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Dumb Dado Question

Some 40 years ago when I was in high school the shop teacher would stack regular saw blades together to make dado cuts. Why shouldn't that be done?

Tom

Reply to
Tom Lewis
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For starters many saw blades centers are not flat. They may be hollow ground and you would end up distorting the blades. Most are not designed to crosscut and leave a smooth bottom unless your are using a rip blade and are going with the grain. A good dado set is precision matched so that the bottoms of the cuts will be even. This is not likely to happen with common blades and especially if one of the blades has ever been sharpened.

Reply to
Leon

Accuracy for one. With the combination of blades you can get most any thickness and easily adjust with shims for a few thousandths if need be. It is easy to compensate for the undersized plywood.

hey are also made to work together as a set. Blades may vary a bit from one manufacturer to another so just grabbing blades at random would not give repeatable results. Ed

Reply to
Edwin Pawlowski

What looked to a youngster like a stack of regular blades, was probably a stack of, you guessed it, stack dado blades. Even 40 years ago.

O'course you could stack 6 Forrest blades to do a 3/4" dado and it would only set you back $600.

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Reply to
Pounds on Wood

I always thought the answer was chip removal and also the fact that the inside chippers only have two teeth set on opposite ends which allows for setting them inside the teeth of the outside blades.

Dumber question yet is the 8" Delta dado stack. One of the outer blades says "this side out". That's it. Does it mean facing out, which would work if I put next to the inside arbor plate which somehow translates to "this side in"? Or does it mean that the blade goes next to the arbor nut, ("out" from my perspective) but then it has to be positioned such that the "this side out" is actually facing in.

Who's on first, etc.

Reply to
Tom Kohlman

Look at the tips of the outer blades (not the chippers) you should have one side that some teeth are pointed toward the outer side of the blade if you look at the other blade the teeth should be pointed to the opposite side. this is how you figure out which is the left and the right side blades.

CHRIS

Reply to
Chris Melanson

Thanks Chris...now take me one step further!!! Left vs. right on the teeth I can do...now what do I do with that information??? LOL

So we come to a common point of reference, on the arbor nut side do I want teeth pointing in or out (or up or down or north/south or east/west or horizontal/vertical)...better yet, there is a washer welded onto each outer blade around the arbor hole...do they face towards the chippers or towards the arbor washers? (I could make a case for either way...towards the chippers to act as a shim, towards the arbor washers to stabilize the blades). Have actually tried them both ways and can't see much difference other than the latter seems to make for too tight of a dado but perfect if I add one or two of the cardboard shims that came with it.

thanks again

Reply to
Tom Kohlman

Let's take this one more step. The chippers have usually two or four teeth. You put four of them together between the outer blades to make the thickness you want. here do you place the teeth of each. One in back of the other? Stagger them? Put some distance between them? Does not matter at all?

Ed

Reply to
Edwin Pawlowski

"This side out" means outside of the stack. Given that and the teeth facing the correct direction, means you got it right. "This side out" would be meaningless if it meant outside on the arbor, since there are left and right hand arbors out there.l

Reply to
Pounds on Wood

Tom,

assuming it wasn't a dado set he was using, it is likely the blades were steel and not carbide tipped. Should you have a stack of carbide spinning at

3450rpm and one blade either slips or stops, the remaining blades will have so many teeth missing it'll look like the nightshift at the WaffleHouse.

This assumes the freed teeth haven't turned you into a colander and you are still physically capable of looking at the mess.

Reply to
Greg Millen

Assuming the chippers are perfectly made, (balanced), it wouldn't matter as the rotational forces of the chipper(s) would place even load on the arbor/bearings as they spin.

However, that would be a bad assumption. Nothing's perfect, and since I don't have a several-hundred-dollar set of dado blades, I assume mine are less perfect than others. ;>

I stagger them as best I can so that there is even distribution of weight about the arbor. I get little, if any, vibration using this method. (I've never done it any other way, so I don't know that I'd get any vibration jamming all the chipper blades' teeth right next to each other, either.)

Fwiw, Michael

Reply to
Michael Baglio

"Tom Kohlman" wrote in news:k9Hec.18196$ snipped-for-privacy@news4.srv.hcvlny.cv.net:

I was confused by that too. I came to the conclusion that the printed side should face the arbor. That gets the orientation of the teeth right as well as the little spacer disks that they have fixed on the inside of the outer blades.

