# glue joint bits



## mtsaz100 (Jul 20, 2017)

HI- has anyone used (I'm sure someone has) a glue joint bit? I am trying to use this amana 45790 --its new- so should be good- its a big hefty bit. The issue is that things are going along smooth and then it just grabs the wood and rips a chunk out. I'm doing small cuts--just enough to leave the pattern of the bit on the wood, but my question is what is the problem? lol.

I am doing this in a router table- and wondering if the speed needs to be faster or slower, or if I need to take some tiny tiny cuts- and just eventually work my way to the depth of the pattern of the bit. That would make sense with a chinese bit- but this is supposedly a very good bit. 

I want to use a 45 degree drawer lock which is also a big beast- but I want to get this problem resolved first. Any help or advice would be greatly appreciated. Here is a pic I downloaded of the bit and the pattern it leaves on wood. I am only trying to cut enough to leave that zig zag pattern- no deeper. Thanks!!


----------



## Cherryville Chuck (Sep 28, 2010)

It's the wood you are using it on. Some woods and grain patterns are extremely hard to avoid tear out on. If you look at the piece of wood from the side where it tore out I'd be willing to bet that the grain is sloping up towards you as you are feeding. Smaller cuts can help but won't always solve the problem. If you can imagine the geometry involved then the heavier the cut you are taking the closer the angle at which the bit exits the wood is to 90* to the face. This force applied at 90* is what wants to shear the grain layers apart. So the lighter the cut the closer that angle is to being parallel with the face of the board and consequently less shear force.


----------



## JOAT (Apr 9, 2010)

With the strength of modern wood glues, I really don't see the need for a tool like that. Anything I have glued that I wanted to take apart later to reclaim the wood for another project I've always had to knock it apart, with a short sledge hammer, and several blows. And the wood is what gave, not the glue.


----------



## Terry Q (Mar 2, 2017)

Are you using that bit on the end grain to make longer boards, or on the edge to make wider boards? Personally, I'd only use that kind of a bit on end grain for making longer moldings and such. Like others have suggested, no reason to use anything for edge gluing. 

The larger the bit, and the more mass, the slower the speed. There are many tables suggesting speeds for various bit diameters. I have several router bits that have tables that come on the packaging or instructions so try that first. Otherwise you can go to any web site that manufactures router bits to find the suggested speeds. Not that hard though, if your smallest router bits require the fastest speeds, and the big panel raising bits require the slowest speeds, then everything else falls in between. 


In woodworking there is always more then one way to accomplish something.


----------



## Quillman (Aug 16, 2010)

Fence to be offset = east/west depth of cut.
Moreover, that cutter is way too big, even for 3 hp routers.


----------



## DonkeyHody (Jan 22, 2015)

I agree that it's probably the grain of the particular board you're using. Also agree that such a joint is not needed for edge jointing except for alignment. I don't think the bit diameter is your problem, especially since you're only cutting at the rim instead of almost to center like a big panel-raising bit does. The only time I ever slow my router speed down is with my 3 3/8 inch panel-raising bit. All other bits, I spin them fast and adjust the feed speed and depth of cut. 

Try a different piece of scrap and see if you get better results.


----------

