How many Pocket holes?

[BigEaredWannabeWoodWorker]

Hi All,

Is there a rule of thumb when using pocket holes? How many per foot of joining boards?

I'm thinking minimum of 3 per foot? Gluing and screwing of course.

Thoughts?

 

[sometimewoodworker]

Is there a rule of thumb when using pocket holes? How many per foot of joining boards?

Unfortunately the rule of thumb is “enough”

If joining boards long grain to long grain the pocket hole screws are just providing clamping pressure while the glue cures and the joint if prepared correctly needs very little assistance, in my opinion for regular wood edge to edge I would use about 1 per 250mm

 

[Eric The Viking]

You need to be a bit more specific: what _exactly_ are you trying to do, in what wood, with/without glue, and what are the dimensions involved? Even then, the best thing is to get the correct screws (length and thread style) and experiment. long-to-long grain and end-to-long grain will have different strengths.

If you are using "proper" pocket hole screws, there are several types of screwthread, depending o the application. I use Kreg screws*, and they sell at least two types, for hardwood and softwood, and I think a third for man-made boards (MDF, chipboards, etc.). On the occasions when I have used the wrong sort, results have not been satisfactory. There are also different lengths depending on stock dimensions.

If you are using them simply to hold work together for glueing, as Jerome suggests, you have a bit more leeway, but the glue faces will be pulled out of alignment by the pocket screws, so you need to clamp the joint flat before starting. I have tried to manage without doing this (as seen in umpteen YouTube videos) - that way lies madness and a bulging scrap bin.

Over to you...

*because I like them! Other sorts are probably just as good.

 

[Cordy]

When I joined these top boards on a planter I put 4 in a 4.5 inch wide board
The joint is still holding good !

 

[sometimewoodworker]

When I joined these top boards on a planter I put 4 in a 4.5 inch wide board
The joint is still holding good !


View attachment 96102

That joint, being an end grain joint will need a significantly greater number of screws and at a much closer spacing as the end grain has very little gluing strength so the screws are providing most of the strength. I would probably have used only 3 screws but no harm in using 4.

 

[sometimewoodworker]

you have a bit more leeway, but the glue faces will be pulled out of alignment by the pocket screws, so you need to clamp the joint flat before starting. I have tried to manage without doing this (as seen in umpteen YouTube videos) - that way lies madness and a bulging scrap bin

I’m often using dominos to avoid the need for clamping.

 

[AJB Temple]

How do does the use of dominoes avoid the need for clamping? I regularly use dominoes in glue ups (usually using one of the Titebond variants) and and I always clamp as well to get a good tight mating surface.

 

[sometimewoodworker]

How do does the use of dominoes avoid the need for clamping? I regularly use dominoes in glue ups (usually using one of the Titebond variants) and and I always clamp as well to get a good tight mating surface.

The pocket hole screws do the clamping

You did notice that this is a pocket hole thread?

Naturally if I don’t have screws I use clamps, but the reason for screws is to clamp the joint while the glue is curing.

 

[Eric The Viking]

Pocket hole clamps usually go across the joint, at right angles to the glueing faces. This is so they don't slip out of alignment in glue-up, because the screws go in at an angle, and ordinarily there are no pilot holes in the second workpiece to guide them.

 

[BigEaredWannabeWoodWorker]

So I'm building a work bench for my garage out of hardwood plywood 18mm thick.
The carcass sides will have 4 in the bottom and to the base and the strengthners (4 of them are 4" wide ) will have 2 in each side. All glued. The pocket hole jig is a titan one and the screws are 1-1/4 course thread.

Is that enough screws? Are they correct.

This is one of my first projects and its to get my garage into a workshop (for me and my hobby).
Any tips?

 

[craigs]

The pocket hole screws do the clamping

You did notice that this is a pocket hole thread?

Naturally if I don’t have screws I use clamps, but the reason for screws is to clamp the joint while the glue is curing.

just use lamello clamex

 

[sometimewoodworker]

This is one of my first projects and its to get my garage into a workshop (for me and my hobby).
Any tips?

The make of jig is irrelevant, The fact that you’re using plywood certainly makes a difference in that you don’t have any 100% long grain to long grain joints so you have to treat it a little more like an end grain to end grain joint.

This means that you need more pocket screws as they will be providing some of the structural support.

With my plywood I use the course thread pocket screws not the fine threads pocket screws, the course thread pocket screws are for softwood the fine thread are for hardwood.

However it would be good for you to do a test joint and test it to destruction using both fine And course pocket screws to see which works best for your particular plywood.

You haven’t given enough information about the design and placement of the pocket screws in your bench to really give advice on that. My plywood workbench uses no pocket screws just glue and screw KD fasteners.

 

[Robbo60]

So I'm building a work bench for my garage out of hardwood plywood 18mm thick.
The carcass sides will have 4 in the bottom and to the base and the strengthners (4 of them are 4" wide ) will have 2 in each side. All glued. The pocket hole jig is a titan one and the screws are 1-1/4 course thread.

Is that enough screws? Are they correct.

This is one of my first projects and its to get my garage into a workshop (for me and my hobby).
Any tips?

Workbench. Have you looked at WWMM and his design for a BMW (Basic mobile workbench)?