Insulated vs. bare metal stators

[moray james]

you chould be able to find it in powder coating as well as liquid form. The real clai to fame in the ESL field for nylon 66 is that it has the least amount of creap away from sharp edges of just about any of the useful coatings. This means that you achieve the highest built of coating at the edges where corona will also be the highest and os the best dielectric by default. I matters little if you use a stronger dielectric material if you cannot achieve sufficient build at the edges. This is a primary issue with perforated stators rather than with wire stators.

[Few]

Thanks for the responses guys. Moray: My nylon inquiries were made in the context of magnet wire so I won't need to worry about powder coating performance etc. Thanks, Calvin, for the reassurance; the relative similarity between the resistivity and dielectric constants of pvc and nylon were what I had mind when I suggested that readily available nylon coated magnet wire might be a reasonable substitute for pvc coated hook-up wire. I'm still a little concerned about the hygroscopic nature of nylon, since I really want to get away from performance that varies with the weather, but perhaps it's not as big an issue as humidity dependent diaphragm coatings. Anyone have any thoughts on that? And then there's the other issue of finding an adhesive to hold the nylon onto my crossbraces, which at the moment I'm intending to make out of black garolite XX (paper-based phenolic).

[Mike Beck]

Henkel Loctite 444 should do a good job bonding the nylon to garolite. You can contact the applications engineer for Henkel loctite in your area and he will send you a sample along with the Prism primer. Put the 444 on the garolite and the primer on your wires, then place together until set.

[moray james]

make sure that you have a constant draw of air away from the work area venting outside when you use any kind of krazy glue. It does krazy stuff to your body and health. Personally I used these types of adhesives industrally for several years plus with a chemistry lab fume cupboard and still I had issues. I would not use this stuff to build with. You are on your own to do so if you will. I would investigate options. Having the actual bonding done at a pro shop would be safe for you and them if they are equipped to work with toxic solvents. Worth considering in my opinion. It took me years to deal with the health issues caused by such adhesives. Good luck.

[Few]

Thanks both for the adhesive suggestions and for the warnings. I have a fume hood in my lab, but unfortunately the hood's not long enough to accommodate 6' stators. Maybe I could do one half at a time. On the other hand, at the pathetic rate this project has been moving, by the time I'm ready to glue it may be warm enough to do it outside--even in Maine.

[Mike Beck]

Moray is right about the fumes. I just haven't found too many options for adhesives that will stick to thermoplastics. You might try a polyurethane glue (like Gorilla) but these foam and are messy. Good luck.

[Few]

A brief update on my wire stator construction journey: In my search for an adhesive to bond nylon coated magnet wire to garolite XX (paper based phenolic) on a whim I tried the crappy hot melt glue that's sold in craft stores. I laid some 22 gauge magnet wire across a strip of garolite, and then put a dab of hot melt glue across about 3/4" of the wire. To my surprise, when I pulled the wire to see how much tension the bond could withstand, the wire broke before the hot melt glue let go. That happened three times, so it wasn't just a single weak spot in the wire. I tried the same experiment with some steel filled epoxy and the epoxy/nylon joint let go. I wish I knew more about the type of hot melt glue I have, but it seems to work surprisingly well.

I was concerned that it might be hard to make a nice clean bead of hot melt glue over the wires in a stator, and that excess glue would intrude into the gap between the wires and the diaphragm. I found, though, that after the glue has been applied and allowed to cool, a heat gun can be used to remelt and "reflow" the glue in order to pretty up the joint a bit.

I haven't tried the technique on a full test panel yet (that's next), but I was so surprised that it showed any promise at all I thought I'd post my prelinary results. The hot melt glue certainly beats out some of the alternatives in terms of quantity of fumes generated.

Few