On 21/7/20 9:10 pm, klaus.kragelund@gmail.com wrote:> Cutting with high pressure water?Water jet cutters use the water only as a carrier for an abrasive.
Laser Cut Plexiglass
Started by ●July 20, 2020
Reply by ●July 21, 20202020-07-21
Reply by ●July 21, 20202020-07-21
On Tuesday, July 21, 2020 at 6:35:03 PM UTC-4, rangerssuck wrote:> On Monday, July 20, 2020 at 10:14:18 PM UTC-4, Ricketty C wrote: > > I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? > > > > I know little about the material really, but they talked about it splintering, 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. > > > > The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. > > > > I don't know much about laser cutting of quarter inch thick material, 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. > > > > BTW, multiple pieces of this material are assembled to create a wide 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. > > > > -- > > > > Rick C. > > > > - Get 1,000 miles of free Supercharging > > - Tesla referral code - https://ts.la/richard11209 > > 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?I don't have details. I'm EE and this is an ME issue. The pieces are roughly 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 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. There will be little interest in any manual work in making any of this. They want the unit to be quickly manufactured in qty 10's of thousands. Inexpensive as well. To some extent the less developed countries need ventilators less than countries like the US. Ironic, no? -- Rick C. -- Get 1,000 miles of free Supercharging -- Tesla referral code - https://ts.la/richard11209
Reply by ●July 21, 20202020-07-21
On 21/07/2020 12:01 pm, Ricketty C wrote:> On Monday, July 20, 2020 at 10:34:05 PM UTC-4, RheillyPhoull wrote: >> On 21/07/2020 10:14 am, Ricketty C wrote: >>> I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? >>> >>> I know little about the material really, but they talked about it splintering, 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. >>> >>> The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. >>> >>> I don't know much about laser cutting of quarter inch thick material, 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. >>> >>> BTW, multiple pieces of this material are assembled to create a wide 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. >>> >> >> 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. > > These guys seem to like trendy things. They were having trouble finding 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. > > There are some poor thinkers in the crowd who don't get what is the important 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. >A cutout is simple with cnc, the lasers use a cnc rig anyhow. Sounds like a change in providers would be an idea :-)
Reply by ●July 21, 20202020-07-21
On Tuesday, July 21, 2020 at 9:03:03 PM UTC-4, Ricketty C wrote:> On Tuesday, July 21, 2020 at 6:35:03 PM UTC-4, rangerssuck wrote: > > On Monday, July 20, 2020 at 10:14:18 PM UTC-4, Ricketty C wrote: > > > I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? > > > > > > I know little about the material really, but they talked about it splintering, 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. > > > > > > The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. > > > > > > I don't know much about laser cutting of quarter inch thick material, 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. > > > > > > BTW, multiple pieces of this material are assembled to create a wide 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. > > > > > > -- > > > > > > Rick C. > > > > > > - Get 1,000 miles of free Supercharging > > > - Tesla referral code - https://ts.la/richard11209 > > > > 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? > > I don't have details. I'm EE and this is an ME issue. The pieces are roughly 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 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. > > There will be little interest in any manual work in making any of this. They want the unit to be quickly manufactured in qty 10's of thousands. Inexpensive as well. > > To some extent the less developed countries need ventilators less than countries like the US. Ironic, no? > > -- > > Rick C. > > -- Get 1,000 miles of free Supercharging > -- Tesla referral code - https://ts.la/richard11209OK... 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 finish on the plexi. laser cutting does give as smooth an edge as any other method 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 the shape and a second to ease the edge - roundover, bevel or chamfer.
Reply by ●July 21, 20202020-07-21
On Tuesday, July 21, 2020 at 9:29:04 PM UTC-4, rangerssuck wrote:> On Tuesday, July 21, 2020 at 9:03:03 PM UTC-4, Ricketty C wrote: > > On Tuesday, July 21, 2020 at 6:35:03 PM UTC-4, rangerssuck wrote: > > > On Monday, July 20, 2020 at 10:14:18 PM UTC-4, Ricketty C wrote: > > > > I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? > > > > > > > > I know little about the material really, but they talked about it splintering, 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. > > > > > > > > The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. > > > > > > > > I don't know much about laser cutting of quarter inch thick material, 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. > > > > > > > > BTW, multiple pieces of this material are assembled to create a wide 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. > > > > > > > > -- > > > > > > > > Rick C. > > > > > > > > - Get 1,000 miles of free Supercharging > > > > - Tesla referral code - https://ts.la/richard11209 > > > > > > 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? > > > > I don't have details. I'm EE and this is an ME issue. The pieces are roughly 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 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. > > > > There will be little interest in any manual work in making any of this. They want the unit to be quickly manufactured in qty 10's of thousands. Inexpensive as well. > > > > To some extent the less developed countries need ventilators less than countries like the US. Ironic, no? > > > > -- > > > > Rick C. > > > > -- Get 1,000 miles of free Supercharging > > -- Tesla referral code - https://ts.la/richard11209 > > OK... You refer to "the plastic bag" but don't seem to define it anywhere.I've been talking about the vent program I'm working on. "manual resuscitator"> If this is a thin plastic bag, you're gonna want a very smooth surface finish on the plexi. laser cutting does give as smooth an edge as any other method 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 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 unaffordable 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 cutting boards. Very inexpensive and durable. That can deal with the sharp edges of the plunger and protect from abrasion. -- Rick C. -+ Get 1,000 miles of free Supercharging -+ Tesla referral code - https://ts.la/richard11209
Reply by ●July 22, 20202020-07-22
On 2020-07-21, George Herold <ggherold@gmail.com> wrote:> On Tuesday, July 21, 2020 at 9:03:33 AM UTC-4, dca...@krl.org wrote: >> On Monday, July 20, 2020 at 10:14:18 PM UTC-4, Ricketty C wrote: >> > I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? >> > >> > I know little about the material really, but they talked about it splintering, 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. >> > >> > The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. >> > >> > I don't know much about laser cutting of quarter inch thick material, 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. >> > >> > BTW, multiple pieces of this material are assembled to create a wide 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. >> > >> > -- >> > >> > Rick C. >> > >> > - Get 1,000 miles of free Supercharging >> > - Tesla referral code - https://ts.la/richard11209 >> >> 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. :^)I've seen the cast type machined (table saw, router). I know nothing about extruded acrylic so that's a partial confirmation. -- Jasen.
