Dado blade questions

[jonmulzer]

What is the general consensus around here about dado sets for the BT3000? What issues do you have exactly with an 8" set? I believe most around here run 6" sets, what is the deepest dado you can cut? There is one occasion where I will have to cut 3/4" by 1 3/4" dadoes if at all possible.

Next question, if I were to get a miter slot accessory table, can you use a commercial tenoning jig with it?

[LCHIEN]

the FAQ goes into great detail on the dado issues.
Maths not too hard...
same for regular blade as dado, no matter
10" blade will cut 3.5" deep on the BT3
8" will cut 2.5"
6" will cut 1.5"

tennon jig, yes, can be used with miter slot.

[Uncle Cracker]

I've never needed a dado deeper than my 6" set will cut. Any larger blade is just a waste, even if you have the clearance (which you won't).

[jonmulzer]

So the 8" set does not fit at all for 3/4" width?

[dbhost]

The 8" blades are not generally considered a good idea for any T.S. under 2HP. I believe the BT3xx uses a 1.5HP 15 amp motor like my BTS21 does...

As far as 6" dado blades go. I can tell you one thing for sure. I own a Skil 6 inch stack dado set, and am NOT happy with it. It cuts VERY unevenly. I have been trying to cut 3/4" half laps in 2x4 stock using this setup, and to say the least, they are NOT glue up worthy without some SERIOUS work with a block plane and a sander to level it all up... I can not find this Dado set on the Skil website, or online anywere for that matter. BUT...

It appears to be the EXACT same item as the Vermont American 26741 6-Inch Stacked Steel Dado with a different name screen printed on it. Which is partially why I purchased it. I have owned and used Vermont American tools for many years with great success. This has been a SERIOUS disappointment.

Maybe I am doing something wrong. I doubt it though...

[Uncle Cracker]

There are potential clearance problems in the BT3000 for 8" stack dado sets when rigged for the wider widths. You will want to avoid this. A dado set is an expensive thing to buy just to find out that it won't fit your saw. How often are you gonna need a dado deeper than 1-1/2"?? And a good point was made in earlier posts about the power limitations in the BT, which will be exacerbated by cutting deep dadoes. Get a good quality 6" (like a Freud, or similar) and then relax...

[rnelson0]

And a good point was made in earlier posts about the power limitations in the BT, which will be exacerbated by cutting deep dadoes.

Unless you have a really beefy table saw, deep dados should be handled the same way deep router cuts would be - do multiple passes increasing the depth of cut each time. If you're cutting a 1.5" dado, you're not working with plywood anymore so you're probably working with something fairly hard. Even if your saw has a high horsepower motor, you're going to lengthen it's life by avoiding a deep plunge in a single pass.

[John Hunter]

Next question, if I were to get a miter slot accessory table, can you use a commercial tenoning jig with it?

I just built the one in this article for my bt3, it rides on the fence and I have been very happy with it. http://www.bt3central.com/articles/files/ten-jig.pdf

[rnelson0]

Nice jig. Designed properly, you could combine a raised panel jig and a tenoning jig into a single jig, assuming your maximum size for each was the same. You wouldn't want your tenoning jib to be so huge as to be unwieldy, after all.

[jonmulzer]

Unless you have a really beefy table saw, deep dados should be handled the same way deep router cuts would be - do multiple passes increasing the depth of cut each time. If you're cutting a 1.5" dado, you're not working with plywood anymore so you're probably working with something fairly hard. Even if your saw has a high horsepower motor, you're going to lengthen it's life by avoiding a deep plunge in a single pass.

Not if it is 1 3/4 x 3/4 x 3/4. For what I would say is a type of T-Bridle joint but I am fairly sure there is another name for it. I can get by with 1 1/2 though so a 6" set it is. I will just have to modify my joinery plans by cutting the matching dado for the bridle 1" deep instead of 3/4".

[Black wallnut]

In this picture:



look for the arrow and the vertical line near the mount for the riving knife. It is in this location that most folks have had clearance issues with 8" dado stacks. Many have carefully ground off this boss to make the needed clearance.

[jonmulzer]

Thank you very much Mark, that answers my question perfectly and I can easily handle modifying that to use the dado stack that I want to.

[LCHIEN]

I disagree with Mark.
When installing a 8" dado, there will be very little clearance at the point he indicated. Filing or grinding May be needed but in my case was not. However, this requires leaving the 1/4" spacer on. The dia. of the 6" allows the blade to get closer to the motor, and you take off the last 1/4" spacer. I'll quote the FAQ:

"Generally the 6" size is considered the best size for the BT3x. It handles most practical depth cuts and it is also the size recommended by Ryobi. The 8" dados work but have very little clearance and usually cost more. The exact problem with 8" dados is this: With the clearance problems you must leave the smaller ¼" spacer on the arbor next to the motor. All is fine up to about ½ inch or 5/8" stack of dado blades. Once you try to put more than about 5/8" (like ¾" or 13/16") then this can push the leftmost outer blade onto the threaded part of the arbor. Then that blade will be off-center by about .010 (the differences in the thread height to the arbor) and the cut will have a non-flat bottom on that end. You may also have to leave off the outer blade washer as the nut will be on the very end of the threads."

I might add that leaving the blade washer off is a questionable practice. Done it but never felt comfortable doing so.
So an 8" dado stack will work up to 1/2" after which the outer blades ride on the arbor threads making them uneven and you have to leave off blade washers.

[Black wallnut]

Loring how about posting a picture detailing exactly where an 8" stack has clearance problems. Where do the blades hit with the spacers removed? I stand corrected.

[pelligrini]

On my 21829 Craftsman clone I run into the same problems as stated by loring and in the FAQ. I can't use a 8" stack without the 1/4" washer. In the photograph you posted I had clearance issues where the boss curves at the corner where it meets the side. It wasn't so much the length of the boss, just at that joint.

The first time I used a wide stack the arbor nut hit the outside edge of the blade enclosure when I lowered the blade too.

I finally used a thinner washer instead of the stock 1/4" and it gave just enough clearance to clear the curved joint. I bent the outer guard enclosure a small amount to provide clearance at the end of the arbor.