coils glue

[Unregistered]

hello
made 20sm coil but have to glue
what is best resin epoxy or cyanoglue ?
what is good glovves for resin epoxy ?
other glue ?

sorry for my english
Vladi

[KinnyP]

Hi Vladi,

Your English is fine! I have no second langue and can appreciate your problem.

I just finished a 14” multi radius coil and had the same problem. I was told by someone that has made coils for years to use shellac. It did the job, but took several days to dry properly. KinnyP

[ciuccacci]

Hi Vladi,

Your English is fine! I have no second langue and can appreciate your problem.

I just finished a 14” multi radius coil and had the same problem. I was told by someone that has made coils for years to use shellac. It did the job, but took several days to dry properly. KinnyP

Hi Vladi

tray to use this:
http://en.wikipedia.org/wiki/Glue_gun

to fix the wires and this

http://www.wonderhowto.com/how-to/vi...-resin-157877/

to make the mold and for the final realization epoxy fiber glass

The mold takes 12 hours to dry and the epoxy 1/2 Hours

Ciao

[o.mag]

HI
to paste the coils of a coil coating and son between them. must still pass the coil to its outline in the oven
approximately 30mm to 180 ° C (depending on the template that limits the heating of copper)
or used the material from a winder which is a significant move in the coil to soften the varnish (30s)

olivier

[grungymike]

glues and adhesives

Cyanocrylate (crazy glue) is great stuff but doesn't seem to take a shock or thermal cycling very well, tends to be kinda brittle. The fast curing epoxies (like Devcon 5 minute) cure a little bit flexible, and will glue almost anything to anything. Polyester (fiberglass) resin will probably work well too, at about 1/3 the price of epoxies. There's also some newer silicone and acrylic polymer adhesives designed for construction use that might work well. Take a look at the various adhesives used in boatbuilding, those guys use some amazing stuff...

Throwaway latex gloves will protect your hands from any detrimental effects of epoxy resins, not to mention keeping a person from glueing their fingers together when using the cyanoglues (go ahead and laugh, I've done it).

gm

[DEMAC]

some tips

polyester adhesives,cheaper (Very)more than epoxies have contractions in the order of 0,3-2%,more or less(depending on curing time,type of catalizer).

epoxies,on other hand,goes usually inbetween 0,01-0,3%.are superior in adhesion,and expensive.

i use polyester to bond first bobin (on a dd),and then epoxi for the second,more delicate on setup.

take care:epoxies bond over poliester,but poliester dont bond over epoxies,is only a superficial compromise,dont last!

in this way,is secure and economical assemble the coils.

best regards

[WM6]

polyester adhesives,cheaper (Very)more than epoxies have contractions in the order of 0,3-2%,more or less(depending on curing time,type of catalizer).

epoxies,on other hand,goes usually inbetween 0,01-0,3%.are superior in adhesion,and expensive.

i use polyester to bond first bobin (on a dd),and then epoxi for the second,more delicate on setup.

take care:epoxies bond over poliester,but poliester dont bond over epoxies,is only a superficial compromise,dont last!

in this way,is secure and economical assemble the coils.

best regards

Thank you!

Which product you use?

[DEMAC]

I WILL TRY TO EXPLAIN IN MY LIMITED ENGLISH

FOR POLYESTER

YOU CAN USE ANY RESIN FOR BOAT BUILDING. I BUY LOCALLY FOR US$ 12
A 4 LITRES CAN.

POLYESTERS CAN BE PROCESSED WITH TWO TYPES OF DIFFERENTS CATALYZERS/ACELERATORS(YOU CAN NOT MIX TYPES,USE ONE OR THE OTHER
SYSTEM)

MEK PEROXIDE CATALYZER/COBALT ACELERATOR OR BENZOILE PEROXIDE CATALYZER/DMA ACELERATOR

THE FIRST ONE IS "NORMAL TIME" COMPOUND

THE SECOND,IS REALLY FAST,THE DMA STINKS BAD,BUT THE MIX IS REALLY HARD IN SHORT TIME(AND CONSECUENTLY,CONTRACTION IS VERY HIGH)

YOU MUST KNOW THAT POLYESTERS HAVE MAXIMUN STRENGH ONLY AFTER 6 MONTHS APROX,BUT YOU CAN GET 80% AT RAZONABLE ROOM TEMPS (22-28 ºCENT) AFTER A MONTH OR YOU CAN GO ON OVEN TO 50-70ºCENT FOR 2 OR 3 HOURS(AFTER CURED MIX,NO MORE TACK ON SURFACE).THE ABSOLUTE LIMIT OF DEFORMATION IS ABOUT 135ºC.

