I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike

wrote in message
ps.com...
I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike

I used 1/4" ply. Worked fine.
Lexan "should" work, but plastic can shatter and throw out shrapnel. I
would avoid it.

I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike

I would think it would work but after some use it would scratch up badly.
I'm unsure of its stability with heat. It melts easily.
I use 9mm Baltic Birch (3/8") Plywood. Stable and strong.

Dave



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wrote in news:1156283102.389344.3920
@p79g2000cwp.googlegroups.com:

I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike


Lexans attribute is that it does not scratch as easily as other plastics.
I use 3/8 all the time for jigs. It is used as trays and stuff for
wheelchairs.
1/4 is a little thin for a sled but I think it will work if you are
careful. Chamfer edges, holes and slots; cracks will propagate.

Bill

Lexan shatter? Unless you freeze it, it's less likely to shatter than the
piece of oak you're cutting on the sled you built.

"Toller" wrote in message
...

wrote in message
ps.com...
I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike

I used 1/4" ply. Worked fine.
Lexan "should" work, but plastic can shatter and throw out shrapnel. I
would avoid it.

"CW" wrote in message
news
Lexan shatter? Unless you freeze it, it's less likely to shatter than the
piece of oak you're cutting on the sled you built.


Really? Oak must be pretty shatter prone, because I have seen many of peices
of Lexan or acrylic sheeting shatter. I tried to cut a peice with a CMS
once, wasn't pretty.....

Where can one purchase Lexan and what sizes does it come in?

wrote in message
ps.com...
I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike


1/4" will probably flex too much for a sled

LRod wrote:
On Tue, 22 Aug 2006 22:06:10 -0400, "TBM" wrote:


"CW" wrote in message
news
Lexan shatter? Unless you freeze it, it's less likely to shatter than the
piece of oak you're cutting on the sled you built.


Really? Oak must be pretty shatter prone, because I have seen many of peices
of Lexan or acrylic sheeting shatter. I tried to cut a peice with a CMS
once, wasn't pretty.....

Really? Acrylic yes, but you'd be hard pressed to get Lexan
(polycarbonate--different stuff altogether, I believe) to shatter.
Post pictures if you do. In fact, it's used to make shatter proof
features, even bulletproof in thicker construction.

Yesterday I was milling some parts of 3/8" Lexan sheet. On my metalworking
vertical mill with a regular 2 flute end mill for aluminum. What I can say
Lexan is amazing stuff. Tough, not melting, not brittle, pure pleasure to
work with. 1/4" deep 1" wide single pass cut is very smooth, shavings from
the mill are clean and don't have a slightest sign of melting. Aluminum is
much worth--it DOES melt and sticks to a mill. Regular 6061 alloy
machinability is considered fair. I would give Lexan "Excellent" grade.
Pure pleasure. It would definitely made fantastic jigs. Much better than
oak.

---
************************************************** ****************
* KSI@home KOI8 Net The impossible we do immediately. *
* Las Vegas NV, USA Miracles require 24-hour notice. *
************************************************** ****************

--
Posted via a free Usenet account from http://www.teranews.com

On Tue, 22 Aug 2006 22:06:10 -0400, "TBM" wrote:


"CW" wrote in message
news
Lexan shatter? Unless you freeze it, it's less likely to shatter than the
piece of oak you're cutting on the sled you built.


Really? Oak must be pretty shatter prone, because I have seen many of peices
of Lexan or acrylic sheeting shatter. I tried to cut a peice with a CMS
once, wasn't pretty.....

Really? Acrylic yes, but you'd be hard pressed to get Lexan
(polycarbonate--different stuff altogether, I believe) to shatter.
Post pictures if you do. In fact, it's used to make shatter proof
features, even bulletproof in thicker construction.

--
LRod

Master Woodbutcher and seasoned termite

Shamelessly whoring my website since 1999

http://www.woodbutcher.net

Proud participant of rec.woodworking since February, 1997

email addy de-spam-ified due to 1,000 spams per month.
If you can't figure out how to use it, I probably wouldn't
care to correspond with you anyway.

