DADO Blade issues

[T Beckner]

All
I have a Craftsman wobble DADO blade that cuts a slant to the bottom of the DADO. For the life of me I can not figure out whats wrong with it. I have another one which does not do this and they seem like they are set up the same.
Any safe ideas on how to fix this.
Thanks
Terry

 

[Mark Gottesman]

A photo would help diagnose. Both the cut and the blades.

If you compare the two blades are the teeth sharpened the same?

I do think that the wobble dado is doomed to give you a rough cut, sloped sides and arced bottom due to the way it works. The wider and deeper the dado the more this will be evident.

I would suggest that upgrading to a stack dado as your situation allows will solve your problem.

Have to admit that spinning an off balance piece of metal at 3600 rpm does not sit well with me.

 

[McRabbet]

A wobble dado blade can only cut a square groove when it is set for no wobble at all (i.e., the dado is the width of the blade). As soon as it has wobble set into it then the outside edge of the cut is no longer perpendicular to the axis of the saw shaft -- it will produce a radiused groove that is more pronounced as the wobble is increased. There is nothing wrong with it -- it cannot do what you want, which is a square groove or dado with a flat bottom. The only advantage I can think of is that it is cheap (but sadly, you get what you pay for). The SD508 dado blade that is currently for sale in the Classified Ads has a pair of outside cutter blades and then a set of chipper blades that stack to fom a "wide" stack of blades of the exact width you want that cut a very clean square-bottomed dado. Stacked dado sets are far superior to wobble dados --- do your self a favor and replace your wobbler with a stacked one. I own a Freud SD508 and it is a precision saw accessory. If you cannot afford one, you can cut square dados with multiple passes of your saw blade with 1/8" offsets per pass (cut the outer edges of the dado first and then the waste part in the middle).

 

[JimD]

I disagree a little with the previous posts but not in the fundimental message. The teeth of wobble dados are ground to give a flat bottom cut at only one width. Typically that is about 1/4 inch. I have one that is ground to give a flat bottom at 3/4 inch. The most typical dado gives a concave bottom at wider widths. Mine gives a convex (raised) bottom at narrower widths. This can be removed to give a flat bottom. It is harder to deepen the more typical concave bottom dado to give a flat bottom.

But the inevitability of a non-flat bottom for many width dados is inherent in a wobble dado. A stack dado does not have this drawback. I also find mine to be much easier to set. I do not like having to take the wobble dado off, loosen the locking screws, turn it a little and try again.

Jim

 

[T Beckner]

All
I have 2 of these and use them for stuff which does not matter 2 much on looks and assetics.
I do have a stacked set which I use for nice things.
One wobble blade cuts the 3/4 DADO with a flat (to the eye) bottom And the other cuts kind of a rounded slopped cut at 3/4. They were given to me and I use them mainly for building bee equipment and such.
I will try and take a few pictures this weekend if I can since the weather is cold I'm staying out of the shop for a while.
Thanks
Terry