# bit for Jack Miter molding joint



## tshaw47 (Sep 12, 2007)

found a molding joint I would like to try. The advantage is that the miter is less likely to open in winter. I understand the Jig construction but can't find a bit that seems to work.

My assumption is a 45 degree champher. Like a v groove but with an end mill if that makes sense. A top bearing for a guide in the template. Unable to attach the Jack miter article link, but I did attach a picture of the cut. The author mentions grinding the bottom of the bit flat, but I would prefer an engineered solution.

I appreciate any suggestions.


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## Mike (Nov 22, 2004)

I appreciate what you are trying to do, but I think a reminder of how wood moves might be in order. Wood fibers are very much like a bundle of straws. Moisture enters through the ends very easily, but most of the movement is cross grain as it expands or contracts. You should see very little difference in length. I use angle cuts on molding but I do the cuts with a small flush cut saw with fine teeth or in my miter saw. I really think there is little advantage to this particular cut in the photo. Even so, the answer to your problem is you can buy bearings to fit on the shank of your router bits, they are even inexpensive. I have never seen a bottoming chamfer bit but I imagine one of the companies makes them. You might look at the MLCS web site or perhaps Eagle America offers them.


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## Joe Lyddon (Sep 11, 2004)

*W e l c o m e . . A b o a r d !!​*


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## bobj3 (Jan 17, 2006)

This may help
But the bit will be hard one to find..


http://www.metacafe.com/watch/797840/woodworking_joint_the_jack_miter/
http://forums.jlconline.com/forums/showthread.php?p=172732&mode=linear


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