Wooden coil housing

[Mullihaka]

Having no access to vacuum forming equipment, I tried making the housing of styrofoam. That's quite rigid and light. When pouring in the epoxy, I found the reason why it is not widely used: it melts.

I took a piece of 9mm thick plywood and made the housing with jigsaw and router. The slot around the circumference should be snug fit, ie it would not need apoxy at all, just few drops of glue to prevent the coil from popping out.

The overlapping part needs some glue as well, as it is not possible to route the slots exactly at correct nulling.

My goal is not to use epoxy, as the brand I used, seems to get hot and expand a bit thus changing the phase shift.

This coil housing is made for TGSL. As it's the first prototype, it's of coarse made. If it works, the final housing will be sanded, polished, painted, decorated and scented.

I intend to glue the coils in place and then cover the whole with several layers of varnish.

The housing weigths 155 grams. The coils are 80 grams together. I guess it stays well under 300 grams finished.

Any experience on plywood housings?

[simonbaker]

Excellent job! I don't have router but wanted to do exactly same idea. Actually I wanted to wind the wire on the plywood, but then it really has to be exact because no ability to shift for null!

The problem may be the weight. But it should be sturdy enough. You can always experiment with removing more and more wood. dfbowers coil weighs about 425 grams. My resin coil weighs about 475 grams. So maybe you're OK.

I am amazed that epoxy curing causes so much phase shift. I'll believe it. I'm not sure it matters too much.

I am thinking of gluing coils directly to thin piece of paneling wood, no routing at all. Maybe use clay to make mold and pour some resin. Not so pretty, but easy???

Anyway, keep trying. I want to know how it works out.

Regards,

-SB

P.S. I attached smaller version of your picture for convenience.

[dfbowers]

Excellent job! I don't have router but wanted to do exactly same idea. Actually I wanted to wind the wire on the plywood, but then it really has to be exact because no ability to shift for null!

The problem may be the weight. But it should be sturdy enough. You can always experiment with removing more and more wood. dfbowers coil weighs about 425 grams. My resin coil weighs about 475 grams. So maybe you're OK.

I am amazed that epoxy curing causes so much phase shift. I'll believe it. I'm not sure it matters too much.

I am thinking of gluing coils directly to thin piece of paneling wood, no routing at all. Maybe use clay to make mold and pour some resin. Not so pretty, but easy???

Anyway, keep trying. I want to know how it works out.

Regards,

-SB

P.S. I attached smaller version of your picture for convenience.

Be careful what you decide to paint it with! Epoxy is ok but if you get it "wet" with any kind of paint at all it might warp. I was horrified once when I tried to paint one and it destroyed the null. One thought:

You are on your way to making a vacuum form!! That's where I started before I decided to make a coil shell from a wooden coil.

Don

[Mullihaka]

How did you manage to make the picutre smaller? I couldn't figure it out.

[J_Player]

How did you manage to make the picutre smaller? I couldn't figure it out.

There is a free online program called irfanview which dislays pictures of all types and is able to re-size them without major degradation. You can choose what size you want. It is best to save phoros as JPG files to keep the size small. for text, gif files work best for small size and clear text.

Download irfanview free here:
http://www.irfanview.com/main_download_engl.htm

Also, download the plugins to make it work with all formats here:
http://www.irfanview.com/plugins.htm

Note: Irfanview is a multimedia program that will show all kinds of pictures, and play videos or music. This is the choice player for computer geeks who want a fast low-overhead picture and music player. There is no adware, but be sure to un-check the google toolbar option during installation, or you will be the proud owner of google toolbar. Irfanview does a lot more than simply resizing. You can do some major enhancing.

To resize photos, open the photo in irfanview, then click Image > Resize/Resample. After you have sized the image to your favourite size, then save it with a new name. See below for some samples:

Best wishes,
J_P

[Krzysztof]

Hi Mullihaka.
Try this: a small, free, and nothing else stirred in the computer.
http://wiseval-photophant.uptodown.com/en/
Best regards Chris.

[lunamay]

witam uzytkownika Krzysztof
mam pytanie. czy robiłes tgsl a jezeli tak to jak wyglada i jak działa

pozdrawiam marcin

[Krzysztof]

Hi Lunamay.Nie Marcinie. Używam czasem Cibola z zasobów rodzinnych.
Generalnie konstruuję MAG, ciągle nowszy, zawsze w podróży.
Best regards Chris.

[lunamay]

rozumiem a czy zbudowałes juz jakis działający mag? mozesz przyblizyć jego parametry?

pozdrawiam

[sadowski25PL]

Hello,
Bracia Polacy
Czy mozemy pisać po angielsku?
Dla dobra czytających.

Polish Brothers...
Can we write in english?
For good of readers?

Cheers,
Sadowski

[satdaveuk]

Excellent job! I don't have router but wanted to do exactly same idea. Actually I wanted to wind the wire on the plywood, but then it really has to be exact because no ability to shift for null!

The problem may be the weight. But it should be sturdy enough. You can always experiment with removing more and more wood. dfbowers coil weighs about 425 grams. My resin coil weighs about 475 grams. So maybe you're OK.

I am amazed that epoxy curing causes so much phase shift. I'll believe it. I'm not sure it matters too much.

I am thinking of gluing coils directly to thin piece of paneling wood, no routing at all. Maybe use clay to make mold and pour some resin. Not so pretty, but easy???

Anyway, keep trying. I want to know how it works out.

Regards,

-SB

P.S. I attached smaller version of your picture for convenience.

