Yes, it's an excellent material for many projects. It is crack
resistant, far more so than acrylic, but it can and will crack under
extreme stress, especially when cold. It is less stiff than acrylic,
seems less stable dimensionally, and is soft enough to scratch easily.
Maintaining a nice surface finish, especially clear and transparent, can
be difficult. Commercial glazings have some kind of scratch resistant
coating, but they still scratch far more easily than acrylic.
Poylcarbonate can be abrasive polished, but with more difficulty than acrylic.

Like all materials, it has it's virtues and problems.

Dan Mitchell
==========

jim rozen wrote:

In article , Doug Goncz says...

Very nice material, once fabricated it is indestructible. It doesn't crack when
the drill bit goes through the way acrylic does either, and generates long tap
chips as opposed to acrylic dust.

It's polycarbonate IIRC.

Nice to see you here again Doug.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

I figured half a page of map printout is 5 1/2 x 4 1/4 inches, so I added 3/8
inch on all four sides and came up with 6 1/4 x 5 for the Lexan blank.

I had about a 16 x 20 sheet so I clamped a bar across the stock at the four
inch mark and set to the usual v grooving with the back point of a sharp craft
knife. No joy. So I deepened the score with three passes with the point of the
knife. The bar was right at the edge of my 1/2 inch thick overhanging bench, so
I leaned on it an it snapped cleanly. Then I did the same for two six inch
piece from the four inch width.

I drilled and reamed four 1/4 inch holes for my 3/16 inch jig saw blade for a
square tab on the back panel, but didn't saw or bend it.

I test drilled a scrap #25 and tapped 10-24 threads. Nice material, plenty of
elongation, but clean yield to failure, good tight threads. You use coarse
threads in plastic because the material is so much weaker than the fastener.

I marked everything out with a carpenter's square and Sharpie fine point, and
used the automatic center punch in 14 places, five down each side, and four
along the bottom, more to the outside than totally evenly spaced, as the
division came out one off. I just marked off 1/2 inch increments and picked
every other mark from the outside.

Then I laminated the parts together with double sided Scotch tape, taking care
now to keep it clean, and faced the bench with paper. I drilled 14 places #25
through both parts, and should have held the edges together with pliers. I
separated them and tapped 14 places.

I jigsawed the tab, bent it out by hand (one inch is about as much as I can
handle with my thumb braced), and using the relieved corners to concentrate the
stress, the tab bent out square and flat. Then I marked it and made a mistake,
not thinking ahead, used the drill as a side mill to move the hole, and taper
reamed for the strange 7mm bolts with 5mm button heads. Who ever heard of that?

I loosened the handlebar cap and added the map holder with its 14 screws in
place, then I tightened the screw on the map holder and carefully tightened the
other screw, as the seats were no longer quite square. I'd checked before to
make sure this would work.

All it needs now is a cork block on the back, since it goes booing, but it can
hold anything from a single page of quarter letter size to a whole travel
booklet with the screws backed out. And you can adjust the screws with a dime!

What fun. Too bad there is no rec.crafts.plasticworking, as there is a
rec.woodworking. Too bad they didn't put rw in the heirarchy as rcw. Oh well.

Very nice material, once fabricated it is indestructible. It doesn't crack when
the drill bit goes through the way acrylic does either, and generates long tap
chips as opposed to acrylic dust.

Next step, take it off and belt sand the sides flush with the screw head line.

All this for the new recumbent, a Lightning Cycle Dynamics Thunderbolt SWB
model with 24-35-51 / 34-28-23-19-16-13-11 even double step gearing. 657%
range, and AC and DC generators coming on line soon. Big ones.

The map holder is for the difficult navigation through Tyson's Corner Center
streets, hills, and traffic, to Paradise on the other side of the Dulles Access
Road, starting at Spring Hill Recreation Center. Paradise is the residential
area called Knox Hill or something, and is multi million dollar homes. The
community rec center is a lake. On the other side of Paradise, with its green
lawns, tall trees, and rolling, winding roads, is Difficult Run Stream Valley
Trail, leading to the little beach on the shores of the Potomac.

Why don't you join me some time? Bring a suit; one you like to take off.

Here's to Sun on Skin, Vitamin D, strong bones, and a good attitude!

