Vacuum forming coil housings.

[growdude]

The vacuum form box

I'm looking for plans for the box or jig I've got my coil mold form made

[dfbowers]

You mean the vacuum form box or the wooden form for the shell?

Don

[growdude]

coil vacuum former

can some one please post plans on how to make former itself assembly etc?

[dfbowers]

Hi dfbowers,

Sorry, bad wording here! I mean, what prevents the coils from moving when pouring the epoxy in? The density of the epoxy may be close to that of the taped coil, so it might even lift the coil a bit thus spoiling the balance.

Do you spot glue the nulled coils in place with hot glue or something before the epoxy time?

Yes, I just use CA glue to secure the coils first. I also find it helpful to glue a few strips of plastic (scraps from making the shells) as a little bridge between the Tx and Rx coils where they overlap. They are less likely to shift as the epoxy cures.

[Mullihaka]

Hi dfbowers,

Sorry, bad wording here! I mean, what prevents the coils from moving when pouring the epoxy in? The density of the epoxy may be close to that of the taped coil, so it might even lift the coil a bit thus spoiling the balance.

Do you spot glue the nulled coils in place with hot glue or something before the epoxy time?

[WM6]

It looks to original

Excellent work, petravka. Congratulation!

[dfbowers]

Hi folks,

How do you keep the coils in place when pouring in the epoxy?

How about pouring it in in the peripheral area only on the first run and leave the overlapping section free. When the first cast is hard, then pouring the rest and hoping the best. Does the wet epoxy melt the dried one so that when casting in two phases we get a solid, one lump (instead of two blocks, which are not stuck together)?

Hi, Mullihaka.

I set my shells on 3 blocks of wood before pouring epoxy. The important thing is that the surface that you lay your shells on is perfectly level. I use a ruler with a glass level inside.

Then, I do a single pour as epoxy has a hard time bonding to itself. I have seen where you can bond a second pour to a cured layer by adding a top layer of fiberglass or cotton to the top of the first before it cures.

Here is another tip: Put your epoxy into a squeeze bottle that has a nipple on the end. Then you can squirt the epoxy more exactly where you want it to go. I use an empty plastic bottle for contact lens solution.

Don

[Mullihaka]

Hi folks,

How do you keep the coils in place when pouring in the epoxy?

How about pouring it in in the peripheral area only on the first run and leave the overlapping section free. When the first cast is hard, then pouring the rest and hoping the best. Does the wet epoxy melt the dried one so that when casting in two phases we get a solid, one lump (instead of two blocks, which are not stuck together)?

[petravka]

Plastic

Petravka nice work, what type of plastic is it ?

Polistiren 1.4mm

[6666]

Petravka nice work, what type of plastic is it ?

[dfbowers]

[petravka]

DD 27cm

It looks to original

[Jerry]

Thanks petravka, the pictures say everything I need to know.

Good work.

Jerry

[petravka]

DD 27cm coils

[Jerry]

Thanks Jerry (and Don) for excellent report on this subject and the various subtleties.

It's too bad you can't put the form in the oven under the plastic and let it just melt down over the form. I guess that's what the really high-end plastic forming devices do, combine oven and vacuum table. I like the low-tech approach, but clearly takes skill and practice.

I have to go make a grilled cheese sandwich now...

-SB

As strange as it may seem I did give that some thought. I have a stove top heating element around here somewhere but I could not find it when I wanted to do this project so I used a pizza oven instead. The shell I made is for an 8 inch DD coil. Ten inch is going to be about the limit of what I can get in this particular oven.

Jerry