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If I break one more piece of plexiglass.....

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Excretious:
My Cp is 47" x 23"......... i didnt go for lexan because i woulda had to pay 50 bucks whereas the plexi cost me 12.  

Just chiming in to point out that Lexan is NOT "just a couple bucks more"


And yes, i cracked my first 4'x2' piece of plexi and had to get a second one.  I predrilled all my holes with a 1/8 bit and when i was ready to start using the hole saw........ MY VERY FIRST HOLE in the plexi pulled up and spider webbed.  So what i did was used a drill bit called a 'uni-bit' to open up all my 1/8 holes to about a 1/4" or whatever it was to get the holesaw pilot bit thru.

A unibit is just a drill bit that starts at 1/8 and progressivly works its way up to a 1/2" hole?  





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mccoy178:
Thanks for all the tips.  I had used a pilot bit to start all the holes.  This went fine untill the end.  Maybe I got lax or whatever, anyways, I think I will use the bits in reverse and take my time.  I am using the plexi due to cost and because I am using my own artwork underneath.  My CP is 20x36, so I am using the most economical option.  Also, I wanted to mention that I am also going to use smoked grey 1/4 plexi on the monitor.  From what I have seen, it looks pretty cool.  Thanks again.

RandyT:

Lexan isn't the end to all ends either.

Lexan is softer than Plexi.  It's not as rigid, will loose it's lustre more quickly, and scratch easily.  It also will "yellow" much more quickly than plexi when exposed to UV and it's usually pretty expensive.  But, it will stop a bullet if the piece is thick enough, and it's more likely to bend than break.

Plexi has properties closer to glass.  High optical clarity, good rigidity and fairly inexpensive.  It can be a little tricky to keep from cracking (always drill bolt holes a little oversize to allow for thermal expansion and don't overtighten the bolts.)  It's brittle, but won't shatter into a hundred sharp pieces like glass.  It will break, but you're less likely to get a serious cut on it.

A tip given to me by a "plastics guy" was to use a drill bit with one of the flutes ground off at the tip.  The breaking usually occurs when the bit exits the other side and this supposedly keeps the tip from binding and causing the crack.

YMMV.

RandyT

OSCAR:
I also use plexi instead of lexan for exactly the same reasons that Randy mentioned.  I've used plexi for marquees, bezels, on cp's, etc., and I have yet to ever crack a single piece in the countless times I've cut or made holes in a sheet.

I do stand by the recommendation that a router is the absolute best way to cut plexi.  Well, other than a laser or water jet, but not many of us have that option.  :)

One other suggestion I would have is not to put too much pressure on the plexi when using a drill.  As the hole is being cut, you don't want to force the bit into the plexi faster than the bit is removing the material.  If you do, then you are applying a point pressure that may cause a crack as the material gets thinner right where you are drilling.

With a router the bit removes material so quickly and cleanly, I doubt it is even possible to cause plexi to crack.  When doing button holes, I use a template bit (the kind with the bearing on the top side of the cutter head) and clamp the plexi to the underside of the wood control panel.  Then I plunge directly though the plexi with the router bit (no pilot holes with a drill) and use the control panel as the template.  Some pics of this method can be seen at: http://www.oscarcontrols.com/sinistar.

Xiaou2:
 Plexi wasnt just used for conversions.  In a
Namco ran arcade, all the games got plexi on
them... new and old.  

 Plexi does keep hand oils and sticky crud from
messing up the artwork.  Its easier to clean the
smooth flat surface rather than a bumpy
overlay.  Keeps sharp  objects from scraping
artwork.  Keeps art overlay from lifting due to
glue wearing out - inflexibility - and
enviornmental changes.  Protects art from
fading from UV rays.

 Cutting plexi is tricky.. but not that bad.

  The biggest troubles arise if you do not
clamp the material.  Any vibrations will cause
the fractures.

 1) Keep plexi covering on till your finished - else
it will  scratch while your woring on it.

 2) Clamp plexi to the control panel.  Use a soft
clamp, or pop something like a folder rag in the
jaws to avoid scratches from the clamps.

 3) Drill using a drill guide to reduce vibrations..
or better - use a drill  press.   Trying to freehand
drill will most likely result in cracking as even a
small kick or varience in your cutting angle will
cause a crack.

4) Bit selection:
   a) Fostner bit = cleanest smoothest cuts!
      but most expensive bits.  A little slow to cut

   b) Spade Bit - very fast cutting, nice holes.  
        Need drillguide or press to use well.
        Cheapest bits. (buying a full set is usually less
        costly overall, and nice to have all the sizes)

    c) Holesaw - med speed holes.  Have to unclog the
        bit each holes. A little rough.  Get a dedicated bit
        rather than a multi head  interchangable one as
        they arnt very durrbale, will break fast.  bi-metal
        will cut thru all: metal, wood, plexi.  Good bits are
           fairly costly, but will last a long time.

     d) Circle cutter - a little tricky to use..  needs a drill
         press to use.  Good for obscenely large holes.

*** Drill tips:

Drill at HIGHEST speed setting - BUT - drill
down as SLOW as possible.  Letting the
speed of the drill heat the plexi to the point
of making it melt slightly so that it will not
crack.   Some drill in reverse - but thats not
nessessary... and still can cause a crack if you
drill too fast downwards.  A drill hole that
would take about 1 second in a harder
material,  would take about 10 or more
seconds to avoid cracks.

 5)  Drill a hole that will be for a bolt that
      will hold the plexi to the panel.   Once that
      is drilled, pop the bolt in and lightly tighten it.  
      Do each of the corners one at a time this way.  
     This will help to keep the the material in place
      and might even choose to remove the clamps
      afterwords

  6) Drill the Plexi and the control panel hole at
      the same time to reduce problems with
      wandering (where plexi holes and wood holes
      dont line up well).   OR

  6b) Drill a the panel from the bottom, but,  
        must add another piece of wood to the
        bottom & clamp that as well (making a
        plexi sandwhich).   OR

   6c) Drill pilot holes,  then use a router to
         cut the rest - following the edges.   I use
         a 1/4" rotozip bit for good results... hadnt
         tried a standard bit.
 
   7) Smooth edges of holes by lightly hand
        sanding them with a high grit paper.

 Cutting Edges:

   Routers will work great for this.

   I have cut plexi with a tablesaw tho - and it
does work...  but its messy and chips the edges
a bit.   It may have been better if I had tried to
sandwhich the plexi in between wood before
the cut - but didnt think about that at the time.

  Scoring does work as well.   Clamp a straight
edge to the plexi, then run razorblade across
the edge into the plexi.  you will need to repeat
this several times.  After getting fairly deep into
the material... you may then try to break the
parts appart.  Make sure to clamp the halves
tightly so that one of the edges is overhung
over a table edge or simular.

 Scoring may still need a good deal of sanding
and maybe some shapeing.  I recomend
practicing this a few times before the actual
piece.

   
 

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