Laser Cut Plexiglass

There are some problems with laser on plastics, for instance if the blue colour has the same freq as the laser it will not cut it and similar with clear, the laser passes through and other colurs have problems as well. You would be better served with a bevel rotary bit.

ass. Anyone know if that is true?

tering, etc. The issue is that it has a corner on the edge that is causing some wear to a plastic object it is pushing on.

ck me as odd like adding rollers instead of a flat surface.

ut if the laser can be tilted, a 45 degree bevel would be easy. Even a 30 degree tilt would do a lot to relieve the corner.

ece attached to the arm which then presses on the plastic bag. So it's onl y to the two outer pieces that need to be beveled.

These guys seem to like trendy things. They were having trouble finding a laser cutting outfit when the virus initially shut down everything. I aske d why not CNC and they talked like that was so much more expensive. I can' t imagine CNC being hard or expensive for a simple cut out, but I have to s ay I don't know.

There are some poor thinkers in the crowd who don't get what is the importa nt part of a problem sometimes. I don't want to talk down to people, but i t's been more than once I had to explain how to look at a problem.

Wouldn't want to try it. Oblique incidence of light creates extra reflection power, and driving acryiic sheet beyond linear optical response is likely to be a nuisance.

If the plastic refracts the light, you'l get lots of power outside the kerf, by internal reflection.

Abbeon has a bunch of cutter options for plastic and beveling jigs are available.

A sharp corner can be rounded with a flame, see 'flame polishing acrylic'.

Cutting with high pressure water?

I would consider using a table saw.

Dan

There are two types of plexiglas, one is cast and the extruded. And one (I think the cast) can be machined, the other cracks if you try and machine. (As your machinist. :^)

George H.

yeh, extruded tends to melt, stick to the tool and then you are fubar

and don't clean acrylic with ethanol, it cracks into pieces like breaking hardened glass

I have cut a lot of plexiglass with a CO2 laser It cuts very well and does not leave particularly sharp edges. I have cut both clear and "smoke" colors. The laser is infrared, so visible colors aren't likely to make a difference.

You can soften cut edges with a flame, but you can also round them with a scraper - it goes way faster than you might expect.

How thick is the plexi you're looking to cut? what kind of sizes and tolerances?

Water jet cutters use the water only as a carrier for an abrasive.

ass. Anyone know if that is true?

tering, etc. The issue is that it has a corner on the edge that is causing some wear to a plastic object it is pushing on.

ck me as odd like adding rollers instead of a flat surface.

ut if the laser can be tilted, a 45 degree bevel would be easy. Even a 30 degree tilt would do a lot to relieve the corner.

ece attached to the arm which then presses on the plastic bag. So it's onl y to the two outer pieces that need to be beveled.

s not leave particularly sharp edges. I have cut both clear and "smoke" col ors. The laser is infrared, so visible colors aren't likely to make a diffe rence.

scraper - it goes way faster than you might expect.

rances?

I don't have details. I'm EE and this is an ME issue. The pieces are roug hly an inch by four inches but shaped like an elongated foot ball. I think multiple pieces maybe a quarter inch thick are stacked with small spacers to form a wide rocker shape for pressing down on the plastic bag.

The wear shown looked like it was just at the edges. They talked like it w as from abrasion, but if it's just at the edge it would seem to be the edge of the plastic scraping the bag as it is pressed and released. There may be some motion longitudinally, but there will also be wear laterally as the bag compresses and bends.

There will be little interest in any manual work in making any of this. Th ey want the unit to be quickly manufactured in qty 10's of thousands. Inex pensive as well.

To some extent the less developed countries need ventilators less than coun tries like the US. Ironic, no?

A cutout is simple with cnc, the lasers use a cnc rig anyhow. Sounds like a change in providers would be an idea :-)

glass. Anyone know if that is true?

intering, etc. The issue is that it has a corner on the edge that is causi ng some wear to a plastic object it is pushing on.

ruck me as odd like adding rollers instead of a flat surface.

but if the laser can be tilted, a 45 degree bevel would be easy. Even a 3

piece attached to the arm which then presses on the plastic bag. So it's o nly to the two outer pieces that need to be beveled.

oes not leave particularly sharp edges. I have cut both clear and "smoke" c olors. The laser is infrared, so visible colors aren't likely to make a dif ference.

a scraper - it goes way faster than you might expect.

lerances?

ughly an inch by four inches but shaped like an elongated foot ball. I thi nk multiple pieces maybe a quarter inch thick are stacked with small spacer s to form a wide rocker shape for pressing down on the plastic bag.

was from abrasion, but if it's just at the edge it would seem to be the ed ge of the plastic scraping the bag as it is pressed and released. There ma y be some motion longitudinally, but there will also be wear laterally as t he bag compresses and bends.

They want the unit to be quickly manufactured in qty 10's of thousands. In expensive as well.

untries like the US. Ironic, no?

