toroid construction
Kristian, Sat May 12 2007, 07:13AMI 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?
Re: toroid construction
Tom540, Sat May 12 2007, 07:24AM
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
Tom540, Sat May 12 2007, 07:24AM
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
Re: toroid construction
Sulaiman, Sat May 12 2007, 11:45AM
This worked well for me, very quick and easy (fourth post down)
Sulaiman, Sat May 12 2007, 11:45AM
This worked well for me, very quick and easy (fourth post down)
Re: toroid construction
Cain, Sat May 12 2007, 12:42PM
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
Cain, Sat May 12 2007, 12:42PM
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
Re: toroid construction
Jrz126, Sat May 12 2007, 02:53PM
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.
Jrz126, Sat May 12 2007, 02:53PM
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.
Re: toroid construction
Marko, Sat May 12 2007, 07:49PM
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.
Marko, Sat May 12 2007, 07:49PM
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.
Re: toroid construction
Tom540, Sat May 12 2007, 09:45PM
Jrz,
Thats an interesting speaker box you have hanging in your garage.
Tom540, Sat May 12 2007, 09:45PM
Jrz,
Thats an interesting speaker box you have hanging in your garage.
Re: toroid construction
GreySoul, Sun May 13 2007, 04:50AM
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
GreySoul, Sun May 13 2007, 04:50AM
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
Re: toroid construction
Part Scavenger, Tue May 15 2007, 05:11PM
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.
Part Scavenger, Tue May 15 2007, 05:11PM
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.
Re: toroid construction
Marko, Tue May 15 2007, 08:14PM
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!
Marko, Tue May 15 2007, 08:14PM
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!
Re: toroid construction
GreySoul, Tue May 15 2007, 08:52PM
Firkragg, good point. the commercial 2-part polyurethane foams for shipping/insulation seem to expand and cure in a sealed package just fine... the problem I had was with DAP foam and Great Stuff brands...I thought they were the same stuff, but I was told by someone at the time they weren't.
-Doug
GreySoul, Tue May 15 2007, 08:52PM
Firkragg, good point. the commercial 2-part polyurethane foams for shipping/insulation seem to expand and cure in a sealed package just fine... the problem I had was with DAP foam and Great Stuff brands...I thought they were the same stuff, but I was told by someone at the time they weren't.
-Doug
Re: toroid construction
Tetrafluoroethane, Wed May 16 2007, 12:31PM
I also have had great success with the stacked & carved foam. I even had the home improvement store I bought it from cut it for me (24" sqares). For the stacking I used spray adhesive, but anything that won't eat the foam should work. Shaping was done by hand with a wood rasp and sandpaper. I just used Al tape on mine, but it works very well. I never had a problem with heating, but then I never tried to run my coil on over 900 watts. Though I have run it continuously for extended periods though (about 30 min).
Tetrafluoroethane, Wed May 16 2007, 12:31PM
I also have had great success with the stacked & carved foam. I even had the home improvement store I bought it from cut it for me (24" sqares). For the stacking I used spray adhesive, but anything that won't eat the foam should work. Shaping was done by hand with a wood rasp and sandpaper. I just used Al tape on mine, but it works very well. I never had a problem with heating, but then I never tried to run my coil on over 900 watts. Though I have run it continuously for extended periods though (about 30 min).
Re: toroid construction
Kristian, Fri May 18 2007, 08:47AM
Hi all, I took a break from the topload construction for a while. I've been going down to the Geek Group headquarters for the past few weekends and getting some help and advice on other aspects of my project. Their willingness to help is amazing.
Anyway, I'm back at the topload creation. I'm about to attempt to cover the pool toy with paper mache. Parts Scavenger, that idea brought me back to when I was a kid and would cover balloons in paper mache. Once it hardened, you could pop the ballon and the paper mache would keep its form. The pool toy is a balloon. Perfect! (I hope)
I was thinking that once it is dry, I would put a few coats of poly on it to smooth it out a bit. It should be fairly durable. Then I'll cover it in al tape or foil.
Could any of you guys that have done the aluminum foil with success post more details on the process? I would like to have this done by noon on Saturday. I'm running out of time and I have so much to complete before the Tesla-thon June 2.
