Ideas for a sled for dadoes

[Phillip Mitchell]

I got a new (to me) table saw a couple months back and am still in the process of re-making sleds, jigs, etc that didn't crossover from the old saw. New saw is a Powermatic 66, for reference.

I just did a small project with dadoes and stock that was nearly 40" long at the longest. I used a Rockler branded miter gauge because that's what I had lying around, but I wasn't impressed. It had a flip stop block, but the gauge was too short for some of the cuts I had to make. There was also more slop than I cared for in the adjustable runners that fit in the miter slots. I tried several times to get it tightened down to be snug, but didn't have much success getting it right on. There was slop/flex in the 90* setting as well that made it really difficult to end up with a perfectly square and true dado from one side of the board to the other (8" or so.)

Seems to be a cheaply made tool. It was included with the sale of the table saw and this was the first time I've used it long enough for form an opinion on it.

I found some good threads here using the search bar, but most of the photos are MIA bc of off site image hosting.

Anybody care to share their favorite sled for dadoes? Ideally I will design in such a way to use replaceable zero clearance inserts that I can swap out when I go narrower or wider with the dado stack for zero clearance on all my cuts. I find having zero clearance on both sides of the blade to be a bonus when not using a stop and trying to line up your stock with the blade. Sometimes a piece is too long for a stop or using rip fence/block as a stop.

Thanks for any ideas!

[Rick Potter]

Probably not what you wanted, but I would consider using a nice straightened and dressed 2x4 with two metal miter slot guides. Making zero clearance blade inserts is easy, and you can plow a dado on the face, where the fence hits the blade, and make a dozen simple inserts held in with two screws placed where the blade cannot hit them.

By the way, I bought some flat aluminum at HD that was 1/4" thick and 3/4" wide. Fit the miter slots on my Unisaw real nice, and the three foot piece made two guides. Measure first, sometimes their metal turns out to be sized metric, like the 14" steel rod I just bought. It was 6MM.

[Bill Adamsen]

Longer the slides the more accurate. There are a number of companies that make slides but I think they are hard to attach. I like simple hardwood slides, hard maple is good but I'm sure I've used all sorts of wood successfully. I mill to fit, then glue to the bottom of the sled by shimming under the slide in the track so that it projects above the table top so it can be glued. You can glue up the glides as a pair with a single large sled bottom, or independently cutting off the blade side overlap. I once measured my slides and they were pretty consistently 0.749"+/-.001" over the length (for a 0.75" track) with few sections thinner than that. I make the slides long enough that they are substantially in the tracks no matter where the cut in the sled. My sleds are tight enough that they don't work in extremely humid weather. Even so, there is play. Sort of the same amount each of us knows our sliding miter has when needed.

The fence is installed (glued and then possibly screwed) square to the cut. Both front and especially rear fence should be tall. Over time you will find the uncut portion of the fence gets smaller and smaller. I often make a separate "indexing" fence - essential for box joints and useful for repeatable cuts such as tenon shoulders, but could also be used for stock length to the left. For finger joints, dados and rabbets – "kerf fillers" you can glue into the kerf left by the blade in the fence avoid tear out when the next depth of cut is less than the prior. Most important, a well protected zone where the blade exits the rear fence. Sawdust will exit this tunnel with force.

To control tear out I just build a sled for each purpose. I have sleds for 1/4" and 3/8" box joints and one for crosscuts I no longer use (I have a slider). My sleds are relatively small, but I would build to the size I expected was required. Wide crosscuts (panels for instance) would require special thinking for keeping the slides in the track when initiating cuts.

[Bruce Wrenn]

I prefer to to dado's using router and guide. I build cubbies for local "Y's". The cubes are 16" nominal size, six long and four high. There is no way I could do thee on TS, as verticals have to align perfectly. I spend hours building dado jig so I can do a 8' piece pf plywood on one side, and then turn it over and do other side. For cutter, I use a reverse helix, down shear (prevents tear out.)

[Prashun Patel]

How wide were your dados?

Even the best of the miter gauges blink at 40" long stock. I would prefer a sled with better support for that.

[glenn bradley]

My sleds use replaceable inserts for the base and the fence. I can re-use sets used for dados, various angles and such. I haven't made a sled without this feature for years. It may be something you want to factor is. It is easier to store a few sets of inserts in a drawer than a herd of sleds. That being said I have three or more

sled sliding stop block (5).jpg

[Phillip Mitchell]

Prashun,

The dados were 1 1/2" wide by 1/2" deep; I was using a 3/4" wide dado stack. I think part of my issue is that even when "locked" at 90* to the blade, there is some flex in the miter gauge back and forth (relative to that 90* squareness to the blade.) As I push the gauge and stock through the cut, it could have easily moved out of square by the time I was getting through the board. I chalked it up to the gauge being "well used." Or that I just need to make a more stable sled for cross cutting and that I'm expecting too much from a miter gauge.

[Bill Adamsen]

The dados were 1 1/2" wide by 1/2" deep; I was using a 3/4" wide dado stack.

That is a lot of cross section of material being removed ... rereading it I'm guessing you made multiple passes. A sled would work well ... certainly better than a standard miter.

[Bill Adamsen]

My sleds use replaceable inserts for the base and the fence.

That is fancy! I just glue in a replacement strip and recut.