What to look for in a "good" dado blade set and/or am I using it wrong?

[osx-addict]

Hi all.. I know I'm asking a loaded question and I know that people have different opinions on this topic, but I'm looking for a good quality dado blade (6" is probably fine for my needs). I purchased, a LONG time ago (~15 years?), an Oldham (made in USA) Dado blade (like thisone) that had never been used until this weekend.. I setup my new Arbor for it and found that it cuts OK but does a poor job on the edges with tear-out in my 3/4" plywood.. Admittedly I was using it for a jig so looks don't matter but IF I were to need a good looking Dado this item will not cut the muster...

Ideally I believe part of the issue with this Oldham model is that it does not have enough teeth on it.. Should I be look for one that has more than 16 teeth? I see some other mfg's out there with at least 20-30 teeth on the same sized 6" set (e.g. Oshlun (30 teeth), Shopsmith (20 teeth)).. Perhaps It's a process issue on my end? Also, on this particular set I find the bottom is not as clean as it ought to be -- for a precision cut I'd probably want to use a chisel to clean the bottom -- is that normal?

P.S. I should note that this Oldham blade is not carbide or anything -- just Steel and I believe probably on the 'very' cheap side of the world -- perhaps that's part of the problem..

[holsgo]

for starters can you show a pic? Is the tearout inside the dado? I've got a 40 year old wobble and a stacked and haven't yet experienced a problem like you describe. If you put the stack together are there any teeth looking out of order as you look dead on to the stack? A fall or bend in the outer blade would certainly cause a problem. Lay the blades flat on your tablesaw and see if there is curvature. Maybe running it too slow? Now the bottom will require cleanup but the inside corners should be pretty sharp with a stacked. Wobble, well, not so much. Shoulder plane perhaps to clean the dado up proper.
Wet plywood will tear out easily.

[osx-addict]

I'll see if I can get some pics (not at home right now). The plywood is the cheapie crud offered at the local home center -- perhaps chinese.. Not sure. The tear-out was on the edges as I recall -- not in the dado itself -- the surrounding untouched (or should be untouched) wood. I do not recall the speed setting I was using but it was one of the "saw" settings.

[beeg]

Did you use a SLOW feed rate?

[pennview]

If you want a splinter-free dado in cabinet-grade plywood, you'll have to spring for a top-rated dado set like Forrest or Freud. I'm sure there are other brands out that that will do the job well, but these two brands are about as good as it gets.

[foxtrapper]

Plywood loves to tear, regardless of the blade. I'd suspect most of the trouble is feed rate, and the low quality plywood. Try some scrap and see how well it responds to simply slowing down your feed rate.

[billmeyer]

One thing you might check, I embarrassed myself this way. Make sure the blades are not installed backwards. I got interrupted once installing my dado set and got terrible results- luckily in scrap material. It took me awhile, but I finally realized my dumb mistake.

Bill

[JPG]

One thing you might check, I embarrassed myself this way. Make sure the blades are not installed backwards. I got interrupted once installing my dado set and got terrible results- luckily in scrap material. It took me awhile, but I finally realized my dumb mistake.

Bill

Bet THAT slowed down the feed rate!:eek::D

[mountainbreeze]

I have this set and it worked quite well on some mid-grade plywood. It doesn't come in a fancy box but it does have 6 tooth chippers and metal shims. My first project that I used it for was to make a wooden box for it

[beeg]

Here's one on sale for a few more hours.

http://www.shopsmith.com/ownersite/specials/7DU135.htm