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Pocket screws good enough?

1K views 16 replies 10 participants last post by  JimDwight 
#1 · (Edited by Moderator)
Question regards upper part,shelves, in rendering. 25.5 deep, 88" h, 80"w are overall dimensions. Trying to avoid cleats. Birch plywood will be used. All gets painted. As is now,no back, but maybe a 1/2" back wouldn't be a bad idea. All built on site.Pocket screws hold them shelves and/or how would you highly skilled professionals fabricate? Thanks!

Brown Rectangle Wood House Brick


Brown Rectangle Wood House Brick
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#2 ·
The floor is going to carry all of the vertical weight of the shelf system. So, I assume, all you are trying to do is overcome any tipping forces and hold the units against the wall. I don't have any engineering calculations to back it up but, I don't like pockets screws in this application. You will need longer and larger diameter screws than are ordinarily used in pocket screw applications. Making larger pocket holes in 3/4" material leaves less material to hold the screws and potential load.

You could build in a continuous rail (like a face frame) along the top back that would be screwed and glued into the back of the top shelf and exposed perhaps 3/4" to 1" below the top shelf. Then use that to screw through into each stud. Once painted, it will hardly be noticed as anything other than part of the system.

If you are going to put on a 1/2" plywood back, that will be very adequate for screwing through into the studs. However, if you are going to do that, you should screw the back to the shelf unit rather than use nails. If the screws into the studs are placed just above one of the shelves, they will hardly be noticeable if at all.
 
#3 ·
Why the 25.5 depth? I think it's to deep, and material wise, 24"deep lets you get 2 rips out of a sheet.
I would shorten the depth and put a back on it.
I did something similar. I dadoed all my shelves and screwed them, then used bondo over the holes and seams.
I doubled the material for the (1 1/2") width and didn't use a face frame.

Cabinetry Furniture Property Building Wood
 

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#4 · (Edited by Moderator)
The floor is going to carry all of the vertical weight of the shelf system. So, I assume, all you are trying to do is overcome any tipping forces and hold the units against the wall.

- bilyo
Thank you, bilyo, but question pertains to attaching shelves to verticals w/o using cleats for shelves to rest on and providing adequate strength so won't sag.

Looking closer at that rendering, it appears that my main concern will be w/the upper and lower full length horizontals. But i dont have to run those full length or if i do, could stack. Cut uprights, put shelf, more uprights then shelf. I'm sure I've made absolutely no sense. Thanks!
 
#5 · (Edited by Moderator)
Why the 25.5 depth? I think it s to deep, and material wise, 24"deep lets you get 2 rips out of a sheet.
I would shorten the depth and put a back on it.
I did something similar. I dadoed all my shelves and screwed them, then used bondo over the holes and seams.
I doubled the material for the (1 1/2") width and didn t use a face frame.

Cabinetry Furniture Property Building Wood


Nice.

Reason for 25.5 is because all is existing. I brought up same point re material waste. Odd that its done that way. Existing adj shelf system on top of base cabinet is going away. They hate seeing all holes. And the existing depth finishes out with the band of a coffer ceiling.

I can step the face of upper unit back then attach a 1 by rip from face frame of new to existing coffer band. Save them a bunch of money by doing so. Literally half on material cost.

Thanks
 

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#6 ·
I take it you also don't want to use dados? That would be the strongest way to do it. I am not one of the "highly skilled professionals" you mentioned ;-) but I think that is how a HSP (and even I) would do it. I think that dados will make it look more professionally done too. If you don't want to use dados, for most of the joints you can probably just drives screws in the from the other side and simply countersink and plug with a dowel before painting.

While it may work, what I don't like about using pocket holes for the horizontal shelves is that with the screw angling upwards it is technically possible for it to pull out with enough downward force, especially since you can only go in as far as the thickness of the vertical piece you are attaching it to. Admittedly, it would probably take quite a bit of weight or stress to make that happen. If you screw in horizontally from the opposite side, you can put a much longer screw in (with pilot hole) and it cannot really be pulled out.
 
#8 ·
I take it you also don t want to use dados? That would be the strongest way to do it. I am not one of the "highly skilled professionals" you mentioned ;-) but I think that is how a HSP (and even I) would do it. I think that dados will make it look more professionally done too. If you don t want to use dados, for most of the joints you can probably just drives screws in the from the other side and simply countersink and plug with a dowel before painting.

While it may work, what I don t like about using pocket holes for the horizontal shelves is that with the screw angling upwards it is technically possible for it to pull out with enough downward force, especially since you can only go in as far as the thickness of the vertical piece you are attaching it to. Admittedly, it would probably take quite a bit of weight or stress to make that happen. If you screw in horizontally from the opposite side, you can put a much longer screw in (with pilot hole) and it cannot really be pulled out.

- Lazyman
I agree re pocket screws and screwing in reg screws from opposite side.

I am somewhat dado averse.I'd be doing it in the field w/hand router. Setting up straight edges for router. Doable, but gosh darnit, time consuming and only a slight margin for error. But i think i'm leaning in that direction.Thanks
 
#10 ·
A router jig like this from Woodsmith or this one from Stumpy Numbs will make it pretty easy to do. Nice thing about this jig is that you don't have to find a router bit to exactly match the thickness of your PW.
 
#11 ·
Not a professional but… i would use dominos, if you have one and screws from the outside where they will be hidden and glue where they would be visible. The domino depths can be differnet in each part to prevent seeing them from the outside. I am currently building a bed with drawers in the rails and cabinets for my daughter's room. I am using 40mm dominos for the connections, 15mm deep in one side and 25mm in the other. This keeps the cutter from punching through the visable portions. This method also almost eliminates my usual errors not adding the length that would be needed for a dado, and it is quick.
 
#16 · (Edited by Moderator)
In my shop these are all blind dadoes.

Glue and screws in the areas that won't be seen.
Glue and clamps at all the other joints.

Assemble and pre-finish in the shop without the backs attached.
Final assemble after finishing.
Install in logical sections.
 
#17 ·
I also do not do this for money but will offer my thoughts. Most of your connections can be made with through screws and glue. That leaves a much smaller hole to fill and is also quicker to do. Some of them won't show. Where you cannot use a through screw, a pocket screw would work and avoid the need for clamping/preasembly. The few you cannot use a through screw on could also be done with slots that interlock. It would be strong but if you want you could put one pocket screw in at the long edge of the slot.

I like to use what I call locating dados. I only go about 1/16 deep so it isn't to add strength. But it helps a lot getting pieces in position. Another way to cut long ones, which you don't seem to have, is with a special jig on a track saw track. It works well and would work for even short ones if you want to go that way. A big advantage is the router is guided in both directions to ride the track. I use a DeWalt track saw and a PC router, no need for Festools to do this.

If you were not painting I would plug through screw holes with matching wood. But for paint, putty or bondo will be easier and less likely to show.
 
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