Bench top attachment

So...how did you mount yours? I'm trying not to use any materials other than wood & glue on my bench {excluding the vise hardware} and could use some experienced thoughts/comments... {the top is 3 layers of 3/4" mdf, banded in maple, if that matters}...

I was/am leaning towards locating dowels and weight alone, but, believe it or not, I've made a bad decision or two in my time :eek: :D................Thanks in advance :thumb:
 
Despite the lamination (my bench top is 4 layers) MDF is not self supporting. Just as in all those sagging router table threads we've read, your top will need to be well supported. This assumes several contact points between the base and the top (rough diagram for example only, I'm still having my first cup of coffee). I understand the desire to avoid metal fasteners but, I just ran a half-dozen 1/4" lag bolts up through oversized holes from under the supporting ribs. You could use dowels and receiver holes in the same positions to avoid the metal fasteners.

bench pegs.jpg
 
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Dowels or blocks glued to the underside that keep it locked within the frame would work. I used glue blocks and it's still strong. A problem might arise if you had a vise mounted to the frame pushing on something using a dog hole on the top, but even then dowels or glue blocks should keep it in place.
 
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Thanks Glenn, I should of added more info to the mix...Here's a shot of the bench, the cross supports are approximately on 9 1/2 inch centers with about 12" on the outside ends. Think this is still going to be a sagging candidate? :dunno:
View attachment 87947

I am such a dork! You had shown that base in your 'flattening' thread . . . Doh! :doh: I would think that support area should be just fine. I use the same 5 front to back ribs on my 55" wide, 24" deep base for a 30" x 84", 4 layer top. It has been fine for years with a fairly heavy vise at each end (one face, one tail). the dowel idea should work there but, I really like Ted's idea of some blocks attached to the bottom of the top in the inside corners. Same basic effect either way you choose.

vises 002.jpg
 
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My bench top sits on 3/4" dowels. The top is three layers of 3/4" plywood plus 1/8" temper board replaceable top surface. It has been quite a few years and I have not replaced the temper board as yet.

Glenn and I (guess who did the heavy lifting) flipped the top over a few weeks ago to install a new vise without having to work over our heads. I think we found that I had put in three wood screws (Don't get old your brains leak out). Regardless the top came off easily to be laid back down up-side-down for vise mounting.

Glenn, you have a younger brain than I have. Did those screws have anything to do with holding the top down?

The bench top is 27" by almost 6 feet. (There is a story behind that "almost" but I'm not telling it.)

Ken, How about one sheet of 3/4" plywood under two sheets of MDF. That should take care of any, even microscopic, tendencies for the MDF to sag. It would also give dog holes a bit more bracing.

Enjoy and have fun with your bench. A good bench is a truly wonderful thing to have.
JimB
 
Thanks Jim, I was going to go with 4 layers of MDF like glenns, but I hadn't taken the bench frame height into the equation, and even though it only added 3/4 of an inch, it seemed odd placing my hands down on it during testing. The ply under it sounds good though, that ingenious son of yours mentioned adding a strip underneath the top, inline with each row of dog holes for extra strength. So we have a plan now on that aspect and I'm going with the corner blocks as well. All is good now thanks to you wonderful folks...as usual :thumb:
 
I've been working more and will be for a while. But I wanted to mention something from the old RAS days. If you search for a Mr. Sawdust table, you will find he layered the top (two 3/4" boards), but between them, he glued some steel strips, thin edge up, for support (keep from sagging).

This would take planning for dog hole purposes, but might help.
 
I've been working more and will be for a while. But I wanted to mention something from the old RAS days. If you search for a Mr. Sawdust table, you will find he layered the top (two 3/4" boards), but between them, he glued some steel strips, thin edge up, for support (keep from sagging).

This would take planning for dog hole purposes, but might help.

I've got that Mr. Sawdust RAS book, and it was a big help getting my old Red Start up running. I use it all the time.
 
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Ken, How about one sheet of 3/4" plywood under two sheets of MDF. That should take care of any, even microscopic, tendencies for the MDF to sag. It would also give dog holes a bit more bracing.
.....

NO NO NO NO - not MDF and ply together. The sheets of MDF should be laminated together - two sheets loose are twice as stiff, twice as strong as one, but two sheets laminated to become one thicker sheet that is 8 times as strong as one. Three sheets laminated are 27 times as strong/stiff as one, etc. (third power of thickness) BUT I laminated a sheet of plywood to a sheet of MDF (I couldn't decide which would be better) and it becomes concave or convex with the changes of the weather. Not a big change, but irritating.
 
Nope, no ply here, I have 3 sheets of 3/4 laminated and will run another strip of mdf under the top between the supports for the strength benefit of the dog holes. Things are on the back burner until friday or so, still a ways yet to go...Merry Christmas to one and all!
 
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