Replies

1. 
   dwolsten | Jul 18, 2006 02:02am | #1

   I'm working on a Prairie-style lamp which I'm going to put mica shades in as well. Are you sure of your measurement? 25mm = 1 inch. All the lampshade mica I've looked at on the net is probably less than 1/10 of that thickness. It's basically mica flakes bound with shellac, which gives it the amber tone.

   I haven't gotten my mica yet, but from what I've read, it's easy to cut with a scroll saw or coping saw. I'll probably try a simple hacksaw or similar as mine will only have straight lines. It should be fairly lightweight, so I plan to just use hot-melt glue to hold it in the rabbetted frames.

   I'll probably get mine from Woodworker's Supply; one sheet costs about $25 there.

1. 
   non trad stu | Jul 18, 2006 04:28pm | #2

   Oops! I meant to say 25 thou ! I obtained my mica here in western NC at  Tar Heel Mica Co. Plumtree NC, whom I just found (I don't have their phone number but can get it if you wish).  Anyway, they manufacture amber colored mica in 3' square sheets (will cut them down) in 5 thou increments starting at 5 thou. Cost for 25 thou 3' sq sheet was $29.  Interestingly they charge by the pound. I did look at Woodworkers Supply but their 18" X 36" involves a  $10 shipping surcharge.  I just received 2 X 18" sq sheets I ordered from Amazon.com at a cost of $42 total plus shipping!  So  the NC folks are decidely cheaper but I don't know their shippiing costs.

   Tar Heel told me NOT to  use a toothed blade of any kind to cut mica, it frays the edges they say.  They use a large version of a paper guillotine but that's impractical for me. I hope all this helps.

1. 
   dwolsten | Jul 18, 2006 09:43pm | #3

   I wonder exactly how much it frays the edges. I'm going to be mounting mine in rabbetted frames, so the very edges won't be visible anyway. Is the stuff too thick for scissors? Or how about scoring with a box cutter? Just some ideas.

1. 
   non trad stu | Jul 18, 2006 11:36pm | #4

   I don't know but will experiment.  Turns out the the woodworking dept at the college I'm attending (I'm a seventy year old woodworking student) has a 36" paper cutter and it works fine.  However, I take your point and since I'm going to use a similiar approach perhaps I'm fussing too much.  Talked to the instructor about glue and he really didn't have any ideas.  Shellac does not take glue well at all he says but thought super glue or such might work.

1. 
   jazzdogg | Jul 25, 2006 06:37am | #9

   If the edges will be held in a rabbet and you still need a little adhesive to secure your mica, how about a few dabs of silicon adhesive? It grips tenaciously, remains flexible, and should help prevent rattling.

    -Jazzdogg-

   "Don't ask yourself what the world needs. Ask yourself what makes you come alive, and go do that, because what the world needs is people who have come alive." Gil Bailie

2. 
   non trad stu | Jul 25, 2006 02:12am | #6

   After some experimenting here's what I've come up with re cutting mica.  The box knife or exacto knife did not work well at all despite repeated scoring.  It was tedious to get the mica cut all the way through and even then not all the way along the line, bending to sever the  balance just resulted in very ragged and torn edges.

   The 30" paper cutter worked very well resulting in clean straight edges but needing some effort to shear al the way.  Care had to be taken in positioning the mica as close to the pivot point as possible.

   Best of all was running the mica over the table saw!  To do this I made a smal sled such as one would use for veneer cutting.  That is, it's a piece of hardboard with small wooden fences fore and aft with one runner to engage in the left hand mtre gauge slot.  After a cut is made with the blade (I used both a fine kerf and a plywodd blade both gave excellent results) I raised the blade baely enough above the sled to cut the mica.  I then ran it with a hold down piece of wood over the cut line.  Quite safe if the hold down is wide and thick enough.  Gave very clean edges.

   Have yet to resolve the glue problem.  Hope this helps.

1. 
   dwolsten | Jul 25, 2006 02:26am | #7

   This is some great info. I'm a little confused by the sled thing, however: is there some reason the mica can't just be cut as-is right on the saw, without a sled? Also, is this hold-down a piece of wood clamped down right at the line of the cut, or am I misunderstanding?Thanks again!

2. 
   non trad stu | Jul 26, 2006 02:03am | #11

   I must admit I did'nt try that and perhaps should.  My instructor's opinion is that at 25 thou the mica could slip under the table saw fence unless it is really flat to and in contact with the table along it's length.  Also at this thickness there will be cosiderable vibration unless held down, best done in a sled.

   The sled is a mini version of a cross cut sled.

    

3. 
   dwolsten | Jul 26, 2006 02:40am | #12

   Oh I see. Sounds like a good idea then. I'll have to try this when I get my mica.

