# Joining with a 7.5 degree angle



## Turtle (Jan 17, 2013)

I have some trouble with joining. I am constructing a circle using 24 panels of cedar. They are 15" long. I must get a 7.5 degree angle on the long sides so I can join them all together to form a 30" circle. Picture the panels all standing up to form the circle. Does anyone have some advice so I may get a good join? Sure would appreciate anything you folks might have that would help. Drums are very important to indian people so I strive to make them as though they are fine furniture. Here are some pics.


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## bobj3 (Jan 17, 2006)

multi glue joint 

MLCS Euro door, door lip, finger pull, drawer lock bits, glue joint router bits

===


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## rwl7532 (Sep 8, 2011)

You are making a stave drum.
My advice would be to practice your angles using cheaper wood and making a smaller (e.g. 14" diameter) drum. 

A Wixey digital angle gauge must be 'dialed' in. That is, since it doesn't show all the decimal places, you should swing your blade back and forth to determine the true 'middle' point that is the true angle of 7.5

Getting the angle right is step one.


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## mgmine (Jan 16, 2012)

As Ralph suggested get a Wixey digital angle gauge. They seem to get repetitive results better than others. Also I would use a Incra miter gauge on a table saw. If you make these more than once (which looks like you do) then the investment will be worth it.


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## Turtle (Jan 17, 2013)

Thanks for the advice. I do have a digital angle guage or I would not be able to do this very well. I was thinking that I should probobly take a smaller final cut instead of just one cut. The real tricky part is putting it all together before the glue begins to set up. That pic looks a lot like my big drums except I bullnose the ends before assembly.


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## rwl7532 (Sep 8, 2011)

Routing the bearing edge after glue up and after rounding the outside and inside is how I have done it. Special jig required for a drum of your size.


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## rwl7532 (Sep 8, 2011)

Also, make certain your table saws insert is level with the table on all sides.


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## steamingbill (Jan 13, 2013)

*do it in 2 halves*



Turtlemakesdrums said:


> I have some trouble with joining. I am constructing a circle using 24 panels of cedar. They are 15" long. I must get a 7.5 degree angle on the long sides so I can join them all together to form a 30" circle. Picture the panels all standing up to form the circle. Does anyone have some advice so I may get a good join? Sure would appreciate anything you folks might have that would help. Drums are very important to indian people so I strive to make them as though they are fine furniture. Here are some pics.


This works with any polygon with an even number of sides - geometry rules - 24 sides = 360 degrees so 12 sides must be 180 degrees and 180 degrees is what you get when you do the sanding I have described below.

I did it like this for an 8 sided thing.

After you have done all of your testing to get the 7.5 degrees right.

Glue up 2 lots of 12 panels to form two "semi cylinders" a bit like the letter "n"

Do a dry run to see if the two semi cylinders meet perfectly.

If they do not then they will probably be close - glue some fine sandpaper to a perfectly flat surface and run the semi cylinders on the sandpaper so that the bottom of the two stalks of the "n" get abraded

When you have rubbed it so that the first and last edges of both "n"'s are sitting perfectly flat on the sandpaper then they should meet and glue together quite well.

This works with any polygon with an even number of sides - geometry rules - 24 sides = 360 degrees so 12 sides must be 180 degrees and 180 degrees is what you get when you do the sanding I have described below.

Worked for me with an 8 sided thingummy.

Bill


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## woodworkingmenace (Feb 7, 2013)

If I were going to do a lot of those drums, I would have made a smaller version of it, put wax paper around it and stapled it, then, got the angles, and put some slow setting glue around the edges and put it on the outside of the smaller one, and band clamped them.

But, silly me, I always did do things the hard way LOL 

I wish you well...

Jesse


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## woodworkingmenace (Feb 7, 2013)

Just a thought, couldnt you have made wedges and put some two sided tapes on the planter, both before and after the blade and then ran the boards over the blades to get your 7.5 degree angle? (This is taking into the account that the wedges and tape 'make' the 7.5 degree angle already, and its close enough so that you run along the fence).