DONT GO OVER 70º,IS BETTER THAT WAY.

DONT PUT A STILL NO CURED MIX ON OVEN.THE MIX MUST BE CURED BEFORE.

CATALYZER/ACELERATOR GENERATES HEATH ON CURING PROCESS AND IF YOU SUM THIS HEATH AND OVEN HEATH,GO FOR DISASTER.

FOR THE MIX WITH RESIN,I USE CALCIUM CARBONATE UP TO TWO PARTS OF CALCIUM ONE PART OF RESIN.

YOU MUST PREMIX THE ACELERATOR ON RESIN.IS HARD TO MIX LATER WITH THE CALCIUM INCORPORED.
THE ACELERATOR(COBALT,VIOLET COLOUR),SELLS USUALLY IN TWO DIFFERENT CONCENTRATIONS,2% AND 10%. I USE 2%,MORE CONTROLLABLE.
THIS IS COBALT DILUTED ON STYRENE,THE BASIC COMPONENT OF POLYESTER.

IF YOU GO WITH TO MUCH CALCIUM,YOU CAN ADD RESIN OR STYRENE.

FINALLY,FOR CATALYZER,TRY TO USE NO MORE THAN 3%,NOT LESS THAN
1,5%. IF YOUR POT LIFE IS TOO FAST,YOU MUST GO DOWN WITH COBALT

NOT WITH CATALIZER(A VERY COMMON ERROR)


FOR EPOXI

I USE A VERY CHEAP FOR VARNISHING ELECTRIC MOTORS BOBBINS
BUT IN THIS SCENARIO,THINGS ARE DIFFERENT.

I MIX BY INSTRUCCIONS A AND B PARTS,AND THE I PUT CALCIUM CAREOUSLY DEHUMIFIED ,(60-80ºC 2HOURS EPOXIES ARE VERY INTOLERANT TO WATER )

WHEN CALCIUM GOES AMBIENT TEMP,ADD 20-40% BY VOLUME TO MIX.

FOR EPOXIES YOU NEED 30ºC FOR A GOOD START, AND 40º BETTER.

THAT TYPE OF EPOXIE(VARNISHING) CAN BE HEATH CURED UP TO 100ºc
BUT YOU HAVE TO TAKE ON SIGHT THAT THE MIX ON HIGH TEMPS,LIQUIFYS TEMPORARY,YOU LOST DENSITY AND FLOWS UP TO YOU ACHIEVE CURING TIME,IN SOME CASES A BENDITION,A MALDITION IN OTHERS.

DONT PUT TOO MUCH CALCIUM ON MIX,ONLY THE NECESSARY.YOU CAN USE IN BOTH RESINS GLASS MICROESPHERES TOO.

MAY BE I LOST TO EXPLAIN SOMETHING,ASK,NO PROBLEM.

BEST REGARDS AND GOOD HUNTING

[technos]

You can not just throw any old glue on your coil and expect it to work well. You need to use tried and true "coil Q dope." There are a couple of recipes on the web. The problem with using other substances is that they will be too brittle (aka super glue) and crack readily under stress (thermo cycling as another poster alludes to) and then your coil becomes loose and inductance (and hence your detector's performance) flops all over the place. And if you use something like thick epoxies then coil Q will suffer and then your coil becomes lossy and doesn't go as deep.

I'm surprised that this hasn't been brought up already!

[grungymike]

Q???

That's why the forum exists, and that's good input. I didn't know about the dielectric effects of thick epoxies, I've read one article that recommends using sand covered with epoxy, for ballast for an an underwater coil.

