Rounding dies for 8" air tank

[Frank S]

After rolling the body for the air tanks I am making I needed to close the gap and round the ends just a bit
to do this I rolled a couple pieces of 1/4 x 2" flat bar in the sheet metal roller I made to the diameter the tank was supposed to be. then did the final shape to the dies with a torch

this allows me to get the finished shape completely round plus I can control the amount of gap I want for welding a lot easier and better than just using a chain clamp around the tanks

[DIYer]

Thanks Frank S! We've added your Rounding Die to our Welding category,
as well as to your builder page: Frank S's Homemade Tools. Your receipt:

Rounding Die by Frank S

tags: die, welding, fabrication

[metric_taper]

This is probably not the last tool needed to make these air tanks.
I think I saw in another photo the tank end caps (hemispherical), did you FAB these as well?

[Frank S]

This is probably not the last tool needed to make these air tanks.
I think I saw in another photo the tank end caps (hemispherical), did you FAB these as well?

No fortunately the end caps of the old tanks were in good shape. Otherwise I would have sourced new ones. However making them could have been done through a method of spinning. Which I already have a tool that I could slightly modify to use for spinning the bell shapes
pipe end forming tool
By holding this against a spinning disk backed up by a shaped forming die I would have no problems in making my own end caps.

[Rocky71]

Thanks, Frank! Question- how did you learn metal spinning? I've been wondering if it's something that can be self-taught.

[Frank S]

Thanks, Frank! Question- how did you learn metal spinning? I've been wondering if it's something that can be self-taught.

Rocky I visited a spinner in Sydney Au back sometime in the early mid 1970's. I needed to interview him and get his statement regarding an AWOL I had been sent to retrieve and return to Germany. I was intrigued by what I saw the men in the spinner shop doing so I asked a lot of questions of the process. the AWOL I was there to pickup had made friends with the guy while they were in Vietnam together a few years earlier. For my report I needed to learn why a career soldier of 17 years would suddenly risk not only his career but being brought up on desertion charges so late in his career.
However I probably asked the man more questions about the process of spinning than I did about the AWOL. Then after I had returned from my TDY detail I read a few books on the subject I even found an ARMY technical manual that briefly touched on spinning. It wasn't until many years later that I tried my hand dabbling briefly with spinning. I never tried free form, I only tried spinning over a predetermined machined shape or like in the case of the pipe ends just rolling over the lip.
One word of caution if you are considering learning the are of machine spinning get some books and read of course now there are many videos out there on the subject. If I had the time and was so inclined to make videos I would do one in a step by step process from machining the die to making a special flat faced spring loaded live center with a very stiff spring in it. I learned that from the spinner in Sydney. Having a center with a real stiff spring is useful incase during the spinning process you push too hard and cause the tail stock to back off, a red line indicator will let you know if that is happening and you can reset before wearing a hunk of deformed metal moving at near orbital velocity. That brings up another key point rotational speed is your best friend . The centrifugal force will aid in moving the metal keeping the wobble down to a minimum preferably non existent. Working from the center outward in small increments is another. Not trying to get the final shape over the die until close to completion is the 3rd factor.
Here is a short video I found that shows some of the process as well as one way of how to work the tooling

Edit I almost forgot the AWOL was not intentional it turned out the Sargent First Class had 60 days accrued leave and had to use some of it up so he had flown to AU and looked up his old chum. Mates doing what mates do and believe me I have a few mates in Au as well so I know. Nearing the end of his leave they had bar hopped it a little too much he had gotten separated from his mates wound up in Kings cross had gotten rolled woke up in a hospital not knowing who or where he was nothing left on him but his dog tags and his military ID and $300.00 US stuffed in his socks. It was days before being taken to the police station still not fully aware of himself. My unit was contacted and I was detailed to bring him back since his leave had expired over a month prior and the 1sg felt it best if he were escorted home.

[metric_taper]

I've seen a video from a local shop north of Waterloo, Iowa that was doing copper based sheets. They had flames directed at the piece to do this process. I assume this was to make the shaping better (soften the material) as well as anneal work hardened material during the spinning.
So I thought back to a video I saw earlier this year from a Youtube channel I watch, the guy adds humor to his metal working;

This is part 1, and clearly he has not read any manuals on this. There is a part 2 as well;

[Rocky71]

Outstanding! Thank you, Frank, exactly the details I was looking for. Glad to hear the SFC made out ok too- hope you all made it bad to the world none the worse for wear & Thank You very much!!

[Frank S]

Outstanding! Thank you, Frank, exactly the details I was looking for. Glad to hear the SFC made out ok too- hope you all made it bad to the world none the worse for wear & Thank You very much!!

Rocky; I would suggest that you or anyone else interested in the art of spinning or even thinking about trying it to first look to a source of reading materials 2nd since we live in an info overload world of videos to watch a few and take notes of how one guy does it and compare with how another does it a little differently. then start out with a small disk of the metal of their choice each type of metal has its unique properties when spinning.
I am by no stretch of the imagination any kind of expert on the subject so never consider my word as the final gospel of how to do it. I have spun a few different types of metal. IE Aluminum ( must be annealed) copper ( needs to have periodic heating while spinning to prevent work hardening) Brass (only certain grades lend to spinning very well.) Even some sintered or pressed metals can be spun but usually requires free form while using a duel contact roller tipped spinning bar and very careful moving of the metal to prevent it exploding, cold rolled mild steel one of the most common metals in the world for roll forming will wobble uncontrollably at the edge if try to move it too far too fast without working the full diameter, this is also true for several of the other metals. Hot rolled mild steel spins like cold rolled but until the surface mill scale is worked off you will be bathed in dust Wear a respirator. Don't even try cast iron or any other porous metal the very select few sintered metals previously mentioned excepted, and even those can only be spun shaped ever so slightly. Some grades of stainless steel are nearly impossible to spin even annealing won't help. as with exotic alloys.
A good rule of thumb is if it can be press formed cold or without having to be heated to near its melting point it can be spun, with care and practice.