Just cut a bunch of tenons on the table saw using a Freud Super Dado. Even though I used the cross-cut sled with a stop and hold-down, I’ll have to say that they really didn’t turn out very well.
Stock was all consistent in size, but tenons weren’t. Some were too thin, some too thick. All were quite rough. Seems as though the height of the teeth vary, leaving grooves and ridges. For now, I’ll go back to cutting them on the band saw, but I’d like to try to get better results on a future attempt. Any suggestions?
Jeff
Replies
Seriously consider loose tenons! For the best home made slot mortiser see FWW # 141. By making mortises in rails and stiles your alignment is perfect every time and since the slots are all the same you are insured of a perfect fitting tenon.
Rick
I've had this problem when I've sent a dado to be sharpened and they didn't take the time to joint the dado set to the same height. Take the dado set to your local saw shop and ask them to joint all dado blades and cutters to the same height.
BTW, with a regular blade in your sled, make a series of 1/4" cuts and see if they are consistent. If they are,then it's the dado blade heights. If they aren't, then it's a sled problem.
hope this helps,
silver
I suspect this is part of the problem. If teeth are at different heights, there is bound to be a lot of tearing and gouging. But gosh, the set is brand new; you think they'd be ground properly.
Jeff
Thanks everyone. None of the problems you suggest seem to apply. Saw is only a few months old, 3 hp. Jet. Everything tight; throat plate flush to table top and snug. As I mentioned, the wood is clamped down so that shouldn't be the problem. There is a possibility that sawdust got under the sled, but I won't be able to tell unless that should repeat itself.
I've considered floating tenons, but I usually avoid using a router if possible. (Don't think mine has been out for a year now. I hate those things and they frighten me.)
By the way, Forest Girl, the Freud site has instructions for stacking the dado.
Jeff
Thanks for the tip on the Freud site, Jeff. BTW, if there's anything actually wrong with that dado set, I'm sure they will stand behind it.
I had a problem cutting a rabbet a couple weeks ago, turned out that the 90-degree stop on my saw was no longer perfect. Even though it was darned close, the rabbet looked like...well it looked bad. Readjusting to a perfect 90 degrees made a huge difference.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Jeff,
I'm concerned about your dado set and wonder if you will perform a test for me. If you have a scrap piece of melamine (or laminated wood), please stack the dado and make a cut across the melamine that just barely scuffs the surface. That's the easiest way to evaluate the dado for accuracy. Any imperfections will stand out like a sore thumb. By all means, DO NOT HAVE THE DADO SHARPENED! It will void your waranty. I'll be anxious to hear the results.
Charles M
Freud, Inc.
Thanks! I'll check in the A.M.
Jeff
Jeff,
For what it's worth, I also have a super dado and I get the same problem when I use it on the RAS, but it works fine in the TS. I've never really figured it out either.
Don
Don, I have a large (10") diameter dado set on my RAS. Found that the cuts were clean, except for the little scribe lines along the edge from the side cutting blades.
But my thickness/depth from end to end was quite hard to adjust. I did finally get it by trial and error, slipping shim material under the front of my table and sliding it back until the depth of cut in the front equalled the back.
Lots easier to eliminate sawdust and sled variables on the RAS IMHO.
Best, Mike
Mike,
Yep, I get the scribe marks from the side blades, but no problem with depth from end to end or front to back. I'm using an 8" super dado though and I wonder if the 10" may not be flexing? Curious though, I much shimming did it take on the table to compensate in the cut?
Don
Charles,
Tried the light cuts in melamine on particle board, as well as some heavier cuts and they're all smooth as a baby's bottom. Will try working with it some more and see if problem repeats itself.
Thanks,
Jeff
that don't make any sense to me tendons changing thickness from one to the other. Unless you got saw dust under the sled or under the board on the sled or the blade adjustments is loose and is moving by it self or is it the blades are to big for the arbor and the nut us loose or the board is to long and need to be supported because it lift next to the blade.
roughness in the cut sure.
I have the Freud 6" Dado set (Safety Dado, I think). It cuts very cleanly. Although I've not made any tenons with it, I know that when cutting dados, I have to make sure that the stock is firmly down on the table, as if it floats up even a fraction-of-a-fraction, the dado depth will not be consistent.
Also, take a look at how all the parts of the dado are fitting together when they're mounted on the arbor. The blades should all come together tightly. There are no instructions with my dado for how the blades should relate to each other, so by trial and error I've learned to shift the various blades so they sit tightly together without the teeth interfering.
Other miscellaneous things to watch are sawdust, as mentioned, your throat plate being absolutely flat to the tabletop. Anything that can change the riding of the stock on the table.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
What manufacture table saw do you have?
Also, the two outside blades on dados are ground to cut a slight bit deeper than the chippers. This is to get a clean shear on the sides of the dado.
Rough is par for the course with Dado Tenons. Try using a Tenon Jig for smoother tennons.
I am at a loss how the thickness could be so inconsistant. I would imagine that some inconsistentcy would be normal, e.g., a 32nd or 64th or so, but much more than that would have me scratching my head. What is the thickness variation?
I have a Systematic Stacking Dado and it is fine. I usually mill them oversize and pare them down anyway with a sharp chisel or sandpaper.
I would check out the operation of your saw with other blades and see if there is any runout using other blades. If not, then there is a problem with the Dado Set. Try another brand.
These things aren't perfect, and I had to return a set a while back because the hole was not a true 5/8", it was too tight and wrecked the threads of the arbor.
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
I had a similar problem awhile back and found that my sled was warped ever so slightly. I never noticed it in normal use but when cutting shoulders for the tenons the height was inconsistant.
Take a close look to determine that your sled is actually riding flat on the table and not just a hair high, especially in center where the blade passes thru. Downward pressure while attempting to hold the piece tightly to the sled will change the depth of cut.
Good Luck, Hugh
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
So that's the origin. I've always heard a similar version (... but (madam) you will still be ugly.) attributed to Winston Churchill, but then the old boy was not above a little borrowing when it suited his needs.
As I noted above, the cuts seem good now. Just will have to keep an eye on it .
Jeff
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