Any plastics place. It's quite common. 4x8 sheets. Thickest I've seen it was
2".

"Tom" wrote in message
m...
Where can one purchase Lexan and what sizes does it come in?

So, which was it? Lexan (polycarbonate) or acylic. Completly different
stuff. I know, it was clear stuff, right?

"TBM" wrote in message
...

"CW" wrote in message
news
Lexan shatter? Unless you freeze it, it's less likely to shatter than
the
piece of oak you're cutting on the sled you built.


Really? Oak must be pretty shatter prone, because I have seen many of
peices
of Lexan or acrylic sheeting shatter. I tried to cut a peice with a CMS
once, wasn't pretty.....

wrote in message
...
On Tue, 22 Aug 2006 22:06:10 -0400, "TBM" wrote:


"CW" wrote in message
news
Lexan shatter? Unless you freeze it, it's less likely to shatter than
the
piece of oak you're cutting on the sled you built.


Really? Oak must be pretty shatter prone, because I have seen many of
peices
of Lexan or acrylic sheeting shatter. I tried to cut a peice with a CMS
once, wasn't pretty.....



It had to have been acrylic which will crack/shatter very easily.
It does have the benefit that it doesn't scratch very easily.

Lexan on the other hand will never shatter even hitting it with a
sledge hammer, but will easily scratch.

Acrylic is much brittler (is there such a word as brittler?), but I have had
lexan shatter when cutting it with a CMS. It sent some pretty impressive
shards out.

wrote:

When lexan was first introduced they made frying pans out of it to
show some of it's properties.

You got frying pans, we got individual size pie plates.

Put it in a vise to try to crack it.

No luck, it bent but didn't break.


BTW, like TeamCasa, I'm a birch ply kind of guy for sled bottoms.

Lew

"CW" wrote in message
news
So, which was it? Lexan (polycarbonate) or acylic. Completly different
stuff. I know, it was clear stuff, right?


Both.

In article , TBM wrote:

"CW" wrote in message
news
Lexan shatter? Unless you freeze it, it's less likely to shatter than the
piece of oak you're cutting on the sled you built.


Really? Oak must be pretty shatter prone, because I have seen many of peices
of Lexan or acrylic sheeting shatter. I tried to cut a peice with a CMS
once, wasn't pretty.....



Really, lexan (polycarbonate) is very different from plexiglass
(acrylic) in how it reacts to stress & strain. Plexiglass will shatter
quite easily but lexan usually deforms. You can actually bend the
thinner stuff in a sheet metal brake.


--

Larry Wasserman Baltimore, Maryland

CW wrote:

Lexan shatter? Unless you freeze it, it's less likely to shatter than the
piece of oak you're cutting on the sled you built.

Normally Lexan (polycarbonate) will bend into a pretzel long before it
shatters, but there is one way to make it brittle. Lexan is
mechanically tough, but chemically it's weak. Lots of common chemicals,
including household solvents and detergents, can change its behaviour
like this.

I used to work on big production-line machinery. One toolroom had a
mis-match between its very expensive 1/2" Lexan safety shields around
all the CNC machines and the cutting fluid they were using. Eventually
there was a mishap on one machine and a chunk of metal came loose. It
hit the screen and went straight through it, shattering the glazing
like a Hollywood saloon window. They had to change cutting fluids,
then replace every screen in the place.

Normally I'd have scrounged the scrap, but this stuff was so embrittled
that plant maintenance couldn't even unbolt the screen panels from the
frames without most of them cracking or breaking.


I'd also advise against Lexan for jig making. You don't need that level
of impact resistance and the stuff's a pain to work with.

wrote:
I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike



I usually have piles of plywood and MDF cabinet offcuts available for
jigs. I would have to purchase Lexan to use it. Wood is easier to
shape, brad nail, and glue for a quick jig. Typically, I'll buy Lexan,
UMHW, plastic laminate, metals... only when I have a specific
requirement, and only if it'll be for a many-use tool.

