Sunday, May 10, 2015

My Version of Pocket Hole Joinery

A strong joint can be made using only  screws and a 2x8. No
 glue or dowels are used and after a few tests I show how it can
 hold up the rear and front end of a car. 

See video on how to make and watch some testing.

Pocket hole joinery has been used in piano construction for years. I have seen many 
and just recently took these photos. This is underneath a 100 year old  grand piano, 
and the wood post shown here is a support for the legs.

Here I will show you my version of the pocket hole joinery. They may look different but use the same principle and  require  few tools to make. Since I don't have any of the fancy jigs to make           pocket holes I will do them free hand.

    The tools I will be using are a square, pencil, bit driver, 3/4" Forstner drill bit and a cordless
    drill. The wood is 2x6 fir and the screws are  #14  3 1/2 inch . Clamps may come in handy but
    I have made some without them.  

The basic idea is to use the Forstner bit and after starting the hole tilt the drill 
 at an angle and drill  free hand to get this result. I did it free hand but for this 
 article I measured the angle and it was roughly  15 degrees. 

 Here you can see how the screw will fit the two pieces. The marked line is 
necessary to give the correct distance for the screw so it won't go through the 
adjoining  piece. The size of the Forstner bit, screws and distance will change 
depending on the piece you are working on.

                              I used some clamps to keep everything lined up and put the 3 1/2 inch 
                              screws in. I did  not predrill and drove the screws into both pieces. 

         I flipped it over and now have what looks like a step stool. I put it on the 
         ground and stood on it. I weigh 210lbs and jumped on it and it's solid! I 
         will now have to move onto something bigger.

                               Here I  move on to my next test. I will use the same technique 
                               but this time I will use 2x8 fir and double up the sides and put 4
                               screws in each side instead of 2. With my new Large Compass I 
                               make marks that are evenly spaced and drill them out.

                               I used the same # 14  3 1/2" Robertson screws and drove them into
                               the wood.  No glue or dowels!  To hide the holes some 3/4" dowel 
                               caps can be made and inserted!

                                         The piece is ready for testing. It feels solid and ready
                                         for some heavy weight.
                                             This time I will be using my car.

                                  The rear end...  

                               The front end....I did not want to try this but my kids insisted so 
                               I slowly rolled my car on the block and was blown away that it held up. 

               Another photo of the front end. The car is an Acura TL and weighs 4000 lbs  plus 
               my weight.

               The block worked out great and I did use it again to do a retake  video of the rear end 
               again. Even after all this weight testing it is still intact. I would not crawl under a car 
               with this block but for this test I was very pleased. 

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