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View Full Version : Suggestions for Cutting, spacking, and gluing wooden hoops?



rcnewcomb
01-20-2007, 03:27 PM
I'm looking for cutting and gluing suggestions for the following:

Finished product: wooden hoops 11" in diameter, 2 5/8" high, with walls that are 1/2" inch thick

We want to stack different hard woods (maple, walnut, bloodwood, etc.) and have them glued together to create the hoop.

We will probably make glueups slightly larger than 11" inches using pie shaped pieces to avoid exposing end grain. I'll probably use is 4/4 or thinner wood since the desire is to show contrasting woods in the 2 5/8" tall hoop.

Given the 1/2" thickness of the hoop wall I'm not convinced that vacuum hold down will work since I would only have 16 square inches of area on the finished item (11" circle minus 10"circle). Leaving a skin and running them through the planer is an option. Are there other holddown methods I should consider?

The next problem is what is the best way to glue the laminations together. I could create a form, but what is the best way to apply uniform claming pressure? Should I try either a vacuum press for compressed air to apply clamping pressure? (I would have to build either of these clamping systems but I do already have vacuum and compressed air in the shop.)

Any suggestions on minimizing or cleaning up squeeze-out?

- Randall

mziegler
01-20-2007, 07:13 PM
Randall, I would use tabs to hold the hoops to in place. Then rout the tabs to a skin while still on the bot so they will snap out easily. Use your favorite hold down method on the waste piece, screws, clamps, vacuum, brads or whatever. For gluing the laminations together I would rout a 5 point star piece to hold hoops in place. Place a board on top of the hoops and use 3 hand clamps. Mark

robert_cheal
01-20-2007, 07:42 PM
Randall,

If it were me I might try something like this:

Layout several pie pieces on each type of wood, bore 2 ea. 1/4" holes at centerline of each pie the distance in the middle is 2x the distance on the each end. Cut the 2 holes in each pie and hold the piece down with 1/4" machine screws into a T-nut. You have already build a jig with the T-nuts matching the hole patterns of your pie pieces. Then cut out each pie piece, then glue each layer together using 1/4" dowels in the hold down holes. Each layer could straddle the previous joint. Top and bottom layers would have the dowel hole cut at 1/2 the board thickness and use tabbing to cutout these pieces. The dowels would hold the rings together as you glued up each layer, if the dowells were tight a few C-Clamps would keep everything together.

This idea is spur of the moment but maybe some of it could work for you.

Robert

charles_o
01-21-2007, 12:51 AM
What if you were to glue up three rings of 7/8" thick trapezoids
4712 with the joints of each layer offset and glued to a piece of scrap with a layer of paper between the ring and the scrap. You could use bands to hold the rings together and c-clamps and another scrap of ply to distribute pressure. Once dry, attach the assembly to the Shopbot and using light passes cut the inner and outer sides of the ring. Separate the ring from the scrap at the paper joint and sand,

charles_o
01-21-2007, 01:03 AM
or you could turn them.

http://www.woodturningonline.com/Turning/segmented_turning/index.html

myxpykalix
01-21-2007, 08:52 AM
If part of what you are talking about in glueup is glueing one ring on top of another then you can use a jig like i use to glue up rings cut on my ringmaster. It is very simple to make. Take a square piece of plywood bigger than your rings. Drill a hole in the center of the plywood and run a 12" long threaded rod thru it with a nut on both sides of the plywood to tighten it down.
Lay 2 rings down to be glued take a second piece of plywood with a hole in the center lay it on top of the rings then use a butterfly nut screw it down the threaded rod to apply even clamping pressure all around the ring. Hope that was what you were talking about, if not...NEVERMIND!

myxpykalix
01-21-2007, 08:59 AM
Also the way this device works is it will take a flat 3/4" piece of wood and cut 1/4" rings out from the outside to the inside and the angle is set to 22 degrees. This allows for the outermost ring (the top) when set under the second ring (in glueup, upside down) the angle of the bottom of the top ring matches with the top of the second ring and so on to make a conical shaped bowl.

davidallen
01-21-2007, 12:10 PM
If I were doing it, I'd use a band clamp (or large hose clamp) to hold the pieces together to form the ring.

To machine the hoop, I'd glue it down on a flat piece of ply with a layer of paper between the ring and ply. The ply can be screwed to the table and after machining the paper joint can be split and sanded to clean up.

mike_ross
01-21-2007, 09:41 PM
To clamp your laminations together you could use an inner form that supports your shape and an over sized outer ring. A short length of fire hose pressurized with air between the rings would be quick, clean and cheap.