Cutting Mica

[saxymojo]

Hi
Does anyone know the best way to cut mica and where it can be bought uncut? I heard it is usually cut on a lathe, is this right? and how would you hold it to cut it?

Thanks Marcel

[Steve]

I'd like to see a video of someone doing it. I tried it once and I wouldn't ever attempt it again!

[Brad]

Marcel,

I found this link: http://www.imechanica.org/node/2700 which basically suggests laminating the mica between sheets of glass, cutting with a diamond saw, then removing the glass.

Are you try something precision like a repro diaphragm or more general like a panel for a lampshade? If the latter, a tile saw should work fine.

Brad

[estott]

I'd try turning a sharp edge on a piece of pipe of the correct diameter and carefully twisting it into the mica.

[bostonmike1]

Marcel---- p.m. me with the particulars(size ,shape etc) and i will precision machine it in my machine shop or i will make a fixture so you can do it yourself. good to hear from you again. no charge for either way you wish to go. your friend Michael

[gramophoneshane]

I wonder if a laser cutter could be used on mica. They'd be too expensive to buy for home use, but there might be a local TAFE college that could run off a supply of different sizes for you?

[Shane]

Small sheets of mica are available at hardware stores... maybe not Home Depot, but old-style hardware stores. The "normal" use for mica is to use it in the small indicator window of an old style heater. The mica can withstand high temperatures and is see-through, so the user can observe the flame through it. The high temperatures would destroy glass if it were used for this purpose.

I've actually been able to cut mica with a pair of sharp scissors. It works, though the cut isn't as "clean" as it would be in ordering a diaphragm from a phono supply place.

One word of caution: my experience with making my own diaphragms has yielded reduced volume versus pre-made diaphragms.

[RJSoftware]

A grinding stone works well for these kinds of cuts. Cut near with the sizzors and then fine tune with the grinding wheel. A dremel grinder should work well.

RJ

[larryh]

I always have some small sheets of mica on hand for oil stove chimneys. Not a common site any longer. I have always cut it with a small scissors that is very sharp. It cuts it pretty easily and well, but as mentioned it will splinter a bit along the edges as mica is want to do under stress. As to being quieter it is no doubt due to the fact that most of the packaged stove mica as found in hardware stores is split to a thiner size than the original phonograph ones were. I haven't make one in years that way, but I don't recall the results being too bad, but I would say an old original would be best.
If your read your old Victor literature they always suggested you have your mica replaced every six months or so by your dealer. I have a feeling it was a totally unnecessary process mostly designed to provide business for the dealers. As long as the mica is not damaged in anyway the results should be the same now or 50 years ago. Most of my excellent sounding machines have very old diaphragms and they are as clear as the day they were made.

[PhonoJack]

Gentlemen,

If you're thinking about cutting mica for personal use in a reproducer, I wouldn't go through the trouble. You want the correct thickness. There are at least a dozen sizes (diameters) of mica diaphgrams too. You can buy a complete kit: machine cut mica, gasket material, (you specify what type of reproducer), gaskets (correct size). Some dealers even throw in a piece of bees wax. You can get this (in the US) for less $10-12 including shipping.

For the small price, you can also help by doing business with one of the dealers who support our hobby. Dealer expertise at no extra charge too!

PhonoJack