Thread: Home made Dado blade

Originally Posted by echnidna

Probably coz it's a fashion here, specially in this forum.
They're illegal on Table Saws in Europe due to the dangers.
They were really designed for Radial Arm Saws and work very well on the correct machine.

Sorry, I don't think so, They were about long before the RAS was ever concieved. I think you will find that mosr RAS have too short of an arbor shaft to hold multiple blades. Cabinet & Unisaws have long Arbors and can hold Dado blades but Contractors' saws and table top saws have much shorter arbors and can only accept 1/2" wide combinations. You need 2 full threads showing past the nut, to be safe. (2 all the way around)

Dado heads were first introduced as Gang saws where more than one blade was attached to the arbor, a spacing was placed between the blades, Then some one came up with the idea of chippers to clean out between the kerfs. Old Gang saws were constructed somewhat like today's molding machines except the arbor was under the table.

As for more dangerous than a router, I find they are safer if you respect and follow basic table saw safety. Use feather boards, Guards, push devices, etc. Dado with a router is taking a big bite in wood with an exposed spinning cutting thing held by your hands and slinging chips in your face and eyes. I think I would rathe do some extra setup and push my wood through with a pusher ot stick. I vote for the stack dato cutters over the router, althoug I have done both and still do both.

For me, the biggest pain in using dado blades is having to change the blade on my tablesaw and set the thing up. Although if you are doing a lot of them, there's no doubt it is a much more efficient process than multiple passes with a router.

I've seen the comments about dado blades being prohibited on European table saws. Personally, I understand neither the hysteria nor the logic.

I use a stacking dado in my Unisaw frequently. It doesn't loosen up as some have suggested. In fact, when I tighten the dado blade or any other blade I only use a wrench and fingers. I brace the wrench against the throat opening and pull on the blade (or dado) towards me until snug. After use, the blade must be braced to loosen with the wrench.

The only additional danger that I see with a dado is a wider kerf. But then, one is not supposed to put one's fingers into the spinning blade.

Using ordinary saw blades to create a dado effect is not a really good idea because the teeth are sharpened differently from that of the "standard" dado tooth grind.

Using washers or spacers to separate blades to create a dado is probably not the best idea either. Unless the spacer is hard steel and machined to have two parallel sides, the blade closest the arbor nut will wobble.

Using a soft material as a spacer such as hard wood, will make the wobble even worse. I'm not sure exactly why but, I think that as the arbor nut is tightened, an uneven pressure is placed upon the blade by the arbor nut possibly due to the threads. I think that it is just the way that threadded nuts work. Anyway, the uneven pressure causes the hard wood to compress unevenly causing blade wobble.