How to cut plastic?

6307 Views 28 Replies 14 Participants Last post by MT Stringer, Sep 7, 2019

MT Stringer

Discussion Starter · Jul 1, 2019

That's the question for the day. I have a big plastic cutting board. I would like to use the CNC to make several boards out of it.

I think it is high density polyethylene. White plastic. I think it is about 1/2 inch thick. I need to go out to the shop and take measurements.

Probotix Asteroid with the Bosch 1617.
I have both 1/8th and 1/4 inch upcut bits so if it is thicker than 1/2 inch, I will use the 1/4 inch bit.

The real questions are how fast/or slow do you cut. At the lowest router speed?

I hate to ruin the board if it melts, but if it does, I will be OK. Learning experience.

All advice and suggestions appreciated.
Thanks in advance.
Mike

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Pro4824

· #2 · Jul 2, 2019

https://youtu.be/SiLWI62N5pc

Interesting, I might have to try this myself.

MT Stringer

Discussion Starter · #3 · Jul 2, 2019

Thanks for the link. As much as I watch You Tube videos, I haven't tried to find any help there.

Actually, I have used my machine in over a year. I have had several medical issues and that has brought me to a complete stop. But, I am in a lot better health now and the energy has returned. Step one will be to fire it up and re home everything.

I had to search Router Forums to find my post asking how to set up different coordinate systems. I found it, and all is well. Several projects are waiting in the wings.

Thanks again.

MT Stringer

Discussion Starter · #4 · Jul 2, 2019

18 x 23 3/4 x 1/2 inch...and it is not flat!

Pro4824

· #5 · Jul 2, 2019

MT Stringer said:
18 x 23 3/4 x 1/2 inch...and it is not flat! <a href="http://www.routerforums.com/images/smilies/frown.gif" border="0" alt="" title="Frown" ></a>

1/2" is probably a little thick but I wonder if you can clamp it down and maybe use a heat gun to help it lay flat on it's own? Post some pictures when you get started on it and I'm glad to hear you're feeling better!! Joe.

Reactions: 1

DesertRatTom

· #6 · Jul 2, 2019

Really glad you're feeling better now Mike. I had a similar experience and am only now getting back to decent health myself. My experience with cutting plastic is pretty limited, but I know the bit/blade quickly gets covered in plastic scraps, and if I go fast enough, it semi melts, but rarely sticks to the blade or bit.

Reactions: 1

honesttjohn

· #7 · Jul 2, 2019

I know Toolstoday and Precise bits have bits for plastic. Regular bits will leave tear out on acrylic, but the "for plastic" bits leave a smooth edge.

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difalkner

· #8 · Jul 2, 2019

I use zero flute bits for acrylic but haven't tried to cut HDPE. I wonder how those would work? They sure work good on acrylic.

David

Reactions: 2

beltramidave

· #9 · Jul 2, 2019

difalkner said:
I use zero flute bits for acrylic but haven't tried to cut HDPE. I wonder how those would work? They sure work good on acrylic.

David

+1 on zero flutes!

ger21

· #10 · Jul 2, 2019

:laugh2:
They are "O" (oh) flute, not zero flute.

Regular bits will leave tear out on acrylic, but the "for plastic" bits leave a smooth edge.

Regular bits can cut acrylic fine. They just don't clear chips as well. If they are sharp, they will cut cleanly. Try climb cutting.

Reactions: 5

difalkner

· #11 · Jul 2, 2019

ger21 said:
:laugh2:
They are "O" (oh) flute, not zero flute.

I try and learn something new every day and this is early enough I can go back to bed!! :grin:

Thanks, Gerry. I guess it's mistakenly referred to often because when you do a search for either O flute or 0 flute you get basically the same results.

David

Reactions: 1

MT Stringer

Discussion Starter · #12 · Jul 2, 2019 (Edited)

I like the idea of using a heat gun. Just so happens I have one, a Harbor Freight model...and a work bench full of holes for my clamps!

Lots of advice and suggestion posted. Thanks to all. I guess I need to get to the drawing board and get after it.

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OCEdesigns

· #13 · Jul 3, 2019

I milled a small piece of Delrin which is kind of similar to HDPE. I used a 1/4" O flute upcut and climb cutting. I went 10,000 RPM and 30 IPM but also cut at .0625" because I wasn't sure how it would react. I could have done .125" pretty easy. I was afraid of melting.

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harrysin

· #14 · Jul 3, 2019

Cutting sheet plastics of all kinds I've always used the table saw and to clean the edges of Acrylics I run a gas flame along the edges.

Reactions: 2

Pro4824

· #15 · Jul 3, 2019

MT Stringer said:
I like the idea of using a heat gun.

Let us know if it works!
I don't have any "Oh" 🙂 flute bits so off to give Amazon some more $$$
Amana one is nice with the cool looking blue coating but I think I'll save the extra $15 and get the Freud.

Freud 73-206 1/4-Inch Diameter by 3/4-Inch Height O Flute Up Spiral Plastic Cutting Router Bit with 1/4-Inch Shank https://www.amazon.com/dp/B001J9K5XI/ref=cm_sw_r_cp_apa_i_sVmhDb6XAKS2E

Reactions: 1

MT Stringer

Discussion Starter · #16 · Jul 3, 2019

2

harrysin said:
Cutting sheet plastics of all kinds I've always used the table saw and to clean the edges of Acrylics I run a gas flame along the edges.

Thanks Harry. I think I will make one out of scrap plywood to see how it looks in place. It will sit on the shelf of a Blackstone 36 inch griddle. My thinking is to countersink and glue some magnets underneath so it will stay put. The outer edge will hang over the shelf by 2 1/2 inches, thus providing a larger work area and a place to set my drink!

Since there are two shelves, I may have to abandon the idea of cutting up the plastic cutting board for now, and go with solid wood. I know there is heat involved, so I have a plan to shield it also. That will come later. One project at a time.

Edit: The two slots are for scrapers or spatulas to fit in.

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Reactions: 1

subtleaccents

· #17 · Jul 4, 2019

Hi Mike, I cut a lot of HDPE. I Have had great success using the 3/16" "O" flute.
With 1/2" material my cut speed is 85 ipm at 14000 rpm. When cutting the liquid groove I just use a 2 flute carbide tipped 3/4"diameter core box bit. Never had any trouble with getting a good finish.
I usually dress all cut edges with a 1/16" radius round over bit. The untreated edges are like a razor blade.

Reactions: 1

Stick486

· #18 · Jul 4, 2019

subtleaccents said:
i usually dress all cut edges with a 1/16" radius round over bit. The untreated edges are like a razor blade.

and nick sensitive

subtleaccents

· #19 · Jul 4, 2019

Stick486 said:
and nick sensitive

So true!

subtleaccents

· #20 · Jul 4, 2019

MT Stringer said:
Thanks Harry. I think I will make one out of scrap plywood to see how it looks in place. It will sit on the shelf of a Blackstone 36 inch griddle. My thinking is to countersink and glue some magnets underneath so it will stay put. The outer edge will hang over the shelf by 2 1/2 inches, thus providing a larger work area and a place to set my drink!

Since there are two shelves, I may have to abandon the idea of cutting up the plastic cutting board for now, and go with solid wood. I know there is heat involved, so I have a plan to shield it also. That will come later. One project at a time.

Edit: The two slots are for scrapers or spatulas to fit in.

HDPE doesn't accept glue too well. Not much sticks to it for any length of time. The only thing my HDPE distributor says works is Spray 77. Forget who makes it. Maybe someone here may remember the manufacturer.

Reactions: 2

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