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kbrunco

Brace and Bit Help Needed

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Hello all. I am trying to make some legs for a work bench with mortise and tenon style stretchers. I glued several doug fir 2 x 4's together for the legs and am now attempting to use a brace and bit to bore out the mortises. I can't get the bigger bits (using a 25/32 at the moment) to keep a good bite in the wood. After about 1-in they stop pulling themselves through (that is also about the depth I think the tip is breaking through the first board before going into the second one). If I use the 3/8 bit I have no problem. It just takes A LOT more drilling and then cleaning the mortise. I have tried sharpening them, which has helped by getting it to go as deep as it is now. The bits aren't super fancy. I picked them up new (some generic brand) off ebay. Any suggestions on what I need to do?

Quin

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With larger bits, we have to work harder to turn so when we put some weight behind the rotation the brace invariably sways from side to side. This tweaks the lead screw in the cut and tends to ream out that hole so that after about an inch of depth the hole is too wide for the screw to grip any longer. The key is to focus on keeping the brace vertical with very minimal side to side movement. I find resting my forehead on the pad isn't enough here and I have to put my shoulder behind it to hold it steady. To restart those hole you have "stalled" in, hit the center of the hole with a scratch awl or bird cage awel to but a small hole for the screw tip to sit in and grip again. You could also drill a pilot all the way to depth with a 1/8 bit and that will give your auger tip something to always bite on.

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If your are currently using a 10” brace (5” radius), you could pick up a 14” (7” radius) brace which would give you more leverage. Shannon’s advice to keep it perpendicular to the surface still apply (no wobble).

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I have had a little experence with this. I found that as long as the spurs and cutters were sharp and screw was clean and sharp, I did not need to really bear down on the brace so I had an easier time keeping the bit going true. I was using a 1' bit for drilling mortises through 6x6 yellow pine. It did take me quite some time to drill those 8 mortices though.

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Thanks for the advice guys! The pilot holes and resting my forehead on the brace is helping. I still wobble but not as bad and if I go slow I can get it to bore through.

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