On 2/16/2013 9:02 PM, Gramp's shop wrote:
The woodworkers show was in town today and I brought one of the broken screws and a sample to get some opinions from the graybeards. Here's what they had to say:

1. Square drive screws don't allow the driver to slip off -- like philips head -- when the screw is tight leading to breakage if I overtighten.
2. Screw should be lubed -- soap or wax.
3. Pilot hole should be larger diameter than I chose.
4. There was too much torque on the Makita driver. My driver does not have adjustable torque, but the drill does.

So, I took some scrap and used the same screw, drilled a larger pilot hole, lubed the screw with dish soap and drove it with drill at a lower torque setting. Worked fine, problem solved.

Larry



On Friday, February 15, 2013 4:47:40 PM UTC-6, Gramp's shop wrote:
I'm affixing the face frame for the buffet to the leg/side assembly. The legs are 1 1/2 hard maple. The face frame is 3/4 hard maple, in which I drilled 3/8 deep 1/2 inch hole to accommodate the screw and a plug. Drilled a pilot hole to depth.



I used 1 1/2 inch number 8 McFeeley coarse thread square drive screws. Four of the six screws snapped after I removed the clamps.



My guess is that I had too much torque on the driver. I'm going to redrill and use number 10 screws.



Any other thoughts?



Larry

Don't use dish Soap Larry,
YOu want a dry soap. The wet soap may cause binding.
Get a candle.. simple. If you don't like rubbing the candle on the sharp
threads, drill a small hole in the candle... then pull it out on an
angle, that should be enough wax.



--
Jeff