Look in any metal shop,, wood shop, plastics shop, etc... Most shop
jigs will be made from whatever materials they often work with, because
they have some, they work with the material often, and the correct tools
and sundries are already handy.

The bottom line is if you like to spend time and effort building pretty
jigs, Lexan would probably work fine. Aluminum is nice, as well. On
the other hand, if you make many jigs on the spot, specifically for an
operation at hand... There's nothing wrong with either approach, it's a
personal choice.

"willim" wrote in message
...
wrote in news:1156283102.389344.3920
@p79g2000cwp.googlegroups.com:

I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike


Lexans attribute is that it does not scratch as easily as other plastics.
I use 3/8 all the time for jigs. It is used as trays and stuff for
wheelchairs.
1/4 is a little thin for a sled but I think it will work if you are
careful. Chamfer edges, holes and slots; cracks will propagate.

Bill

Actually Lexan (Polycarbonate) is much softer than acrylics like
Plexiglass. That is what gives it its impact resistancs, down side is at
does scratch much easier than Plexiglass.

Also cost about 2X Acrylic, 1/4" thk is around $10.00 sq/ft.

Kevin

Ahhh yes... the acrylic/Lexan mistaken identity. A simple flame test
tells the difference. Google it, because my lawyer advises against
sayng too much *G*

Lexan is good enough for jet-fighter canopies, I'm told.

But the whole discussion is moot because all you need to do is call for
a price on Lexan.

I have built many a display case for a variety of jewelry stores, and
often used Lexan with a sheet of glass on top (scratch restance and
hammer resistance in an affordable sandwich).

In my solid surface fabrication, I make a lot of
jigs/patterns/templates, and I invariably use MDF and Baltic
Birch...OR..solid surface left-overs.

My favourite jig material is 1/2" phenolic, which can be bought with
laminate already attached.

Nothing quite like it.

r

I see. Either you don't know what you are talking about or you're incredibly
inept.

"TBM" wrote in message
...

"CW" wrote in message
news
So, which was it? Lexan (polycarbonate) or acylic. Completly different
stuff. I know, it was clear stuff, right?


Both.

"CW" wrote in message
nk.net...
I see. Either you don't know what you are talking about or you're
incredibly
inept.

"TBM" wrote in message
...

"CW" wrote in message
news
So, which was it? Lexan (polycarbonate) or acylic. Completly different
stuff. I know, it was clear stuff, right?


Both.




This coming from a top poster?

Lexan is shatter resistant, not shatter proof. I PERSONALLY had a peice of
3mm lexan fly apart in many small peices. Maybe you don't consider that
shattering, but I do. I also have had simular experiences with plexiglass,
which should not come as a suprise.

Regardless, there is no reason to be an asshole, so welcome to my killfile.

"TBM" wrote in message
...
This coming from a top poster?

The correct way, of course.


I PERSONALLY had a peice of
3mm lexan fly apart in many small peices.

Glad I don't work around you. Takes talent.

"CW" wrote in message
nk.net...
I see. Either you don't know what you are talking about or you're
incredibly
inept.


I don't have any experience with Lexan, but another poster in this thread
also experienced a peice of lexan shattering in a CMS. Possible they are
confusing Plexiglass with lexan, it's a common misperception. What is the
reason for the snarkiness?

On Thu, 24 Aug 2006 10:05:16 -0400, "Locutus"
wrote:


"CW" wrote in message
ink.net...
I see. Either you don't know what you are talking about or you're
incredibly
inept.


I don't have any experience with Lexan, but another poster in this thread
also experienced a peice of lexan shattering in a CMS. Possible they are
confusing Plexiglass with lexan, it's a common misperception. What is the
reason for the snarkiness?

