Sheet metal roller, ideas?

If you only want one you might find paying a fabrication company to do it a lot cheaper than buying an expensive machine. I always find them helpful if you start off by saying 'no paperwork, cash payment'. If you really want to do it yourself, would it be acceptable to do it in a bender, multiple flats rather than true cone?

Carl,

Is this the outfit you were thinking of?

https://www.metal-craft.co.uk/

I had to Google Caldera Cone as not being the outdoor type I had never come across the term.

Now though, I'm curious. All of the Caldera Cones I see being sold, offered, reviewed, and recommended point out the benefits of light weight, portability etc. Carl does not say what metal he wants to roll into a cone but given that its 3mm thick its going to be relatively heavy and with the dimensions shown is going to a very robust item! Even even soft aluminium needs a fair bit of force.

I'm all for making something if I can but I doubt it would have crossed my mind for one of these.

Ian P

Thank you very much for all the replies. John, it is Metal Craft I was thinking of but they don't seem to do a suitable machine. I seem to remember seeing a set of rolls that you could fit into a bench vice that could be then stowed when not in use.

Duncan, your plan is sound, however I would like to get hold of a set of rolls because I may want to do more such work in the future and also I might get my calculations wrong! It is far less embarrassing to have to go back and make another part myself than to have to ask someone else to do it again!

Ian - I think I may have used the wrong terminology. I meant that I need to fabricate a truncated cone. I looked at the caldera cones on the net and they seem to be some sort of camping stove, like a Trangia. I thought the term caldera was the name for a truncated cone shape. What my truncated cone is for is a rocket engine nozzle. It will be 3mm thick 6082 plate.

A few years ago now I was in a shipyard where a new cone shaped fairing for an azimuth thruster was made. The ship that the thruster belonged to had lost the original part in an accident involving a large submerged log off the coast of Equatorial Guinea. The fairing was made from 1 inch thick steel plate. the cone was laid out in the flat on the plate using standard sheet metal techniques. Then the pattern was profile burned out. The resulting bit of plate was then rolled in a large set of powered rolls. Once the cone was formed, it was seam welded while still in the rolls - the rolls being the perfect jig to hold the part while it was welded. Then one end of the bearings for the rolls were removed - the rolls being designed to do this - and the cone was slipped off. When I say slipped off I mean using an overhead gantry crane on to a waiting forklift. The cone must have weighed a quarter of a ton.

So I was thinking about doing this but on a much smaller scale. Although I would not weld my cone in the rolls because I think I'd like to joggle the seam and TIG weld it on both sides to get a nice strong joint. TALAT among other places recommend this type of joint in aluminium plate.

I will keep looking for a set of little rolls.

Thanks again,

Carl.

For a one-off of the size in the OP, you could consider turning it from a solid piece of round, or suitable cored round, aluminium, if you have a large enough lathe.

I think you will need something more substantial than vice or bench mounted rolls to roll 3mm material even ali. Ring rollers would be small and capable if it were a parallel ring but you will not get a steep taper as you describe from short rolls.

May sound a bit daft, but on a one off equipment mock-up at work we needed an aluminium tube in a hurry that was bigger than any we had and delivery of a block to turn to size would have been a week. Our foreman did the following:

1. Take some plate and fold it carefully into a half circle by using lots of little folds and lots of comparisons with a template printed by the design office..
2. Did the same with a second plate
3. Turned some formers to the internal diameter on the lathe for each end
4. Tacked the two plates to the formers, then did a butt weld down the seams between the plates.
5. After cooling, put it in a lathe and turned the outside to make the correct diameter.
6. Cut off the former tack welds. Could have turned the inside at this point had the internal diameter been important too,

Total time - a morning. The same approach could be taken with a cone.

Regards,

Richard.

Thanks for all the posts. I can get a set of rolls that will cope with 2.5mm thick ally plate relatively easily. I had already considered the possibility of turning the part from a large blank, and indeed i may still do this. Just looking at all the options.

Carl.

This piqued my interest!

How hard would it be to produce small thin sheet metal (brass or steel) cones of about the size of an old type oil can? 3-4" high and base diameter about 2 1/2" or so?

These seem to have a rolled seam or soldered seam with a circular sheet metal bottom soldered in.

I have a LARGE stock of old damaged oil cans of all sizes with perfectly serviceable brass spouts, nozzles and caps etc which could be used for the tops etc.

Cheers,

Martin

So basically a bucket without the bottom.I`d never heard of the term Caldera cone. Made cones all the time in my previous life as a sheet metal worker. If it was 1/16" ali you could easily bend by hand over a suitable round form but 3mm is pushing it.

From the sheet metal workers bible:

Edited By mark smith 20 on 14/06/2017 10:54:25

Edited By mark smith 20 on 14/06/2017 10:54:54

Edited By mark smith 20 on 14/06/2017 10:57:13

I seen people making simple DIY bending rollers out of cheap conveyor rollers, adapted of course as you don`t want them all spinning on their axis.

The 3mm thick material would require a rather robust slip roll. It pretty well takes it out of the range of hobbyist equipment. My first choice would be to find a fabricator that could roll the cones for you. Second choice would be to build the rolls, I would start with the G H Thomas design and scale it up for a roll diameter of 50 to 75 mm. Unless you anticipate doing larger work in the future I would suggest keeping the length of the rolls under 300 mm.

I rolled some rings using this machine:

https://www.harborfreight.com/gear-driven-ring-roller-36790.html

I was using 3 mm x 50 mm stock and it was a struggle.

Good luck

Hello John,

Thanks for the information. I can get hold of a set of rolls that can cope with 2.5mm thick aluminium. So I can re-jig my design to account for the available tools (have a decent margin on safety factor) or I can use a bit of extra grunt for the extra 0.5mm.

You may find the job easier if you go for one of the softer alloys that bend more easily than 6082.

Do the rolls you can get allow for taper rolling?

Caldera is the hole in the cone of a volcano.

Neil

Edited By Neil Wyatt on 15/06/2017 07:42:20

Would something like a Gabro BF620 folder roll this up. I regularly swap out the top folder clamp bar for a 3" diameter steel tube and I can then roll bends on to flat sheet. I have not rolled anything quite than thick but have been able to fold 1/8" steel flats up to 2" wide. I would have thought it would do your 2.5mm by 130mm long aluminium. You would need to calculate the angle to move the plate to get the appropriate bend.

Colin

Purely for interest try Googling 'Caldera Cone' and then 'Caldera' on its own.

The search results are completely different!

Ian P