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Pocket hole joinery for book shelves

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Hudson Carpentry

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As long as the piece your screwing to has enough thickness to take a screw to a decent depth and your gluing then it will be fine. I haven't watched the video so assume you mean for the carcass. Pocket screws are not the strongest but as the glue is stronger then the screw fixing anyway its not to much a worry.
 

Kane

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In the video it's pocket hole for the shelves as well which is where my concern is :) - all material is 3/4 ply apart from the face frame ...
 

Hudson Carpentry

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Shelves are normally floating so by fixing them with pocket screws your adding to the strength. If your having a face frame then once again more strength. I would very much like to see a thicker carcass though as 3/4 isn't that much and would be worried about the screw either being to small or too long.
 

9fingers

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I'd be tempted to rebate the sides a few mm (3-4mm) to give more support to the shelf and let the screw concentrate on pulling the side together.
You can get pocket hole screws in 1/4" length increments and by adjusting the depth stop on the drill you can optimise the depth of the screw for maximum strength whilst stopping it breaking through.
You can also pocket hole screw the face frame on.

Google for sagulator to find a tool to calculate how much the shelves will sag.

hth

Bob
 

Hudson Carpentry

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Rebate/housing/dado is a good idea but it being ply I can see the screw going in further then expected by braking the layers from the force. Its happened to me a few times.
 

Lord Kitchener

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If you have the slightest concern that the fixing method isn't strong enough, just use more screws. For heavily laden shelves I would use maybe 5 rather than three screws. No need for glue, especially with birch plywood. For the shelves to fail that means that 5 srews would need to shear. Always look to see which direction the forces are acting.

I always think it's funny when people think that screws aren't strong enough, it must be a nuisance their doors falling off all the time!
 

Benchwayze

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So there's someone else blinded with science folks! :lol:

Pocket hole screws are great for some applications. The makers would have you believe they are a revolution in woodworking and are radically changing the way all furniture is built.

I like them, but only to hold carcasses that are going to be supported by other means (Biscuits etc) or other parts of the job itself. (Such as a box carcass inside a frame for workshop cupboards and kitchens.) I just can't force myself to rely on screws alone whether they be dry-wall or pocket-hole screws. :wink:

LK...
I would say a shelf full of books is weight of a different kettle to a cabinet door. (hammer)
 

BTR

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I have used pocket hole joinery whilst making shelving for my shed to hold tools etc and also a couple off book shelves i just used glue and pocket screws no problems so far.
 

Benchwayze

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BTR":3nx4qbfe said:
I have used pocket hole joinery whilst making shelving for my shed to hold tools etc and also a couple off book shelves i just used glue and pocket screws no problems so far.
We have earthquakes in Brum don't forget!
:mrgreen:

It's just me BR.

Yes I have a Kreg, and it has its uses. I admit though, if they do give way, it's probably the material we choose to build with that causes the problem! :D
 

Lord Kitchener

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Benchwayze":3drt8ppq said:
LK...
I would say a shelf full of books is weight of a different kettle to a cabinet door. (hammer)

You could say that, and it would be true, just not relevant. Most full size internal and external doors are held on with screws as well, not just cabinet doors.

But that aside, the important thing is to look at each situation individually and assess an appropriate construction and fixing method for each. The material itself, the thickness of it, the number of screws used, all of these things have a bearing on suitability. Sometimes using glue as well is a waste of time and an actual nuisance. For instance, on birch plywood, if it is going to be varnished, any glue squeezeout will cause patches of different colour where the glue has sealed the surface and prevented the varnush from soaking in.
 

Lord Kitchener

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Benchwayze":15szyb9z said:
And all because I suggested Kreg screws have limitations?
Ah well. I bow to superior knowledge. :wink:

I'm guessing that's sarcasm?

EVERYTHING has its limitations, but that's no reason for automatically assuming that every fixing method needs to be backed up in every situation.

All I'm saying is that each situation should be judged on its merits, and approriate decisions made, after research and experimentation if necessary.
 

Benchwayze

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LK My apologies if I sounded sarcastic. I don't use it often because I'm not very good with it. But I still don't think I said that EVERY situation using screws needs to be backed up with other jointing methods.

I did try to make a carcass (Carcase?) out of 18mm Ply on Thursday, as it happens. 40" x 20" x 18" wide. with a central divider. The job was decidedly wobbly with Kreg screws alone, so I backed off the screws and applied some glue. (I wasn't going to stain this, so I contented myself with wiping the excess glue away with a damp cloth. ) Now it's stronger, and as it's going inside a frame, I shan't bother with biscuits.


