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Need stave angles

15K views 32 replies 7 participants last post by  Hammerheadhowie  
#1 · (Edited by Moderator)
I found a post from 2014 describing some of the information I need but not enough. My plan is to build a round, barrel like (without the bulge in the middle) structure that will support a manhole cover I have to make an outdoor table. The blog I read said that you need the final drum size (22" diameter), and wall thickness (can be variable but probably an inch) to be able to determine the number of staves and the proper angle to cut the staves. I am definately still missing some pertinent info to figure this out. I have a lot of home improvement experience but am a novice woodworker. As simple of an explanation as possible would be appreciated. I was never great at math. This is my first blog entry ever by the way.
 
#2 ·
There are several online calculators you can use to determine the angle to cut the staves and how wide to make them to acheive the size drum you want. Here is one. I simply searched for stave calculator and got several other examples as well. You basically need to know the diameter, wood thickness and how many sides you want to use. You may want to play around with the number of sides to get an easy angle to setup on your table saw. If you don't want a base with straight sides, this splayed miter joint method might help you determine how to make those cuts.
 
#4 · (Edited by Moderator)
Each stave is a slice of pie. A circle has 360 degrees, so if you divide 360 by the number of stave you are going to use you get the angle of the pie slice, then divide that is half to get the angle to set your table saw.

360/20=18/2= a blade angle of 9 degree for either side of your stave.

The more staves you use the rounder appearance you will get. I found 18 staves (10 degree saw blade tilt) looked nice when I made small whiskey barrels, but I wouldn't go with fewer than that.

Edit: the easiest formula is blade angle=180/#of staves you want to use.
 
#8 ·
Alright, the stave calculator is awesome (kind of like a concrete calculator) but I still have a question. In the diagram, it shows the edges of the staves protruding past the outside diameter which I don't want. Does that mean that I should make my outside diameter input less than the 22 1/2" I was thinking so that the wood does not stick out past the lid (manhole cover)?
 
#9 · (Edited by Moderator)
I assume you are talking about the diagram below. The calculator assumes you are going to make the staves out of flat boards and shape it to round. Shaping the long staves to round before glue up might be a little challenging. If I were doing this, I would glue it up and use a hand plane (for example) to round the corners to make the entire barrel round. The narrower the staves the less you will have remove to make it round but you will have more corners to shape. Does that make sense?

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EDIT to add: Do you also need to make the interior round? If so, the same rule applies-the narrower the staves the less work to round them; however, doing that after the glue up would be pretty tough so you might need to cut coves on the table saw or possibly with a router table or jig.
 
#12 ·
OK, still struggling a bit. The calculator says I need an angle of 7.82. I tried subtracting 7.82 from 90 but that did not work, the outside and inside measurements for the stave did not come out right. How do I figure that angle? I am doing 23 staves with an outside diameter of 21". Chart says the outside cut should be roughly 3" and the inside roughly 2 1/2".
 
#13 ·
Just looked at the calculator again, think i am having trouble with the ring thickness vs the segment thickness. Not sure what the ring thickness is for but I now see that my segment thickness is not near big enough. It is calling for an 1 1/2 and I have about 3/4". I am sure that could account for my discrepancy. Guess I need to mess with the calculator to have it work out to my 3/4" thickness.
 
#15 · (Edited by Moderator)
Let's clarify.
The chart is for making a round ring. You put in the perimeters of the ring you are wanting to make and it tells you how thick of wood, and what size of segments it takes to get that ring.

Are you making your stand round, or just trying to use flat staves?
If you are just using flat staves, ignore the rest and just go with the outside segment lengths.

To start, approx. how wide of pieces do you want to use?
How thick is the material you are going to use?

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#16 · (Edited by Moderator)
The ring thickness is how thick the side would be after you round both the inside and outside. It calculates how thick the starting board has to be (segment thickness) in order to get the round exterior and interior diameters and maintain the final ring thickness. Since you do not plan to round the inside diameter, you can put any number in there because you only care about the outside diameter. If you play around with the calculator inputs, you will notice that the ring thickness parameter does not affect the outside segment length result. You can also ignore the segment thickness and the inside segment length results. Just use the outside segment length to setup your cuts. Basically, you will use the angle and the outside segment length as the outside (long) width of your stave.

