a side rabbet plane. The trick there is to cut the slot just under and then trim the sides (hence side rabbet) with the plane just until the mating piece fits snugly.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View woodbutcherbynight's profile

woodbutcherbynight

6133 posts in 3254 days


#4 posted 09-09-2020 05:11 AM



The shims are for times when the desired thickness is in between two combinations of chippers. Most stacks have two 1/8” outer blades, allowing you to cut 1/8 and 1/4 inch grooves. There will be a set of chippers with them, usually, one 1/4 inch, two 1/8” and a 1/16”. As gdaveg warned, the chippers never go on the outside of the blades.

With those alone, you can set up stacks for cuts ranging from 1/8” to 13/16” (assuming your arbor is long enough) in any increment of 1/16” (but not 3/16”—can t do just a blade and a chipper). But what if you need something to cut a dado for 1/2” ply, which is nominally 15/32”? There s no 1/32” chipper to hit that mark, so what you can do is set the stack up for 7/16” (two outer 1/8”, and a 1/8” and 1/16” chipper), and then add shims to increase it by 1/32” (0.03125”).

Your shims should be color coded with a chart showing the thickness of each. If not, just grab some calipers. Add the combination of shims that most closely equals the space you re trying to fill, in this case 0.031 inches. (Truth be told, 0.03 is close enough). The shims should be distributed between the blades and the chippers to widen the set evenly. The cutters on the chippers are wide enough that you ll still get a clean, flat cut.

If you really want to nail your dados, rabbets and grooves, invest in a side rabbet plane. The trick there is to cut the slot just under and then trim the sides (hence side rabbet) with the plane just until the mating piece fits snugly.

- Rich

Good points and I would add if you don’t have any planes at all you are missing out. They can alot to enhance your skillset and final product. I edge band often and find a few strokes of the handplane levels it out very quickly and evenly. Rather than just sand it down. If you take a block plane and start a chamfer before you do a roundover on the router table it prevents tearout.

-- Live to tell the stories, they sound better that way.

View LittleBlackDuck's profile

LittleBlackDuck

5397 posts in 1666 days


#5 posted 09-10-2020 01:46 AM

B’h’, follow the good advice above… and to that I will add my 6c (inflation) worth…

I find shims a PITA, and have invested in a ”specialised dado set” and a ”set up jig”… both that could cause you a Big hurt on the wallet.

Now I’m not spruiking the everpriced Woodpecker jig or ”my dado” set products but the concept. You should be able to fabricate a setup jig in your workshop for bugger all cost… Have a gloss over my review... you probably could use the concept to minimise trial and error on the physical tablesaw arbor… you should be able to get accurate 1st. cuts or at least on the 2nd arbor mounting after modification.

-- If your first cut is too short... Take the second cut from the longer end... LBD

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