PSN-L Message - Subject: RE: A Sticky Question

Meredith and Jerry,

I didn't have a problem with Chris' rectangular design. I = used a Dremel tool disk to cut slots in the PCB material. I built the form in 2 = steps. First laid one side flat on wax paper and then inserted the spacers in = the slots and epoxied the parts. After they set up for about an hour, I = turned it over inserted the first assembled part into the other side piece and = epoxied the complete assembly. Then let it cure over night. I filed down the = sharp edges of the spacer parts and it's ready to start winding. I wrapped a = slice of parchment paper around the center section before winding wire. If the = wire breaks, unwind it and start over again. This is a learning process. I = used Duco Cement smear around the wire at the very end to lock it in = place.

Gary

From:= psn-l-request@.............. [mailto:psn-l-request@............... On = Behalf Of meredith lamb
Sent: Wednesday, July 21, 2010 3:01 PM
To: psn-l@..............
Subject: Re: A Sticky Question

Hi Jerry,

Actually I've no real recommendations as too material. As too the implications of the thickness I'd be more
prone to use as thick a material (i.e., 1/16" or better) as = possible just for pure mechanical long term holding properties.
Once winding begins then the expansion forces naturally begin to try to "break" the glued material bonds; and
such may well be seen long term. Realistically; it's like wrapping = wire around your finger, the mounting pressure
begins to hurt with more and more wire wraps. Coil frame = deformation is too be expected. Epoxy glass PCB
is pretty tough stuff as is; but the glued joints will be the weakest = member irregardless.

I'm sure I'll hear text "screaming" if I recommended something = like 1/8" thick PCB board; but, it would sure
be much more solid long term than anything else. Yes; the = thickness is rather ancient electronically, but
it might be found surplus I suppose....or simply glue two 1/16" = thick plates together. Yes; I suppose it would
likely upset some of the coil dimensions or, of course, the obvious = lesser magnetic field intensity with its use.

Chris's original square coil design is a difficult project for = sure. Sometimes I wonder if a (~pure) copper plate couldn't
achieve the same "coil frame", and with silver solder to the = joints (and cleanup filing), might even be sufficiently strong
and yet also give somewhat of a eddy current motion dampening. = Hopefully in time; perhaps Chris be feeling better
enough to tell me, us, that; that approach is ~ so and = so.......... :>)

Take care, Meredith

On Wed, Jul 21, 2010 at 2:33 PM, GPayton <gpayton@.............> = wrote:

Thank you SOOOO much, Meredith! This input is = exactly what I was looking for. Some of my replies got off on the wire and winding, which is still good information, but not exactly what I was = seeking.

Do you have a preference or recommendations of = material to make the coil bobbin? As I mentioned, Chris had suggested the = Epoxy Glass PCB material, but I had problems trying to construct the spool with such = small dimensions and the adhesive too.

Thanks again,

Jerry

----- Original Message -----

From: meredith lamb =

To: psn-l@..............

Sent:<= /b> Wednesday, = July 21, 2010 3:18 PM

Subject: Re: A = Sticky Question

Jerry,

Yes, glue is a real problem over a variety of materials that need to be = glued.

As far as commercially available brands (USA), there is one plastic glue = I've come to favor; and that is
Devcon brand, Plastic Welder. Its a two part mixing glue that is = meant for a variety of materials
like hard plastic, vinyl, pvc piping, fiberglass (and metals and concrete). Net volume 25ml. Available
in Ace Hardware stores and likely a variety of other sources; for = roughly $6. Its a plunger outlet nozzle.
A little can go a long ways with your use. One problem with re-use = is clearing out the plunger tips
with a nail (etc.) to allow free flow. It's flammable, stinky = stuff, and best to ventilate or use outdoors.
It makes no mention of being waterproof; but I've used such in a = magnet/metal holding fixture in a
bathroom for ~ 3 years; and has seen no failure yet. This does not = bond to polyethylene or polypropylene
plastics.

I've used it on cloth to metal, metal to rubber and once even (clean) = carbon plate to carbon plate with amazing
(no failure yet, over ~ 2 years). Some of these parts come into = physical force contact and separation;
but thus far its has been holding well.

Once mixed it begins to harden very fast. Although tricky to do, = removing unwanted excess might call
for another person (or holder) to hold the glued object, and wiping the unwanted excess off with a damp cloth.
I usually let it dry for a full day; but it could be shorter = duration.

How well, long term it actually holds is probably dependent somewhat on = having clean surfaces to begin
with. The actual holding force is unknown...I'am not sure at all = as to the forces exposed to with coil
winding forms. One might conceivably try out bonding scrap pieces, letting dry, and physically trying
to separate, bend, torque them; before application into your final = project.

Another glue is the same brand; Devcon 2 part "5 minute = epoxy", but its relegated only to metal & wood,
concrete, glass & china and ceramics. Probably good for ~ = frame parts holding.

Take care, Meredith

On Mon, Jul 19, 2010 at 7:42 AM, GPayton <gpayton@.............> wrote:

In years past, I had difficulties in finding a "manual" coil winder and ended up with an old fashioned had drill. (As you know, you have to search using the correct words or = your mouth pursed just right to be successful.)

Anyway, that hand drill is what I ended up = with. The EBay choices shown by Barry are interesting. Thanks, = Barry.

Never-the-less, in past, I had more trouble finding = proper shaped ready-made spools or bobbins to wind a coil. And, if I = tried to construct a rectangular shaped form, I had trouble getting the = sandwiched parts to stick together! I suppose that I did not have the correct adhesive. I tried several without satisfaction.

If anyone knows the secret to building a = rectangular form, materials & glue, I'd appreciate knowing it.

Regards,

Jerry

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