# Pocket Hole Question re:drill through?



## Valid8r (Nov 8, 2008)

Can anyone tell me why the small part of the Kreg drill bit is not intended 'breakthrough' (to go through all the way the piece with the pocket hole)? At least as I understand it, the stop collar prevents the fine/small part of the bit from actually drilling a hole through the 'backside' of the piece containing the pocket hole. 

It seems to me that if you don't do so, that you then face the situation that when you do screw the two pieces together, that when the screw starts to push through those few millimeters of stock (to break through), those fibers are going to push out into the joint space and tend to try to force the joint apart a little bit. In fact why is it that we don't try to get any form of a pilot in the 'jointing' piece? I suppose the answer to this is that the Kreg style screws are self tapping?

Thanks for any help explaining this to me.

Jon


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## TimPa (Jan 27, 2010)

i'm guessing that a drill through would necessitate sanding/carving of the raised fibers around the exit hole area, something you probably want to avoid. a successful joint is tight, so the remaining wood left from not drilling through is obviously pulled back into the screw area bu the self tapping threads as you mentioned. my pocket holes joints are about 50% successful, as the boards tend to misalign as the screw draws them tight. i need to improve my clamping system i guess.


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## mics_54 (Oct 28, 2008)

I just recently began using a kreg pocket hole jig/tool. It seems to work as advertised and makes decent joints. I do use a vice grip clamp when joining rails to stiles. I also notice on some test pieces the protruding hole material created by the self tapping screws that was mentioned and I don't think this is a problem unless you removed a previously assembled rail and replaced it with a new rail and tried to rejoin the pieces.

I'm not 100% convinced that a pocket screw joint is stronger than a typical dowel, bisquit or spline joint...what I do know is, it's faster, cleaner and much easier to fix mistakes. Looks like a money maker to me.


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## Rob (Oct 31, 2006)

I have the 10" metal plate installed in my workbench, along with the attaching clamp. It's important to keep the two faces flush as well as tight against each other when driving the screws. I make sure the clamp exerts enough pressure so the two faces don't spread apart when driving the screws. 
Before installing this plate, I used the clamp that came with the kit. It works fine but is a PITA to hold the two pieces of stock over the side of the workbench in order to clamp them.
I have 100% success with the jig and the screws and love the system. Couldn't keep shop and make money without it. And yes, when the piece (and price) calls for it, I do mortise and tenons and all the traditional joinery. But for simple kitchen cabinets or bookcases where the pilot holes aren't seen, I go to the Kreg Jig.


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## thekctermite (Dec 23, 2007)

TimPa said:


> my pocket holes joints are about 50% successful, as the boards tend to misalign as the screw draws them tight. i need to improve my clamping system i guess.


Using a Kreg faceframe clamp will eliminate that problem for you Tim. $25 well spent to save a lot of frustration.

Valid8r, the reason for the small part of the pilot hole is so that the piece that you're screwing through draws tight to the piece you're screwing into. Without that hole the pieces might not draw tight. Same reason that many screws have unthreaded shoulders on them.


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## Valid8r (Nov 8, 2008)

Termite, can you elaborate on your explaination? At this point my question is more of curiosity certainly not challenging. If the 'small' hole was a 'through hole' (through the screw head piece) so you could see daylight if you looked through it, how would that do anything but make the joint tighter? Thanks,
Jon

Also, I've seen that new faceframe clamp and am going to buy one this next weekend.




thekctermite said:


> Using a Kreg faceframe clamp will eliminate that problem for you Tim. $25 well spent to save a lot of frustration.
> 
> Valid8r, the reason for the small part of the pilot hole is so that the piece that you're screwing through draws tight to the piece you're screwing into. Without that hole the pieces might not draw tight. Same reason that many screws have unthreaded shoulders on them.


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## wooddude9 (Sep 6, 2008)

If you drill all the way through the tip of the bit drill into the bottom of your kreg jig, and do that too many times something will break or wear out. Also the space between the bottom of the hole and the next piece allows the screw grab and drive before it touches the other work piece. And that keeps the screw from pushing the pieces out of alignment and lets the face clamp do its job.


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## jlord (Feb 1, 2010)

I sometimes use the cast iron top on the table saw when assembling face frames. Just use the face frame clamp & clamp it down on the top when driving in the screws. It's kept the joint flush compared to just using the clamp it"s self.


