RE: [TCML] Envirotex Lite , High Torque drive

[Quarkster <quarkster@xxxxxxx>]

Jim -
 
Regarding coil form speed, it's surface velocity of the coil form that's important for resin application, not motor speed directly.  Too high a surface speed will make it difficult to "spread" the viscous resin properly, and result in the formation of raised circumferential rings of resin on the form. I find that a complete revolution of the form every 2-4 seconds is about right for coils 2" to 6" in diameter.  
 
Most of your other questions were covered in detail in my previous writeups on the process of applying this material; it looks like you may not have looked them up in the archives ("Envirotex Lite Coating Tips", June 2006).
 
I definitely WOULD NOT try to use a "putty knife" to spread the resin; use a 4" wide "foam paintbrush".You are not "trowelling on" the resin like a thick coat of stucco on a wall, you are applying a thin coating that eventually coalesces into a very level, very uniform, very smooth layer. Use just the very tip of the foam brush, gliding gently against the surface of the windings. After the entire form is coated, the final smoothing pass is made with the tip of the foam paintbrush just barely touching the form.
 
I evaluated many types of applicators/spreaders for applying the resin, and the foam paintbrushes work best by far. A distant second best are the knife-edge rubber squeegees used for fiberglass cloth/polyester resin laminating work.
 
The "pot life" of the Envirotex Life is affected by ambient temperature, with higher temperatures reducing the time until the material starts to gell. At 65-68F, pot life is at least 1/2 hour. For a large coil, I would not recommend trying to use it at temperatures above 75 deg F.
 
As previously noted, if you want a perfect, glass-smooth finish, you must exclude (as far as possible) all airborne dust, carpet fibers, flying insects, etc. I coat my coils in a closed, tiled bathroom that has had the countertop and floor damp-mopped to remove all dust. The size of your coil may prevent you from using a bathroom, but I wouldn't recommend coating a coil in a garage unless you have no other option. One good gust of wind outside (or even a rapidly opened door) in a typical garage will stir up a tornado of dust, and absolutely every dust mote, fiber and dog hair will be very visible in the glassy surface of the cured coating. I would think coating a coil "outside" would be a disaster, as far as airborne particles.
 
As far as the foot-pedal motor control, it's a great asset during winding, but I see no benefit during coating. Stopping the form during resin application just results in resin dripping off the form and being wasted. Remember that once resin has started to be applied, the form MUST rotate continuously until the resin has cured.
 
If you have a lot of time and $$ tied up in this secondary, it might be worthwhile to coat a piece of 4" or 6" dia PVC pipe as a "test sample", to get a feel for the whole application process, etc. before you try to coat a large, expensive secondary. This way, if you encounter problems, you can learn from them, and modify your technique before you try the "real thing". 
 
Regards,
Herr Zapp

--- On Tue, 7/28/09, Jim Mora <wavetuner@xxxxxxxxx> wrote:


From: Jim Mora <wavetuner@xxxxxxxxx>
Subject: RE: [TCML] Envirotex Lite , High Torque drive
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
Date: Tuesday, July 28, 2009, 3:46 PM


Hi Steve, Et Al,

Excellent information\experience sharing! And thanks to all others! Do you
have any idea what is an estimated ideal rpm or rpsec. I set up a spread
sheet to convert frequency readout on my motor drive controller to rp/sec.
Very real precision. I don't want the hassle to program the drive which does
most anything except pour the enviortex on:-).

I'm going to control the speed simply via an analog potentiometer with a
foot pedal for hands free operation. The over kill here is for winding a
22-24" sonotube which goes on the winder when the other coil is dry -
assuming I don't create a tex disaster:-)) I am assuming your tool is a 5"
spackle putty knife. I do want Evirotex lite yes? Does it like it hot? There
will likely be bugs to deal with - no wind or dust though. There are less in
the morning but it is much cooler. 

It's a good thing my wife is very patient with me and all my considerable
eccentric stuff. We won't have a deck for awhile this time :-^))

Jim

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Steve Ward
Sent: Monday, July 27, 2009 1:26 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Envirotex Lite , High Torque drive

Jim,

For what its worth, i recently coated a 12.75" x 47" winding with 32 oz (2
coats at 16oz each) of envirotex to get what i consider a suitably thick
coating.  The coating is thick enough to prevent damage in the event of
flash-over.  I use a normal coat of poly-urethane varnish on the wire itself
so that its firmly held in place with the thin varnish that will wick into
and under the windings.  The epoxy will NOT do a good job at wicking into
the coil, and is really just a surface coating.  Before application of
epoxy, be sure to wipe down the whole coil with an alcohol-saturated rag.

So you better go for the gallon kit, probably putting on 20-24oz per layer.
I do 2 thinner layers rather than 1 really thick one usually.  I use a metal
spatula thing i bought at home depot, i think its for drywall mudding, and
is about 5" wide.  Just keep the coil rotating SLOWLY (maybe 20-30 RPM) and
keep pouring it on ahead of the spatula to spread it out.  With the right
touch you can really get some seriously thick layers on the coil if the spin
rate and application technique is just right.

Another tip, despite what they tell you, i use a low speed drill and a
home-made mixing attachment to stir up my epoxy.  The mixer is just a bent
up piece of wire (im sure you can figure something out).  I dont suggest a
paddle or anything for a drill-powered mixer.  Anyway, you will see the
epoxy mix turn cloudy, keep mixing and it will return to a very clear
appearance, this is good!!  Hand stirring often left my mix a bit on the
cloudy side, while it still cured clear it seemed to take an extra long time
to set.  A thorough mixing to the clear stage seems to be the better way.

Steve

On Sun, Jul 26, 2009 at 6:43 PM, Jim Mora <wavetuner@xxxxxxxxx> wrote:

> Hi All,
>
>
>
> Thanks much for the shared experiences on "Pupman" on Envirotex Lite
> application.
>
>
>
> I recognized the how fast a high torque drive could go from my friend to
my
> worst enemy. Luckily, my motor drive has a provision for about every
> interface including a PC and Ethernet!
>
>
>
> Also, it has provision for an external emergency stop and an external
> potentiometer speed control. I bought a cheap guitar pedal and gutted the
> China audio taper electronics and added a 2K linear potentiometer for
speed
> control. It was necessary to mod the throw to get better pot circulation-
> anyone know where to get a half turn pot??? Nothing comes up with Google.
> I'll put a mushroom stop button in a die cast foot stomp box.
>
>
>
> A couple of questions though:
>
>
>
> I want to buy Envirotex LITE correct?
>
> Any idea how much to mix for a first coat a 12.25"  x 61.25" #18.
>
> I buy wholesale from a local paint store; so, a gallon may be a good thing
> if available rather than buying in quarts?
>
>
>
> I look forward to a glass like coil rather than my thin-ish poly coated
> coils.
>
>
>
> Thanks Much,
>
> Jim Mora
>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>
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