I am building some turned columns from 8 quarter oak. I have sawed tapered staves that are 58 inches long and 3 inches wide at the base. I then jointed them on a long bed jointer. I have worked with these and can not get the joints tight enough for glue up. I have 9 adjustable steel bands to hold the column together during glue up. I have a 2 to 5 thousands gap about 3/4 deep in all the perimeter joints and can not seem to work them out.
Does anyone have any tips for building such a column and how is this done commercially to get gap free joints.
Thanks for any help you can offer
Replies
Doug,
It's often easier if, instead of trying to fit and glue all the staves, you do them in pairs, or threes. Direct clamp pressure by cutting clamp blocks from 2 X 2 stock that have a step, or offset, near one end, that will hook over the outside edge of the stave. Near the edge to be clamped, cut a notch into the block for your clamp to draw against, putting the pressure across the joint. (Alternatively, you can cut wedge shaped blocks and glue them to the staves, with a sheet of paper between, so you can split them off after clamping.)
Then you can fine tune the fit of the sub-assemblies as needed. Expect to do some hand planing when you present the two halves to one another.
If the assembly is 8 sided, it helps to cut all 45* of the angle on both edges of every other stave, as an angled rabbet, as it were. Then you will have a shoulder on the inside of the joint to butt against, instead of two bevelled edges sliding past one another. In this case, I'd clamp up three staves at a time, then present the two sub-assemblies to the last two staves, clamping with band clamps, or glued-on blocks.
Straight stock is almost a must, as bowed or crooked staves will cause much heartburn as you try to pull them straight and keep things aligned and maintain the angle of the bevel.
And, I like to make a "set-square" out of a piece of thin scrap, that can be used to check the bevel angle during glue-up, by fitting it over the joint being clamped, two or three places along its length. (It's possible to tweak the angle a little bit by shifting one end of the clamp up or down, effectively opening or closing the joint.) A bevel square, (T-bevel, sliding Tee) can be used of course, but has a tendency, at least in my shop, of going off its set when dropped (knocked on the floor) in the heat of clamping, checking bevels, and shifting clamps to pull joints tight.
Ray
Thank you for the good advice. I particularly liked the 45 degree cut idea. I will try that on my 2nd column. I never expected this to be easy but has turned into a much more time consuming project than expected. I have glued thousands of feet of lumber together with relative ease and expected this to work much the same. I had to make one extra stave since one was bowed slightly and would never match up.
Thanks Again!
Doug
doug d ,
You can overcut the angle slightly so the outside of the joints will be tight , sometimes splines are used for alignment and glue surface as well .
dusty
http://www.amanatool.com/routerbits/multisided-gluejoint-bits-54270.html
A friend started a custom column business and he was able to offer stainable columns, plus he understood the technical details of the proper historical orders and such overlooked details as entasis ( a slight bulging of the column just below the middle) He used a joint like the bit linked above. No splines, plus he did columns up to 12' tall on a home ornamental router type lathe.
Thanks for taking the time to respond to my request.
Doug,
RickL beat me to the punch. I build octagons with a similar Eagle America bit quite often. Pretty much no gaps and seamless construction. Joint one edge straight on the jointer, rip your staves on the tablesaw and rout the sawn edge only.
The main column in this pic was done with that bit (sorry for the cruddy photo):
View Image
Lee
Well I make percussion instruments on the side.
Tapered stave construction and all.
The clamping does pose some unique challenges. I've tried the band clamps, and pipe clamps etc.
None of them are strong enough to overcome even a well behaved
piece of woods personality.
I don't know that it is worth your time to set up but:
I make a series of rings (mine are welded steel) that fit around the outside dimension, with an inch clearance on all sides.
Then a pile of wedges.
Slip the ring over the area to clamp, slide wedges in all around and
a few hammer taps- Tight!
To be honest, none of the other methods I've tried have really pulled
it together.
PS
The gluing two or three at a time method often leads to the final
joint not lining up. Maybe not a problem for most things, but for
drums I don't want uneven pressure in the shell.
Edited 6/6/2008 10:37 am ET by Henley
Henley ,
The steel rings are a great idea , thanks for your tip .
dusty
Thanks, I have a good supply of steel and some metal working equipment including a mig welder so rings will be no problem. What thickness steel do you make the rings from? Will 1/16 work or should I use 1/8 perhaps.
Doug
I've tried all sorts of things.
It's more a question of scale, and how close the wood is to
start with.
I would stay away from the 1/16.
I made mine for the long haul. My orbital ring roller could handle
1/4 so that's what I used.
If it's just for this project, it shouldn't matter. Even if they
bend out it still works.
Make sure you leave enough room for the wedges (don't ask).
You don't want to span to far between rings, so make enough.
The ends are prone to opening so place a ring right on the ends. Obviously time is of the essence!!
Plan your moves, and if necessary use a slower setting glue.PS
You almost always need to trim the ends square. Set up a jig
or you'll be sorry.PPS
Good luck Chuck
Hey I just Re Read your OP.
Sounds like your angles are off.
The best method I've found is order a chamfer bit with the right angle.
Two passes on the router table and your golden.
Every joint is 2-5 mils out 3/4" deep. What about the remaining depth? If your angles are off, the gap will obviously decrease in the remaining depth. Have you checked your angles at various locations along each stave?
Are you going to mount these on a lathe and turn them when you are finished with the glue-up?
Greg
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Edited 6/8/2008 7:32 am by Cincinnati
Thanks for your response Greg. By the way I grew up in Fairfield north of you.
Yes, I am going to turn them on me lathe. I am making 2 of them. I will also be makeing caps and bases for them. They will be Tuscan tapered columns.
I have been pretty sure my problem was an angular one but getting the angles almost perfect has been the issue. I was prety sure someone in the forum could offer some helpfull info without me trying all sorts of things and perhaps some spoiled lumber.
Doug
If you are trying to run an angled cut edge over the jointer, it is difficult because of the little bearing surface against the fence. Too much propensity for slight shift. I would make a jig that would either change the fence angle to the proper angle, or that I could run through the jointer with the work piece and would hold it at correct angle.Greg
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No offence but:
Ben there-done that.
It all comes down to having to set a saw somewhere some time
perfectly.
Unless you have an instrument to do that the problem remains.
The chamfer bit is exact. Then the only issue is feeding it
through carefully. I've found it's rather easy to do, and as
a precaution I feed it through twice. The only other method that's worked for me is to lay
out whatever angle I'm after on a full size sheet of ply.
Then use just the small part I need from that.
In effect your margin of error is reduced the farther you project
the angle.
This did work, but you waist a good bit of material.
Also you generally need more then just a triangle of ply wood
for the jig. So your back to compounding errors with multiple pieces for the jig. The chamfer bit is always right, there is no blade deflection
and reasonably safe.
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