Skin cancer be damned. (Until I get some.)

I made it as far as the lake last time and realized I didn't bring enough
calories. Water, I had, but three snack bars just isn't enough. Next time I'm
bringing jerkey, snack bars, and fruit.

I have osteoporosis and green leafy vegetables with yogurt dressing, sun on
skin, and more weight in my backpack as I do my errands each week is part of my
therapy. I also take Caltrate but that's just chalk. Just a little
osteoporosis, around 50% of one standard deviation.

Fighting hard, I remain


Yours,

Doug Goncz ( ftp://users.aol.com/DGoncz/ )

Read about my physics project at NVCC:
http://groups.google.com/groups?q=dgoncz&scoring=d plus
"bicycle", "fluorescent", "inverter", "flywheel", "ultracapacitor", etc.
in the search box

I figured half a page of map printout is 5 1/2 x 4 1/4 inches, so I added
3/8
inch on all four sides and came up with 6 1/4 x 5 for the Lexan blank.

I had about a 16 x 20 sheet so I clamped a bar across the stock at the
four
inch mark and set to the usual v grooving with the back point of a sharp
craft
knife. No joy. So I deepened the score with three passes with the point of
the
knife. The bar was right at the edge of my 1/2 inch thick overhanging
bench, so
I leaned on it an it snapped cleanly. Then I did the same for two six inch
piece from the four inch width.

I actually very surprised that it broke at all by scoring it...it usually
will just bend.

Unless you actually had a piece of plexiglass.

Mike

In article , Doug Goncz says...

Very nice material, once fabricated it is indestructible. It doesn't crack when
the drill bit goes through the way acrylic does either, and generates long tap
chips as opposed to acrylic dust.

It's polycarbonate IIRC.

Nice to see you here again Doug.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

The Davenports writes:

I actually very surprised that it broke at all by scoring it...it usually
will just bend.

Unless you actually had a piece of plexiglass.

Polycarbonate is supposed to only deform, not fracture. But I have cracked
pieces myself such as by violently vibrating them with insufficient
clamping when recipro sawing. It may have something to do with aging.

From: "The Davenports"

I actually very surprised that it broke at all by scoring it...it usually
will just bend.

Unless you actually had a piece of plexiglass.

Mike

No, it was marked Lexan and covered with the original plastic protector.

It snaps when you score it only if the score mark is deep, narrow, fresh, and
therefore has a sharp tip radius. Like cutting glass, you have to set it up,
score, and then work quickly before the stresses you've induced in the plastic
are relieved. Concentration of stress at the score induces fracture.

The high elongation means you really push, storing lots of energy, and the pop
on fracture is near deafening. I wear hearing protection even for my B&D hand
electric drill. Should have had it on then, my ears rang. Like a gun shot.

But it does snap, and cleanly. Saves time and frustration sawing.


Yours,

Doug Goncz ( ftp://users.aol.com/DGoncz/ )

Read about my physics project at NVCC:
http://groups.google.com/groups?q=dgoncz&scoring=d plus
"bicycle", "fluorescent", "inverter", "flywheel", "ultracapacitor", etc.
in the search box

Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael

In article , Doug Goncz says...

All it needs now is a cork block on the back, since it goes booing, but it can
hold anything from a single page of quarter letter size to a whole travel
booklet with the screws backed out. And you can adjust the screws with a dime!

Oh, keep polycarbonate away from organic solvents.

If you want to see why, take a test piece, drill a hole in it,
install a bolt and nut - and use locktite on the nut.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

On Thu, 13 May 2004 07:15:23 -0400, the renowned "Michael Tracy"
wrote:

Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael

The shards can go quite a way. I put them in a plastic bag to snap
CDRs before throwing them out (like shredding documents).


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

SP wrote:
On Thu, 13 May 2004 07:15:23 -0400, the renowned "Michael Tracy"
wrote:

Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael

The shards can go quite a way. I put them in a plastic bag to snap
CDRs before throwing them out (like shredding documents).

It's probably possible to recover most data from a snapped CD.
It will be very hard work, but feasible if it's worth enough.
Like shredding documents.

