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I made a octagon shaped box to hang on a fence, nothing fancy.  I am having trouble trying to figure out the best way to join the 8 pieces together with pocket screws.  Each piece is 9 inches long with each end has a miter cut at 22.5 degrees cut from a 1 x 6.  I tried pocket screw but 1 1/4 inch screws did not have enough bit and 1 5/8 were to long and protruded out of the 1 by.   Any and all tip are greatly appreciated.

thanks, bill

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Hi Bill, I will attempt to explain a method of which you can use pocket holes to assemble a mitered joint.  This might take more than one page.

Miters and building odd figures like an octagon is a tricky situation until you understand angles and combinations of placing angles against another surface to gain a desired configuration like that of an octagon or even an odd sided figure such as five or seven sides in a box or a frame.
 
I have often built bases and frame for not only for stained glass but I have build boxes for such things as light fixtures in some of the custom cabinet work that I have been required to do. 
 
In this situation where you are wanting to build an octagon box and wanting to join the frames using pocket screws and if you do it by cutting miters on each end you will have a tough time using pocket hole joinery as you have found out that the screws do not work as well as hoped.
 
I have a method of doing this but is not the same as the normal as you have the correct angles of 22-1/2 degrees on each end.  The results is a octagon when assembled end to end but the use of screws is difficult.  Glue is not the best option as it results in a weak joint as you are gluing end grains.  You could use a spine in the joint but this is a tedious method and still is not as strong as a glued and pocket screw joint.
 
The method of determining the 22 1/2 degree angle is done by dividing the 360 degree circle by 16 which is the number of miter end cuts that are mating each other.  This is the method to determine any angle needed in building such configurations such as a seven sided angle.    360 degrees divided by 14 (the number of cuts that mate each other)  and the results is 25.7 degrees.  In determining degrees when you have a fractional number left over round it off is one method or split the number.  With a highly accurate miter saw I always round to the higher number as you get a tighter joinery with out distorting the project.  In this equation the results is 25.71 degrees so drop the one and make it an even 25.7 degrees.   What you dropped is the amount that you would need a micrometer to measure and wood will move more that that,  had it been 27.75 I would have added a degree.
 
Now to my method of building an octagon and using pocket hole joinery my math changes as I will be cutting eight pieces at the angle of 45 degrees.  Why, I only cut one end and leave the other end at 90 degrees.  That means that I only have eight pieces of wood to join into an octagon.  Since the degrees needed to complete an octagon is 22.5 degrees  then I need to double the degrees of cut.  This means it has to be 45 degrees.
 
In the sample that I have included I am using 13/16"  lumber by 2 and 1/2 inches wide.  I cut one end at 45 degrees and leave the opposite at 90 degrees.  Now a word about determining the size of your finished octagon.  The best way if to cut a length that you know will more that be enough for one piece and use some scrap wood and experiment with it.  The size of an octagon using this method is determined the same way as that when cutting miters on both ends  but is cut after cutting the 45 degree on the one end.   To adjust the final size of the octagon you must cut the 90 degree end off.  What I do is cut a 45 degree miter in one end of 8 pieces of scrap that is a little longer that the pre determined size of a leg of one of the 8 in the octagon.  Lay the pieces out on a flat surface mating the cut end to a 90 degree end.  Make sure all of the eight pieces are equal in length.  It does sound complicated however will be come clear once you see the enclosed photos. 
 
In the example that I am enclosing the length of each leg is 7 & 1/4 inches long from the toe to the 90 degree end.  It resulted in an octagon that is 18 and 1/4 inches wide. This means that you must determine the length of each leg that you need and once determined you will then bore the number of holes you desire for the joinery of the octagon.    Once bored you will begin assembly by screwing into one of the miters and continue this around the octagon.  In my example I used two pocket holes bored for screw insertion on the inside.   It must be noted here that  you must also determine if you want the screws to be on the inside or the outside and bore accordingly.  You are screwing into the miter so do not bore any holes in the end with the miter in it.
 
