water-based glue

[dfbowers]

Thanks, gives a picture of how these glues work, very interesting.

How does "resin" (the kind used with fiberglass) fit into this?

-SB

I tried two part epoxy from the hardware store in one coil. Too much shrinkage and spoiled the null. It cured flexible and when the coil was moved at all it would produce false signals. Must be a slow cure.

We do a lot of jetski work and have mats of fiberglass laying around. I was using it as a filler to lighten things up, but I don't think it's necessary though. Look really close at the coil that I sent you and you may see a few strands imbedded in it.

Since then, I have just been making my coil shells thinner and thinner to get the weight down.. and the epoxy I have been using is still stiff enough. Now, barely enough to cover the windings..

I also thought about using auto body filler like "Bondo" or something like that.

Anyone ever try it?

Don

[simonbaker]

I tried two part epoxy from the hardware store in one coil. Too much shrinkage and spoiled the null. It cured flexible and when the coil was moved at all it would produce false signals. Must be a slow cure.

We do a lot of jetski work and have mats of fiberglass laying around. I was using it as a filler to lighten things up, but I don't think it's necessary though. Look really close at the coil that I sent you and you may see a few strands imbedded in it.

Since then, I have just been making my coil shells thinner and thinner to get the weight down.. and the epoxy I have been using is still stiff enough. Now, barely enough to cover the windings..

I also thought about using auto body filler like "Bondo" or something like that.

Anyone ever try it?

Don

I was looking at that auto filler too -- just wasn't sure how it would do in thick volumes. Also a little expensive.

Just to prove it's a bad idea, I may actually try some pottery clay -- the price is right!

-SB

[J_Player]

Well after a few IB coil failures, I would stay away from Semi -Rigid potting compounds. I would select something that is Hard, light and has no shrinkage when curing. Even some epoxies will not fit the bill!!

I will put some numbers to it. The only compound that I have tried so far that has worked perfectly is "MG Chemicals 832B-375ML". That's not to say that many others will not work, but it has a "Shore D" hardness of about 80.

I would be interested to know exactly what flexible material you used. My concept of using a flexible material is for the coil and potting material to be enclosed in a rigid coil cover or form that prevents the potting material from moving. I can see where a D-D coil or IB coil would have a problem if they were able to move.

How does "resin" (the kind used with fiberglass) fit into this?

Hi Simonbaker,
The resins used with fiberglass don't fit into this unless you are considering using them. I mentioned them because they are related in some strange way to the epoxies by virtue of the fact they become hard by forming chemical bonds rather than evaporating materials that keep them thin. These days, fiberglass is usually bound with polyester resin, vinylester resin, or epoxy resin. Epoxy is considered the best of the bunch for it's strength and waterproof qualities. The surf boards that are produced today seem to perform about the same regardless of which kind of resin is used, so they all appear to be the same to the people who use them. All of these resins cure relatively hard compared to materials like caulk, and they all have better shrinkage properties than the materials which rely on evaporation to become hard.
But there are different epoxies and different polyester/vinylester resins. For example, never use 5-minute epoxy on a coil. This epoxy is known to be inferior for long term use in harsh environments. I once used 5-minute epoxy to seal some leaks in a boat hull, and I found that when I placed it in the water, it became rubbery within 12 hours and lost all it's strength. The patch failed in less than 24 hours. On the other hand, when I used Gougeon brothers epoxy designed for wooden boat building, I never had a problem with water damage or joint failure. (This is available in inexpensive repair kits from Westmarine (http://www.westmarine.com/webapp/wcs...classNum=10297 ), or as expensive bulk quantities as well). The point is you will find better results for a coil if you avoid hardware store epoxy glue kits and look for a product that is designed as a 4-hour, or better yet, a 24-hour epoxy which has published specifications.
I really don't know the stiffness properties of the different epoxies. But I presume the epoxies that are guaranteed to be waterproof are probably more stiff than the 5-minute epoxies like the one I watched turn to rubber in less than half a day. Another tip that may help to choose a good epoxy... Gougeon Brothers "West System" epoxy for boat building is one of many manufacturers of high quality epoxy. They most likely have their resins made by a large chemical company, then branded and shipped to their retail outlets. The chemical companies who manufacture epoxies for the different retailers usually have engineers on their staff who can tell you what retail products to use that will suit your purposes.
Check online for manufacturers that you think have staff engineers who can help:
http://www.thomasnet.com/products/ep...-460402-1.html
or
http://www.directindustry.com/indust...ive-73468.html .