Reply by ●July 22, 20202020-07-22
onsdag den 22. juli 2020 kl. 03.15.17 UTC+2 skrev RheillyPhoull:> On 21/07/2020 12:01 pm, Ricketty C wrote: > > On Monday, July 20, 2020 at 10:34:05 PM UTC-4, RheillyPhoull wrote: > >> On 21/07/2020 10:14 am, Ricketty C wrote: > >>> I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? > >>> > >>> I know little about the material really, but they talked about it splintering, 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. > >>> > >>> The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. > >>> > >>> I don't know much about laser cutting of quarter inch thick material, 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. > >>> > >>> BTW, multiple pieces of this material are assembled to create a wide 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. > >>> > >> > >> 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. > > > > These guys seem to like trendy things. They were having trouble finding 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. > > > > There are some poor thinkers in the crowd who don't get what is the important 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. > > > A cutout is simple with cnc, the lasers use a cnc rig anyhow. Sounds > like a change in providers would be an idea :-)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 the machine and hit cut
Reply by ●July 22, 20202020-07-22
On Wednesday, July 22, 2020 at 9:26:03 AM UTC-4, Lasse Langwadt Christensen wrote:> onsdag den 22. juli 2020 kl. 03.15.17 UTC+2 skrev RheillyPhoull: > > On 21/07/2020 12:01 pm, Ricketty C wrote: > > > On Monday, July 20, 2020 at 10:34:05 PM UTC-4, RheillyPhoull wrote: > > >> On 21/07/2020 10:14 am, Ricketty C wrote: > > >>> I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? > > >>> > > >>> I know little about the material really, but they talked about it splintering, 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. > > >>> > > >>> The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. > > >>> > > >>> I don't know much about laser cutting of quarter inch thick material, 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. > > >>> > > >>> BTW, multiple pieces of this material are assembled to create a wide 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. > > >>> > > >> > > >> 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. > > > > > > These guys seem to like trendy things. They were having trouble finding 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. > > > > > > There are some poor thinkers in the crowd who don't get what is the important 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. > > > > > A cutout is simple with cnc, the lasers use a cnc rig anyhow. Sounds > > like a change in providers would be an idea :-) > > 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 the machine and hit cutYes, 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 metal 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. -- Rick C. +- Get 1,000 miles of free Supercharging +- Tesla referral code - https://ts.la/richard11209
Reply by ●July 22, 20202020-07-22
On Tue, 21 Jul 2020 13:57:07 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>tirsdag den 21. juli 2020 kl. 22.24.07 UTC+2 skrev George Herold: >> On Tuesday, July 21, 2020 at 9:03:33 AM UTC-4, dca...@krl.org wrote: >> > On Monday, July 20, 2020 at 10:14:18 PM UTC-4, Ricketty C wrote: >> > > I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? >> > > >> > > I know little about the material really, but they talked about it splintering, 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. >> > > >> > > The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. >> > > >> > > I don't know much about laser cutting of quarter inch thick material, 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. >> > > >> > > BTW, multiple pieces of this material are assembled to create a wide 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. >> > > >> > > -- >> > > >> > > Rick C. >> > > >> > > - Get 1,000 miles of free Supercharging >> > > - Tesla referral code - https://ts.la/richard11209 >> > >> > 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. :^) > >yeh, extruded tends to melt, stick to the tool and then you are fubarThe 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.>and don't clean acrylic with ethanol, it cracks into pieces like breaking >hardened glassPlexiglass (and many other kinds of plastic) do not appreciate cutting oil either. Joe Gwinn
Reply by ●July 22, 20202020-07-22
On Monday, July 20, 2020 at 10:14:18 PM UTC-4, Ricketty C wrote:> I had someone today tell me it would be hard to bevel laser cut plexiglass. Anyone know if that is true? > > I know little about the material really, but they talked about it splintering, 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. > > The ideas they talked about to solve this issue included some that struck me as odd like adding rollers instead of a flat surface. > > I don't know much about laser cutting of quarter inch thick material, 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. > > BTW, multiple pieces of this material are assembled to create a wide 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.I got an image of the "plunger" which the team is calling the "hand" I guess because the bag is designed for hand operation. https://slack-files.com/TUTSYURT3-F017H6M216H-6c3fe964c0 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. -- Rick C. ++ Get 1,000 miles of free Supercharging ++ Tesla referral code - https://ts.la/richard11209
