Expert: Stuart Mawle - 2/18/2005

Question
Noticed , for sale , at a craft show , a very atractive wooden bucket[ +/- 1" high ] . If I were to try and make one - How do I calculate the angle of the upright pieces within the circle to make a tight fit .
ATB- Barry  

Answer
You didnt say whether the bucket is straight sided or had sloping sides so I have given you a description of the way I would do if it was a sloping sided bucket. If it is straight sided then you can still use the method but it wont be so complicated and the next paragraph is only relevant.

There isnt a magic formula to say what the angle is as you have to set these sort of woodworking jobs geometerically (draw it/set it out). I set out on a piece of plywood or white hardboard. What you are trying to do is to develop the staves, wooden pieces that form the sides of the bucket. Alot depends on what angle is required for the bucket so you may have to draw the circles besides each other but if you can you want to draw the smaller inside of the bigger one. The first thing to do is to create a centre point on the sheet materal making sure you can draw the big circle on. Using a trammel, draw the outer circle (open end of bucket), then using a rule measure the thickness of timber from the circle inwards. Set up the trammel to this point and draw a circle. I should think that for a bucket you would want the staves to be approxmately 18mm (3/4") thick. Next, draw the inner circle (bottom of the bucket) then using a rule measure the thickness of timber from the circle inwards. Set up the trammel to this point and draw a circle. Using a protractor mark points off. I cant tell you what degree to use as alot depends upon size of the bucket but I would start by trying 20 degree intervals. Dont do all, just do a few, if it doesnt look right then you can increase up to 30, or decrease to 10 degree intervals. Basically the smaller the staves in width the more circular the bucket will look. Taking a long rule, line up the degree mark to the centre point then draw the line through both circles to the centre point. Its only at this stage whether you know if you need to change the degree intervals. Remember to do a few then if you are happy do the entire circle. Once done you can count the exact number of staves you will need to make the bucket, remember to do a few extra just in case.

Next you have to draw a part of the bucket showing the lenght between the circles and the sloping sides. Using a square mark a line off one edge near to the drawing. Draw a parrallel to the edge going both sides of the square line. With a trammel go to the slope side and set up points where slope insects horrizontal lines representing the cirlces. Mark this along the squared line. Draw a parrallel line to the edge through the marked point. Next using a compass bysect the biggest stave end width (outer circle)then using a ruler align this point to the centre point and draw a line through both cirles. Using the compass set it up to half the distance of the biggest stave end then with the point on the square line and mark either side on the nearest parrallel line. On the furthest parrallel line repeat but using half of the smallest end stave width. Finally draw a line through the marks. You should have the true shape of the taper stave. I hope this helps you. Stuart Mawle