Some final notes that comes to mind about resins:
1. Bondo auto body filler is the same polyester resin and catalyst that is used to make surfboards, but the resin is mixed with clay to give it some thinckness. I presume the clay does not cause problems with the electrical properties of the coil system.
2. If you are considering using water-based glue, there are two kinds found at hardware stores: Elmer's white glue, and a second similar glue called carpenter's glue that has a yellow color. The yellow glue is the same as the white glue, but has aliphatic resin added, which gives it greater strength. The cost is almost the same, but the yellow glue is actually stronger than most wood that you are trying to bond, and will fail at the wood instead of at the glue joint. Personally, I would avoid both of these as a potting compound.
3. I have not used any of these methods to build coils. I am only talking about what I know about the resins. How they actually work with coils can be seen by experimenting.

Best wishes,
J_P

[simonbaker]

I would be interested to know exactly what flexible material you used. My concept of using a flexible material is for the coil and potting material to be enclosed in a rigid coil cover or form that prevents the potting material from moving. I can see where a D-D coil or IB coil would have a problem if they were able to move.


Hi Simonbaker,
The resins used with fiberglass don't fit into this unless you are considering using them. I mentioned them because they are related in some strange way to the epoxies by virtue of the fact they become hard by forming chemical bonds rather than evaporating materials that keep them thin. These days, fiberglass is usually bound with polyester resin, vinylester resin, or epoxy resin. Epoxy is considered the best of the bunch for it's strength and waterproof qualities. The surf boards that are produced today seem to perform the same regardless of which kind of resin is used, so they all appear to be the same to the people who use them. All of these resins cure relatively hard compared to materials like caulk, and they all have better shrinkage properties than the materials which rely on evaporation to become hard.
But there are different epoxies and different polyester/vinylester resins. For example, never use 5-minute epoxy on a coil. This epoxy is known to be inferior for long term use in harsh environments. I once used 5-minute epoxy to seal some leaks in a boat hull, and I found that when I placed it in the water, it became rubbery within 12 hours and lost all it's strength. The patch failed in less than 24 hours. On the other hand, when I used Gougeon brothers epoxy designed for wooden boat building, I never had a problem with water damage or joint failure. (This is available in inexpensive repair kits from Westmarine, or as expensive bulk quantities as well). The point is you will find better results for a coil if you avoid the Home Depot epoxy glue kits and look for a product that is designed as a 4-hour, or better yet, a 24-hour epoxy which has published specifications.
I really don't know the stiffness properties of the different epoxies. But I presume the epoxies that are guaranteed to be waterproof are probably more stiff than the 5-minute epoxies like the one I watched turn to rubber in less than half a day. Another tip that may help to choose a good epoxy... The epoxy sold as Gougeon Brothers "West System" epoxy for boat building is manufactured in California by Safetypoxy. The chemical companies who manufacture epoxies for the different retailers usually have engineers on their staff who can tell you what retail products to use that will suit your purposes.

Some final notes that comes to mind about resins:
1. Bondo auto body filler is the same polyester resin and catalyst that is used to make surfboards, but the resin is mixed with clay to give it some thinckness. I presume the clay does not cause problems with the electrical properties of the coil system.
2. If you are considering using water-based glue, there are two kinds found at hardware stores: Elmer's white glue, and a second similar glue called carpenter's glue that has a yellow color. The yellow glue is the same as the white glue, but has aliphatic resin added, which gives it greater strength. The cost is almost the same, but the yellow glue is actually stronger than most wood that you are trying to bond, and will fail at the wood instead of at the glue joint.
3. I have not used any of these methods to build coils, so I am only talking about what I know about the resins. How they actually work with coils can be seen by experimenting.

Best wishes,
J_P

Ok, so those resins were covered in your "Epoxies... etc" paragraph. I am planning to use that resin to start with.

Thanks for these notes. Where do you get your information about glues? I often wonder what the differences in glues really are -- there needs to be a really good book (based on real tests, not just theories) that shows the properties of all available glues, and also shows which brands are essentially the same.

Thanks for explaining the difference in yellow carpenter's glue and the white elmer's glue. I always wondered about that. Do they have similar shrinkage/expansion? Any other differences?

Regards,

-SB

[J_Player]

Ok, so those resins were covered in your "Epoxies... etc" paragraph. I am planning to use that resin to start with.

Thanks for these notes. Where do you get your information about glues? I often wonder what the differences in glues really are -- there needs to be a really good book (based on real tests, not just theories) that shows the properties of all available glues, and also shows which brands are essentially the same.