Kristian, Fri May 18 2007, 08:47AM
Hi all, I took a break from the topload construction for a while. I've been going down to the Geek Group headquarters for the past few weekends and getting some help and advice on other aspects of my project. Their willingness to help is amazing.
Anyway, I'm back at the topload creation. I'm about to attempt to cover the pool toy with paper mache. Parts Scavenger, that idea brought me back to when I was a kid and would cover balloons in paper mache. Once it hardened, you could pop the ballon and the paper mache would keep its form. The pool toy is a balloon. Perfect! (I hope)
I was thinking that once it is dry, I would put a few coats of poly on it to smooth it out a bit. It should be fairly durable. Then I'll cover it in al tape or foil.
Could any of you guys that have done the aluminum foil with success post more details on the process? I would like to have this done by noon on Saturday. I'm running out of time and I have so much to complete before the Tesla-thon June 2.
Re: toroid construction
Reaching, Fri May 18 2007, 08:57AM
I use the aluminium duct that you get in your local store and fill it up with this 2 component cement you use for a car. then i smooth it all with sandpaper to get a clean surface. an then i tape the alu on it.
this works fine but you need much time to get it right
Reaching, Fri May 18 2007, 08:57AM
I use the aluminium duct that you get in your local store and fill it up with this 2 component cement you use for a car. then i smooth it all with sandpaper to get a clean surface. an then i tape the alu on it.
this works fine but you need much time to get it right
Re: toroid construction
Part Scavenger, Fri May 18 2007, 12:21PM
I'm on my break @ work right now... I'll see what I can dig up when I get home, but it's pretty much the same as I did with the bottle caps on my site. Only, I cut the Al foil (just regular kitchen foil) into 1" strips, sprayed it with contact cement (shiny side out), let it get tacky, and applied. You want to attach the foil right in the middle of the foil and on the outer rim of the toroid. This makes sure the strips overlap correctly. I overlap about 1/4 on the rim, but by the time it makes it to the center, it's almost 3/4. Smooth down with your fingers, then roll with the wallpaper roller or a spoon or something. Careful with the spoon, it tends to tear the foil. Then get a piece of cardboard or something, cut it round, cover it with foil, and glue it in the top to cover up all the ends...
I think I've got some pics when I get home.
Part Scavenger, Fri May 18 2007, 12:21PM
I'm on my break @ work right now... I'll see what I can dig up when I get home, but it's pretty much the same as I did with the bottle caps on my site. Only, I cut the Al foil (just regular kitchen foil) into 1" strips, sprayed it with contact cement (shiny side out), let it get tacky, and applied. You want to attach the foil right in the middle of the foil and on the outer rim of the toroid. This makes sure the strips overlap correctly. I overlap about 1/4 on the rim, but by the time it makes it to the center, it's almost 3/4. Smooth down with your fingers, then roll with the wallpaper roller or a spoon or something. Careful with the spoon, it tends to tear the foil. Then get a piece of cardboard or something, cut it round, cover it with foil, and glue it in the top to cover up all the ends...
I think I've got some pics when I get home.
Re: toroid construction
Cain, Thu May 24 2007, 02:19PM
I'm currently making a toroid out of 6 inch ducting that i have covered in the expanding foam and am now carving it down.. i am thinking about trying to turn it... its in the early stages at the moment, but here she is:
Cain, Thu May 24 2007, 02:19PM
I'm currently making a toroid out of 6 inch ducting that i have covered in the expanding foam and am now carving it down.. i am thinking about trying to turn it... its in the early stages at the moment, but here she is:
Re: toroid construction
Ken M., Fri May 25 2007, 12:50AM
Mmmmmm Looks like a giant glazed donut! Looks pretty for early stages, is it working out, as in easy to craft, light weight?
Ken M., Fri May 25 2007, 12:50AM
Mmmmmm Looks like a giant glazed donut! Looks pretty for early stages, is it working out, as in easy to craft, light weight?
