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Old 30th January 2010, 02:08 AM   #1
Few is offline Few  United States
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Default Attaching ESL spacers to stators?

Hello fellow diy-ESL enthusiasts. I'm finally getting close to the point where I will put my stretched magnet wire stators together with some spacers and a diaphragm. I'd like to build on your experiences if you're willing to share them.

My previous experience is with perforated steel stators and double-side 3M foam tape as spacers so I'm entering new territory. I'd like to find a way to make it possible to take apart a panel without the sort of hell I went through with my previous foam tape and steel stators. Here's the situation: My stator frames are made of Garolite (phenolic from McMaster-Carr). I have polypropylene sheets with 1 mm and 2 mm thickness to try as spacers, and an inner tube-based diaphragm stretcher. I'd like to be able to glue the spacers to the diaphragm but because I'm not sure which thickness of spacer will work best, I want to have a convenient way to remove the spacers from the stators without struggling to undo glue joints. Has anyone come up with a creative way to accomplish this? Do most people glue the spacers to the stators as well gluing the spacers to the diaphragm, or is there a good way to make the spacer/stator frame joint less permanent?

Thanks in advance.
Few
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Old 30th January 2010, 02:23 AM   #2
mavric is offline mavric  United States
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ask CharlieM, he is very well educated about that question. He is teaching and coaching me as well. Roger Sanders book makes alot of sence, however, some of the data is outdated, that is why i am trying a different material for esl panels.as far as spacers, try to send Charlie a message, he is very helpful. that is my recomendation for your post. I have listened to his personal stats, impresive, very much so.
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Old 30th January 2010, 02:47 AM   #3
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I'm afraid I don't have any good ideas on this one, Mavric. I'm with Few on this one... looking for a better way.

I shorted a panel once and had to take it apart. It was nightmare: The foam tape pulled the coating off my stators and I had to strip and redo both of them and it took days to get all the paint out of the holes, which is why I wouldn't combine painted stators and foam tape spacers again if I could find a better way.

The most innovative method I've seen is JonasKarud's magnetic strip spacers, which may not lend itself as well to wire stators as it did with Jonas' perf stators but I would seriously consider magnetic strip spacers.
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Old 30th January 2010, 03:07 AM   #4
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I wouldn't combine painted stators and foam tape spacers again if I could find a better way.
Having said that, if you did use double sided foam tape, you only need to stick the diaphragm to one stator with the tape--- you would not need to bond the two stators together along the edges with tape, as is usually done. Rather, you could configure your speaker frame to hold the stators in contact without having them bonded with tape. For the internal foam-tape-support spacers, however, you would probably still need to have them bonded to both stators and both stators to he diaphragm. Still, if you used dots or narrow strips for the spacers, it would be far easier to pull the stators apart than if they were bonded at the edges also.

Few, I've been following your wire-stator threads... can't wait to see the results!
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Old 30th January 2010, 01:28 PM   #5
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I still like JonasKarud's magnet spacers the best but if that doesn't work for you, I had another thought.

I haven't seen your wire stators but I assume they consist of a periphery frame with some horizontal wire supports added. I also assume your diaphragm/stator spacing will be at least 1/16". If so, here's an idea:

-Use 1/16" plastic or fiberglass strips for your spacers and make them as wide as your frame will accommodate.

-Temporarily clamp or tape spacers frame, then drill & countersink through spacers and frame every 2" along outer perimeter. Holes to be minimum diameter to accept an 8-32 or 10-32 screw.

-If you frame is thick enough to allow it, counterbore the opposite side so that the screw nuts could likewise be flush or below the surface. If your frame is not thick enough for this, you could actually drill smaller holes and tap-thread the holes to match the screw threads and omit the nuts. (I believe you can tap phenolic but I haven't tried it)

-Attach spacers to frame using countersunk-head nylon screws. Ensure that screw heads sit flush to the surface.

-Apply a thin grade of high-bond strength double-back adhesive tape to the spacers. There are suitable non-foam type tapes available under .010 thick that you could use with the 1/16 spacers and keep the d/s near where you want it.