Thanks for explaining the difference in yellow carpenter's glue and the white elmer's glue. I always wondered about that. Do they have similar shrinkage/expansion? Any other differences?

Regards,

-SB

My information is derived from a lot of years dealing with chemists who formulate paint and corrosion resistant coatings. The people who taught me also have a broad background in chemistry focused on resins that range from the epoxies to alkyds used to make paints. I also studied the resins and adhesives used for boat-building. In my case, I had to know the answers and I had to be right the first time, because my livelihood depended on it. So I read as much as I could to try to be smarter than the chemists. (I probably wasn't successful at becoming as smart as them, but I learned a lot of stuff that is only useful to painters, boat-builders and coil builders).

There are real books that you can read to see all the things I talked about. But the answers are all scattered in small fragments buried in tons of technical publications. Where I really learned is by calling chemists who actually work for paint and adhesive companies. You will be surprised how much you can learn by calling Dow chemical, or DuPont and asking for an engineer to help with an application you want to develop. They have full-time engineers on staff just for that purpose who are anxious to answer all your questions, as this helps them to prove they must remain on the payroll. I also learned a wealth of information from calling and talking to chemists who are in charge of formulating products for small companies. These guys sometimes know stuff that the big companies haven't figured out yet, because they tried their own experiments to solve problems the big companies haven't thought of.

The difference between white and yellow glue -- I don't know about the shrinkage. I suspect they are about the same. I know the yellow is stronger because I have used it for years. I also know the white glue will dissolve if you keep it wet long enough. As best I can remember, I think the yellow glue can also dissolve if it is wet long enough, but it was a lot more resistant to moisture than the white glue. The aliphatic resins are probably responsible for the better resistance to moisture.


p.s. If you are going to start with fiberglass resin (polyester resin), look for the kind called "casting resin", not the kind called "gel-coat". The casting resin is pure polyester without additives. Better is to use an epoxy like Gougeon Brothers epoxy (http://www.westmarine.com/webapp/wcs...classNum=10297 ).

Best wishes,
J_P

[simonbaker]

My information is derived from a lot of years dealing with chemists who formulate paint and corrosion resistant coatings. The people who taught me also have a broad background in chemistry focused on resins that range from the epoxies to alkyds used to make paints. I also studied the resins and adhesives used for boat-building. In my case, I had to know the answers and I had to be right the first time, because my livelihood depended on it. So I read as much as I could to try to be smarter than the chemists. (I probably wasn't successful at becoming as smart as them, but I learned a lot of stuff that is only useful to painters, boat-builders and coil builders).

There are real books that you can read to see all the things I talked about. But the answers are all scattered in small fragments buried in tons of technical publications. Where I really learned is by calling chemists who actually work for paint and adhesive companies. You will be surprised how much you can learn by calling Dow chemical, or DuPont and asking for an engineer to help with an application you want to develop. They have full-time engineers on staff just for that purpose who are anxious to answer all your questions, as this helps them to prove they must remain on the payroll. I also learned a wealth of information from calling and talking to chemists who are in charge of formulating products for small companies. These guys sometimes know stuff that the big companies haven't figured out yet, because they tried their own experiments to solve problems the big companies haven't thought of.

The difference between white and yellow glue -- I don't know about the shrinkage. I suspect they are about the same. I know the yellow is stronger because I have used it for years. I also know the white glue will dissolve if you keep it wet long enough. As best I can remember, I think the yellow glue can also dissolve if it is wet long enough, but it was a lot more resistant to moisture than the white glue. The aliphatic resins are probably responsible for the better resistance to moisture.


p.s. If you are going to start with fiberglass resin (polyester resin), look for the kind called "casting resin", not the kind called "gel-coat". The casting resin is pure polyester without additives. Better is to use an epoxy like Gougeon Brothers epoxy (http://www.westmarine.com/webapp/wcs...classNum=10297 ).

Best wishes,
J_P

Thanks again! Sounds like you should be writing that book...

I remember now my interest in white glue for binding coils -- I'm so cheap, I figured if the coil was no good, I could soak it and recover the wire... that's uber-cheap (ober-cheap?)!


-SB

[Rov]

Whats wrong with PVA white glues,seems you dont know how to use it for purpose?procratinate about this or that properties? Have you used it at all?
Tradespeople use this successfully for very broad range of use in Industry an other.
Clamp and bind your product an let it set appropriately,No Brainer!
Cheers!

