cutting thick sheets

qc · Post by qc » Thu Mar 13, 2008 2:51 pm

i'm in the midst of doing some trial runs of a scratchbuilt and have an area where i want to make a "tread". imagine the tread on your shoe. i'm (most interested) using 0.04" thick styrene. i have a pattern to cut out (to make the "treads") then glue it to a backing piece. the pattern consists mostly of 3/16" strips (both cut-outs and remaining). but the tread does not consist only of these strips in a bunching of parallel lines.

my problem:
1-the thickness of the 0.04" is a bitch to cut through.
2-the "returns" at the end of the long slices are hard to cut with an exacto, and have to be "stabbed" to make the cut instead of "sliced"
3-the parallel strips (once all cutouts are removed) are slightly warped side-to-side-- likely due to the thickness of the exacto "wedges" the plastic apart and pushes the plastic to the side...and if the adjacent plastic is not wide to resist this lateral push, then it warps.

i was considering getting a surgical scalpel. would this be thinner and easier to cut the plastic. is this a worthwhile investment?

any other ways to help with this problem? or should i just back down to a 0.03" thick sheet and not fight this battle?

(i realize the explaining of this problem is a little funny...i'd be happy to explain in diff ways, if needed)

many thanks

Mark Yungblut · Post by **Mark Yungblut** » Thu Mar 13, 2008 3:44 pm

Take and old #11 blade and break the tip off. Use that and scribe with the back of the blade. This will cut a channel not spread the plastic. You can keep scribing until it is a clean through cut. then just a little sanding will be required.

For really thick stock I use a plexiglass cutter which cuts the same way it is just heavy duty.

Cheers,

Mark

Kylwell · Post by **Kylwell** » Thu Mar 13, 2008 4:30 pm

What about some .040 Evergreen strip in 3/16?

USSARCADIA · Post by **USSARCADIA** » Thu Mar 13, 2008 5:32 pm

The scalpels are usually thinner and will break easier. Try the scribing method, just keep scrbing deeper and deeper until it will break. Unless you have access to a band saw..........

As Kylwell mentioned, the precut strips would be the easiest way to go.

qc · Post by qc » Thu Mar 13, 2008 9:32 pm

yeah...ran by my LHS...saw the strips. was pleasantly surprised to see so many different widths in each thickness. i'm seriously reconsidering using those precut strips...so nice and ready to use. just have to learn how to make perfect butted joints (with help of aves) to make it look like one piece.

many thanx on the help.

am going to try the broke-tip-#11 also anyway.

Kylwell · Post by **Kylwell** » Thu Mar 13, 2008 9:49 pm

A drip of liquid solvent (Tenax, Ambroud, etc) will make them seamless.

With a wee bit of sanding.

futch · Post by **futch** » Thu Mar 13, 2008 11:01 pm

0.04" thick styrene.

i read the title, openend the thread and read .04.
.04 is girlie thickness man!
i only have to look at .04 and it falls to pieces.

what you need is LEVERAGE sir!

i'm doing this with evergreen .06 - lots of sheets - getting clean breaks.
if your making lots of small strips then score a swag of parallel lines, 3/16th apart (or go buy 5mm flat rod and spare the hassle).

snapping with leverage is easy and done in one of 2 ways. sandwich between 2 chopping boards or planks of wood, leaving enough styrene exposed to snap a piece off. with the flat of your hand push down slowly until it cracks, then pull up in the opposite direction. voila.

plan B, wedged the sheet into a crack - such as a door jam or kitchen draw. hold both ends, try to support the center then snap and keep on snapping until you get your parts.

the trick is to have clean hard edges to snap against.

snap!

seam-filler · Post by **seam-filler** » Fri Mar 14, 2008 10:56 am

For thicker plastic I use an Olfa P-Cutter.

It's effectively a draw-knife which takes a V-notch out of the plastic. A few passes and you can get through really thick plastic or acrylic.

Olfa P-Cutter

qc · Post by qc » Fri Mar 14, 2008 2:52 pm

futch,
this isn't a SNAP application. i'm not MAKING strips. i'm ..."extracting" strips out of a larger piece. think thick grating..but instead of square holes, think long rectangular holes. no snapping off the edge--its extracing rectangles from the interior body.

k'well,
thanks for the welder reminder. just yesterday i suddenly realized i've been doing all my work with CA and forgot about welder. picked me up a bottle while i was at the LHS.

however tho.
found that my magical strip i need is 0.04" x 0.1"....and that was the one pkg that they (my LHS) didn't have when i went. was out of stock in both plastistrut AND evergreen. crazy coincidence....hopifully there isn't something more...like they don't produce that shape anymore. plastistrut site says they have it. am continuing my search at other stores this evening.

thx again for the help guys.

Mr. Badwrench · Post by **Mr. Badwrench** » Sat Mar 15, 2008 6:43 am

It sounds like you are trying to slice thru the plastic rather than carve thru it. A thinner blade won't help with that, it is still cutting, like a knife thru a very stubborn loaf of bread. As Mark said, use the back side of an exacto blade. Breaking the tip off sounds a little wonky, it will leave a little bend in the tip. But you can grind the tip back, maybe .050 or so. Then draw the back edge of the tip across the plastic. It will excavate a little chip, just like it's milling it out, which in fact, it is. It also makes cleaner cuts than trying to slice thru it with a smooth, sharp blade.

Shinnentai · Post by **Shinnentai** » Sat Mar 15, 2008 8:49 pm

I don't think I'd have the patience to do all that fiddly cutting. I'd hand etch it in brass instead.

futch · Post by **futch** » Sun Mar 16, 2008 7:38 pm

qc wrote:futch,
this isn't a SNAP application. i'm not MAKING strips. i'm ..."extracting" strips out of a larger piece.

i understand what you're doing. i would approach with strips and create the tread that way. SNAP ;-) stack and bevel strips to maintain angles. accurate and sharper detail in the corners. what you're trying to do will die in the corner areas - but it is not clear what level of quality you are trying to achieve, and your approach may be acceptible.

Chacal · Post by **Chacal** » Tue Mar 18, 2008 2:51 pm

Can you gain access to one of those guillotine paper cutters? Not the sliding knife type, but the guillotine type, with the big heavy thick lever-type blade. That ought to do it.