On Thu, 13 May 2004 21:56:23 GMT, the renowned Ian Stirling
wrote:

SP wrote:
On Thu, 13 May 2004 07:15:23 -0400, the renowned "Michael Tracy"
wrote:

Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael

The shards can go quite a way. I put them in a plastic bag to snap
CDRs before throwing them out (like shredding documents).

It's probably possible to recover most data from a snapped CD.
It will be very hard work, but feasible if it's worth enough.
Like shredding documents.

Yeah, it's crossed my mind, but there is delamination that would
destroy about 1/4 of the data. The rest would be in chunks. Just as
with shredded documents. It's not like I'm trying to protect against
NSA-class enemies, just someone fishing the disk out of the garbage.
If anybody of that class wants my data, I'm sure they have other, more
intrusive, ways of getting it.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Spehro Pefhany wrote in
:

On Thu, 13 May 2004 21:56:23 GMT, the renowned Ian Stirling
wrote:

It's probably possible to recover most data from a snapped CD.
It will be very hard work, but feasible if it's worth enough.
Like shredding documents.

Yeah, it's crossed my mind, but there is delamination that would
destroy about 1/4 of the data. The rest would be in chunks. Just as
with shredded documents. It's not like I'm trying to protect against
NSA-class enemies, just someone fishing the disk out of the garbage.
If anybody of that class wants my data, I'm sure they have other, more
intrusive, ways of getting it.


Best regards,
Spehro Pefhany

best, cheapest way to destroy a cd; stick it in the microwave....

On Thu, 13 May 2004 07:15:23 -0400, "Michael Tracy"
wrote:

Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael

If you plan on mailing a CD to someone, don't label it as such -
postal workers get their jollies snapping them.
Gerry :-)}
London, Canada

SP wrote:

On Thu, 13 May 2004 07:15:23 -0400, the renowned "Michael Tracy"
wrote:


Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael


The shards can go quite a way. I put them in a plastic bag to snap
CDRs before throwing them out (like shredding documents).


Best regards,
Spehro Pefhany
They, the CD's that is cut nicely with a tin snip or lighter version in the normal office. :-)
I do a V cut - and the data is scrambled on the edges as well.
Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

Ian Stirling wrote:

SP wrote:

On Thu, 13 May 2004 07:15:23 -0400, the renowned "Michael Tracy"
wrote:


Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael

The shards can go quite a way. I put them in a plastic bag to snap
CDRs before throwing them out (like shredding documents).


It's probably possible to recover most data from a snapped CD.
It will be very hard work, but feasible if it's worth enough.
Like shredding documents.
I doubt it - as the layer is foil like and lots of it is lost.
Sure - plenty of 'sectors' there - if one can spin it somehow or have
a sitting machine that looks down and frames itself somehow.

Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

"Martin H. Eastburn" wrote:

SP wrote:

On Thu, 13 May 2004 07:15:23 -0400, the renowned "Michael Tracy"
wrote:


Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael


The shards can go quite a way. I put them in a plastic bag to snap
CDRs before throwing them out (like shredding documents).


Best regards,
Spehro Pefhany
They, the CD's that is cut nicely with a tin snip or lighter version in the normal office. :-)
I do a V cut - and the data is scrambled on the edges as well.
Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

microwave!

Martin H. Eastburn wrote:
Ian Stirling wrote:

SP wrote:

On Thu, 13 May 2004 07:15:23 -0400, the renowned "Michael Tracy"
wrote:


Polycarbonate is supposed to only deform, not fracture.

Ever try to break one of those ubiquitous AOL CD's? CDs are all polycarb -
the snap is loud and the energy released is quite impressive for such thin
material.

Michael

The shards can go quite a way. I put them in a plastic bag to snap
CDRs before throwing them out (like shredding documents).


It's probably possible to recover most data from a snapped CD.
It will be very hard work, but feasible if it's worth enough.
Like shredding documents.
I doubt it - as the layer is foil like and lots of it is lost.
Sure - plenty of 'sectors' there - if one can spin it somehow or have
a sitting machine that looks down and frames itself somehow.

I was assuming a scanning machine of some design.
From what I've seen, I think a usable copy of the data may exist
on the layer that's left behind after the foil peels off in some cases.
The foil layer is immediately over the dye, that's coated onto the
CD.