Different thicknesses?

[David White]

Before I get into the shop and spend time experimenting with scrap wood I want to know if anyone has already figured out the correct settings for joining two different thicknesses of boards.  I am specifically interested in joining a 3/4" board to a 1/2" board.  One could setup the jig as if two 1/2" boards were being joined.  Even though the screw is not in the center of the joint the world wouldn't end.  However I like precision and that wouldn't cut it.  My guess, before testing, would be to set up for a 3/4" joint but to use a 1" screw rather than the 1 1/4".  I searched the Kreg info and can not find this issue addressed anywhere.

Anyone want to save me some time?

[Ben Socratous]

I have had a bit of a play with doing this using scrap mdf offcuts. I have found that the best way is to use all the settings (depth, screws, etc) for the thinner piece and make sure that the pockets are in the thinner piece ie screw from the thinner to the thicker stock.

[David White]

Thanks for your reply and I agree with your answer but the specific question dealt with attaching the thicker piece to the thinner piece. (i.e., a 3/4 shelf to a 1/2 side, say for a book case) I'm not looking for a work around, as there are many, but want to do this specifically.

Ben Socratous said:

I have had a bit of a play with doing this using scrap mdf offcuts. I have found that the best way is to use all the settings (depth, screws, etc) for the thinner piece and make sure that the pockets are in the thinner piece ie screw from the thinner to the thicker stock.

[Douglas Golding]

My understanding is that the setting of the depth stop on the drill and the positioning of the jig always and only relate to the thickness of the wood being drilled into. The length of the screw always and only relates to the thickness of the wood being screwed into. I think that, if the jig and depth stop are set correctly for the wood being drilled, the part of the screw contained within the wood between the base of the pocket and its exit hole will always be about the same, regardless of the total length of the screw. Therefore, the amount of screw that protrudes from the exit hole in this piece (and penetrates the other piece of wood) will always be determined by the length of the screw being used. So use a 1 inch screw to fix to half inch thick boards.

[David White]

Again another good response but I will now present my opinion though I have not tested it yet. I was on a fishing expedition with Kreg about the amount of additional information on the pocket hole jig that the owners could use. I think that they should make more specific info available and at the very least respond the the questions posed in this forum.

Given the scenario that I have presented here I believe that the jig should be set for the the thicker board so that the screw will cross the center of the joint. By raising or lowering the jig the center line of the joint will move in and out and the screw will be centered in the 3/4" (thicker board). The setting of the drill collar should be at 1/2" setting and use the 1" screw. This arrangement should have the screw centered in the joint and secured that same as if two 1/2" boards had been joined.

Douglas Golding said:

My understanding is that the setting of the depth stop on the drill and the positioning of the jig always and only relate to the thickness of the wood being drilled into. The length of the screw always and only relates to the thickness of the wood being screwed into. I think that, if the jig and depth stop are set correctly for the wood being drilled, the part of the screw contained within the wood between the base of the pocket and its exit hole will always be about the same, regardless of the total length of the screw. Therefore, the amount of screw that protrudes from the exit hole in this piece (and penetrates the other piece of wood) will always be determined by the length of the screw being used. So use a 1 inch screw to fix to half inch thick boards.

[Bob Farmer]

David, good question... I had that issue too. Did you run a search before you added your question? This has been discussed here a few times before, Kreg has given input on those occasions.

http://kregjig.ning.com/forum/topics/screw-size-for-different-sized
http://kregjig.ning.com/forum/topics/is-there-a-kreg-jig-screw

[David White]

I searched everywhere that I could think of including Kreg Videos that I purchased and I can't find a particular location for technical questions. I sent them an email and I was directed to this forum. I think that getting technical info should be easier than this.

Bob Farmer said:

David, good question... I had that issue too. Did you run a search before you added your question? This has been discussed here a few times before, Kreg has given input on those occasions.

http://kregjig.ning.com/forum/topics/screw-size-for-different-sized
http://kregjig.ning.com/forum/topics/is-there-a-kreg-jig-screw

[Bob Sanders]

I think the biggest problem is that there are far too many variables to answer your question simply. There's no magic bullet solution for every joint of different thickness. What kind of joint is it? Are you drilling into the smaller piece or the larger piece? Will the two workpieces be flush or offset? Are you edgebanding or working on a leg and rail joint? We can't, and I'm sure KReg can't, give a good answer unless we know what yoru specific situtation is. I would guess that's why there isn't anything on their site in great detail because there are too many variables to account for.

In my opinion, the answer to your question is simple... trial and error. Build some test joints, and then adjust accordingly. That's what I do.

[Douglas Golding]

I think you'll be making a mistake if you set the drill collar to 1/2 inch. It should correspond to the jig setting for the piece into which you are drilling the pocket hole, ie, 3/4 inch. It's the use of the 1 inch screw (nothing else) that responds to the 1/2 inch thickness of the piece being fixed to. If you set the drill collar to 1/2 inch I think your 1 inch screw will be too short for a good fixing because the pocket hole will be too shallow.

David White said:

Again another good response but I will now present my opinion though I have not tested it yet. I was on a fishing expedition with Kreg about the amount of additional information on the pocket hole jig that the owners could use. I think that they should make more specific info available and at the very least respond the the questions posed in this forum.

Given the scenario that I have presented here I believe that the jig should be set for the the thicker board so that the screw will cross the center of the joint. By raising or lowering the jig the center line of the joint will move in and out and the screw will be centered in the 3/4" (thicker board). The setting of the drill collar should be at 1/2" setting and use the 1" screw. This arrangement should have the screw centered in the joint and secured that same as if two 1/2" boards had been joined.

Douglas Golding said:

My understanding is that the setting of the depth stop on the drill and the positioning of the jig always and only relate to the thickness of the wood being drilled into. The length of the screw always and only relates to the thickness of the wood being screwed into. I think that, if the jig and depth stop are set correctly for the wood being drilled, the part of the screw contained within the wood between the base of the pocket and its exit hole will always be about the same, regardless of the total length of the screw. Therefore, the amount of screw that protrudes from the exit hole in this piece (and penetrates the other piece of wood) will always be determined by the length of the screw being used. So use a 1 inch screw to fix to half inch thick boards.

[Dan]

This thread has already been referenced, but it has some good info in it

Attached is a pdf file that you may come in handy.

[Jim Taylor]

Here is a better chart rendition. For some reason the other pdf does not show which piece is which.

[Donna Foster]

Thank you for the chart. I haven't had this problem yet but I've actually thought about it and wondered what I would do in any of these situations. I will print it and keep it with my Kreg jig (which I love) Thanks again

Jim Taylor said:

Here is a better chart rendition. For some reason the other pdf does not show which piece is which.

[Kurt]

I know its way late but just thought I would post this cause I was wondering the same thing.