Anybody tried any of the silicone construction adhesives?


I'll go do a web search for coil Q dope (first I've heard of it, but I'm a beginner here) and report anything interesting I root out...

gm

[grungymike]

yeah, huh?

re. coil Q dope-

polyester peanuts dissolved in toulene...


1) Mouser Electronics lists MG Chemicals Super Corona Dope #4226-1L

2) www.cliftonlaboratories.com has a good amount of info on the subject, including a recipe for homemade.

Apparently, polystyrene (or teflon) doesn't screw with coil performance like other adhesives. Looks like this ain't new knowledge either.

Learn something new every day, thanks for the heads up!

gm

[technos]

I've read one article that recommends using sand covered with epoxy, for ballast for an an underwater coil.

Anybody tried any of the silicone construction adhesives?

gm

Every once in a blue moon you will see an article about this. The last one I saw quite sometime ago tested a number of different substances for radio coils. Silicone was pretty bad too, iirc. But at these low frequencies (sub 100 kHz) I don't think it is much of an issue as the link you posted suggests. The main issue I would have with it is that the silicone I'm familiar with comes out of the tube quite thick, and wouldn't seep into the wires of the coil as well (if at all) to form a good mechanical bond between the individual turns of the wire and keep the coil solid. Further, many silicones are a flexible substance, and does not offer much structural support to whatever it adheres to. If you are dead set on using it, it would make more sense to use q-dope on the coil. and when that dries use the silicone on the outside.

Don't get me wrong, I like silicone. But it's application seems mostly limited here. Plus it is expensive. The off the shelf GC q-dope is pretty expensive (as the link noted outpacing inflation) where the recipe is quite economical. Myself, I'm looking for alternatives to forming my own ABS plastic coil forms (or buying them from Hays Electronics for that matter).

It seems to me that if you cast your coil in a resin (can be pricey as well), that it would have a negative buoyancy and possibly be better than "epoxy sand" Gads, I'm not too sure about shoveling sand into the coil! Who knows what kind of iron and hot rocks are in it!

[ODM]

Polyethylene has a low dielectric absorption, and seems to be used as a coil former material for RF coils and as insulator in low loss coaxial cables.

In pulse induction and generally whenever fast edges are concerned, the bandwidth required for a fast transition should be given consideration - though most of the time the amount of dielectric surrounding the coil is rather fine, and its effect negligible compared to the damping time of the search coil RLC circuit.

Wasn't Q-dope originally used as fixing lacquer for tuning coils in radios? The reasoning behind its use, I recall, was mostly to fix the form of the coil to keep it from bending and hurting the Q with misalignment, and to both displace and keep out moisture from cardboard winding forms? The low dielectric absorption probably helped as well, but it did not really increase the coil's Q but instead helped maintain it during use.

[technos]

Wasn't Q-dope originally used as fixing lacquer for tuning coils in radios? The reasoning behind its use, I recall, was mostly to fix the form of the coil to keep it from bending and hurting the Q with misalignment, and to both displace and keep out moisture from cardboard winding forms? The low dielectric absorption probably helped as well, but it did not really increase the coil's Q but instead helped maintain it during use.

You are not going to be increasing the Q of the coil with any glue/dope that you use. The whole idea is to keep the Q that you have (not decrease it) with the glue/coil dope that you use. Why you want to "fix" a coil is to keep the coil mechanically sound, because they can fall out of tuning. Also, and this is the biggie (esp. for PI detectors), if the strands of the coil come loose that will increase the capacitance of the coil and hurt the ability of the coil in dealing with fast rise times (not that it does not do that to some extent by the nature of an RLC circuit). Of course the depends a lot on the construction and type of the coil, but you don't want the individual strands vibrating more than necessary (with the magnetic fields) or falling apart with mechanical vibrations through use. The only way to really tell how your adhesive performs imho is test the coil construction and measure it's characteristics.

[Bandit1611]

Is the q dope to secure the coil in its wound form? Or can you also use it to secure the coils into the housing as we'll?