Vacuum forming coil housings

[dfbowers]

I have been experimenting with making my own coil shells with some success. I have been using what I have on hand. I the example below, I used a simple plastic sign, heated in an oven to 425 degrees and placed onto a vacuum form.. Really easy to make.

But.. I have been looking for a source of Plastic commonly used to form detector coils, something a little more durable. Anyone have a connection?

Also, can anyone tell me where I can find "the right kind" of epoxy filler domestically? I seem to remember Carl or someone mentioning it an a post somewhere. Maplin??

Thanks!

Don

[Molzar]

Really Cool! Wish I could make these...unfortunately the oven is wife's domain....Maybe I can use hair dryer?....OH that is wife's domain too!!

How do you trim after forming? How are you making forms? Are you also making covers? or just filling up with epoxy?

McMaster Carr has all sorts of raw material (plastics in sheet form) and tons of other useful hardware stuff. (Epoxies Too!!) Prices are good, fast shipping, good company....

http://www.mcmaster.com/

Molzar

[mindfree]

Excellent workmanship!

[dfbowers]

Thanks for the information. I started with a wooden box and just drilled tiny holes, like an air hockey table. Then hook up a shop vacuum.

I use a wooden former for the coil housing. The sheet of plastic gets put on a frame while it goes into the oven. Leave it in for about 1 minute @ 425 degrees. When it starts to sag, turn the vacuum on, take the frame out of the oven REALLY fast and lay it on top of the vacuum form table. Voila!
I have heard that you can use a bandsaw to cut off the excess, but I just use a Dremmel cut off wheel on a drill press.

Here is what the finished coil looks like:

[mts]

I used to do a lot of vacuum forming back in the day and it can be a lot of fun. I used to drive to Dayton from Columbus to buy my sheets of plastic. Most plastic dealers have 4'x8' sheets of just about any vacuum formable plastic you could want.

I had a similar table and frame setup (I probably still have it down in the basement somewhere). These are surprisingly easy to make and the guidelines you've provided are right on the money. As soon as that plastic starts to sag by about 2" you need to rip it out of the oven and place it on the bench right away. There were a couple of times that I wasn't paying attention to the plastic and it drooped down onto the lower oven surfaces (my wife was NOT happy). Depending on the thickness of the plastic, once it starts sagging it can droop a good 12" in just a matter of 10 seconds so you have to be right on top of it.

I never really got good at cutting the edges and neatly mating two pieces together. It is surprisingly difficult to do this all by hand. So doing half of a coil housing is relatively easy. Making the other half such that it can be mated to the first one (and be waterproof) is much more difficult.

Thanks for bringing back the memories. I'll have to get my old table and plastic out and make a few coil housings. My kids have never even heard of vacuum forming so they would probably get a kick out of seeing it done. There are so many things we see in everday life that are vacuum formed and we never really take time to recognize it.

[mts]

By the way, this is also a very inexpensive way to make your own custom coil covers. You could buy a 4'x8' sheet and probably get anywhere from 12 to 20 coil covers out of it depending on how much waste you had with each cover.

The place I used to get my plastic from was called Laird Plastics. They have distributors all over the country. I see that they even have one in Columbus now so I wouldn't have to drive to Dayton anymore.

You also need to be careful about heating plastic in your oven. If I remember correctly, heating PVC can give off dangerous gases. Burning plastic can also give off dangerous fumes. It is better to use a dedicated oven or heating device in a well ventilated area. Ask the experts wherever you end up getting your plastic and they can direct you to the safest and best fit for your purposes.

[WM6]

Here is what the finished coil looks like:

Masterpiece. Congratulation.

[bklein]

would a hot wire work to trim the excess or just make a mess of it?

Barry

[mts]

Yes, a hot wire cutter would work well. That's what the pros use. I never tried one though.

[dfbowers]

I think that I found what I was asking for - Epoxy.. I will order some and try it:

http://www.maplin.co.uk/module.aspx?moduleno=4057

Or another one that looks like it may be fit-for-purspose:
http://www.mouser.com/ProductDetail/...ZJjsFrDg%3D%3D

I will post again here when I finish the next one.

Thanks everyone for the help.

Don

[dfbowers]

Still, another:

http://www.mouser.com/ProductDetail/...tMdf5xlKQhWcq2

[dfbowers]

A few of my coil formers.

[homefire]

Here is a kick butt source for you.

http://www.ridoutplastics.com/adandcem.html

[technos]

Here is another link for potting resins;

http://rtvmoldmaking.com/cgi-bin/p/a...tv-mold-making

The thing about going this route is that instead of vacuforming (for those of us that don't have the neat equipment yet) is that you could use the wooden forms to make a rubber mold and pour the casting resin into the rubber mold. Skipping the vacuforming all together (unless it was to make a coil cover).

The only question I have with these resins/epoxies/potting compounds is which one would be best for coil Q.

[dfbowers]

I did order some ABS plastic, .060" thickness from Micro - Mark. http://www.micromark.com/SearchResul...K+STYRENE+.060 I will post again as soon as I give it a try. The vacuum forming part is too easy not to.