[simonbaker]

Whats wrong with PVA white glues,seems you dont know how to use it for purpose?procratinate about this or that properties? Have you used it at all?
Tradespeople use this successfully for very broad range of use in Industry an other.
Clamp and bind your product an let it set appropriately,No Brainer!
Cheers!

I tried it and it seemed my coil changed properties, like it got weaker somehow. But I don't believe it really, that's why need other opinions.

Also, white glue seemed to shrink more and more over a year, but I was not using it like a carpenter in small joint -- I poured it under and over coil to contact glue it to wood disk. It does not seem so good for that -- probably need glue that has more "bulk".

Gorilla Glue is supposed to expand -- interesting idea, but might move null around, maybe not. But much more expensive than white glue.

I think there should be a way to use white glue, so not giving up completely.

Regards,

-SB

[IBGold]

You need to get all the moisture out with PVA other wise you get problems so I now I use circuit board spray and it works a treat for what I do.
Regards, Ian.

[guiseppi]

PCB spray is probably acrylic lacquer.

I've just used some urea formaldehyde (Rhino resin, one shot resin, cascamite, polymite are trade names) which is a waterproof resin which is very easily mixed with only water.

I did not use it in the coils, however, but to secure the finished coils in the head. I mixed 1 part resin, 1 part unperfumed talc and enough water to make it not too wet. Cures in a few hours to a soft plastic, which means a little adjustment can still be made, then by the next day is a very tough plastic.

If using epoxy, look for filler materials, like fibreglass strands or microballoons.
The microballoons I'd recommend to use in heads if you want it lighter or even just to save on using lots of expensive resin.

[simonbaker]

PCB spray is probably acrylic lacquer.

I've just used some urea formaldehyde (Rhino resin, one shot resin, cascamite, polymite are trade names) which is a waterproof resin which is very easily mixed with only water.

I did not use it in the coils, however, but to secure the finished coils in the head. I mixed 1 part resin, 1 part unperfumed talc and enough water to make it not too wet. Cures in a few hours to a soft plastic, which means a little adjustment can still be made, then by the next day is a very tough plastic.

If using epoxy, look for filler materials, like fibreglass strands or microballoons.
The microballoons I'd recommend to use in heads if you want it lighter or even just to save on using lots of expensive resin.

Interesting ideas, thanks! Microballoons for light weight, and "putty" for adjusting. Is it fairly non-toxic?

-SB

[der_fisherman]

Simon,

I can give it a try just to see if I have the same experience with coils becoming less effective. The only drawback I would see would be shrinkage, setting time and maybe conductive. For me, hot glue seems to be a quick way to set coils in shells first, but it must be from a HOT glue gun as some are low or medium heat and don't stick too well.

I can see the concern for epoxy as it's not the most people friendly stuff. I have used it but only under an exhaust hood or outside as I have heard horror stories about people suddenly developing bad allergic reactions. Not to mention, it's impossible to clean up off the wife's carpet!

While epoxy is still wet, denatured alcohol or meths will remove it, as well as cleaning your hands.......it works still when its just getting sticky, but once hard, no chance.

regards

Andy

[simonbaker]

While epoxy is still wet, denatured alcohol or meths will remove it, as well as cleaning your hands.......it works still when its just getting sticky, but once hard, no chance.

regards

Andy

Good tip, thanks.

[Rumcajs]

This would require risking a coil, but I'd like to know the answer.

Is water-based glue bad for gluing/binding a coil?

I used it once and it seemed like the coil was less effective after gluing -- but I don't trust my setup. Many other things could have gone wrong also.

I would like to confirm whether this is a myth or not.

Ultimately I'd like to find techniques that avoid harsh chemicals to work with if possible. Lacquers, varnishes, urathanes, etc. give off fairly powerful chemicals. I'm still planning to use resin for potting/housing the coil, but it would be interesting to find some benign substance instead of that too.

-SB

Hi Simon!
Please visit this site: and *mainly* see fig 1.6
http://www.helpwithdiy.com/decoratin...e-sealant.html
or search in the web this kwd: Silicone Sealant

(The silicone sealant available in the all hipermarkets, for example Tesco, OBI, Cora, etc. The sealant gun is good tool for maintaners. In the private world it is extra cost only.
Simple you putting the back cover with bigger screwdriver or hammerhead , etc. The colorless type is used about in the window glass. I think, it is good for you.)

Please *not* use water-based glue for sealing. The Farady-shield is alu-foil (practically kitchen foil) and the connected ground-cable wire is copper.
The corrosion/oxidation is generate serious contact problems. This contact problem is occurs in the good-named industrial heads...

Brg

Rumcajs