How to make a cone out of sheet metal

I have been doing cone out of sheet metal and today I was wondering if there was an easier way to do than my way wichh is to trace it on metal and then roll it to shape and spot weld it in place. Do you guys or lady out there have any better way or easier way to do it.

Cheers


B.J. Severtson's picture

good luck Larry

good luck Larry


visitor's picture

cone forming

Many good points above for cone forming (read frustrum); which usually presents the problem of requiring a fair amount of hand work (layout & bending) unless you have a decent enough quantity to justify tooling up for it.

Unfortunately, I've found nothing really beats the layout-roll(or)hammer-weld for small production. Spinning or pressing works very well (as pointed out above) provided you can justify the expense.

If you plan on routinely making cones in different sizes, you can look into purchasing a slip roller, but take note, you'll have to also make/purchase some kind of roller stop to keep the cone aligned -- I don't think its reasonable to expect to accurately feed by hand. (It's on my list to experiment with this, but I never get around to it, so we usually just make them the old tried-and-true method)

There are some shortcuts you can take, but they generally revolve around material, size, pitch(angle) and structural integrity of the finished part.

Good Luck.
Tom
Spinner
New Joisey


dickgerty's picture

sheet metal development

Best book I ever came across on this subject is by William Cookson---written in 1975 and to my knowledge has not been surpassed-----you can get it from the library and photocopy what interests you. -Regards-Dick

sorry--name of the book 'advanced methods for sheet metal work'


visitor's picture

How to make a sheet-metal cone

I read most of the above posts and while found a few to be helpful, nothing that really lets me get started and progress beginning to end. There's all too many folks jaw-boning. If you don't have specific instructions, or are simply selling a book or product, why not just keep silent?

Now as for making cones, if you plan on making more than a few of a particular cone design, first you want to make a dummy. You can do that by opening up a large sheet or two of newspaper and rolling it into the size cone you want; (use the middle crease as the point on one end.) Glue the outer edge and as far down the inside edge as you can reach. (Note: in lieu of newspaper you might want to use a sheet of flexible plastic or stiff paper with one side treated/ varnished to better resist the next step.) Set your cone into a piece of PVC pipe, point down. Mix up some cement/sand mix (used for playgrounds) and water, pour it into the cone. You might want to add a piece of threaded rod down the center with enough sticking out to manipulate the cone once the cement dries; you can either tighten the rod extension in a vice, or set the cement cone on a flat surface. Place your sheet metal over the cone and begin tapping it with a hammer up and down while flexing it around the dummy. Eventually it will take the shape of your inner form, and even serve as a support upon which to weld the seam. The dummy serves as a precise shape and anvil to create and size multiple sheet metal cones.

Other materials can work in lieu of cement for the dummy, i.e. urethanes, fiberglass resin, epoxies (expensive) with various types of fillers, or sawdust, cement and/or casein glue. Point is you want something tough enough to take the pounding without crumbling.

Hope this helps.


Gene Olson's picture

Wow. That sounds pretty

Wow.

That sounds pretty heavy for a 30" dia cone of light copper. Shucks one doesn't even need a roller to bend that.
If you cut the pattern right and solder the edge neatly, you can tune it on your knee.

If you want to make a project out of it, I'd suggest making an English wheel big enough to replace the upper with a go cart slick, (or a urethane caster but you will need more passes)

The wheel can be used to make radial passes on the pattern and it can give you a nice uniform cone, and having a good English wheel in your quiver is a real plus.

Gene Olson
Sculptor
Elk River, MN


Rich Waugh's picture

I'm with you, Gene. Way too

I'm with you, Gene. Way too much trouble to go to, simply to make a shape that is mathematically generated and sure to come out uniform if the blank is cut properly. And, if you're going to that much trouble to make a sinking form, why not just turn a master chuck and spin the things from discs? The set-up time would be about the same, but the spinning would be way quicker than sinking, and produce a much more consistent and regular surface. Maybe I'm not understanding something here.


visitor's picture

Copper sheet metal cones.

As you might guess im new to sheet metal particularly in regards copper ecxept the most basic
such as frequent copper annealing to prevent work hardening.I had some very limited experience in HS years ago with sheet metal and fabricating boxes before.Also shears, Brakes, and rollers to an extremely limited extent.I find myself involved with a hobby requiring fabrication of sheet metal cones specifically 1-3in diam. cones with as closed an end as possible as well as repeatable dimmensions as possible with a cone angle of 45%-60% approximately 1mil thickness.Quite thick I believe but the thickness could be built up using multible sheets or some layered piece to = a single piece.Basically a funnel with precise repeatable dimensions with minimal variations from the original design.
Likely epoxied to secure the pieces dimensions.With my limited exoerience and funds i would prefer rolling by hand around a precut form.But arent there some relatively inexpensve sheet metal brake,roller, shears etc for some $140? chinese of course!
Ive also become interested in sand casting of various metals with a low melting point such as AL,copper but of course with very simple designs to begin with though having forged spring steel knife blade blanks a properly constructed coal fired forge wiil easily melt spring steel with OTC
components mainly firebrick and a discarded reversed vacum
cleaner.Any help /suggestions with the cone forming or books regarding backyard hobby sandcasting Id sure appreciate the info!!


Rich Waugh's picture

YOu say these cones are

YOu say these cones are rather thick, but you then say they are 1mil - that is incredibly thin, not thick. .001"? We're talking less than the thickness of a piece of cellophane. Or did you mean 1 mm? That's still pretty thin, only .040" or about 18 gauge B&S.

If you're dealing with 18 guage copper, the quickest, easiest and most dependable way to make several of these cones is to spin them on a lathe. Even a small wood lathe will work for spinning small copper pieces like this. With spinning, repeatability should be within the realm of a few thousandths of an inch form one piece ot the next, and all within five thousandths of an inch of specified diameters.

Spinning also has the advantage of creating cones that are seamless.

Hope this helps.

Rich


visitor's picture

how to make cone

how do you them spin on a lathe ,id like to now how


Will Jones's picture

Cone development

Little more "jawboning" to come, I'm afraid - that's kinda what the site's about! cone templatecone template I did enjoy Rich's comments about the magic $10 machine.

I've seen a lot of(and bought a few)plans along the lines of "build your own flux capacitor from scrap!!!!"

And most of them do work but require such specific and hard to find scrap you'd be better of saving your time and saving up your money for a commercial tool.

There was an Australian guy on ebay the other day asking for (If I remember right) a hundred thousand bucks for the plans to make a machine to form helixs (helii ?)in round bar and tube !

Anyway, thought I'd share a quick'n'dirty cone drawing trick I learned a few years ago that's worked fine for me. Draw the profile of your cone on a piece of scrap. Using centrepoint of top and bottom lines as centres draw semi circles projecting from top and bottom of your profile. Cut this shape out and fold the semicircular bits at right angles to the main piece.

You’ve kind of made a skeleton of a half cone. By rolling this shape over a piece of paper, or the material you’re going to make the cone out of, the semicircular projections describe the outline of what you need to cut.(for a full cone you need to start again where you left off after rolling it over once)

 You can make the template out of timber or whatever if it’s easier.

 Don’t know if this makes sense, but it requires no maths and avoids the need for a huge space and massive compass to mark out the large radii on a big cone.


visitor's picture

dimension check of cone

do you check dimension of made cones after welding?
if yes, based on which standard or code?

my mail address:nassrolla_ebrahimi@yahoo.com