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Registered Member #62119
Joined: Sun Feb 04 2018, 04:59AM
Location: Cedar Rapids, Iowa
Posts: 136
Even though you didn't say, I am assuming that you are seeking a large toroid. About 15 years ago, this company (O.W. Landergren) made a batch of large aluminum toroids custom-ordered by the TCML (Tesla Club Mailing List) in a group purchase for tesla coil use. I bought one (30" x 9") and they are beautiful. You can't even see the seam. It won't be cheap though. Back then, I believe I paid $275 for mine. That was for a batch quantity of about 20 as I recall.
If you are seeking a toroid, and 30" x 9" is big enough, you might want to contact them and find out if they still have the forms left over from the TCML group purchase from back then. This may lower the cost because they wouldn't have to make a new form.
Another consideration about spun toroids is weight. I haven't weighed mine but I would estimate that my 30" x 9" weighs at least 20 pounds. The weight of a toroid increases linearly with the major radius but increases according to r**2 for the minor radius. In short, a large spun aluminum toroid can be very heavy and unmanageable. My 30" x 9" spun toroid is about as heavy as I would want a toroid to be because I frequently remove it from a 6' high tesla coil.
Even though nothing beats the appearance of a spun aluminum toroid, if you want a really large toroid I would consider making it from wire mesh and ribs to keep the weight down.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Thank you for the pointers!
I am actually looking for hemispheres, for the tank-ends of a rocket propellant container. Weight is an issue, but wire mesh certainly won't hold any O2
Registered Member #62119
Joined: Sun Feb 04 2018, 04:59AM
Location: Cedar Rapids, Iowa
Posts: 136
It would have been helpful if you had originally specified your application. Since you posted this under the tesla coil group, the obvious assumption was a toroid. I would still check with the O.W. Landergren company. It is a full-service metal spinner. I have one of their toroids and the quality is excellent.
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Aluminum spinning services?
