Correct screw length for this joint

[Joe]

I'm going to join 2x4's, such that the pocket holes will go into the 3.5" side of one piece and this will be attached to the 1.5" side of the other piece. 

I know that if the 3.5" side was going into another 3.5" side, I should use 2 1/2" screws. Seems like my application would be best served by slightly longer screws, but I can't find pocket hole screws longer than 2 1/2". Would these work ok?

[KregRep]

Hi Joe,

Although you will be drilling in to the board from the other direction, it is still only 1 1/2" thick. So you will actually be joining 1 1/2" stock to 1 1/2" stock. And yes, 2 1/2" screws will be sufficient for this application. Also be sure to set your jig for 1 1/2" material. 

If you have any further questions, feel free to contact Technical Support directly at 800-447-8638 or [e-mail]

Thanks!
KregRep

[Joe]

Here's a pic with 2 1/2" screws with 2x4's. These are too long. Think I need to use 2" screws, maybe even 1 3/4"? These were made with a HF pocket hole jig I borrowed from a friend. I wonder if this is because HF bit has a different length for the step bit - it measures ~0.54" from the end of the 3/8" portion of the bit. 

Could also be because with HF jig doesn't center the hole on 1 1/2" material. I suppose ideally one would want the hole to exit the pocket hole piece at 0.75" (edge to center of hole). With this jig, the edge to center of hole is ~0.5". I noticed that the drill guide is the same for 1 1/4" and 1 1/2" thickness material. Helps cut costs I suppose.

This jig is good enough for this rough project, but I think when I get my own jig, it'll have to be the Kreg.

[james wilhelm]

HI Joe , If you are talking about a harbor freight  jig , I think you will be better off  to go with the Kreg  HD. Jig , I have one and have never had any problem, s with it , work,s good for me !!  Happy wood working  and have a good day , JIM !!!

[Joe]

No 1 3/4" Kreg screws at my local Lowes, so I picked up some 1 1/2" and 2" Kreg screws.

While I was at the store, I compared the HF step bit to the Kreg step bit. The HF pilot portion is ~0.1" longer than the Kreg. And the hole comes ~0.5" from the edge, rather than being centered on a 2x4 at 0.75" from the edge. And yet the 2.5" screws are clearly too long to join 2 pieces of 2x4 as pictured above. 

So I'm having a hard time understanding how this would have worked with the Kreg jig. With the pocket hole made by the Kreg, even less of the screw would be in the first piece (by ~0.1") and because the screw would enter more centered into the second piece, there is even less material for the screw to travel through. Can someone explain this?

Also, with the Kreg guidance on screw length for materials, is the idea for the tip of the screw to be *just* shy of exiting the second piece?

[james wilhelm]

HI Joe , I will do a test board with my HD Jig tomorrow  and take some pics.  of the same set up you have pictured , If the Jig is set to 1 1/2"  the bit is set to 1 1/2 "  and the screws are 2 1/2 "  there is no way they should be sticking out so far , as a standard 2 x 4 is 1 1/2 ' x 3 1/2 " , will do this in the morning and post it for you , have a good night  , JIM !!

[Joe]

Thanks Jim. 

Yes, the 2x4 pictured above is actually 1.5" x 3.5". One thing I noticed is that with the HF jig, the tip of the step bit comes very close to the edge of the wood. After drilling the pocket hole, when I look down the hole, there is sufficiently little wood at the end that I can see light pass through. To be clear, the bit does not punch through, but it's so close to punching through that light can transmit. Maybe the Kreg setup is designed for the tip of the step bit to not get so close to the edge of the wood?

So in the above pic, with a 2 1/2" screw, just over 1/2" of the screw (not counting the head) is in the first piece, leaving just shy of 2" in the second piece. And even at the angle it goes through the second piece, it's too long for the 1.5" deep side of the 2x4.

[james wilhelm]

Welcome Joe , will do the test board in the morning , will get back to you by 10:30 am ET. .  with the pics.  hope this helps , JIM !!! 

[Joe]

Here are same size pieces (2x4) with 2" Kreg screws.

[james wilhelm]

HI Joe this is my test board , used my K 4 Jig , set jig at 1 1/2 " and collar on bit  at 1 1/2 " , the top screw is 2 " and the bottom one is 2 1/2 " , also sent a pic . on the location of pocket holes hope this helps, JIM !! did not have the one board standing up , but it should be the same !!

[Joe]

Thanks Jim, this is helpful. Pretty huge difference between our two setups in terms of how far the screws protrude out of the first board. Given what I mentioned earlier regarding the differences in the two step bits, I'm guessing the explanation is that the Kreg step bit stops further away from the end of the first board.

Can you guesstimate (or does Kreg provide info) how far the tip of the step bit stops from the end of the first board? I.e., how much wood is left in the first board for the screw to penetrate?

With the HF step bit, you can see a bit of light coming through the end of the pocket hole, even though the bit hasn't punched through the board.

[james wilhelm]

HI Joe, it seem,s like the jig and bit you are using is drilling the hole to deep , I will take a measurement from the pocket hole to the end of the board and send it to you !!  You can also call customer service @ 1-800-447-8638 , they may be able to give you the hole measurement,s you want , are you using a cordless drill to drive your screws ?  May be set a little to high !!  Have a good day ,JIM !!

[james wilhelm]

HI Joe , did take some measurement,s  and added a few pics. , from the front edge of pocket hole it is 2 " to the edge of board , from the edge of pocket hole to the head of screw it is 3/4 " and that should give you about 1 " of wood left  in the hole to the end of board edge , no light showing through the hole !! Also added a pocket hole with my HD Jig  and a  2 1/2 " screw in the middle , comes out about the same as the other 2 1/2 " screw !!!  Don,t know what else to tell you except to get or try a kreg K 4 or K 5  and see what happens , good luck , JIM !!