BTW, you might want to adjust the the number of staves until you get an easier angle to set. For example 20 or 24 yield 9° or 7.5°, respectively. Also I highly recommend a digital angle gauge for setting the blade angle. I use mine all the time. If nothing else, I use it to verify that my table saw blade is actually set to 90°.
 
#17 ·
One other note. I would set the extra ring thickness (fudge factor) in the calculator to zero as well. This parameter adds extra thickness to the inside and outside to give you room for shaping. Since your plan is to simply round the corners, you don't need that.
 
#18 ·
For grins I decided to model the staves in Sketchup similar to LeeRoyMan to see how the calculator works out using 24 staves and it is spot on. Instead of the odd decimal fraction, I resized to 2-3/4 and 2-7/8" staves. If you make the staves 2-3/4" wide (7.5/82.5°) it results in a diameter just under 21" and if you size them to 2-7/8", the resulting diameter is just under 22" (with the corners a shade over 22"). If you go all the way to 3", it will be about 22-3/4".
 
#19 ·
Wow, thanks for all of the info and basically doing all of the calculations for me. Yes, I definately do not need the inside round and will be fine with the outside being sanded relatively smooth with a random orbital. I do have a digital angle gauge which is why I was ok with the oddball angle but the angles you came up with are fine with me. Thanks for mentioning getting rid of the fudge too, I was not really sure what to do about that. Last thing is setting the angle. Is it 90 degrees minus 7.5 degrees to get the digital gauge reading?
 
#21 · (Edited by Moderator)
For future reference, if you use the angle gauge to set the blade to 90 first and while the gauge is still attached, zero it, then you can set it directly to 7.5-no math required. ;-)

Have you thought about how you are going to clamp it? Some band clamps would work well if you have or buy some but there are other gluing strategies too.. BTW, it is a good idea to leave the glue out of 2 joints on opposite sides during the initial glue up-basically make 2 halves. The reason is that small errors while cutting add up pretty quickly with 24 staves so getting a perfect circle is next to impossible. Dry fit everything and make some adjustments with a hand plane or sandpaper before the initial glue up. Leaving 2 joints unglued allows you to make one more adjustment to get a good tight joint before you finally glue it together.
 
#22 ·
Ok, so- I got the staves cut yesterday, I think they came out good except for some minor warping on a couple of them. I attempted (solo) to join them by laying out three lines of 3" painters tape on my assembly table then carefully laid the staves, long side down, on the tape with the edges tight together and lined up with the edge of the table to keep them straight. I kind of knew that it may not work but I gave it a try- putting glue in all of the joints and trying to roll it up. It is just too big- the tape did not hold and it all fell apart when it was still not even really close to coming full circle. I had to scrub the heck out of all of the pieces to get the glue off. I just checked on line for ideas and sadly, did not find anything helpful (which is unusual). It seems like if I used the same method but could get them turned up vertical that it might work. I have a couple of extra hands today and may try that. Do you have any suggestions?
 
#23 ·
I just saw your last reply from yesterday. Good Idea on the angle gauge, will use it in the future. I had planned to wing it on the clamping (if I can actually get the thing together) using a small ratchet strap, a rope and some strong bungees I already have but decided this morning that I will get off my wallet, make the 10 min trip to Lowes and buy a couple of band clamps (going to check on line now to see if they have any in stock) since it looks like I am going to need all of the help I can get on this thing. I will try your suggestion of leaving two joints without glue. I tend to be impatient on things and sometimes sacrifice quality for speed, need to quit doing that. I looked on line some more for glue up ideas and pretty much only found the same thing that I am already doing. Hopefully with a couple of more people to help, we can get the thing stood up vertically and git er done.
 
