I’m new to the pocket screw-hole type of joinery. One thing that affects screw joinery is “bridging” at the joint caused by the screw displacing wood fibers into the joint – prohibiting a clean, tight joint.
“Bridging” is typically avoided by drilling a pilot hole that crosses the joint interface, removing the wood fibers in advance that would contribute to the problem.
The instructions for my new pocket screw jig (and all others that I can find on line) shows the pilot hole stopping short of the joint interface. I’ve experimented by taking my test joints apart, and do find that bridging does occur, even using the pocket joint jig.
Is this normal? Am I missing a step that should be obvious, but isn’t? Or is the bridging that occurs using the pocket hole bits and jigs so slight that it simply does not matter? What is other’s experience?
Mike
Replies
Can't imagine why they would want you to stop the pilot hole short. The commercial machines bore the pilot all the way through. I'd say set your depth stop so that the pilot penetrates. I have a Castle machine and there is absolutely no bridging.
I've had a Kreg K2 jig for years, and have tried it both ways (hole through, stopped short). I've never noticed any visible difference in the joint using either method once glued and screwed.
Thanks for the respoonses. It occured to me this morning to go to the Kreg site and look at their FAQ's section. Here is their response to this question:
"Do I need to drill all the way through the edge of the workpiece?"
No. We recommend setting the depth collar so that the tip of your drill bit rests approximately 1/8" from the base of the jig for 3/4" material. Why you ask? By not drilling all the way through the edge you won't have to deal with the possibility of having a burr that you will need to remove before joining your pieces. The self-tapping tip of the pocket hole screw will easily drill through the last 1/8" of an inch and drill its' own hole into the second workpiece, drawing the pieces tight without having to pre-drill.
"Do I need to drill a pilot hole into the second workpiece?"
No. The self-tapping tip of the pocket hole screw accomplishes this task for you. Even in very hard woods like hickory and maple no pre-drilling is required which saves an immense amount of assembly time.
I'm sorta surprised by the answer, but it supports what the instructions implied. Apparently it makes no difference.
Mike
I've been using the Kreg system for a couple of months and have had no problems as long as I;
Set the drill depth just short of full penetration of the workpiece
Clamp the pieces tightly before I screw them together.
Run my cordless drill on the slow setting and use light pressure on the screws. Let the self drilling tips do their job.
Dial back the clutch setting on my cordless drill. Overtightening the screws isn't a good thing and I even managed to break a couple before I figured this out.
I'm completely sold on pocket screw joinery. It used to take several hours to biscuit join, glue, clamp, and let a faceframe dry. Now, it's only an hour, or so, and they're ready to use when the last screw is in. I've also been using pocket screws to attach the faceframes to the carcasses.
This is a minor point but the term bridging is not the same as just having some pushed up wood fibers interfere with a joint closing up.
Bridging is what happens when a screw is not given a clearance hole in the outer component of a joint which prevents the screw from pulling the joint together because the threads are fully engaged in both pieces.
John White, Shop Manager, Fine Woodworking Magazine
I have read both descriptions - but I recognise that just because it's written doesn't make it so.
I think that I got fixated on the pushed up fibers based on a recent article on how to build a sanding machine using MDF. The author went so far as to recommend that, after drilling the pilot holes, that you chamfer the pilot hole on both pieces of MDF where they interface in the joint. Perhaps that's a problem unique to MDF.
What is the proper term, by the way, for fibers pushed up into the joint interface by the action of an unpiloted (at the interface) screw? Or does such a thing even exist?
Mike
I don't know if they have a technical name, but the phrase(s) I use if they become a problem aren't fit to use in a family forum such as this - lol.
I couldn't agree more on the value of pocket screw joinery. Fast, easy and strong. Perhaps not the most easthetic joint in the world, but in most cases where it's used, so what?
So far, I've managed to completely hide most of the pockets and when they've been "visible", those tapered plugs do a good job of disguising them.
Re:
I've also been using pocket screws to attach the faceframes to the carcasses.Dave45,I have some friends who attach faceframes to carcasses as you describe. They use a small Kreg like mine and always drill both holes. That way, if they're assembling and disassembling along the way, for whatever reason, they have a fresh hole for final glue and screw. Makes sense to me, though it doubles your pocket drill time.
I haven't had to take one apart.......yet (lol), but my last faceframe wasn't dead flat so I had to add a couple of screws to suck it down tight. Next time, I'll lay the faceframe on the carcass and mark the "high" spots so I have screws where I need need them most.
I'm just finishing a straight china hutch and will be starting a corner hutch soon. I'll probably have to spend a couple of hours practicing pocket joinery on 45* joints.
In another post, I mentioned using those diagonal plugs to disguise the pockets. Here's a picture of one on the hutch. It isn't invisible, but the shelf should make it fairly unobtrusive.
