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Metal Spinning

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colinc

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Not exactly wood-working, but has anyone any experience of Metal Spinning?

I need to make some 270mm dia dished ends for a circular cross-section aluminium fuel tank and thought that metal spinning would be better than hand forming them.

Also, I could do with a bit of help turning a former if anyone with a lathe big enough is willing to help. (Am based near Derby).

regards,

Colin
 

jasonB

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I've done a small amount with steel about 2" dia but as it gets bigger the job gets harder as there is more metal to loose, tou will also need a pigged rest and a spinning tool or two.

If its just a half sphere you could go to a metal spinners and they will be able to make the form to suit and do the spining with far less effort.

J
 

flh801978

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I have done some spinning and made a few formers
I'm in sheffield so not so far
whats the fuel tank for? vehicle?
Ian
 

colinc

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adidat":1os1gjez said:
i think it may be for a WW2 plane he is helping to rebuild

adidat
Close but not for that one (pre-war). A friend is building an aircraft of his own design and these are the dished end caps for a cylindrical fuel tank.
 

colinc

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flh801978":18h2is3q said:
I have done some spinning and made a few formers
I'm in sheffield so not so far
whats the fuel tank for? vehicle?
Ian
Ian,

how practical is it to do? The requirement is for a dished aluminium end plate with a flange for butt welding to a cylinder.

regards,

Colin
 

TheTiddles

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You're making a fuel tank for an aeroplane... and you want to do it yourself???!

Aidan
 

jasonB

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I was thinking just the same. The risk with spinning aluminium if you don't know what you are doing is work hardening and then if you keep trying to push it round the former you will get all sorts of metal fatigue that may only show up until a later date. You also need the right grade a alloy to start with as some are far to hard to spin.

Better play safe and get it done by a pro.

J
 

colinc

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TheTiddles":34gb6ad8 said:
You're making a fuel tank for an aeroplane... and you want to do it yourself???!

Aidan
That's what we do, build and restore (mainly wooden) aeroplanes, I'm afraid I don't have much time for furniture making these days but I follow this forum as there are a lot of parallels and you guys have a wealth of knowledge and experience, hence the request for info about metal spinning.

This isn't the first tank to be 'home-made' it is actually one of the simplest I have come across. Don't worry unduly, they are thoroughly pressure tested and inspected before they go into an aircraft.

The question is do we press the ends or is metal spinning viable. Compared with the traditional approach of forming flanges around a wooden former, metal spinning seems less likely to induce cracking and would seem to be a better and more elegant job.

I'm suprised that not more woodworkers have been involved in aircraft building, there seem to be a lot of aircraft enthusiasts here for example. Have added a few links below to projects I am involved with:

Here's an aircraft that had overturned and was in bits when I first saw it. I finished rebuilding it in 2010: http://www.airport-data.com/aircraft/photo/515684.html.

In my garage I'm now building one of these: http://www.airliners.net/photo/Chilton-DW-1A/1814165/&sid=7ddff790ee6373268036dc2caaf8a7b3 That's a 1930's racer built mainly from spruce and 1mm ply, I'm expecting it to take me 2-3 years (at least) to finish it.

Here's a wooden aircraft that I helped a friend complete (he has been working on it for 20+ years) and it first flew in the summer: http://www.airport-data.com/aircraft/photo/661963.html

I am also part of the restoration team working on what is probably the biggest wooden aircraft project in the uk. Details are here: http://www.cometracer.co.uk , here I am, cutting sitka spruce strips (using a Tuffsaws blade of course) on our big old Stenner bandsaw which will then be laminated into 44 foot span wing spars: http://flic.kr/p/9e2iot. Now the fuel tanks on that are something special - they hold more than 250 gallons!!

If anyone is near Derby and fancies lending a hand on the woodwork for the above do please get in touch. We are very well supported by metalworkers, but people skilled in woodwork seem much harder to find. Interested visitors are always welcome of course.

regards,

Colin
 

jasonB

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Colin if your lathe is not big enough to turn the formers how are you going to DIY spin the end caps?.

Are you just looking for a shallow dishing or a complete hemishpere? The dished end won't be so hard to do as there is less metal to loose but a half sphere is not for the inexperianced.

As I said you will also want a spinning tool, this looks a bit like a lareg woodturning chised but with a polished and hardened end and a 3-4ft handke so you can get plenty of leverage. You will then want a tool rest with pig holes in the top edge so you can pivot the tool against these so quiet a bit of tool making before you can get spinning.

Another option if just dished with a flange would be to hammer it over a former with a couple of annealings to keep the alloy workable. Once its nearly to shape put it into the lathe and take out the hammer marks with a sanding pad in a cordless drill.

Out of interest this is the steel cap I spun for my traction engine model, its approx 2" dia and teh return edge 5/16" 22swg steel



And this and the next half dozen photos are of a fellow model engineer spinning a steel ring about the size you want. Hes using a double pivot roller tool which is again more suited to teh inexperianced, he still had a failure when the metal split!!

J
 

colinc

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Hi Jason,

just a small amount of dishing in the end is required, enough to stop it 'oil-canning' as the fuel moves about, then a small flange of only about 6mm to wrap over the cylindrical sides to hold it together for seam welding. I can't remember the material gauge now, but it will be quite thin aluminium.

I have access to several sizes of metalworking lathe but I was never that sure about trying to do the spinning myself and was instead hoping to find someone who is proficient enough to do the job for cash.

The 'fall-back' position is to form the shape manually and, as you suggest, beat it over a former to get the flange.

regards,

Colin
 

Melzy

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What is metal spinning??! {sorry if i sound stupid!!}

Melzy!
 

jasonB

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Basically you put a usually wooden former in a lathe, then hold a disc of metal against that with the tail stock and while its rotating use a tool to form the metal over the former, stick "metal spinning" into you-tube, plenty there

J
 
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