Reply to
Secret Squirrel

Forget the arbor, just chant to yourself: "OM, OM, The chippers go on the inside of the stack, the blades go on the outside" ... and you can't go wrong.

Works for me. ;>)

Reply to
Swingman

"Swingman" wrote in news:1dGdncxM2t9DcubdRVn- snipped-for-privacy@giganews.com:

Actually with this set you would go wrong. There are round discs attached to the side of each outer blade. They are not thock enough to eb stiffeners but are just shims that are permamnently affixed to the blades. If you reverse the blades these shims would be on the outside of the set and you would not get cuts in any of the standard sizes.

Reply to
Secret Squirrel

Sorry, but that still sounds like a no brainier to me. I tried to put it gently ... let me put it another way ... and not directed at you personally, you understand:

Despite the fact that I've never seen a set that didn't come with specific instructions, and even supposing that these instructions were somehow MIA, then a good case can be made that anyone incapable of NOT being able to figure that out, or incapable of figuring out how to use all the blades and chippers in any Dado set, would highly likely be better off NOT using one in the first place without personal, hands-on instruction from someone who does.

IOW, dado sets, of any ilk, are not to be taken lightly ... if you don't understand their use, don't rely on second hand information, get firsthand instruction.

Reply to
Swingman

you want the 'flat side' of the teeth towards the other blade(s) installed, and the 'angled out' side of the teeth 'away from' the other blade(s).

If you put _just_ the two outer blades together, with no chippers, you should have a combination that looks like a 'normal' blade.

What you call the washer is probably a 'stiffener', and should be on the outside of the blade pack. i.e. on the side away from the other blade(s).

If in doubt, _read_the_directions_. It is simply *amazing* what one can find out by doing that.

Reply to
Robert Bonomi

Given the option, staggering is preferable. It makes for a more even load on the saw bearings.

A 'staggered' setup does not necessarily imply a uniform set of offsets as you go from one side to the other. sometimes there are benefits to be had if the 'angularly adjacent' teeth are not on physically adjacent chippers.

The extreme case, 2-tooth chippers, with several of them set together, would result in a big 'chomp' as they all come in contact with the wood and "no" chomp, while the leading/descending tooth has cleared the (nearest the user part of the) piece, but the trailing/ascending tooth has not yet contacted the (farthest from the user part of the) piece.

Reply to
Robert Bonomi

I have done this before and have had no problems. I worked in a lab once where they bought cheap 8" blades in bulk (50 at a time maybe?) I used to stack these togther to make dado cuts. They were flat top ground blades and they made a pretty good cut. Not perfect, but better than some cheap stacked dadoes that I have seen.(the baldes were not exactly perfectly the same diameter, but really darn close.)

Some one else stated that this would be dangerous if the blades slipped and the carbide teeth broke off and went flying. I don't buy this argument. First off, as long as you tighten the arbor nut properly, they are not going to slip. Secondly, this is no different than most stacked dado sets. On my delta set, the teeth all overlap each other. if the blades ever slipped (which they don't) the carbide would become projectiles as well. It is not an issue.

I do agree that in general, it is probably cheaper just buy a stacked dado set. (Unless of coarse you have a pile of bulk blades setting there like i did.

Just my opinion.

Reply to
Joe Wilding

If in doubt, _read_the_directions_. It is simply *amazing* what one can find out by doing that.

I ALWAYS DO...problem here is there weren't any...NADA...ZIP...ZILCH...all I got for the $99 was 2 blades, a handful of chippers and some cardboard shims in a cheap piece of plastic.

Reply to
Tom Kohlman

Swingman...I thought you were leaving the group?

It isn't a "no brainer" and the instructions were not MIA...it was a new pack and there were none that I recall but then again I ditched the cheap plastic factory "storage case" after a few uses in favor of a home-made wood box that gives me easy access to the parts, keeps them from banging against each other, doesn't take 20 minutes to get them all back in when I am done plus it holds the dado TS insert so everything is in one place.

I'll ignore your previous comment about chippers sandwiched between the two outer blades. I concluded that must have been a personal reminder from you to you. Do what ya gotta do I guess. Read it often and don't forget your safety glasses.

From what I've gleaned from the left/right in/out up/down posts, I think the answer is the round disks attached on the outer blades face in towards the chippers. That's the way I've always positioned them but have been getting less than stellar results and was wondering whether the blade orientation was wrong. Thanks to all for clarifying.

Reply to
Tom Kohlman

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