[CAUT] S&S hammer flange rail material

[Dan Reed]

If the screw is not going in straight, the bottom of the screw head 
will contact one side of the washer first, and possibly spread the 
force to the rail in a wider area...but still to the side first 
contacted.

Dan


On Aug 21, 2008, at 7:39 PM, Fred Sturm wrote:

> On Aug 20, 2008, at 8:56 PM, Chris Solliday wrote:
>
>> even with the panheads the non uniformity of the threads can throw it 
>> of if
>> you tighten down even alittle too much. I use the washers even with 
>> the
>> pans.
>> Chris Solliday
>
>
> Hi Chris,
> 	I'm not following you. As far as I can see, a washer will spread the 
> pressure of the head over a larger area, assuming it is larger than 
> the head. But it would apply pressure to the flange in exactly the 
> same alignment, it wouldn't change the direction in which the screw 
> head was bearing on the flange. The washer is flat and acts as if the 
> screw head was that much thicker, or at least that's how I think of 
> it.
> 	In my mental picture, the only thing that will cause the flange to 
> tip on the rail (assuming the rail is flat and clean, and the flange 
> bottom is too) is a screw hole drilled off center (fore or aft) or at 
> an angle. I don't see how any difference in the screw threads could 
> affect this, or could cause a flange to tilt when over tightened.
> 	I can see potential benefits to adding a washer. The wood won't be 
> crushed as much, for one (the washer protects the wood from the 
> twisting action of the screw, and if it is larger, spreads the 
> pressure over a larger area). OTOH, if there is a small discrepancy in 
> the angle of the hole, the screw head tends to dig in and crush the 
> related side of the flange, which in my mental picturing, helps to 
> adapt things and level the flange. I see flanges where one side of the 
> screw head has made a bigger indentation, and assume that is what is 
> happening.
> 	Maybe the esteemed Mr. McMorrow had it all figured out as Alan 
> reports, and I've been missing out on the answer all these years 
> because I was a cheapskate and didn't buy his book. Anyway, I can't 
> say as I have seen a really clear analysis of what goes on and why 
> (hence my earlier post giving my own take on it).
>
> Regards,
> Fred Sturm
> University of New Mexico
> fssturm at unm.edu
>
>