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Cutting Plexiglas on a CNC for a WOOD project

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Forum topic by PRGDesigns posted 12-02-2012 03:35 AM 1742 views 0 times favorited 7 replies Add to Favorites Watch
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PRGDesigns

207 posts in 967 days


12-02-2012 03:35 AM

Topic tags/keywords: resource ash blade finishing arts and crafts

Has anyone cut 0.080 plexiglas on a CNC? If so, what kind/size bit were you most successful with? What spindle speed and/or feed rate were you using? How did you hold the plexiglas to the spoil board? Thanks in advance for any consideration you can give this matter.

-- They call me Mr. Silly


7 replies so far

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Mike

302 posts in 1340 days


#1 posted 12-02-2012 04:46 AM

Plexiglas is notorious for cracking. I’d leave the backer paper on and maybe sandwich the plexiglass between two sacrificial boards. You could then clamp the plexi with the pressure of the two boards. I’ve never tried using a cnc to cut plexi. but this might be a way to start. Maybe make some test cuts to see what works best. I would try only adjusting the feed or speed rate at a time instead of both. This should help eliminate unknowns.

Good luck!

-- look Ma! I still got all eleven of my fingers! - http://www.termitecrafts.com

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PRGDesigns

207 posts in 967 days


#2 posted 12-02-2012 05:02 AM

Excellent idea. I have some offcuts of BB plywood I could use for the sandwich. There is supposed to be a hole in the center, which I can use as the hold down screw after drilling it with the CNC. There are also 4 holes around the edges, which will serve the same purpose. Problem solved on the hold down and splitting issue. Now if I can figure out a speed and feed I will be ready to cut. Thanks!

-- They call me Mr. Silly

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bullhead1

228 posts in 902 days


#3 posted 12-02-2012 05:09 AM

Double sided tape to hold down plexi. If your cutting out little pieces inside the outline this will keep the little pieces from becoming flying objects that could possibly do bodily harm. It’s always fun until someone looses an eye! Post your question on one of the cnc forums such as vectric, cnc zone, shopbot, shark etc. on the feeds and speed question. I believe you want a high feed rate so you don’t melt the plastic. I have a cnc but haven’t cut plastic or acrylic yet.

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PRGDesigns

207 posts in 967 days


#4 posted 12-02-2012 05:22 AM

I am cutting a 5.6” circle with one (qty) 1/8” screw hole in the middle and four (qty) 1/8” screw holes along the outside perimeter. I was also planning on cutting a countersink for the screws if possible. My current plan is to use a 120 degree v-bit for the countersinks and make a very shallow cut. I like the sandwich idea between the offcuts of BB plywood to hold down the material. I think I can reuse the same hold down boards for the 24 (qty) circles I need. Thanks.

-- They call me Mr. Silly

View josh's profile

josh

901 posts in 1223 days


#5 posted 12-02-2012 05:29 AM

We cut plexiglass at the shop where I work and we keep the paper backing on. I am sure we use either a half inch end mill or 1/4” end mill. Yes, flying bits = not good. We tape down potential wood missiles with masking take to seal the vacuum hold-down. I am not sure of the spindle speed or feed rate. Have fun and be awesome!

-- Josh; Former Pennsylvanian, current Coloradan

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DLCW

523 posts in 1308 days


#6 posted 12-02-2012 05:29 PM

If you go to the ShopBot forum there are several threads on cutting plexiglass. Bits, feed speeds and spindle speeds.

Do a search on “plexiglass”.

-- Don, Diamond Lake Custom Woodworks - http://www.dlwoodworks.com - "If you make something idiot proof, all they do is make a better idiot"

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PRGDesigns

207 posts in 967 days


#7 posted 12-02-2012 06:13 PM

Thanks. I had previously searched other CNC forums with more confusion than answers on the subject. I searched the ShopBot site after you suggested it and found more consistent information. Thanks for the heads up.

-- They call me Mr. Silly

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