best way to create a cone?

[brian]

Have a project that requires a cone for a table base
The customer wants a veneered surface no edge grain on the cone.
So far I'm thinking about building the cone out of blue foam with 2" slices
then several coats of epoxy.I'm leaning towards putting a layer of plyboo(bendable plywood) on the foam before applying the veneer.

They did request that the base be absolutely round so building it out of staves is out.
I looked into outsourcing this but the cone base alone without veneer was over 600.00 alone.
I have to brush up on my math to cut the veneer right

any ideas always welcome
Thanks Brian

[dana_swift]

If you need a cone from sheet material, its a matter of creating two arcs and two straight lines. Using sheet material allows making a cone of any size which could be used for a mold for urethane foam, since your considering a foam cone.

Cutting the sheet material with the bot is easy, and designing the arcs with PW or aspire is easy.

The distance between the arcs is the length of the cone, and the lengths of the arcs is the circumference of each end of the cone.

So with your numbers: the distance between arcs has to be 28". The shorter arc needs to be Pi * D or 3.14159 * 24 for the short end, which is 75.4 inches. The longer end arc length needs to be 94.25".

A little longer arc length allows overlap for fastening the sides of the sheet together so they form the cone you want.

Hope that leads to some creative ideas-

D

[maxheadroom]

Too many projects are 'over thunk'.

24" dia disk for the top, 30" disk for the bottom - less skin material for covering. Can easily be cut on the band saw or the CNC. Cutting on the CNC, determine radial spacing for 3/4 x 3" x staves connecting top to bottom, engrave to help align staves.

Cut to length on chop saw with proper angle top and bottom. Cover with wiggle wood.... yes it is a sheet goods product, name may have changed but can conform to a 4" radius.

Cut skin extra high to allow trimming top, bottom and ends. Trim top / bottom w/ flush trim bit, belt sand flush. Bondo and sand smooth.

Divide the circumference top and bottom to determine 'wedges' of veneer to cover - 6 - 8. The only critical joint is the last two. If you haven't veneered before this is the time to learn. This project, with the exception of wood veneer will cost be considerably less than 100 bucks, and can easily be finished in about half a day. 2-4 hours for veneer. Layout of veneer is simple geometry.

And yes, I've completed furniture just as this many times. No lathe, no CNC, no foam, no epoxy which provides a base that will support hundreds of pounds or more.

Use the right tool for the job. Only thing the CNC is useful for here are the two discs.

Think WWI airplane fuselage or wooden airplane models from long ago.

[feinddj]

Regardless of the method, making a cone is a bit complex to get it right. I refer to a book that I have had for many years for this type of thing. Circular Work in Joinery. http://www.pdfebookds.com/circular-work-in-carpentry-and-joinery-PDF4-613139/.
I have bought the book at least three times as some people are not as good about returning it as they should. It is a reprint of a 1900s manual for apprentices.

[khaos]

A 3" slope in 28" is a pretty gentle cone. About 5-6 degrees.

Turns out its 6 degrees. Here is a model (http://www.joesboats.com/sb/30-24-cone-28-tall.zip).

Enjoy.

Sprained my ankle so I am stuck at home so I have some time to do stuff. :o

[sam_harbold]

Here is a small program that makes designing Cones fairly simple.

[dana_swift]

Sam: the cone program is pretty cool! Whoever did that, nice job. I like the generality of it. Its a nice use for all that conic section stuff I learned in high school algebra.

Joe: Nice model. It would need to be sliced, but aspire is really nice about such things..

D

[brian]

Thanks guys
Like the cone calculator
As always lots to ponder.
I'm going to make a 1/4 scale for practise then go
for the full size.
Will keep ya posted on how I do this

Brian

[brian]

thought I'd send a picture of the finished cone.
The cone calculator was great.Made it a pleasant project.
I was a little nervous about the final veneering but it was actually fairly simple.
Just need to finish the table top.
Unfortunately I have a customer that wants the wood aged now and isn't willing to wait for time to do it's thing.
Still hoping I can convince them to just go with the natural colour

Thanks Brian

[jTr]

If it helps, remind the client:
1. You cannot change the fact that the Cherry will darken over time = tone it now and it will be several shades darker within 6-12 months of leaving your shop, no matter what color it is.

2. If they accept the above, a light mix of Trans-Tint Brown Mahogany (1/4 oz dye to 32oz of preferred solvent) can do a reasonably good job of making it look naturally aged, enhance the natural depth of the wood without muddying it up like a pigment stain, and will spray or wipe on swiftly and be ready for topcoats in an hour or less.

Good luck - looks like you've done well so far!

Jeff

[sam_harbold]

Brian, the cone looks great.