Introduction: Pimped Kreg R3 Jig
This workshop project makes the basic Kreg R3 pocket hole jig far more user friendly.
Step 1: Intro
I really like pocket hole screws - they’re a strong & neat way of assembling all kinds of joinery projects. But as a hobbyist, I could only justify buying the dinky little Kreg R3. It comes with everything you need to get started in a kit for around £35 ($40) and is a great way of seeing if it’s for you.
The only drawback is that every time you want to drill a pocket hole, you need to securely clamp the R3 to the workpiece, drill, then unclamp and reposition for the next one. So on a big project it can be a bit of a drag.
So in this Instructable, we’ll pimp our R3 and make it function pretty much like Kreg’s K4 offering, which is around £100.
Oh, and before we start, apologies that I use a mixture of inches and millimetres in the text - the standard markings on the Kreg and the descriptions of popular timber thicknesses are in inches, so I’ve kept to that. But here in the UK, I generally work in millimetres when making things.
Step 2: Understanding How Kreg’s R3 Works
Before you jump in it’s important to understand how the R3 works. Basically it has two little grey sliders each side. You adjust these to the thickness of your timber, and they then hook over the edge of your timber, and set how close to the edge of the timber the blue body of the Kreg sits.
Here are 3 examples, based on common sized timber we might fix with pocket holes joints…
For ½” thick timber the blue body of the Kreg sits 9mm beyond the edge of the timber
For ¾” timber the blue body of the Kreg sits exactly in line with the edge of the timber.
For 1½” timber (eg CLS studding), the blue body of the Kreg sits 29mm in from the edge of the timber
It’s important to understand this concept, since in our pimped version, we’ll be removing the grey sliders, and positioning our R3 manually in our jig. (Don’t worry, the grey sliders just clip off without any damage and can be refitted in future if using the R3 without a jig).
Step 3: Make 3 Uprights
These can be made from any scraps you have lying around - I used 18mm (3/4”) plywood.
Cut two pieces 60mm by 95mm. I also cut them on an angle to match the angle on the Kreg - (approx 100 degrees). This looks cool and also avoids the drill collar binding in use.
Next use a router or ideally a router table to cut out a channel along one edge of each. This should be 3.5mm deep and 15mm wide. It’s well worth experimenting on some scrap to get this exactly right, so your R3 can sit snugly in the rebate as shown.
You’ll also need an upright 95mm by 35mm - it must be exactly the same width as the R3 body. Dry assemble the 3 uprights, to make a kind of U shape, and check that your R3 fits correctly before glueing the U shape up and clamping till dry. Leave the R3 in place, to help keep everything square while the glue dries.
If desired, give the U assembly a coat of varnish at this stage.
Step 4: Make the Base
For this you need a piece of ¾” ply, approx 25cm wide x 30cm. You can leave it square, or to keep the weight down, you can trim it down to a kind of delta shape as shown.
Carefully set your U assembly in the correct position on the base, and mark exactly where the R3’s blue body will sit.
Now use a Forstner bit or spade bit to drill a hole 50mm in diameter (or at least the width of your blue Kreg R3). The hole needs to be exactly 9mm deep, and must sit so that the blue body of the Kreg R3 can drop down into it.
Tip! If you can, use a pillar drill for accuracy, or if using a cordless, wrap some tape round the shaft of the drill bit to set the depth. Despite doing this I messed up and drilled a fraction too deep - so I inserted a disc of leather to correct the height - looks pretty cool too!
If desired you can give the plywood base a coat of varnish, or even go one step further and laminate a piece of formica onto it - I did this, as I had an offcut lying around.
Step 5: Fixing the U Assembly to the Base
Position the U shape assembly (with the closed end level with the edge of the base) and mark the position with pencil or tape. The angled top edge makes the U assembly tricky to clamp. So Use a few drops of super glue and accelerator to hold the assembly in place, while you drive in pocket hole screws.
Step 6: Locking Mechanism
Remember, we need to be able to adjust and fix the height of the R3 in the uprights, so we need a locking mechanism. To do this, drill a 6mm (¼”) hole right from side to side right through the U assembly. This should be dead centre left to right and approx 25mm down from the top edge.
Tap a coach bolt through the hole, gluing the head into position with epoxy glue. Now fit a washer and thumb screw nut on the other end. Tightening this should squeeze the U assembly and lock the R3 in place. You may find the nearest size bolt is too long - eg 100mm. If so, temporarily put an ordinary nut on, cut the bolt with a hacksaw, then remove the nut. This cleans the cut end of the thread. Then fit your actual thumb screw.
Step 7: Workpiece Toggle Clamp
For around £9 you can get a ‘push pull’ toggle clamp on Amazon. Be sure to get this type, rather than the more common clamp down type. Experiment with various positions, but you want the clamp screwed to the base so it will have enough travel to clamp the common sizes of timber you will work with. Tip! The tube has a threaded open end, so you thread an M8 bolt into it for adjustment - ideally with a rubber cushion to protect the workpiece.
Step 8: How to Use
Simply set the height of the blue R3 body to match the thickness of the timber you want to drill pocket holes in.
- for ½” timber, push the blue R3 down into the rebate in the base all the way
- for ¾” timber, set the blue R3 dead level with the base
If you like, you can add marks on the upright for less common timber thicknesses you might use.
for example for CLS studding, which is roughly 1½” over here, the blue R3 body sits 29mm up from the base. So I’ve marked the uprights to remind me of this one.
Adjust the toggle clamp to suit the thickness of the timber, clamp in place, then simply drill downwards into it.
Step 9: Bonus Content
As my Kreg jig will be hung up on a French cleat wall, I added a 45 degree plywood rail to the narrow end. I also added a 40mm plywood straight rail under the uprights, so I can clamp it in a vice.
The original Kreg R3 kit has a flimsy blow moulded plastic tray, which very quickly gets cracked and becomes useless. It’s important too, since you use its rebate for setting the collar depth on the drill bit.
So I got an offcut from an old IKEA cabinet door and routered a replica - much more satisfactory!
So I hope you give this a try - let me know how you get on!