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+-- Thread: Dado with dowel reinforcement -- additional reinforcement needed? (/showthread.php?tid=7325748)
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Dado with dowel reinforcement -- additional reinforcement needed? - jihhwood - 12-01-2016
For my wife's shop, I'm working on a 6-foot tall, 3 foot wide, 12 inch deep shelving unit. I'm using birch 3/4 ply. Dado joinery (1/4 inch edge-banding will cover all front edges to neaten things up.) There will be a 1/4 inch ply back on the unit. Top, bottom and fixed shelf will be glued and dowelled; A poplar cleat will be glued and screwed on the underside, rear of the unit top; another cleat will be glued and screwed in the same location on the fixed shelf. Both cleats will be drilled through into studs to stabilize the unit and keep it flush to the wall. The unit won't hang from the cleats; its weight will rest on the floor. There are three adjustable shelves. The assembly should be adequately strong, but I'm a bit concerned about two things: (1) any chance that when the shelves are loaded the unit may fail? (Is the construction strong enough to hold things together?) and (2) bowing of the shelves -- especially the adjustable shelves -- under load. (A side-to-side distance of three feet seems to me to be asking a lot of 3/4 inch ply.) Your thoughts and recommendations will be gratefully received.
RE: Dado with dowel reinforcement -- additional reinforcement needed? - Sawman - 12-01-2016
A question and a suggestion. How deep are the dadoes? I build a number of kitchens and I use a rabbet/dado combo with the dado being 3/8"x3/8". Never a problem. The span of your slf is a bit of a concern. I would beef up the front edge with an "apron" either face applied or underneath. Othewise you will get sag.
RE: Dado with dowel reinforcement -- additional reinforcement needed? - JGrout - 12-01-2016
As long as the joinery is accurate and glue is applied to the dadoes as well as the back is secured with pins in a rabbet you are building the same thing I have for yrs
It will not fail.
Joe
RE: Dado with dowel reinforcement -- additional reinforcement needed? - Cooler - 12-01-2016
You don't say if this is back room shelves or display shelves for the shop.
I built my backroom cabinets for my picture framing business from 3/4" particle board, which I glued up using dados and screws. I painted over everything. But this was backroom stuff and the customers did not see it.
For the front room I used birch ply and some bead board for the back to give it a more homey look. I used face frames and I curved the top piece.
RE: Dado with dowel reinforcement -- additional reinforcement needed? - jihhwood - 12-01-2016
Thanks for the reply, sawman. The dadoes are 3/8" deep, but they run across the entire width of the birch ply (3/4") -- no shoulder. The fixed shelf, top, and bottom are glued and doweled. As to the shelves sagging, I am uncertain whether a 1/4" banding is sufficient; I think it isn't. But I can glue a 1 1/2" or 2" support (on its edge) and run it on the underside, along the back of each shelf. Does that seem sufficient to eliminate sagging?
RE: Dado with dowel reinforcement -- additional reinforcement needed? - jihhwood - 12-01-2016
Thanks, JGrout, for you're reply. Yes, the joinery is accurate and the dadoes are glued. (So are the 5/16" dowels, needless to say). Yes, the 1/4" ply back sits in a 1/4" deep rabbet and is secured with pins (more precisely, wire brads with heads). Do you have any thoughts about the 3' span of the shelves and the need for reinforcement from the underside? Thanks.
RE: Dado with dowel reinforcement -- additional reinforcement needed? - jihhwood - 12-01-2016
Hi, Cooler. Thank you for responding. Sounds as though your front room shelf unit is very nicely done! Mine is for a garage shop, but I want too please my "customer". All entry points on the outside of the unite (dowels into shelves and screws into cleats) are flush with the outside face of the sides. That is, the screws for the cleat are plugged and sanded flush, and the dowels have been trimmed flush.
RE: Dado with dowel reinforcement -- additional reinforcement needed? - Sawman - 12-01-2016
1 1/2" would work but you might like to go a bit wider for appearance sake.
RE: Dado with dowel reinforcement -- additional reinforcement needed? - pdacey08 - 12-01-2016
The AWS (Architectural Woodwork Standards) say that 3/4" veneer core with hardwood veneer on both faces can support 50lb/sf on adjustable shelves for a span up to 35". Fixed shelves would be higher but they don't give a rating for them.
RE: Dado with dowel reinforcement -- additional reinforcement needed? - jihhwood - 12-01-2016
(12-01-2016, 03:53 PM)pdacey08 Wrote: The AWS (Architectural Woodwork Standards) say that 3/4" veneer core with hardwood veneer on both faces can support 50lb/sf on adjustable shelves for a span up to 35". Fixed shelves would be higher but they don't give a rating for them.
Very specific information. I like hard data and appreciate your taking the time to respond. I have to look into Architectural Woodwork Standards -- this would certainly be handy! Will check on line and in hard copy . . . .