Is there an advantage to the Kreg system over Lee Valley's pocket jig? I looked at the Kreg and it just seemed more money and more complicated than I really need. Lee Valley link here:http://www.leevalley.com/wood/page.aspx?c=2&cat=1,180,42240&p=42329
The advantage of the Kreg jig is time. There's an integral clamp that positions the drill guides to the work piece the same way every time. As a result, I can quickily drill a lot of holes. With the free standing jig, it's going to take you a lot more time to get the drill guides properly aligned with the edge of the work piece. This is okay if you are only going to drill a few holes. For a large project though, that amount of setup time will quickily add up.
No matter which setup you go with, be sure to get a face clamp. This clamp goes across the face of both pieces being joined, ensuring the surfaces are flush and don't move when the screws are inserted. The face clamp is included in the Kreg kit.
If you're only going to drill a few holes and are going with the guide only setup: the Lee Valley site has Mini Kreg Pocket Hole kit that includes a guide and drill bit for less than what you would pay for the guides and bit on the page you listed.
storme,
If you haven't seem the Kreg K3 demoed , order one of their demo DVD's. Once you've seem it you'll understand why it's not that expensive. From doing just a few pocket holes to near production work, is posiible with the Kreg K3, which contains the jig and the clamps that are necessary for perfect joints . I have the older Pro pack and like the K3 well enough I'm thinking of upgrading.
Jack
Go for it, JL!!
It took me less than an hour from the time I got mine home to read the instructions, set it up on the bench, run a couple of samples, and make my first pocket screwed faceframe. It just isn't that difficult. By the end of the day, I had also figured out that I needed to dial back on my cordless clutch setting so I wouldn't break any more screws.
My only complaint is the snap-on dust collector. It connects to the 1-1/2" shop vac hose and it only goes on with the connection pointing to the left. I'm a lefty and it's sorta in the way - lol.
Dave,
Yes it's a great unit. I have the older version the Kreg ProPack. Have been doing pocket hole joinery for about 3 years now and think it's the best.While at the woodworking show I saw the K3 system and I ask if they took trade ins but they said no. But I'm still cosidering getting the new K3.
Jack
The real secret here is useing the pocket hole screws. They are self taping. If you were to use other screws, say dry wall screws or standard wood screws, you would need to drill the pilot holes through both pieces.
Jack
I've owned my Kreg 2000 for a few years and have used it for cabinetry to carpentry remodels it's been a very effective and easy to use tool. the Kreg web site is very helpful. when i got mine home the first thing I used the kit for was to build a work surface to mount the unit onto (of course I used pocket hole joints) out of some scrap Birch plywood between unwrapping the box to get to the unit, reading the instructions and assembling the carring case/work surface I probably spent about 2 hours
Sometimes when I am in a hurry I don't press the peices tight together before clamping them...this will cause the joint to be of slightly. So I try to keep the peices tight and aligned.
What does this situation in my life ask of me?
Trimcarp -
I also had to learn (the hard way) to not push too hard when running in the screws. If you let the self tapping screw point do it's job, the joint doesn't try to open up on you.
Well, I've assembled my first cabinet with the Kreg tool. It went pretty well, but I was surprised at how easily the screws pulled out if you tried to use them to pull a part with a curve in it back straight. The hardwood plywood back (for a free standing unit) had a slight bow in it, and I wanted to pull it straight with pocket screws in a dadoed permanent shelf. That didn't work - they just pulled out without affecting the bow (about 1/8 inch across 50 inches). I was using 1" screws (recommended on the box) joining two 3/4" birch plywood pieces at 90 degrees.
It's clear that they can't replace a good clamp set-up (which I thought I had read that they could , but I evidently got that wrong). Had it worked, it would have been perfect, since I had to put together a pretty complicated caul system to get the back flush with the shelf and the shelf screwed and glued in.
If they pull out that easily, I'm assuming that you'd want to stick with another joinery method when there might be racking force put on the cabinet in daily use (such as in a kitchen island, or free standing book case).
Is my experience common, or have I just missed something important?
Mike
3/4" to 3/4" at 90° is normally 1 1/4". Also, for birch ply you'd probably want hi-lo screws, coarse second choice, fine last -- fine will be prone to stripping out, particularly if you overdrive the screws. Don't drive past where it's snug!
Hope this helps.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
helps me! The talk here has me just about convinced to go with the Kreg system - what's recommended? I noticed there's a new kit that just came out, not sure of the name. If I get a tool I tend to get the full monty because inevitably the basic doesn't do what I want but no need to get something I don't use either. I'll be using it to build cabinets for a shop, general purpose tool for me at this point.I'm also interested if these joints can be used outdoors.
