|Forum topic by groland||posted 07-14-2010 02:34 PM||1922 views||0 times favorited||4 replies|
07-14-2010 02:34 PM
I have finished my workbench base and am now thinking about how to attach the top. The top is finger-joint laminated ash 2 3/4 in. thick. The trestle member it sits on is 3 3/8 in. thick for a total thickness of 6 1/8 in.
I am thinking of using 1/2 in. machine bolts and nuts with flat washers to attach the top. The flat washer and bolt head will be recessed into the table top.
I will probably bore 5/8 in. holes for the machine bolts for easy manipulation.
My concern is to allow for expansion of the top. What I am thinking about is to have normal 5/8 in. holes in one trestle, probably the one near to my front vise and, at the far trestle, having an opening about 3/4 – 1 in, a slot, for the bolts so the top can expand and contract.
That would mean the recess in the top that takes the recessed bolt and washer would have to be wider than normal and the bolt hole would too.
I guess I have the following questions.
1.) Is this a reasonable way to go about this, or is there a better/standard method I ought to consider?
2.) Do I need to allow for this much expansion—more or less? (The top is ash boards, ca. 1” thick, finger-jointed end-to-end and glued up into a 2 3/4 in. thick slab.
3.) What would be the best method(s) to do the boring for the expansion bolt hole? (I’m assuming I could use a Forstner bit to bore the recess holes side-by-side. What’s a good method to bore the 5/8 W X 3/4 to 1 in long bolt slot?