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Why do Pocket Holes always come as pairs?

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Forum topic by WoodNSawdust posted 05-04-2015 02:37 PM 1345 views 0 times favorited 16 replies Add to Favorites Watch
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WoodNSawdust

1417 posts in 687 days


05-04-2015 02:37 PM

Topic tags/keywords: question pocket hole joinery pocket holes screws

I was assembling a cabinet today using pocket holes and wondered why do I always see pocket holes in pairs? If I was simply driving screws I would not necessary do them in pairs.

Thanks in Advance.

-- "I love it when a plan comes together" John "Hannibal" Smith


16 replies so far

View Notw's profile

Notw

479 posts in 1264 days


#1 posted 05-04-2015 02:47 PM

are you speaking of the jigs or actually the holes someone else has drilled in wood?

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waho6o9

7275 posts in 2087 days


#2 posted 05-04-2015 02:52 PM

Prevents the joint from twisting is my guess.

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johnstoneb

2235 posts in 1683 days


#3 posted 05-04-2015 02:56 PM

Keeps from twisting somewhat and adds to the strength. Pocket holes aren’t the strongest joint.

-- Bruce, Boise, ID

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WoodNSawdust

1417 posts in 687 days


#4 posted 05-04-2015 02:56 PM

@Notw: All of the plans I see call for a pair of screws every xx inches. I my case I was drilling 3 pair of holes (6 total) over a 20” span. Normally I would drive 3 screws (not pocket screws) on Left, Center, and Right to attach the top to a side.

-- "I love it when a plan comes together" John "Hannibal" Smith

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Richard H

489 posts in 1191 days


#5 posted 05-04-2015 02:58 PM

I have used single pocket holes for very narrow face frames and they do tend to twist and rack if you are not careful. Wherever I can I will use two of them for strength although I imagine once the glue dries on the joint it’s not as big a issue even though end grain to edge grain glue joints are not that strong. That makes me think the biggest advantage of two is keeping everything square during assembly without clamps. If you only used one pocket hole per joint you would probably have to keep clamps on the joint until the glue dried where with two once the joint is assembled you can take it out of the clamps and move on to the next one knowing it will stay square.

If you are talking about glueing two edge panels together I’m not sure. When I have used pocket holes for that (rarely) I just place a pocket every 8-12” same as I would do with biscuits for alignment purposes more than strength. Edge to edge glue joints are pretty strong and really don’t need extra mechanical support.

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TheFridge

5990 posts in 997 days


#6 posted 05-04-2015 03:00 PM

if you have a jig with 2 holes, which most do, why not drill a 2nd hole while your jig is clamped? I would. If it only had 1 hole, then maybe I’d use only one, but in face frames and small pieces you want 2 so I doesn’t twist.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View SirIrb's profile

SirIrb

1239 posts in 741 days


#7 posted 05-04-2015 05:09 PM

To eliminate 3 degrees of freedom.
1st degree: face to face
2nd degree: 1 screw
3rd degree: second screw

One screw would allow rotation.

-- Don't blame me, I voted for no one.

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hotbyte

864 posts in 2486 days


#8 posted 05-04-2015 05:40 PM

So they can sell more screws :)

I try to use a minimum of 2 if pieces are wide enough to prevent twisting and a maximum of 8 to 10 inches or so between screws.

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AlaskaGuy

2433 posts in 1820 days


#9 posted 05-04-2015 05:56 PM

If you drill a double hole pattern you can use these clamps to secure the joint while you drive a screw in the other hole.

-- Alaskan's for Global warming!

View Dallas's profile

Dallas

3599 posts in 1998 days


#10 posted 05-04-2015 06:01 PM

Because it makes wood workers ask silly questions.

-- Improvise.... Adapt...... Overcome!

View MT_Stringer's profile

MT_Stringer

2876 posts in 2742 days


#11 posted 05-04-2015 06:31 PM

I drill two holes in the face frames. Other places I space them out 4-6 inches apart. They make great mini clamps.

-- Handcrafted by Mike Henderson - Channelview, Texas

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Earlextech

1159 posts in 2201 days


#12 posted 05-04-2015 06:36 PM

Because Kreg!
Before Kreg, pocket holes were individuals.

-- Sam Hamory - The project is never finished until its "Finished"!

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SirIrb

1239 posts in 741 days


#13 posted 05-04-2015 07:12 PM

I used to do faceframes with pocket holes. If you put a pneumatic clamp on your table you will cry tears of joy. Nothing like it. Ok, maybe the birth of your first born but thats it.


I drill two holes in the face frames. Other places I space them out 4-6 inches apart. They make great mini clamps.

- MT_Stringer


-- Don't blame me, I voted for no one.

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MT_Stringer

2876 posts in 2742 days


#14 posted 05-04-2015 07:53 PM



I used to do faceframes with pocket holes. If you put a pneumatic clamp on your table you will cry tears of joy. Nothing like it. Ok, maybe the birth of your first born but thats it.

I drill two holes in the face frames. Other places I space them out 4-6 inches apart. They make great mini clamps.

- MT_Stringer

- SirIrb

But Sir, I have a pneumatic thingie! :-)

Ugh! Hard maple!
http://s226.photobucket.com/user/mt_stringer/media/DIY%20Projects/Kreg%20Jig%20Modifications/MyKregPocketHoleJigDemo.mp4.html?sort=3&o=0

-- Handcrafted by Mike Henderson - Channelview, Texas

View barada83's profile

barada83

76 posts in 697 days


#15 posted 05-06-2015 04:57 PM

I think pocket holes are designed to be an excellent way to join face frames. The spacing on the double is set for a typical face frame thickness. They obviously work for other joinery in which the double configuration would be a waste of screws. BTW, there is a single pocket hole drilling jig from Kreg just to emphasize that pocket holes can indeed be used in a single configuration.

-- Mike

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