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Kristian

Sat May 12 2007, 07:13AM

Registered Member #611 Joined: Wed Mar 28 2007, 11:40PM
Location: Hudsonville, Michigan
Posts: 79

I ve seen some really nice toroids in photos here and I need some advice.

My first attempt was 6" diameter aluminum flexi vent around a 18" diameter 1/2" thick plywood disk I covered in aluminum tape. I bent the duct all to shit trying to get it around the disk. I was going to screw the duct to the disk but it didn't work out, so I epoxied it. It ended up a crooked, dented mess.
6"
6" pic two

Attempt # two;
My wife bought a couple of inflatable pool toy tubes for the kids to float around in our pond on. I saw them and grabbed my tape measure. 7.5" x 26.5". I confiscated one and tried wrapping it in foil tape. I have only put four pieces of tape on it so far and I can already see where this is headed. I knew the flat tape wouldn't conform to the curved surface vary well, but I thought I would give it a try.
7.5"

I know either of these will work, but after the time and money I have put into this, I would rather not use something that looks like dented, wrinkly, thrown together bullsh*t.

Could anyone point me in the right direction for making a toroid on a budget that doesn't look like crap?

Tom540

Sat May 12 2007, 07:24AM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617

What you can do is put a layer of a diffrent kind of tape underneath the foil layer. Or get some Bondo body filler and lay some of that down first. Sand it all smooth and then foil it up.

-Tom

Sulaiman

Sat May 12 2007, 11:45AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

This worked well for me, very quick and easy (fourth post down)

Cain

Sat May 12 2007, 12:42PM

Registered Member #624 Joined: Tue Apr 03 2007, 07:50AM
Location:
Posts: 59

you could also cut the tape into thinner width that should reduce the wrinkles... but it also look like the toy itself has wrinkles in it

Jrz126

Sat May 12 2007, 02:53PM

Registered Member #242 Joined: Thu Feb 23 2006, 11:37PM
Location: Erie PA
Posts: 210

Using the pool toy doesnt look too bad, what happens if the toy gets a hole in it though?

I built my toroids using some plywood and the black drain pipe stuff.

I first tied the pipe to the plywood because it was a pain in the butt to hold it there. Once I had it secured, I ran some screws into it. Then removed the string. I covered it with masking tape to smooth it out a bit. Then I glued some aluminum foil to it with a hot glue gun.

you can see the finished product here

Its not super smooth, but it works. and its pretty durable too.

Marko

Sat May 12 2007, 07:49PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

You guys who use tires and pool toys... how would it be if you filled them with some kind of expanding foam, and then put some foil over?

That way it surely won't deflate, and you could even remove the PVC and have solid foam toroid former.

Tom540

Sat May 12 2007, 09:45PM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617

Jrz,

Thats an interesting speaker box you have hanging in your garage.

GreySoul

Sun May 13 2007, 04:50AM

Registered Member #546 Joined: Fri Feb 23 2007, 11:43PM
Location: Albuquerque, NM
Posts: 239

Firkragg .... "great Stuff" and Dap expanding insulation foam requires air and water to cure properly... I learned this trying to fill latex gloves with foam. All you get is a mushy mess.

Personally, my idea was to stack up some blue insulation foam from home Depot and cut and sand it down to size. it's really not hard to work with, and sands well with coarse steel wool, lathe, cheese graters, etc.

To get really fancy you could set up a turn table with a motor and turn the toroid out of the foam with a hot wire and some coarse sandpaper.

The main problem I see with foam of any sort however is that when it gets hot it can emit some pretty noxious fumes.

-Doug

Part Scavenger

Tue May 15 2007, 05:11PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

I made a toroid awhile back out of laminated styrofoam. It was glued together with contact cement, and "turned" with a drill and a wood rasp. That would have been really smooth, but I decided to cover it in paper mache, and sand it. Then I covered it with aluminum foil. Looks really nice. New coil I've been working on BTW...

Another faster thing you can do to smooth out the aluminum duct is to cover it in masking tape before adding aluminum foil. I've got pictures of that process in the "articles" or section of my website. Look at "toploads" IIRC. That turned out ok as far as asthetics. I resorted to that after dropping it and attempting to pop it back out. I could have done a better job, but it got all of the dents out.

Marko

Tue May 15 2007, 08:14PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I used to have some 2-component expanding insulating foam wich would do the jub really well.. so I guess it's all about the choice of foam.

Regarding heating, I don't think it can be so bad with pulsed coils... if styrofoam works I guess other things are safe too!

Regarding aluminium duct, I think it's smooth enough itself.. I would never bother to do doble job by taping it and it seems to work rather well as is!

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