#24 · (Edited by Moderator)
Yeah, assembly is going to be a challenge with so many pieces. Tape works well for smaller glue ups but this may be too heavy to make that work. You may be able to get the tape to work if you lean the staves side by side against a bench or wall and then put the tape on the back but do a dry test first. Another thought would be to use a stronger tape? 3M makes a residue free duct tape that has good stick but comes off easily and leaves no adhesive. Glue squeeze out could be a problem so I would add the band clamps and then remove the tape before it sets. Clear packing tape may be another option. I often use it to prevent wood glue from sticking to things. Another approach may be to use some sort of clamping jig to help hold things in place and you may have to work with the pieces vertically rather than horizontally. Here are a couple of ideas to try.

  1. One idea is to cut a couple of disks that will fit inside, maybe just slightly smaller. Attach the 2 disks with a board between them so that you can hold the staves against it while you assemble. Setup a band clamp around the disk but leave it loose enough that you can slide the pieces between the band and disk. Long elastic bands might work even better if you can finds some-maybe some bungee cords would work? You may have to adjust the tightness as you put in more staves and it might be necessary to put the staves on opposite sides, at least at first. This may require 2 people so that one can help hold the pieces in place as you insert staves between the jig and bands. Make sure that you either wax the edges of the disks or line it with clear packing tape so that you don't glue the jig to your cylinder.
  2. Another approach would be to glue them one at a time using rub joints (see below). Cut a disk into quarters and set 2 of the them on their edge so that they can support the staves as you glue up enough staves one joint at a time to form a quarter of the cylinder and then glue the the 2 quarters into halves using the band clamps, adjust the final 2 joints as needed and glue those halves together.

In case you don't know what a rub joint is, you basically spread glue on both edges and literally press them together while sliding the joint slightly until the glue sort of grabs as you move them into the final position. The challenge is that it needs to sit undisturbed so that there is no stress on the joint until the glue sets. It will be slow but works pretty well. You can use regular wood glue but hide glue will work much better, especially hot hide glue. The Old Brown Glue works better than the Titebond hide glue for rub joints. One nice thing about using hide glue for this glue up is that you don't have to worry as much about cleaning the glue off if a joint fails. Hide glue will stick to old hide glue as long as the joint is flat and smooth.

EDIT: I forgot to add this link to a video about rub joints.
 
#25 · (Edited by Moderator)
Here is what I would do. 2 choices.

Lay the staves face up on the table,
line up the staves next to each other and tape the long seam of each one. (Use 1 1/2 - 2" wide masking tape)
Be sure to make them even at the ends and the edges tight.
Really press the tape on good.

Now that the are taped you have to flip them over to put glue in each joint.
What I would do in this case is clamp long pieces of wood (1Ă—2's) across the top on both sides to hold everything together as you flip them. Be sure you have room for the clamps to hang over the bench so that when you flip it it can lay flat, if you have to fight the clamps it will disrupt everything.
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Now you can put a bead of glue down all of the joints, the tape will keep the glue from squeezing out the face.
once they are glued, clamp the 1Ă—2's back on and stand the wall up, take the 1Ă—2's off and roll the wall into shape and put your band clamps on.
It will be a chore but to me it's the best way.

The 2nd choice would be to do pretty much the same thing,
except only do 6 staves (4 sections) at a time. Then after they dry, glue the 4 sections together.
Only thing is it will be harder to make the 4 sections line up when you put them together. You would have to make sure each section was the exact width as each other or they wont come together at the joints.

I've done several large items the same way. Yours has a lot of pieces but if you tape them good it should work.
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#26 ·
Thanks for all the input guys. I have never heard of hide glue but will check it out. I normally use Tightbond 2 or 3 and occasionally super or Gorilla glue. Rub joints will be painfully slow but I am retired these days so I should probably be patient and give it a try, seems like any method I use to try to do the whole thing at once is doomed to failure. I watched the rub joint video, I will see if I can support it so that I can do at least a few staves at a time. Heading back to get started..