OK... You refer to "the plastic bag" but don't seem to define it anywhere. If this is a thin plastic bag, you're gonna want a very smooth surface fini sh on the plexi. laser cutting does give as smooth an edge as any other met hod I know of. Also, if the laser is somewhat defocused, it may round over the edge some.

You could also cut it with CNC, one pass with a straight mill to cut out th e shape and a second to ease the edge - roundover, bevel or chamfer.

xiglass. Anyone know if that is true?

plintering, etc. The issue is that it has a corner on the edge that is cau sing some wear to a plastic object it is pushing on.

struck me as odd like adding rollers instead of a flat surface.

l, but if the laser can be tilted, a 45 degree bevel would be easy. Even a 30 degree tilt would do a lot to relieve the corner.

e piece attached to the arm which then presses on the plastic bag. So it's only to the two outer pieces that need to be beveled.

does not leave particularly sharp edges. I have cut both clear and "smoke" colors. The laser is infrared, so visible colors aren't likely to make a d ifference.

th a scraper - it goes way faster than you might expect.

tolerances?

roughly an inch by four inches but shaped like an elongated foot ball. I t hink multiple pieces maybe a quarter inch thick are stacked with small spac ers to form a wide rocker shape for pressing down on the plastic bag.

it was from abrasion, but if it's just at the edge it would seem to be the edge of the plastic scraping the bag as it is pressed and released. There may be some motion longitudinally, but there will also be wear laterally as the bag compresses and bends.

They want the unit to be quickly manufactured in qty 10's of thousands. Inexpensive as well.

countries like the US. Ironic, no?

I've been talking about the vent program I'm working on. "manual resuscita tor"

nish on the plexi. laser cutting does give as smooth an edge as any other m ethod I know of. Also, if the laser is somewhat defocused, it may round ove r the edge some.

the shape and a second to ease the edge - roundover, bevel or chamfer.

Yeah, that's what I thought, but they seem to think there is something unaf fordable about CNC.

Someone here indicated there are two types of plexi and one can't be milled without cracking.

Whatever. I'll wait to see what the rollers look like. lol

I suggested using a sheet buffer of the polypropylene material used in cutt ing boards. Very inexpensive and durable. That can deal with the sharp ed ges of the plunger and protect from abrasion.

I've seen the cast type machined (table saw, router). I know nothing about extruded acrylic so that's a partial confirmation.

glass. Anyone know if that is true?

intering, etc. The issue is that it has a corner on the edge that is causi ng some wear to a plastic object it is pushing on.

ruck me as odd like adding rollers instead of a flat surface.

but if the laser can be tilted, a 45 degree bevel would be easy. Even a 3

piece attached to the arm which then presses on the plastic bag. So it's o nly to the two outer pieces that need to be beveled.

ue

g a laser cutting outfit when the virus initially shut down everything. I asked why not CNC and they talked like that was so much more expensive. I can't imagine CNC being hard or expensive for a simple cut out, but I have to say I don't know.

ortant part of a problem sometimes. I don't want to talk down to people, b ut it's been more than once I had to explain how to look at a problem.

a cnc router needs to be much much beefer than a laser cutter, there are no cutting forces with a laser

and a laser doesn't need tooling or work holding just stick the sheet in th e machine and hit cut

xiglass. Anyone know if that is true?

plintering, etc. The issue is that it has a corner on the edge that is cau sing some wear to a plastic object it is pushing on.

struck me as odd like adding rollers instead of a flat surface.

l, but if the laser can be tilted, a 45 degree bevel would be easy. Even a 30 degree tilt would do a lot to relieve the corner.

e piece attached to the arm which then presses on the plastic bag. So it's only to the two outer pieces that need to be beveled.

blue

as

ing a laser cutting outfit when the virus initially shut down everything. I asked why not CNC and they talked like that was so much more expensive. I can't imagine CNC being hard or expensive for a simple cut out, but I hav e to say I don't know.

mportant part of a problem sometimes. I don't want to talk down to people, but it's been more than once I had to explain how to look at a problem.

no cutting forces with a laser

the machine and hit cut

Yes, but why is that of concern? A CNC machine to cut plexiglass does not need to be particularly "beefy" really. Even if a machine for cutting meta l is used, so? It's not like they aren't commonly available.

Maybe laser cutting is a lot cheaper than CNC machining. I don't know.

The classic solution is to flood the cutting area with plain tap water, which will keep everything cool. One can cut either kind of plexiglass, but extruded will tend to warp more than cast.

Plexiglass (and many other kinds of plastic) do not appreciate cutting oil either.

Joe Gwinn

I got an image of the "plunger" which the team is calling the "hand" I guess because the bag is designed for hand operation.

Seems the outer pieces are smaller than the rest and the only spacer is the arm in the center. The arrangement ends up being 70 mm wide, not counting the screws.

Presently I'm looking for a knob that will do this same job without making anything. The ones I've found only go up to about 40 mm. Gear shift knobs or drawer pulls.