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when using this bit --1/4'' shank to make thru dovetails in 3/4" oak i get a lot of router bit chatter--does anyone else have this problem ? i think i will try the 8mm bit and hope it eliminates the chatter.---also have tearout at rear left side of dovetail even when using a backer board.---perhaps the red oak is to hard--any suggestions----tks,joe
Joe, the only 1/4" bit I have is the one that came with the jig. When I noticed this problem for myself on a maple board, I bought the 8mm bit and it took are of the problem. You also need to get the reducer so that you can use the 8mm bit in your 1/2 collet.Quote:
Originally Posted by joe zarnitz
I'm not exactly sure why you're getting tearout, but I don't believe it's because oak is too hard - especially if you're only getting it in one particular place. I'd look at your technique to see if that's the problem or perhaps the backer board isn't tight at this point. Beyond this, I'm can't think of what it might be. Some might suggest that the problem is that you're using a jig to cut your dovetails :D :p But we won't listen to them right now. :)
The 8mm shank bit is stouter and should chatter less, but it's not a horrible idea to plough through with a straight bit first. If you have a second router available, just set it up with a bit slightly narrower than the narrowest part of the dovetail will be and slightly shallower....or do it with the same router. No biggie!
I had the same problem with QS white oak. I also went with the 8MM bit (I don't know why that doesn't come standard) and make sure your backer board is at least as wide as the piece you are cutting and get it flush to the piece and you shouldn't have any problem.
I had same problems and gave Leigh a call. Info can be found on pages 141-143 of their User Guide, "Through Dovetail Pins Tearout" and "Dovetail Tails Tearout".
Chattering - "Note: Spiral up-cut straight cutters generally rout smoothly than the two-flute carbide-tipped bits". And I guess 8mm also works.
Pin Tearout - they list a 6 step procedure to reduce/eliminate tearout.
Tail Tearout - "With the dovetail cutter, most tearout occurs at the top left exit of the cut". They also suggest a "horizontal board end-grain pushed against the back of the workpiece and held in the rear clamp". And "if you have a variable speed router, try changing the speed and experiment with different feed rates".
On page 144, they list 3 others hints "for particularly vulnerable pieces or that last piece of exotic wood".
Regards, Joe