Well, there's at least one historically (and consistently) misinformed
individual so confused, and this one was number two. All after some
very knowledgable responses to the OP indicating the difference
between polycarbonate and acrylic and how it is exceedingly unlikely
to be able to duplicate the effect on one in the other. I get testy
about them, too. Makes me want to give them their sign.

--
LRod

Master Woodbutcher and seasoned termite

Shamelessly whoring my website since 1999

http://www.woodbutcher.net

Proud participant of rec.woodworking since February, 1997

email addy de-spam-ified due to 1,000 spams per month.
If you can't figure out how to use it, I probably wouldn't
care to correspond with you anyway.

wrote in message
ps.com...
I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike


Lexan is good stuff. The down side is that 1/4 inch is really flexible so
you would have to back it up with the plywood anyway. Cost is also an issue
unless you have it scrap.

Others have mentioned shattering. If you avoid sharp inside corners impact
resistance goes through the roof.

Poly carbonate is rather soft and will scratch easily. They do make a
scratch resistant grade but it is usually used for glazing.

One thing that does work great for jigs is Formica laminated
wood/MDF/particle board. The particle board is the last choice except for
cost if you can get sink cutouts cheap and or free. Good till you drop it
or get it wet.


--

__
Roger Shoaf

Important factors in selecting a mate:
1] Depth of gene pool
2] Position on the food chain.

wrote:
I see most crosscut sleds use 3/4" plywood for the base, but why
couldn't I use 1/4" Lexan instead? It's a stable material, isn't it?

Mike


the best thing I've found, just from working with my own shop scrap is
1/4" melamine coated MDF.

"LRod"
Makes me want to give them their sign.

ROTFLMAO
I never heard of Bill Engvall and his "Here's your sign" bit until I got
XMRadio. The first time I heard his show I almost crashed my truck! Very
funny guy.

Dave



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"LRod" wrote in message
...
On Thu, 24 Aug 2006 10:05:16 -0400, "Locutus"
wrote:


"CW" wrote in message
link.net...
I see. Either you don't know what you are talking about or you're
incredibly
inept.


I don't have any experience with Lexan, but another poster in this thread
also experienced a peice of lexan shattering in a CMS. Possible they are
confusing Plexiglass with lexan, it's a common misperception. What is the
reason for the snarkiness?

Well, there's at least one historically (and consistently) misinformed
individual so confused, and this one was number two. All after some
very knowledgable responses to the OP indicating the difference
between polycarbonate and acrylic and how it is exceedingly unlikely
to be able to duplicate the effect on one in the other. I get testy
about them, too. Makes me want to give them their sign.

--
LRod


Since everyone is adamant that Lexan won't shatter, then I must concede I
was mistaken. Perhaps it was in fact plexiglass.

On Thu, 24 Aug 2006 20:58:42 -0400, "TBM" wrote:


Well, there's at least one historically (and consistently) misinformed
individual so confused, and this one was number two. All after some
very knowledgable responses to the OP indicating the difference
between polycarbonate and acrylic and how it is exceedingly unlikely
to be able to duplicate the effect on one in the other. I get testy
about them, too. Makes me want to give them their sign.

Since everyone is adamant that Lexan won't shatter, then I must concede I
was mistaken. Perhaps it was in fact plexiglass.

And just for the record and your own piece of mind, you weren't the
"historically (and consistently) misinformed individual" to whom I
referred.

--
LRod

Master Woodbutcher and seasoned termite

Shamelessly whoring my website since 1999

http://www.woodbutcher.net

Proud participant of rec.woodworking since February, 1997

email addy de-spam-ified due to 1,000 spams per month.
If you can't figure out how to use it, I probably wouldn't
care to correspond with you anyway.

"TBM" wrote in message
...
Since everyone is adamant that Lexan won't shatter, then I must concede I
was mistaken. Perhaps it was in fact plexiglass.



I have shattered polycarbonate, all it takes is a bad design with sharp
inside corners. Avoid that and the stuff is literally bullet proof.

--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.