Pneumatic Diaphragm Stretcher Performance

[maxro]

Vitalstates, your website just made my web browser (Safari) conk-out due to Java overload. Perhaps you could have a home page without all the animations.

Sorry about the OT post.

Neat stretcher and website, by the way, I_Forgot. I will definately try this method when/if I build some ESLs. I have a nearly endless supply of inner tubes, as I work at a bike shop.

Max

[I_Forgot]

Originally posted by Atom66
Hi
What are the dimesions of your stretching table ? I am going to be building one soon to rebuild my ESL63 panels
Thanks
Andrew

It's about 645mm x 440mm. I built it about 18 years ago and it happens to be large enough for the Quad ESL-63 drivers so I continue to use it. If I were building one specifically to rebuild ESL-63 drivers I would make the dimensions proportional to those of the driver. Make the perimeter of the table a bit larger than the circumference of of a bike wheel so that the tube has to stretch over the table to fit.

Originally posted by vitalstates
Hi Mark

I didn't realise you were I_F. I must repeat what Sheldon says: many thanks for the inspiration back in the day.

Back on topic, how does the tube stretcher compare with the more mundane tape and spring method??

Regards

Ed

I have never tried that technique. I hit on the pneumatic stretcher pretty early then moved on to other problems.

Thanks for the kind words. I used to get a lot of email about the site, but the I terminated the email address on the old web page and didn't get around to updating the page so I sort of disappeared for a while. I'll be taking the old pages down soon and leaving a forwarding link to the new stuff. The gmail address should be permanent, unless google starts charging for it. So far posting the address in a graphic has prevented most of the spam bots from getting the address.

Cheers!

I_F

[vitalstates]

Originally posted by maxro
Vitalstates, your website just made my web browser (Safari) conk-out due to Java overload. Perhaps you could have a home page without all the animations.


Max

Hi Maxro

There are only 2 applets on there, but I take your point, I'll reduce it to one....there must be other safari users out there that are suffering.

Regards

Ed

[stokessd]

The spring and tape method is great, I use it all the time now. The requirements are a good flat surface that the tape can stick to. I use a mirror which also helps me see anything on the glass before I put the mylar down.

The method (with props to Rob M. at ER audio who as far as I know invented the brilliant technique) involves a small spring scale, a free Formica sample attached to the spring scale, and a lot of pieces of packing tape.

Start by attaching the 4 corners of the mylar down to secure it to the surface. Then you start at the middle of one side and stick a small piece (say 3" long) of packing tape to the Formica square on the end of the small spring scale with most of it hanging off. You attach the other end to the mylar (say the last 1 inch) being careful to only attach it to the mylar and not the surface next to it. You then pull the scale parallel to the surface perpendicular to the edge of the mylar until the scale reads your desired tension. Then you push the middle of the tape against the surface and in a rotating motion unpeal it from the scale and onto the surface. The next piece is directly opposite the previous piece so the tension is in opposition. Work your way from middle to the both edges, then turn 90 degrees and work the other two sides from middle to edges. It produces remarkably uniform and even tension a couple inches away from the edges.

The downside to this technique is that the tension isn’t as even at the very edges, so you have a bit of waste due to making the mylar piece larger than necessary to use the center part. But I suspect the wastage is pretty similar to inner-tube method. The lowest wastage in my experience is heat shrinking, and is hard to beat for non-tension critical applications. When building my big ESL’s, I was almost forced into heat shrinking due to the width of the mylar vs. the width of the panel I wanted to make.

As a side note, the tape and spring scale method would work great for building curved panels where you ideally only want to tension in one direction.

Sheldon

[vitalstates]

Hi Sheldon

The new website looks great. I say new because its about 4 years since I last visited.

I ought to have said thanks to you for your inspiration as well, better late than never.

Regards

Ed

[stokessd]

Thanks for the kind words

The problem is the content isn't really very new. I've got to get off my butt and build something interesting that is worth putting on the site. I did add a ton of pictures in photo-albums. Nothing too interesting. I'm refurbishing quads and a pair of citation II amps. I've got a set of active 2-way MTM spakers on the drawing board, but I probably won't get to them for a couple more months.


Sheldon