As for bigger and bigger doors... Equals bigger screws and hinges, right up to straps, bands and coach-bolts.

Pax? :)
 

Lord Kitchener

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Benchwayze":3mcwxv2s said:
I did try to make a carcass (Carcase?) out of 18mm Ply on Thursday, as it happens. 40" x 20" x 18" wide. with a central divider. The job was decidedly wobbly with Kreg screws alone, so I backed off the screws and applied some glue. (I wasn't going to stain this, so I contented myself with wiping the excess glue away with a damp cloth. ) Now it's stronger, and as it's going inside a frame, I shan't bother with biscuits.
I can't comment on your carcase as can't quite get it from your description (plus I gave up on the old inches a long time ago, actually have to translate inches into metric before I can visualise them), all I can say is that I make carcases out of 18mm birch ply pretty much every day, did 6 yesterday, and I only use pocket screws and don't have a problem. Nor have had for the ten years or so I've been doing it that way. Nor have any of my customers ever had anything come loose. But I do tend to use more than the Kreg videos suggest.

Funnily enough the reason why I started using them is that I found biscuit jointers weren't giving me the accuracy I wanted, whereas with pocket screws I can clamp the job up and tap the pieces with a suitably padded hammer until they are in perfect alignment. I used glue at first, but soon stopped as I found it wasn't necessary, in the designs I was and am using. Plus, every now and then, I've actually had to dismantle a cabinet for one reson or another, once because it was 1.9 metres high and I couldn't get it into the old cottage it was intended for. Took it to pieces and reassembled it once inside.

Pax? Absolutely.
 

Kane

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Thanks folks - I like to get opinions before relying on what is, after all, an advertising video :)
 

Benchwayze

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Right LK,

Assuming 25mm is one inch.

The carcass front elevation is 40 inches (Approx 1 metre) by 20" (approx. half a metre), The depth, front to back is 19" (Approx. 475mm) In the centre of the metre width there is a partition 29" x 19" ( Approx. 500mm x 475mm ) the box is heavy of course, and as I said was racking a bit, so I added some glue.

That stiffened it up, but I think I might have been best served by making it in two equally sized carcasses and joined them together with a top and a base to hold them firm.

This is to put my Triton Workcentre onto, with castors underneath. ( I don't like the bent legs that come with the Triton and I need it to be mobile anyhow!) I was going to use the box it as described, with shelves on drawer-slides, but I think I will place it inside a box-frame of 50mm x 25mm just to be on the safe side, so it can be rolled about without any worries.

I used 5 screws (recommended size for 18mm material) along each joint across the 475mm depth.

I can't see me using biscuits either, as that might be overkill with the timber framing.
I have been working on a means of making a biscuit-jointing jig, that could also be used as a Kreg screw-jig. Trial runs, are promising, and it seems to keep the parts of the job square and in position without worries. Still in the prototype stage though!
Cheers. :)
 

wcndave

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Back to the OP, I would say there are two factors here. 1 - strength of the overall structure, and 2 - strength of the shelves.

Also not sure there is one right answer.

I haven't watched the video, so not sure what the construction details are, however if I were doing a 2m version of this I would do as follows.

Good 3" rear top stretcher
3" front bottom stretcher
Make the top, bottom shelf and middle shelf from thicker material, perhaps 1" instead of 3/4
Rebate the back and put a 1/4 plywood back in.

All those things together should make a very stiff structure, I would do that with pocket holes and only use glue if it's not to be moved.
The back would be pinned in, not glued in any case.

In terms of other shelves, you might have 3 or 4 based on height of each, I would not rebate and pocket hole, as then you are reducing the depth of the sides where the "weak" part of the pocket hole joint is, and risk coming out the side.

Personally i would do shelf pin holes and then use some bought support pins, as this means the shelves can be adjustable.

If you don't want to / can't drill equal spaced holes in 4 strips, then you could use some support blocks, or as you said, pocket hole them.

It may then be that you have some shelves at 3/4 and some at 1". For me not a problem, however if it spoils the look, suggest you could use face frame, or easier, false lipping on the 3/4 shelves to give a consistent look.

So overall i think you can do this with pocket holes only, however it's the entire structure and it's construction that decides how strong that is, not just attaching shelves to sides.
 
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