Friends:
A friend and fellow student of hand tools makes very interesting replica 18th century military field furniture. He just finished a complicated folding four-poster camp bed modeoed on Geo. Washington’s own. He is now planning a travel case that is essentially a wooden ube with two elongated sides. In other words, if you made a wooden cylinder, split it lengthwise, added flat sides front and back, and flat end caps, youi’d have it.
The cylinder segments are to be coopered. He needs to have smooth rounded interiors as well as exteriors. He’s figured out the exterior work, but not the interior. Can anyone here recommend a way to hollow and smooth the interior so it is evenly curved and does not look like a set of flat segments joined at angles?
Joe
Replies
No easy way
A custom-made sanding block or a round plane. If you use a plane, make sure that the grain of all the staves run the same way.
interior curves
My guess would be that the interior curve was hewn with some combination of inshaves and/or scorps, depending on the required radius, and then scraped smooth. With modern tools, if the radius is constant, one might also be able to shape the interior surface of the staves on a shaper (or, router table) prior to assembly, but that makes assembly a bit trickier. This would involve using a cutter that represents a small segment of the total radius. Or, it could be shaped using the edge of a disk sander of the proper radius, and then sanded smooth.
If coopered up in smaller segments, say 1/4 of a cylinder first, and you made five of them, then you might be able to smooth the outside of the extra quarter to make a sanding form that would fit inside the good cylinders. Or a big flap wheel on a drill to shape cross grain and hand sanding with the grain... I dunno... that's all I got... take it for what it's worth.
different radius
The outside radius of the spare section will have a larger radius than the inside of the other sections. One could, however, cooper and shape a sanding form of the proper radius to fit inside the sections.
different radius
Correct. Good catch. A few ways around this problem. If the stock is thin enough it will flex inward when you pull the outer edges in and attach them to whatever you use to strengthen the inside and use as a handle for the coopered sanding form. This would flex more if you made a 1/2 form instead of a 1/4 one. A slight change in the ripping angle of the slats for the form would tighten the radius too. My only experience with coopering comes from making round bird houses. I have done about thirty of them and if I remember the full circle uses 26 or 28 strips so there is less of a corner between strips than might be the case here using less strips. Also I never have to smooth the inside as I don't give a rip what the little birds and their mom and dad are looking at... all they care to see are worms and bugs.
Another thought: Home Depot solution. Get a cardboard concrete form for making pilings for decks. They come in several radiuses (radiei, radyeye... we need spellcheck) and if slit down one side could be drawn in to change the radius up to a point. A wooden disk screwed into each end would make a solid sanding form. From there it would be a short trip to immagine this thing on a lathe, covered with sandpaper, spinning madly around and being a potential disaster for all present.
Since I have no value with a real solution, my best shot is being a think- outside- the- box- brain- stormer. Good luck to the original poster. I'm starting to get dangerous here.
Simple Cooperage Tools
Simple cooperage tools include a purpose made inshave - bent drawknife - that was used for rough shaping the inside of staves. Of course, neither wet nor dry cooperage required level staves on the inside (the cider did not care), but buckets and other purposes benefitted from smooth interiors. This was accomplished with a hollow plane shaped to the required radius. A scraper could take it to a finer finish if need be. Remember that many tools of the period in play were made by the the craftsman, or directly to his specification.
Google 'cooperage tools' if you would like to see more. There are also a number of Youtube videos showing barrell making.
David R Sochar
Acorn Woodworks
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