As I stated above I have the Pro Pack which is the Kreg 2000 and am considering upgrading to the new Kreg K3 system. Once you get it and use it a few times you will wonder how you got along without it.
Jack
Pocket screws should be excellent for outdoor projects - as long as the wood is up to it. A screw essentially clamps the joint together permanently (as long as the wood doesn't shrink) so a combination of waterproof glue and pocket screws should last for years.
If you were screwing into solid wood it would have worked. Was your plywood soid core? If not I don't believe a 1¼" would have held.
Jack
No, not solid core. It was standard veneer-ply birch plywood. Were it Baltic Birch, I expect that I would have gotten better results.
Overall, I was pleased with the results, inspite of my learning curve. My next task is to construct the face frame and attach it to the case. This should be an interesting learning experience.
At present, I have only the Kreg Rocket kit - nice enough for a trial run, but as others have suggested, if I decide that this is the way to go, I'll upgrade to the K3.
Mike
Mike,
I think you will be well pleased with the K3. If you order some of their DVDs you'll find lots of uses for it. I just did a review on one on trim carpentry with Gary Striegler, a contibuter to FWW, for another magazine. I would give it 3½ stars.
Jack
I've been following these messages with interest as I'm thinking of buying the Kreg system to help put some frames up. The frames are in oak, and my question is will the screws work with oak given the way it reacts with steel screws or would I need to use the self-tapping ones and then back out and replace with a brass screw?
Roger
I use them on Oak and haven't had any problems.
Jack
Thanks Jack.
I'm sure the Kreg is good but I like my Penn State Industries jig. It has a quick action clamp, is all aluminum or steel, has variable spacing, and is less expensive than the Kreg.
Jim
for joining boards at an angle, like attaching faceframes to a carcase, you can't beat the kreg clamps.
they are like vise grips and have one side that is a large flat pad and the other side is a peg that fits into the pocket hole.
if you drill your pocket holes in pairs, you use the clamp in one hole and pu the screw in the adjacent hole, then you move the clamp and the first screw holds the pieces together while you drive a screw in the hole that the clamp was in. drilling two holes is also helpfull if you can't get a screw to bite real well because you have another chance with the second hole.
i bought a whole bunch of the clamps so i can get multiple pieces set up and then screwed off without having to move the clamp as much...
I have a kreg machine and for most things find myself using the K3 instead, because it seems quicker and more convenient to me...also easier to deal with a large panel vertically than trying to balance it on the little table...
the kreg system is great I'm thinking about buying a couple of more K3 units and setting up a jig with them on a t-track so i can position them at the appropriate spacing and then do a production run of cabinet sides without having to move the piece for each pair of holes...
i use my old K2000 for situations where i need to drill holes in a piece that is either to large to conveniently move around or in pieces that have already been attached...
the locking lever on the front of the K3 makes it much easier to use with cabinet sides than the K2000, i'm sure anyone who has spent much time blindly reaching around a large piece of plywood to play a fun game of "where's that damn handle" will certainly agree...
Nothing's as fast as pocket hole joinery for quickies. The K3 is fast and reliable, I only have one and have the base mounted on a piece of MDF salvaged from an old discarded desk. I haven't found the 90° clamp as useful because it's not got the reach for internal shelves, or if your pocket holes are on the inside of the case. I usually just pull out a normal clamp to hold 'em in place, then hit it with the pocket screws.
Still, cut on the TS, join almost instantly with the K3 thrown onto the extension table. It ain't FWW (well, not on the projects I've used it for anyway) but then not every project is. :)My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Jack recommended the trim carpentry video from Kreg, and I'll go ahead and recommend the Cabinetmaking one. It helped me understand much better how to build the carcass and the face frames with the Kreg tools. Be forewarned, it'll make you want to add a few more of their clamps (angle clamp for me, as I already have the face clamp).My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
I did pick up the Cabnetry vidio and have watched it twice already. I'll probably watch it again after finishing this cabinet to see what I missed. That small cabinet being demonstrated goes together in a surprisingly short time! Of course, they don't show rough cutting and dimension cutting the pieces first, but even so.
Mike D
Ahh, the magic of TV. I'm glad my wife understands that David Marks doesn't really build a dining room table with laminated legs in 30 minutes (including time off for commercials).My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Johnd,
you also forgot to mention the editing of the OOOPS.
Jack
The only one who seems to show the OOPS is Roy Underhill in The Woodwright's Shop. I've seen him with bandages and stitches, and he'll comment on it and say how he did it. I see him screw up work and he doesn't edit it out, just laughs it off and fixes or adjusts the design or gets another piece.
Personally, I'm quite happy to use today's tools. But I sure like his attitude, and I sometimes learn really useful stuff from his show.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
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