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## bassin93 (Apr 24, 2009)

rockler now makes a clamp that I feel would work better then the vicegrip style as long as you have two holes drilled. A peg on the clamp inserts into one of the holes and the other end has a shoulder that rest on the outside edge of the other board and when you tighten the screw it draws the two peices together rather then simply clamping the joint from the sides.


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## rrich (Jun 24, 2009)

bassin93 said:


> rockler now makes a clamp that I feel would work better then the vicegrip style as long as you have two holes drilled. A peg on the clamp inserts into one of the holes and the other end has a shoulder that rest on the outside edge of the other board and when you tighten the screw it draws the two peices together rather then simply clamping the joint from the sides.


Have you used it? Do you really like it? I've been thinking of buying one.

To answer the original question.

If you set the depth stop collar to almost break through, you get a perfect joint. The bridging doesn't happen if the clamps are used as suggested above. The KREG screw is a clamping device in addition to screw holding power. If you add a bit of TB-III to the joint, the wood will break first before the joint fails.

BTW - It is almost impossible to use pocket hole joinery without using the appropriate clamps.


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## Rob (Oct 31, 2006)

> Originally Posted by *bassin93*
> _rockler now makes a clamp that I feel would work better then the vicegrip style as long as you have two holes drilled. A peg on the clamp inserts into one of the holes and the other end has a shoulder that rest on the outside edge of the other board and when you tighten the screw it draws the two peices together rather then simply clamping the joint from the sides._


That sounds like the one Kreg makes...maybe not. I have the Kreg clamp that fits this description and it's designed for 90* clamping. I've never used it for regular edge to edge clmaping but it may work.


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## bassin93 (Apr 24, 2009)

The rockler clamp will not work for end to end as the back part of the clamp has to reach over the edge f the projectfor an anchor point. This device would be for face frame type work or 90 degree clamping.

I do have a friend that has purchased one and for what it is intended for seems to work very well. Jeff


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## mayday3374 (Feb 29, 2008)

*my experience in kreg pocket hole joinery*

i do not know why they did not design the pilot hole piece of the bit to break through the end of the board, but when i adjusted the stop collar so the bit would just break through, it made the hole too deep and my screw would poke through slightly on 3/4" boards. i either had to start with a new board or slide a washer over the screw to prevent it from poking thru.. several projects later, i found a system that works every time and gives me perfect joints with pocket hole screws. As mentioned previously, a little TBIII makes a world of difference. I drill my pocket holes and then dry fit my pieces to assemble. I then apply TBIII to the joint, clamp it in place, and align the edges so they are level and square to each other. I then let the glue set up for 20 minutes,drive the screws in, and remove my clamps. I know this requires some patience and slows down the assembly time, but i have had no more troubles with boards shifting out of alignment while screwing pieces together, and i get the added benefit of glue to hold the joint together for the life of the piece that i am building. if you have enough clamps, you can set up multiple joints to be joined at the same time on larger projects, and the 20 extra minutes of doing it this way reduces both your time and frustrations spent on trying to fix a misaligned joint. hope this helps


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## thekctermite (Dec 23, 2007)

Valid8r said:


> If the 'small' hole was a 'through hole' (through the screw head piece) so you could see daylight if you looked through it, how would that do anything but make the joint tighter?


I can't argue with that logic. I presume that they're trying to avoid the inevitable "nub" of wood that you'd get if the small part of the bit penetrated the jointed edge....Torn grain and such.

The idea of gluing and waiting before screwing pocket holes together is good, but kills productivity, which is the main benefit of pocket hole joinery. Face it, most of us use pocket holes because they're strong immediately and we don't have to clamp and wait.

FWIW, I've looked at the Rockler pocket hole clamp and am completely unimpressed. For my money I'd rather have the Kreg clamp that puts pressure/emphasis on a perfectly aligned face. Cranking a little thumbscrew knob down each and every time, and relying on "finger tight" pressure to keep the stile and rail in the perfect position when they want to move when being screwed is no good in my book. Plus, the Rockler clamp gets in the way and must be repositioned once for every two adjacent screws you put in. :thumbdown: The idea of being able to build frames flat on the table is good, but I'd personally opt for the Kreg bench-mount plate that has a clamp. Rockler tried to re-invent something that works really, really well.


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