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12bolts

12bolts

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I have a, roughly, 400 mm dia steel barrel that I am wanting to surround with vertical wood strips to hide the steel underneath. I am planning on using recycled flooring boards. These boards are 90 mm wide x 22 mm thick. So, if we do some quick calculations it comes out to approx 445 mm dia, multiplied by pi gives me 1398 mm circumference. Divide that by 82 mm, (allowing for sawing the edges of the boards) comes out to close enough to 17 boards. If I have it all correct so far, then I think I need to divide 360* by 17 which gives me 21.2*, (this being the included angle between adjacent boards), so now if I saw each board with a 10.5* angle on each edge, in theory I should get pretty close to a full circle that closes in my steel cylinder and has (if I am good enough with the saw) evenly mated edges.
Did I do all that correctly?

Cheers Phil
 
Your math is correct Phil. If you make good cuts you will have enough at 17 boards.

"Billy G"
 
You are correct but things will be FAR easier if you go to 18 boards, now you got 20 degree angles. Nine boards does half, so you can check construction as you go.

Personally, I'd download Draftsight X64 (free) and lay it out in CAD. If you aren't a CAD enabled type of guy, let me know, I'll do it for you. Even if you are from a place where the toilet drain swirls backward :)

karl
 
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I agree on an even number of segments. I assume you will end end gluing these together to form a very rough cylinder? if that is the case, you might want to glue up two "halves" and then run them through a joiner or something to true them up. Then glue the two halves together. That way the cumulative error of the stave angles (trapezoids of wood) will not matter.
 
that's how I did the mast for my sailboat. 42 feet long 10 inch at the base and 6 inches at the top. there was a formula for the whole affair in Woodenboat 20 years or so ago. the tapers over 3 different lengths was a bear, but it went well. assembling the entire circumference is the only way to go and have it accurate, I used 130 heavy duty hose clamps, a setup jig and $150 worth of epoxy. sailed through a hurricane and 20 years of salt water abuse and she still has a varnished beauty. (with a hundred or so touch ups). a piece of plywood (sacrificial) in each end will help quite a bit.
 
Ok Thanks all for the input, Lets see how I go

Cheers Phil
 
12B- all the foregoing is sound advice. What type of wood? You might want to keep in mind that woods swell and shrink as moisture content changes. May not matter, but something to consider.

Doug
 
Yeah thanks Doug,
100 year old Hardwood flooring is as close as I can get you to the species :whiteflag:
A bit of movement shouldnt be too much of a hassle I think.

Cheers Phil
 
just one thing to add to all that good advice is to spline these boards together using good quality finnish or baltic birch - you don't have to go in very deep in each board edge. this will help lock them together.
 
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