Toroid for tesla coil made of 1/4" tubing?

[leod503]

I have built a number of coils to sell on ebay, the toroid is actually the most expensive part if you want a nice spun aluminum one (I do) of any size. A lot of plans have you use 4" dryer duct wrapped in a circle around a pair of pie tins, pretty tacky for a coil that takes me a week and about $500 to build. My question is have any of you tried the newer ones that some people are selling that are made of 1/4" copper tubing wound into a torus on a plastic frame in the shape of one. Are they any good? There are so many variables involved in a coil, and they are very picky about the shape, I am very skeptical.

 

[GhostLoveScore]

Is there a reason why you use toroid shape? I used simple sphere shape on mine and it works too.

 

[leod503]

I guess a sphere is fine for a smaller tesla as it is too far for the smaller arcs to reach the primary, but I tried one for about 2 seconds on my 4" x 22" 15kv 60ma coil and it was striking my strike rail about half of that time. The sphere shape makes it send streamers in all directions equally, where as the toroids emit it around the outer edge. Even with a toroid, you can see in my pic a big arc hitting the strike rail. Thank you for the response, I was beginning to feel all alone.