PlexiGlass is not for beginners :)

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PollyMotion
Posts: 37
Joined: Tue Nov 17, 2015 9:04 pm
Location: Norway

PlexiGlass is not for beginners :)

Post by PollyMotion » Wed Apr 06, 2016 10:13 pm

Hi!

I really struggled with my last project. (Creating a PlexiGlass sign)
Engraving the Plexi was relatively straight forward, but cutting it was a real nigthmare.
I've heard that one should select the type of acrylic carefully in order to succeed in machining it, but I really didn't expect this result:
Failed Plexi.jpg
Failed Plexi.jpg (448.17 KiB) Viewed 2021 times
:shock:

Eventually, to finalize the project, I ended up doing the cutout with a saw :oops:



I'm fairly happy with the end result, but I'm not too prowd of the process getting there :)


-- PollyMotion

CastIrony
Posts: 650
Joined: Mon Jul 21, 2014 10:21 pm
Location: Portland, OR

Re: PlexiGlass is not for beginners :)

Post by CastIrony » Wed Apr 06, 2016 11:37 pm

Yeah, that looks like extruded acrylic, which is reportedly a pain to machine. Cast acrylic usually has paper backing rather than the clear plastic.

(unless there isn't any backing on that and it's just pink plastic, in which case I can't tell what it is from the photo)

I just made an electronics stand out of acrylic last week, and except for choosing the wrong end mill (should have gone with an up-cut spiral to remove the material more efficiently) everything turned out really well.
Last edited by CastIrony on Mon Apr 11, 2016 4:04 pm, edited 2 times in total.
Shapeoko 3 #192 - Complete! Needs limit switches.

Jimf
Posts: 233
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Re: PlexiGlass is not for beginners :)

Post by Jimf » Wed Apr 06, 2016 11:55 pm

Cutting most plastics is difficult unless good feed/speed/rpm and end mill types are used. What others say will work may not work well with the plastic you have. I find it is trial and error sometimes.

I try to get Cast acrylics and use single flute end mills. A little bit of Alcohol can be used as a lube.

Once the plastic starts melting and sticking to the end mill, stop and try either lowering rpm or increasing feed rate. Vacuum the chips away so it doesn't recut and melt.

JeromyReno
Posts: 225
Joined: Mon May 04, 2015 11:28 pm

Re: PlexiGlass is not for beginners :)

Post by JeromyReno » Thu Apr 07, 2016 1:06 am

i cut a lot of plastic and find that the faster you can run it the better. i have a blower that blows air on the bit to help cool it too.

Auarhau
Posts: 243
Joined: Tue Feb 25, 2014 8:46 pm

Re: PlexiGlass is not for beginners :)

Post by Auarhau » Thu Apr 07, 2016 7:14 am

Biltema plexiglass? If so, it's extruded plexiglass.

For this stuff it's important to use a end mill with just one flue and go relatively fast. I wrote some settings for the wiki a long time a go when I still used a dremel.
http://www.shapeoko.com/wiki/index.php/ ... plexiglass

It's perhaps different with a kress and SO3, but the general idea should be the same. I got some nice one flute cutters from Sorotec, especially designed for cutting acrylics and this makes all the difference!
ShapeOko 2. Nema 17 74 oz·in. GAUPS shield on Arduino Uno. DRV8825 Drivers x4 . Kress 1050 FME-1. Z Acme Screw. Threaded inserts table.

B NEGATIVE
Posts: 30
Joined: Sun Jan 10, 2016 4:26 pm

Re: PlexiGlass is not for beginners :)

Post by B NEGATIVE » Thu Apr 07, 2016 4:51 pm

The work machine runs a single flute tool @ 22k with a feed of 3000mm/min,I extrapolated my settings from that.

Single flute is the key,along with cast material.

PollyMotion
Posts: 37
Joined: Tue Nov 17, 2015 9:04 pm
Location: Norway

Re: PlexiGlass is not for beginners :)

Post by PollyMotion » Mon Apr 11, 2016 1:44 pm

Thanks for your input! :)
I'll definetly be trying this some more in a later project. Meanwhile, I think I'll need to order a single flute end mill. Perhaps that's one of the keys to success...
I only tried with 2 and 3 flute, as that was all I had...

-- Pollymotion

eefits
Posts: 87
Joined: Wed Dec 10, 2014 6:01 pm

Re: PlexiGlass is not for beginners :)

Post by eefits » Mon Apr 11, 2016 6:55 pm

I have been cutting Plexiglass for a while and have great success.

I have cut Polycarbonate, Cast Acrylic, Extruded Acrylic with similar result.

I have both 2 flute and single flute designed for Acrylic but I seldom use the single flute because they break easy. I have been cutting with 2 flute as slow as 800mm/m with 20Krpm without problem up to 1.5mm. The key is when it cut the bit slice the acrylic out like ribbon and fly out to every direction. The Acrylic bit that I use is designed to peel and kick out the acrylic so less heat is generated.

Once you find the sweet spot it is routine every time.

PollyMotion
Posts: 37
Joined: Tue Nov 17, 2015 9:04 pm
Location: Norway

Re: PlexiGlass is not for beginners :)

Post by PollyMotion » Mon Apr 11, 2016 9:49 pm

Auarhau wrote:Biltema plexiglass? If so, it's extruded plexiglass.

For this stuff it's important to use a end mill with just one flue and go relatively fast. I wrote some settings for the wiki a long time a go when I still used a dremel.
http://www.shapeoko.com/wiki/index.php/ ... plexiglass

It's perhaps different with a kress and SO3, but the general idea should be the same. I got some nice one flute cutters from Sorotec, especially designed for cutting acrylics and this makes all the difference!
Yes, it's from Biltema...
Thanks for the link! :) Very interesting!

Auarhau
Posts: 243
Joined: Tue Feb 25, 2014 8:46 pm

Re: PlexiGlass is not for beginners :)

Post by Auarhau » Tue Apr 12, 2016 10:27 am

Take a look at the acryl/proacryl ones from sorotec. It's expensive but the ones I've bought from them are very high quality compared to the ones from ebay, and totally worth it in my opinion. Probably the best "upgrade" I ever did was buying a few quality bits like these. I still use the cheaper ones as everyday beaters, but I dig these up when the results really matters.

http://www.sorotec.de/shop/Cutting-Tools/END-MILLS/
ShapeOko 2. Nema 17 74 oz·in. GAUPS shield on Arduino Uno. DRV8825 Drivers x4 . Kress 1050 FME-1. Z Acme Screw. Threaded inserts table.

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