Hey hi Simon
Two great minds think alike I ordered clay 2 days ago, because my idea of using casting sand with glue was a complete flop, which thinking about it I should of never tryed it because unlike metal that sets within split seconds of hitting the damp sand, the resin just sank into the sand and it was a right mess.
Ive asked on another post here would I get away with a lead molding because dflowers stated its only in the oven for 2 mins, if some of you think I may get away with it, I shall give it ago, because I can easlily make the mold with sand casting, I cant use aloy etc because of the tempratures required to melt it, unless you good people can think of a DIY way of doing it
Far as the wood its a good idea but maybe worth considering bulsa wood if thats how you spell it, we used it for modeling, and that is light as a feather.
Im wondering instead of wood which I used years ago for head ends maybe polyester or Upvc and just cutting slots to fit the lugs, the art of what we are all after is lightness, I shall certainly experment with different glues, resin, seem to be to violent for are purpose, the foam is the way forward for filling which again ive used in the past its just been able to get a professional finish like deflowers which looks like one you would buy from a manufacure, credit to him.
Love this group, spend so much time on here between running the business and family commitments know wonder I dont get much sleep these days, im wanting to learn so much from you people and if there was more hours in the day Id have 3-4 projects on the go at once, and actually be able to get out metal detecting.
I have five machines here sat doing nothing, I bought another second hand one off a customer yesturday only a cheapy for £20, dont know why I bought just couldnt say no, you can imagine what the mrs said .
Anyway im rambling on totally off the subject proberly bored you all to tears, such is life.
All the best
Warm regards
Dave

[simonbaker]

Hey hi Simon
Two great minds think alike I ordered clay 2 days ago, because my idea of using casting sand with glue was a complete flop, which thinking about it I should of never tryed it because unlike metal that sets within split seconds of hitting the damp sand, the resin just sank into the sand and it was a right mess.
Ive asked on another post here would I get away with a lead molding because dflowers stated its only in the oven for 2 mins, if some of you think I may get away with it, I shall give it ago, because I can easlily make the mold with sand casting, I cant use aloy etc because of the tempratures required to melt it, unless you good people can think of a DIY way of doing it
Far as the wood its a good idea but maybe worth considering bulsa wood if thats how you spell it, we used it for modeling, and that is light as a feather.
Im wondering instead of wood which I used years ago for head ends maybe polyester or Upvc and just cutting slots to fit the lugs, the art of what we are all after is lightness, I shall certainly experment with different glues, resin, seem to be to violent for are purpose, the foam is the way forward for filling which again ive used in the past its just been able to get a professional finish like deflowers which looks like one you would buy from a manufacure, credit to him.
Love this group, spend so much time on here between running the business and family commitments know wonder I dont get much sleep these days, im wanting to learn so much from you people and if there was more hours in the day Id have 3-4 projects on the go at once, and actually be able to get out metal detecting.
I have five machines here sat doing nothing, I bought another second hand one off a customer yesturday only a cheapy for £20, dont know why I bought just couldnt say no, you can imagine what the mrs said .
Anyway im rambling on totally off the subject proberly bored you all to tears, such is life.
All the best
Warm regards
Dave

been able to get a professional finish like deflowers which looks like one you would buy from a manufacure, credit to him.

(You may have credited dfbowers with some extra attributes he wouldn't lay claim to...)

There are artisans here who can really make fine models that I don't dare to dream of, dfbowers one of the best!

In the spirit of low-tech do-it-yourself I like to experiment with off-the-shelf techniques you can find in your local hardware (grocery, etc.) store, although most of my ideas are huge messes. I think it is worth coming up with really easy, if ugly, construction techniques for any enthusiasts who want to build an MD but simply don't have the time to develop the craftsmanship to build a professional looking machine. The idea is to go for pure function, not fashion.

So I'm interested in what you find out with balsa wood and other techniques. Lead molds sound pretty tricky to me, and not something anyone else could easily do, but if you can achieve it, maybe it works for you.

I have wondered if the light foam material that is used for model airplane wings would make a good base to glue our coils to -- strong and rigid, but light.

It is very important that the coil housing be rigid I think, because flexing and vibrations can probably create large signals.

Those other materials you mentioned may be very good -- I hope you try them and let us know how they work. However, you really need a good, working MD to use them with and a well-built coil for comparison. I am lucky that dfbowers sent me one of his excellent models, and it is invaluable for comparing and trying different circuits, coils, etc.

Keep trying stuff and take photos. I think you have the right kind of crazy to succeed!

Cheers,

-SB

[PaullyG]

I have wondered if the light foam material that is used for model airplane wings would make a good base to glue our coils to -- strong and rigid, but light.

If you kept the coil size down it'd probably work, expanded polypropylene foam as used in slope gliders would be the one to try. Especially the weightier denser grades if you can source them. To increase rigidity/durability and keep the dirt off you can use regular A4 laminating film heated on with a regular iron. It's a bit tricky so practice on some of your offcuts first but with some careful use of scissors and a bit of pre planning it can be done quite nicely. I've used this technique on slope planes before and obviously the last thing i want is wings warping, with care and the right temp it can be avoided fairly easily.

If you need to glue any parts, you'll probably need to use a polyurethane based glue (Gorilla Glue if you can get it, Vise Grip is a similar product here in Aussie land), they expand as they cure which'll require a bit of cleaning up after (tape over the areas you've filled with glue and tape down the separate foam parts) but the joints are as tough as the EPP afterwards. Epoxy could be worth experimenting with, but I'm not sure if it'll have the same longevity, CA glues will also work, though some will eat the foam and again I'd be a bit suspicious of the durability.

We need a dedicated Experiments in coil housings thread, where everything from bucket bottoms to wood fab to frisbees can be discussed.

[WM6]

Wooden coil housing, despite nice looking, electrically not realy apropriate solution (moisture-hygroscopic, dimensional instability, wood act as soil, weight).

[lonelyWOLF]

I tried once From 9mm thickness MDF.