-Across the horizontal wire supports, apply the same thickness of double back adhesive tape, then a 1/16" thick foam rubber strip. These will serve as the internal spacers and diaphragm supports. The foam rubber spacers have no adhesive on the diaphragm side so they will not stick to the diaphragm (they don't need to) but, since you have a ridged support bar backing it up, the foam strip will contact and support the diaphragm as intended.

-Apply the diaphragm to the stator the same as you would with perf metal & tape.

-On the opposite stator, apply similar spacers except place the tape under the spacers (only) to secure them to the frame (no screws). If using a copper foil charge ring, apply it to spacers on this stator.

-Configure a periphery frame to align and clamp stators together without tape.

* Now, let's say in the future you have to replace a diaphragm. Since the stators aren't bonded, they separate when you unclamp them. Now, you can remove the diaphragm as follows:

-If you used nuts to secure the diaphragm/spacers to the stator, remove the nuts to remove the spacers/diaphragm.

-If you tapped the stator and screwed the diaphragm/spacers to the frame, cut away material at screw locations, then remove the screws to remove the spacers/diaphragm.

Hey, it's a thought.... good luck with your project!
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Old 30th January 2010, 03:07 PM   #6
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You can try how I did mine.

Click the image to open in full size.
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Old 30th January 2010, 04:43 PM   #7
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Quote:
Originally Posted by chinsettawong View Post
You can try how I did mine.
Hey, chinsettawng's setup looks very nice, Few. Looks like you got some ideas coming in...
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Old 30th January 2010, 07:23 PM   #8
bentl is offline bentl  Norway
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Hi, if you can drill through both stators and spacers when they are aligned - there are pop-rivets and bolts in various sizes made of nylon!

RS Componens sells rivets of the following brands: RS, Heyco and Richo
Nylon bolts/nuts brands: Heyco, Keystone, Richco RS

RS | Mechanical Components | Fasteners and Fixings | Machine Screws | Metric Thread - Nylon 6.6

Regards

Bent
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Old 31st January 2010, 02:15 AM   #9
Few is offline Few  United States
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Thanks, all, for some great ideas. I've been working on an alternative idea and drawing up some sketches, but didn't want to let the helpful posts go unacknowledged.

Charlie: I'm still processing some of your suggestions. Some are similar to ideas I was wrestling with but I hadn't considered the nylon screws so I'll have to look into the dimensions and see how that might pan out. Thanks very much for the food for thought.

Bent: I have to admit I had no idea there were nylon rivets. Very interesting. I'll have to check those out.

Mavric: The Sanders book can be very helpful (I learned a lot from it) but it also has a few basic science errors so be careful. The rules of thumb are useful. The explanations of Helmholtz resonators are out to lunch, in my opinion.

chinsettawong: Beautiful, but somehow the "picture is worth a thousand words" phrase doesn't apply here. I'm not sure I can tell from your photo how you put things together. Can you elaborate? Looks great!

I'm playing with an idea that might blend JonasKarud's very elegant idea with some of the other suggestions posted here. I'd love to be able to tighten a floppy diaphragm without having to start over, and may have a way to do that. I'm not yet sure whether my idea will gain any traction but I'll post a sketch once I finish it off. Thanks again for the very helpful responses.

Few
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Old 31st January 2010, 08:40 AM   #10
Calvin is offline Calvin  Germany
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Hi,

made my very first stators detachable by use of nylon screws.
Well I quickly abandoned that approach because it was too much work for the sluggard son of my mumīs
Few, from Your description I assume that You are talking about a wire stator.
I used 1,2" wide pvc as frame and glued the diaphragm withdouble sided carpet tape (similar to the glue formula the TESA brand works excellently).
While this held the membrane tension secure over years, it allowed to rip off the membrane and tape from the pvc. Cleaning the pvc with acetone and the frame was ready for a new diaphragm to be installed. The tape needs some time to develop its full glue bond strength. So if You finish the panel within say 2 days, its very easy to remove the tape.
I always coated the diaphragm instantely after glueing and tested the single stator, then pressed both stators together with clamps, tested again and finished the panel or installed a new membrane.
The answer to Your Q which spacer works best is easy: Its always the thinner one!

jauu
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