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Thread: Is it a stupid idea to make my own dado blade??

  1. #1

    Is it a stupid idea to make my own dado blade??

    It suddenly occurred to me that I might be able to make up a cheap dado blade from 7 1/4" circular saw blades by alternating teeth alignment so that the blade bodies lay flat next to each other and the teeth overlap in their cut kerfs. It probably would require more blades than would be economical to make a 3/4 dado blade, but for 1/2" or less it might not be that bad. Would it even be safe to do?? Maybe use shims between them so it doesn't require as many?? Sometimes these blades can be bought for around $5 to $8 each here. I could put together a 1/2" dado for probably under $30. But I don't want to lose a finger or get hurt bad in the process. I have no experience with dado blades at all, so I don't know a thing about what I'm talking about doing here. Seems to me that the required amount of blades might be too heavy to turn them fast enough to work also, or could damage my saw. What are your thoughts??

  2. #2
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    Sometimes these blades can be bought for around $5 to $8 each here. I could put together a 1/2" dado for probably under $30.
    IMHO - it's false economy.

    There's a few "real" stacked dado sets that run under $50.00.
    Harbor Freight sells one for ~ $35. It's on sale now for $27.

    There's another one I can't recall right now that often goes on sale for $39. It's very well thought of by a number of forum members.
    W/luck someone will chime in with the name and where to get it.

    You might also try Sears and see if they have any of the Freud box joint blades left @ the closeout price. I believe I paid around $30. for mine on closeout.

  3. #3
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    Hoh-boy.

    This is not a case where I'd be re-inventing the wheel.

    JMHO. YMMV. Professional driver. Closed course. Etc., etc.....

  4. #4
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    I had the harbor freight blade and it has to be better than a bunch of stacked blades.

  5. #5
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    It might have merit if say, you only wanted to dado for 3/4" plywood shelves. 3 blades @$5 each ($15 total) would give a spaced dado of 3/4"- 1/4" (the blades combined kerf loss) / 2 = both lands @1/4" each, and they wouldn't be too tough to break out. Finish with an old woman's tooth, file, sanding stick or router with bottom cleaning bit and... aw the heck with it, just get the dado set.

    - Beachside Hank

  6. #6
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    Stupid...no, ill-advised...yes. A self made stack will cut grooves but the bottom is likely to be riddled with ridges. Stacked dado sets have bevel edges on the outside cutters, and flat teeth on the inside chippers that are all very closely matched to give low tearout at the exit of the cut, plus leave a nearly perfectly flat bottom....ain't gonna happen with a bunch of ATB blade stacked together. Stacked dado blades also have proprietary overhand designed specifically to work as a set...individual ATB blades are made to work alone, and have an overhang designed for that. Check Ebay and see if there's any $35 to $51 German made Onsrud stacks left...tough deal to beat.
    Last edited by scott spencer; 12-30-2011 at 11:17 AM.
    Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

  7. #7
    Dado sets are designed to be stacked together on an arbor. There is no interference between the teeth on each of the blades. The plates or saw bodies are meant to touch not the carbide, the carbide will break if stacked together.

    The dado set is also ground so that it will give a relatively flat bottomed cut (Forrest, Amana, Freud etc will be better than HF or Avenger). Dado sets will usually include shims that allow for 0.005" adjustment to dado width.

    Another consideration is material to cut. Almost all dados will rip natural wood. Very few dados will leave an acceptable cut in melamine. Of course a zero clearance insert or dado specific sled will help any set.

    The cost of sharpening adds up quickly and may exceed the initial purchase price of an inexpensive dado. I wouldn't consider some dados sharp when they are new. Also, every piece should be sharpened with the set otherwise you will have uneven dado cuts.

    Jerrimy
    I make dirt out of woodworking tools.

  8. #8
    I tried this and considered myself stupid for it. I got a deal on a set of 10 or so 7 1/4" circular saw blades and stacked/alternated the teeth. It works, but it's the sloppiest dado you could hope for. I could get a better cut just taking a full sized 10" 1/8" thick blade and taking several passes. So now, I've wasted a fair amount of money on a bunch of blades I'll likely never use. This could have been put toward a much nicer dado set than the one I actually ended up with. So my advice is just buy a cheap dado set if you're worried that much about cost, much better than paying for a cheap dado set and a stack of 7 1/4" blades.

  9. #9
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    I believe on the bay there are some Onsurud blades, I am sure I remember seeing them there. If you do not find them in a search just look in the guys ebay store, I'm pretty sure he had stacked dadoes.

  10. #10
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    Check out an Oshlun. I have one and it cuts pretty good. Smooth bottom. http://www.amazon.com/Oshlun-SDS-084...5259737&sr=8-2

  11. #11
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    I have done this trick a few times. When I needed a DEEP dado, for instance. I used two crosscut blades for the outside, and a couple "rip" blades as chippers. Didn't go out and buy them, they were just sitting around the shop. The other time I needed this trick, my "normal" dado set was out getting sharpened, so a three blade "set" was used. I suppose I could have used the router and a narrow bit, but I like to used the saw for through grooves. I have broken a router bit or two doing those narrow through grooves. Dado set I use is a 6" set from Vermont American. Hey, it works. SDC11878.jpg

  12. #12
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    I use some pretty cheap blades in my skill saw for demo and rough work, and for that they are fine. But they aren't the most precise things I've seen. I just can't imagine stacking 5 pieces of junk together and getting any decent results. For everything I usei my dado blade to do I require more precision than I feel possible from a disposable saw blade. Plus my dado can be sharpened as many as 10 times, then retouthed by the factory. With the disposable blades, when they are done, you pay again. So yes, stacking skill saw blades to make dados may not be your best option.
    Last edited by Peter Quinn; 12-30-2011 at 12:28 PM.

  13. #13
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    If you want to do it you can. The dados won't be pretty but if you have some blades lying around do it yourself and satisfy yourself. I did it a couple of times back in the old days with non-carbide toothed blades, in the end a wobble dado cuts a cleaner groove.
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  14. #14
    Scott hit the downsides. Many folks have done this and depending on what you are making (an outhouse for example) it would be OK. All kidding aside, IMHO if you want a cheap way to make a dado, use a router bit.
    “If liberty means anything at all, it means the right to tell people what they do not want to hear.” -- George Orwell


  15. #15
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    Another point about circ. saw blades: Two blades will NOT make a 1/4" wide groove, you'll need a shim, OR a third blade. BTDT.

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