Just a thought.

I wish you well...

Jesse


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## OPG3 (Jan 9, 2011)

Kevin, There are basically two types of closed polygons...those with unequal sides & angles, then the other type (with everything equal throughout) is referred to as a "regular" polygon. A regular 24- sided polygon (24- equal length sides & 24- identical angles) is properly referred to as an ICOSIKAITERA. Regardless of the number of sides & angles within any REGULAR POLYGON, the vertices ALWAYS lie on a circle. It will probably be best for you to "Google" icosikaitera to learn other helpful information. I also recommend using a couple of strap clamps for assembly of the finished sides - tape will also work, sometimes. Occasionally, in my shop we have had need to make "staves" that are all exact for the closure of regular polygons. I am kinda lazy, so what I tend to do is get my angles perfectly set and (on my tablesaw) cut long strips with both EDGES having the same angles - then on my chop saw, I simply cut multiple sections of the required length and "GO TO TOWN".
I hope this helps! If an AutoCAD drawing (sent to you as a .pdf file & printable on 8.5" x 11" sheet size) will help, send me all of the particulars and I'll send you back what you need. Metric or fractional (or both) are easily provided, just let me know if I can help.

Otis Guillebeau from Auburn, Georgia (email) [email protected]


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## steamingbill (Jan 13, 2013)

Hey Drum Makers,

How do ensure accuracy of the angles that you cut when you make these many sided polygons - is there a lot of mucking around and fine tuning involved after you have made the cuts ?

Bill


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## rwl7532 (Sep 8, 2011)

steamingbill said:


> Hey Drum Makers,
> 
> How do ensure accuracy of the angles that you cut when you make these many sided polygons - is there a lot of mucking around and fine tuning involved after you have made the cuts ?
> 
> Bill


What I am reporting is based on a one on one session I had with a stave drum maker.
First he made certain that the insert in his (SawStop) table saw was level with the table.
Next he zeroed out the Wixey digital guage.
Then it was attached to the blade.
Next the blade was tilted to the angle desired per reading on the gauge. Not done yet. (the important part) He then tilted the blade back and forth going in and out of the desired angle. By doing this he was able to get a better sense of where 11.5 was. The Wixey hides the extra decimal places so the back and forth allowed approximating where true 11.5 was. (we were cutting for a 20 stave drum).

We applied tape to the back side of the staves set edge to edge. The whole lineup was then flipped over and rolled into a circle to confirm all was well.
Then the line was laid down and glue applied.
There was no mucking around - no sanding to make right.

Test your procedure with cheap wood. Once you have the feel of zeroing in on your angle, cut the expensive stuff.

Do make sure your blade tilts away from your fence.


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## steamingbill (Jan 13, 2013)

*So you have to estimate the 0.5 degree ?*



rwl7532 said:


> <snip>
> 
> Next the blade was tilted to the angle desired per reading on the gauge. Not done yet. (the important part) He then tilted the blade back and forth going in and out of the desired angle. By doing this he was able to get a better sense of where 11.5 was. The Wixey hides the extra decimal places so the back and forth allowed approximating where true 11.5 was. (we were cutting for a 20 stave drum).
> 
> ...


Thanks for the description

Could take a while then if you estimate 0.6 or 0.4 instead of 0.5 

Possible to use lotsa scrap wood for tests ?

Bill


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## rwl7532 (Sep 8, 2011)

steamingbill said:


> Thanks for the description
> 
> Could take a while then if you estimate 0.6 or 0.4 instead of 0.5
> 
> ...


The key is in the doing.


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## Turtle (Jan 17, 2013)

If by 'bearing edge' you mean the ends of the standing panels, I always bullnose both ends before glue up. Much easier that way, and I do make a lot of them. Most are hand drums so I only need 22.5 degrees. It seems like I am doing it correctly according to the advice here. The last 30" drum I assembled came together quite well.


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## rwl7532 (Sep 8, 2011)

Yes, the bearing edge is where the drum head meets the drum shell. What material is used for the drum head for a drum that large?


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