Of importance is that due to the restriction of space when installing on the inside that prevents you from inserting a drill driver in all but the large octagons you should label each piece as shown in the photos attached and pre-screw the screws into the miters.  This will allow you to use a driver used in a 1/4 inch socket -ratchet as shown.  In the example I have enclosed I was able to use a driver and a medium length driver bit in all but the last two pieces.  Since I had pre-screws the screws in the joint it was an easy task to use the socket and ratchet with a bit inserted in the socket. 
Once this is done then you are ready to assemble the octagon.   If preferred, and something that I do recommend, use a good brand of glue in the miters and allow some glue to soak into the end grains seen in the miters.  After two or three minutes re-apply a coat and assemble.
As you assemble the joints keep the inside aligned at the heel of the miter,  The toe will extend out past the joint and will be cut off.  If you are using matching pieces of material the joint will be almost invisible and in fact will fool the eye as you move the actual joint about 1/4 inch past the point where you would normally look for the joint line.  Once assembles cut or sand off the protruding toe of the miters.  The can either be left square with the side or rounded off.     Refer to the attached photos:

Hi Bill, I just sent you a long detailed method of how I use pocket joinery in mitered cuts.  I did not mention any of the other related things to take into consideration if you are building a project where furniture and or cabinet quality appearance is going to be desired.  This is red oak from my scrap bin.

In the example I sent I could have cut all the pieces from a long length of red oak  and kept them in order as they were cut and it would present a better look in both grain pattern and color match.

I used 1 and 1/4 inch fine thread screws in this as it is hard wood.  You will note that he direction of the screw penetration in going in a direction of where there is plenty of wood to prevent the screw from exiting the side.Also note that you keep the heel of the miter flush with the inside of the adjoining piece.  The toe of the miter will be longer but is cut off and or sanded off when done.  This can be done so that it remains square with the octagon sides and or rounded off.  Note that when this is done it moves the eye to appoint about 1/4 inch away from the actual joint.  This will help hide your miter joint.   None of the miters in any of the joints shown required wood filler and this one is left un-sanded and cut off with a flush trim saw when finished.

Any questions you have please feel free to contact me. 

JAY, as all ways a very well written discussion , on how to make a octagon box , well explained and lots of photos  to show how it is done the right way , that anyone could follow and do a good job!!!!!!    As a wood worker on this site , I for one want to thank you for taking the time to write this discussion with photos  to help many wood workers , this is what it is all about , helping others to improve there skills on there projects !!!  What is needed here is for more members to read this type of discussion  and give thank,s to the few that go way out of their way to help others, except maybe a thank you and read their posts !!  I have known Jay for years and he has always been here to help others  and he  ask,s for nothing in return , but a thank you would be very nice , well done Jay thanks again , JIM !!

Bill, If you really want to push the envelope you can.

Its just a matter of thinking about what you want to do.

Here is a small mushroom stool constructed with the Kreg Jig using tapered staves and equal joints.

Make it in quarters then assemble two halves and then assemble the complete base, then add a top.

In this situation I also applied Polyeuthane Glue to the joints as it remains outside in the garden.

The attaching screws for the top were recessed and plugged after assembly

Some paint and job complete!

Jay thanks a ton for the lesson on joining and cutting octagons!  Really appreciate the time and effort you took to answer my questions.  The photos really helped me understand how it all comes together.  If you ever in Shreveport, LA I'll cook you some of my famous gumbo.   I'll tackle my little project tomorrow and see if I am as good as a student as your are a teacher.

Robert, love the mushroom stool, would look great in my garden.  I'll give it a whirl later on.

Thanks Again!  Bill

Thank you Jim for the nice words of appreciation for what I do.  Working with miters can be a complicated thing to do until you learn the fundementals of how to go about it.  I am much like you as I have no problem helping someone learn something that makes their skills better.  I guess that is why I love teaching so much and the classes members that I teach learn quickly as that makes the task easier.   I also do not care about the Thank you's as much as i do care about where or not my posts are read.  I know I have written many of which I have no idea if they are ever read and or if they  help anyone or not as many are never relied to.  Again Thanks for your nice comments. 

james wilhelm said:

JAY, as all ways a very well written discussion , on how to make a octagon box , well explained and lots of photos  to show how it is done the right way , that anyone could follow and do a good job!!!!!!    As a wood worker on this site , I for one want to thank you for taking the time to write this discussion with photos  to help many wood workers , this is what it is all about , helping others to improve there skills on there projects !!!  What is needed here is for more members to read this type of discussion  and give thank,s to the few that go way out of their way to help others, except maybe a thank you and read their posts !!  I have known Jay for years and he has always been here to help others  and he  ask,s for nothing in return , but a thank you would be very nice , well done Jay thanks again , JIM !!



