Dado blade on contractor saw

[Joe Trotter]

I have been pouring over the previous posts trying to find an answer.

I have an older sears contractor saw. It is in great shape, but after reading older posts it appears I may not be able to use a dado set on my saw.

From what I am reading the 3hp rated (1 hp maybe) motor might not be enough to cut a dado. The other concern is the arbor length.

Any thoughts on this subject appreciated.

Thanks, Joe

[Howard Acheson]

To use a dado, the arbor must be of a length equal to the widest dado you want to make. Most stack dado sets go up to 13/16". So you need a arbor of that length plus the width of the nut. You don't need use the washer so you don't need to consider that thickness.

However, Older (pre 2004) Sears contractor saws have a problem associated with the way they have constructed the arbor. You will see a sort of groove between the inner end of the threaded portion and the flat unthreaded space and the inside washer. This groove allows any chipper that sits in that spot to fall into the groove causing that chipper to rotate in a non-circular plane. The non-circular motion causes a deeper groove to cut in that position in the bottom of the dado. In addition, the threaded portion is slightly smaller in diameter than the non-threaded portion of the arbor. Again, this sloppy fit will allow the chippers resting on the threads to cut in an uneven path. In other words, it's almost impossible to get a flat bottomed dado.

The groove can be fixed somewhat by filling the groove with a two part repair epoxy like JB Weld.

[glenn bradley]

My 1970's Emerson/C-man saw had the groove but it did not align directly with a chipper and so proved no problem. The problem Howard speaks of does exist on some C-man's however so you will have to check your saw. If your groove does line up, you can circumvent this by adding a couple of the dado shims prior to putting your first outer blade on.

As mentioned, measure the thickness of your arbor nut, then the length of your arbor shaft, subtract the width of the nut and that is the widest stack you can run. This just means you might not be able to run all the chippers in a stack.

I can run a full stack on my current saw but in practice I run a 5/8" stack for almost everything 5/8" and wider. I just make multiple passes but, that's just me. The Freud Dial-a-Width SD608 would probably not work on your saw as the integrated adjustment mechanism makes it wider than a standard stack. It would not fit my current saw and allow a decent width cut so I went with the SD508 and have been very happy with it.

[Roger Ronas]

I've used an adjustable width dado set called a "short arbor, or short shaft dado stack" found on fleebay made by Delta. Was about 10.00 and a diameter of 8" and width up to 9/16. It only cuts ok, not great by any means. I would rather use a stack and just stack what will fit and make multiple passes.

[Bob Genovesi]

I have a Jet contractors saw and since it's only 1 3/4hp I opted for the Freud 6" Super Dado. I can put all the plates and spacers on without an issue and it spins up to 4000rpm in one second or less...

[Michael Donahue]

If you are happy with your saw for most of your cutting chores and dadoes are the real problem, use your router for dadoes! Here's a great jig for that purpose http://www.woodmagazine.com/woodworking-plans/routing/exact-width-dado-jig/

[Mike Henderson]

I have a Craftsman contractor's saw and have no problems with the dado blade. However, I'd rather cut a dado with my router so I haven't used the dado set in a long time.

I use a top bearing flush cut bit in the router (they're called a "bottom cleaning bit", here's (http://www.acetoolonline.com/ProductDetails.asp?ProductCode=AMA-45563&utm_medium=shoppingengine&utm_source=googlebase) an Amana example). This allows me to set the guide boards flush with where I want the cut. Much easier than trying to use those guide bushings where you have to calculate the offset. And where you have to make sure the guide bushing is centered or only use one side of the router to make the cut.

Mike

[The Amana example is a short bit (won't cut deep). I have other bits that are longer for deeper dados, although you can use the Amana to go deeper because the bearing will ride on your previous cut since it's a flush cut bit.]

[Chip Lindley]

Sears has sold Tons of Craftsman stack dado sets!! I used stack and wobble on my old '74 Sears saw! The stack had to be mounted without the outside arbor flange to cut with a full stack! I'm sure your 1hp is enough to cut some real dados.

[Rick Fisher]

It's just a matter of making a few passes on the wider or deeper dado's. I used to have a Delta contractor saw and it was about the only time I tripped the overload.

It should be fine.

[Joe Trotter]

Thanks for the replies!

I will look into a 6"set. Those freud units are pricey. They must be the cream of the crop :)

Joe