Wednesday, March 08, 2006

Cooper, part 2

The barrels I am making aren't made in the traditional way. These are merely barrels in a decorative sense, not made to be watertight. A traditional barrel is made with thin "staves" that are bevelled on the edges, then bent and held in place with metal hoops. My barrels start out as thick staves which are bevelled on the edges, then a curve is cut into the outer edge. The metal bands that will be attached are for LOOKS, not functional to hold the barrel in shape.

So, with that in mind, I needed to build a jig for my bandsaw to cut that curved outer shape. The staves (for the 8 inch barrel) are all cut into thick trapezoids. But I am going to make some 20 inch barrels too. I bought 2 plans from one company. They sell plans for FOUR different sized barrels. Each plan describes how to make the jig for cutting the curves. But here's what they don't tell you. You can build one jig, for their largest sized barrel, and simply drill and utilize different "pivot points" for making the smaller barrels.

Why is that a problem?
Well, let's say that I only wanted to make an 8 inch barrel. I make the jig, which consists of two parts, sized to make the 8 inch barrel. Then a year from now I want to make a 20 inch barrel. The jig will not work....too small...so I need to make ANOTHER jig for the 20 incher. Now I have TWO jigs taking up space in my workshop. Silly !

I think that company should tell you to SIZE the jig for their largest barrel (20 inch) and tell you to cut the parts to that size. But then each "plan size" just tells you where to drill the pivot points. I don't mind paying them for that information. It's their right to sell different sized plans. But with a little forethought, they could really save a person time and effort.

OR, as an alternative, they could sell 1 book, for a higher dollar amount, that contains a table of dimensions and necessary pivot points for ALL their barrels, but directions to build the jig only once.

Luckily, in my case, I decided that I want to build their smallest and their largest barrels. So I purchased the 2 plans and as I was browsing them I recognized this situation BEFORE making the jigs. SO I have sized the jig for the largest barrel and will make the pivot point modifications for the smaller barrel (which, incidentally is REALLY easy...measure and mark two points, and drill holes at those points).

So, what is the jig?
It consists of 2 parts...a plywood "auxiliary table" that attaches to the metal table of the bandsaw, and a "swing arm." In each of these a hole is drilled (pivot point) and 1 short piece of dowel is inserted into both holes. The dowel marks the center of a circle. The distance along the swing arm and the table where the holes are drilled define a different arc for the outside of the barrel staves. Short stave = small circle. Long stave = large circle.

In a short afternoon I have built the aux table and swing arm. Now I need to fasten the aux table to the bandsaw table and drill the pivot points. I am not strictly going by their plan when it comes to fastening the aux table, but it will function the same.

Pictures will tell a lot, so I will post some in my next entry. And I should be close to having the small barrel done too.

1 Comments:

At 8:15 PM, March 08, 2006, Anonymous Anonymous said...

You lost me. I am sure the pictures will clarify things.

 

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