Bill Wood said:

Jay thanks a ton for the lesson on joining and cutting octagons!  Really appreciate the time and effort you took to answer my questions.  The photos really helped me understand how it all comes together.  If you ever in Shreveport, LA I'll cook you some of my famous gumbo.   I'll tackle my little project tomorrow and see if I am as good as a student as your are a teacher.

Robert, love the mushroom stool, would look great in my garden.  I'll give it a whirl later on.

Thanks Again!  Bill

 

 

Hi Bill, it was all my pleasure as I know you wanted to learn something and i happened to have the experience to help you.   If I am ever in your neck of the woods I will take you up on your gumbo offer and we could spend some time talking woodworking.   i am sure you have a few tricks that you could show me.    Like I said if you have any problems with doing your octagon please let me know and I will see what I can do to help you suscessfully complete your project.    yes that Robert might live a long ways from us but he sure does have some good ideas and woodworking skills.  He can turn out some mighty fine woodworking porjects.  He is another guy I would like to spend some shop time with.   Please post your project when you finish it.

Robert, That is a very nice looking stool that you posted.  I like the way you joined the staves and made a very nice looking and functional piece out of it.  Angles can be fun to work with and you can turn out some very clever and interesting woodworking projects that you can not do without having some knowledge about how to join them into a single piece.  I do not recall seeing you post this project before and if you have not I urge you to do so as it is interesting and displays a lot of thinking and craftsmanship in it.  I think it might stir some interest among the members and show that that there are things out there yet to be made.  It only takes some imagination and desire to build something out of the ordinary.   Thanks for posting and helping out in showing angles and kreg screws. 

Robert, That is a very nice looking stool that you posted.  I like the way you joined the staves and made a very nice looking and functional piece out of it.  Angles can be fun to work with and you can turn out some very clever and interesting woodworking projects that you can not do without having some knowledge about how to join them into a single piece.  I do not recall seeing you post this project before and if you have not I urge you to do so as it is interesting and displays a lot of thinking and craftsmanship in it.  I think it might stir some interest among the members and show that that there are things out there yet to be made.  It only takes some imagination and desire to build something out of the ordinary.   Thanks for posting and helping out in showing angles and kreg screws. 


Robert Brennan said:

Bill, If you really want to push the envelope you can.

Its just a matter of thinking about what you want to do.

Here is a small mushroom stool constructed with the Kreg Jig using tapered staves and equal joints.

Make it in quarters then assemble two halves and then assemble the complete base, then add a top.

In this situation I also applied Polyeuthane Glue to the joints as it remains outside in the garden.

The attaching screws for the top were recessed and plugged after assembly

Some paint and job complete!

Jay, I am sure the only tricks I could show you would be with my cooking skills as I am a working Chef, just a beginner at woodworking. 

Jay Boutwell said:



Bill Wood said:

Jay thanks a ton for the lesson on joining and cutting octagons!  Really appreciate the time and effort you took to answer my questions.  The photos really helped me understand how it all comes together.  If you ever in Shreveport, LA I'll cook you some of my famous gumbo.   I'll tackle my little project tomorrow and see if I am as good as a student as your are a teacher.

Robert, love the mushroom stool, would look great in my garden.  I'll give it a whirl later on.

Thanks Again!  Bill

 

 

Hi Bill, it was all my pleasure as I know you wanted to learn something and i happened to have the experience to help you.   If I am ever in your neck of the woods I will take you up on your gumbo offer and we could spend some time talking woodworking.   i am sure you have a few tricks that you could show me.    Like I said if you have any problems with doing your octagon please let me know and I will see what I can do to help you suscessfully complete your project.    yes that Robert might live a long ways from us but he sure does have some good ideas and woodworking skills.  He can turn out some mighty fine woodworking porjects.  He is another guy I would like to spend some shop time with.   Please post your project when you finish it.

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