4. 
   non trad stu | Jul 27, 2006 01:33am | #16

   And Rennie: Latest on mica cutting.  Bandsaw with 1/2" blade left flacky edges as did (slightly less so) a smaller bandsaw with 1/8" blade.  Neither would pose a problem in covering with wood trim > 1/8" wide.  Cutting straight is a different issue (at least for me) seems to wander more than wood. 

   To my (and my instructor's ) surprise I was able, with an auxillary wood fence clamped to the table saw fence and flush to the table, cut the 36" sq pieces into workable strips.  I noted some "blooming" at the cut and can only guess that it was the friction causing heat and some seperation .  I discovered that if I quickly rolled the edges any flaking rebonded. Still think the sled with hold down gives the best cut.  Am told that carbide is harder than silica and thus the blade of choice.

   Finally, I've been told that "original" contact cement will bond the mica to wood or metal.  Unless I discover something really startling I will not bog you down with more minuetia. 

5. 
   John_D | Jul 27, 2006 08:48am | #17

   I can't recall if you've tried cutting it inside a "sandwich" of sacrificial wood?My goal is for my work to outlast me.  Expect my joinery to get simpler as time goes by.

6. 
   non trad stu | Jul 29, 2006 01:29am | #19

   No I haven't. Time ran out on me but I would be concerned about following the dsired cut line.  How did you do this?

7. 
   cadiddlehopper | Jul 25, 2006 03:16am | #8

   And dwolsten: Brady & Clauser's Materials Handbook says that mica comprises a group of silicate minerals. I think that means it is rough on saw blades. Carbide tips are probably advised. While clamped in your holddown, you might be able to clean the edge a bit with silicon carbide sandpaper. Mica's crystalline structure may cause a rough edge no matter how you cut or sand it. Materials Handbook has 4 pages on mica for the curious.Cadiddlehopper

8. 
   Rennie | Jul 25, 2006 03:29pm | #10

   Has anyone tried a band saw? Seems that a fine tooth blade, or sandwiching the mica between two pieces of hard board, should yield a clean edge.Regard it as just as desirable to build a chicken house as to build a cathedral. Frank Lloyd Wright

2. 
   BruceS | Jul 19, 2006 12:37am | #5

   Check out http://www.micalight.com  Very interesting and informative and they have the answers you are looking for.  I have just  found another medium to make some of my projects a little more interesting thanks to you.  Thanks !

   Work Safe,  Count to 10 when your done for the day !!

   Bruce S. 

    

3. 
   Steinmetz | Jul 26, 2006 04:35am | #13

   How about a tile setter's hand operated 'sled' with a carbide or diamond stylus?

   For curved work. you might buy a set of miniature diamond wheels to fit a Dremel Motor Tool the wheels fit standard 1/8 "
   arbors and come very thin and dime sized up to 1-5/8" in diameter
   Steinmetz.
   Another thought : a glass cutter with a carbide wheel ??

1. 
   QCInspector | Jul 26, 2006 11:43am | #14

   Have you thought of trying tin snips?

1. 
   non trad stu | Jul 27, 2006 01:06am | #15

   No, but I will.  Also see my repy to DWolsten re more info

   Edited 7/26/2006 6:07 pm ET by non trad stu

4. 
   Handrubbed | Jul 28, 2006 10:29pm | #18

   I haven't read the whole thread but I can share my experience with you, having made several mica lamp shades.  All of the edges that I have cut have been straight edges, so I can't help you with radiused cuts.  I ended up using my Forrest WWII thin kerf tablesaw blade with a zero clearance fence facing to prevent the sheet from slipping under the fence.  I got very smooth cuts with minimal flaking of the mica.

   My shades all had oak frames and I used clear silicone caulk to glue the mica in.  Silicone is heat resistant,  and that of course is a factor in lamp shades.  The result was a virtually invisible bond that has not failed over several years of bumps and dust rags.

   Do be careful about getting the shade too close to light bulbs, as the mica will bubble and distort.

   ---

   Edited 7/28/2006 6:32 pm ET by Handrubbed

   
   

   ---

   Edited 7/28/2006 6:35 pm ET by Handrubbed

1. 
   non trad stu | Jul 29, 2006 01:37am | #20

   Thank you for the info.  In an earlier post I recounted using a thin kerf blade with a sled very successfully and you're the scond person to reccomend silicon so I'll have to try that.  Tx again.

1. 
   Handrubbed | Jul 29, 2006 05:31pm | #21

   No prob...the sled is a great idea.  Here a couple of other ideas for arts and crafts style lamps that I have found makes a difference:

   I sprayed all of the metal lamp parts such as the bulb socket with Rustoleum bronze metallic paint.  I looks like old brass now.

   Use cloth covered lamp cord for the wiring.  You will have to order this probably unless you have a really good lamp store in your area.

   The above really enhance the vintage look of the lamp.  If I knew how to post pictures, I would post some here.

   One idea that I tried but rejected was copper appliques over the mica.  The patinated copper turned out great, but I wasn't sold on how it looked on the shade.