Re: toroid construction
Cain, Fri May 25 2007, 04:28PM
yeah very light weight...
and you can use the cheap light weight ducting...
but i used 2 cans of foam on her so far and still have a few small gaps.. but i think i will use an epoxy filler to patch..
as for sculpting..
i have used a long bladed knife so far with great ease, although getting it nice and round will be the challenge, smooth will be easy but nice and even wont be..
i am thinking i might try using an electric plane on her while i rotate it in a lathe ( you could use a drill in a vice i suppose)
Cain, Fri May 25 2007, 04:28PM
yeah very light weight...
and you can use the cheap light weight ducting...
but i used 2 cans of foam on her so far and still have a few small gaps.. but i think i will use an epoxy filler to patch..
as for sculpting..
i have used a long bladed knife so far with great ease, although getting it nice and round will be the challenge, smooth will be easy but nice and even wont be..
i am thinking i might try using an electric plane on her while i rotate it in a lathe ( you could use a drill in a vice i suppose)
Re: toroid construction
Part Scavenger, Fri May 25 2007, 11:21PM
Tip: A coarse wood rasp works great for shaping foam toroids on the lathe.
Part Scavenger, Fri May 25 2007, 11:21PM
Tip: A coarse wood rasp works great for shaping foam toroids on the lathe.
Re: toroid construction
Kristian, Sat Jun 16 2007, 04:50PM
The pool toy I was trying to wrap didn't work out. The plastic expanded over time and pulled the paper mache off. I have since decided to go with a stacked toroid design. I finally wound the secondary. I picked up what was supposed to be 1500 feet of 26 gauge. What came in the mail was only 1lb. I came up a little short. I was hoping to get 22.5 inches of winding on a 4.5 inch form. I only got 19.75 inches of winding. The form itself is 36 inches long, and needs to be cut down to size yet.
The power is 15KV, 60mA NST. The capacitor is 20KV, .015uf. The primary is 15 turns of .25 inch copper tube with .25 spacing in between turns and 1.5 inch spacing between primary and secondary. I need help with the toroid dimensions. My idea for the top load is to wrap 4 inch aluminum duct around the bottom of a flower pot and 6 inch duct around the top. This will give me two stacked toroids. The dimensions are 4" minor, 15.25" major for the bottom toroid and 6"minor, 22.25" major for the top. There is 7.5" in between the center hights. Does this sound about right, size wise?
I was also wondering if anyone had any advise for how high up from the top of the secondary winding I should place this? I will be able to adjust it up to 2 inches up or down on the bolt that it will mount to. Would 2 inches from the top turn to the bottom of the toroid, with the option of going up or down 1 inch, work? Does this give me enough room to play with? Any advice on this would be great help.
Kristian, Sat Jun 16 2007, 04:50PM
The pool toy I was trying to wrap didn't work out. The plastic expanded over time and pulled the paper mache off. I have since decided to go with a stacked toroid design. I finally wound the secondary. I picked up what was supposed to be 1500 feet of 26 gauge. What came in the mail was only 1lb. I came up a little short. I was hoping to get 22.5 inches of winding on a 4.5 inch form. I only got 19.75 inches of winding. The form itself is 36 inches long, and needs to be cut down to size yet.
The power is 15KV, 60mA NST. The capacitor is 20KV, .015uf. The primary is 15 turns of .25 inch copper tube with .25 spacing in between turns and 1.5 inch spacing between primary and secondary. I need help with the toroid dimensions. My idea for the top load is to wrap 4 inch aluminum duct around the bottom of a flower pot and 6 inch duct around the top. This will give me two stacked toroids. The dimensions are 4" minor, 15.25" major for the bottom toroid and 6"minor, 22.25" major for the top. There is 7.5" in between the center hights. Does this sound about right, size wise?
I was also wondering if anyone had any advise for how high up from the top of the secondary winding I should place this? I will be able to adjust it up to 2 inches up or down on the bolt that it will mount to. Would 2 inches from the top turn to the bottom of the toroid, with the option of going up or down 1 inch, work? Does this give me enough room to play with? Any advice on this would be great help.
Re: toroid construction
Part Scavenger, Sun Jun 17 2007, 08:42PM
The general rule of thumb IIRC is that the bottom of the toroid is even with or a little above the last wind on the secondary.
Part Scavenger, Sun Jun 17 2007, 08:42PM
The general rule of thumb IIRC is that the bottom of the toroid is even with or a little above the last wind on the secondary.
Print this page