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 Post subject: Routing Plastic
PostPosted: Mon May 19, 2014 5:04 pm 
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Walnut
Walnut

Joined: Thu Jan 12, 2012 7:54 pm
Posts: 19
First name: Bob
Last Name: McDonald
City: Petaluma
State: CA
Country: USA
Focus: Build
Status: Professional
I was curious to see what router bits other people use for machining plastic when doing pick guards and back plates. I discovered quickly that upward spirals don't always eject the cuttings and they wind up as a ball of party streamers rotating at 19k rpm. That can sometimes mark the plastic, even through the protective coating. Also when drilling 1/8" holes with Precise Bits drill for routers the same problem occurs. With an outside contour, this is not a issue as I band saw the rough shape before cutting with a down spiral. Using a down spiral for inside contours in plastic isn't something I would normally consider. In the past, I've used a 1/4" single flute straight cutter on acrylic with good results and have been thinking this might be worth a try, as the single flute can probably eject the material with less tendency to wrap around the bit. Anyone have experiences or thoughts to share? Thanks,

Bob


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 Post subject: Re: Routing Plastic
PostPosted: Mon May 19, 2014 7:37 pm 
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Mahogany
Mahogany

Joined: Thu Oct 25, 2012 8:45 am
Posts: 42
First name: anthony
Last Name: wickman
City: tallahassee
State: florida
Zip/Postal Code: 32301
Country: usa
Focus: Build
Status: Amateur
I sand plastic with 120grit belt then polish with a tycro cone.


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 Post subject: Re: Routing Plastic
PostPosted: Mon May 19, 2014 10:02 pm 
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Contributing Member
Contributing Member

Joined: Thu Mar 19, 2009 10:16 pm
Posts: 189
Location: Bell Buckle, TN.
First name: kevin
Last Name: waldron
City: Bell Buckle
State: TN
Zip/Postal Code: 37020
Country: USA
Focus: Build
Status: Professional
Use "O" flute bits......(half moon) from a good maker.

Blessings,

Kevin


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 Post subject: Re: Routing Plastic
PostPosted: Tue May 20, 2014 9:35 am 
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Cocobolo
Cocobolo

Joined: Mon Mar 03, 2008 6:51 pm
Posts: 488
+1 on O-flute bits. Onsrud is the brand that we use. Slow your RPM. 19K is way too fast IME. Amana makes a nice bevel bit for plastic. It uses inserts.

We use downcuts for all straight cuts. This requires a light sanding on the back to get rid of the burr. You also need to cut a deeper channel in your fixture to give the chips somewhere to go.

It's been so long I can't remember what a single flute straight O-flute bit cut like on plastic.


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 Post subject: Re: Routing Plastic
PostPosted: Tue May 20, 2014 12:09 pm 
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Walnut
Walnut

Joined: Thu Jan 12, 2012 7:54 pm
Posts: 19
First name: Bob
Last Name: McDonald
City: Petaluma
State: CA
Country: USA
Focus: Build
Status: Professional
Thanks Kevin and Sheldon for the info. I did some investigating and found single and 2 flute O bits with down, straight and up spiral configurations. My natural inclination would be to rout an interior pickup hole with an up cut. This could be an erroneous assumption as I've been routing neck and pickup cavities (in wood) with a down cut bit to keep the top edge clean with good results. Sheldon, it sounds like you're using a 2 flute down cut for interior pickup holes, is that correct? I assume you're also referring to the Amana V groove cnc bit for beveling. I've been using something I got from McMaster, but I don't like the finish it leaves.

I'm using a K2 cnc with a Porter Cable 7518 variable speed router. I'll experiment with slowing down the rpm as suggested. It goes as low as 10k, but loses it's torque down there. Presently, all my work is one off prototypes, so I don't have dedicated tooling for these projects. MDF, double stick tape and screws are my constant companions! Thanks again.

Bob


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 Post subject: Re: Routing Plastic
PostPosted: Tue May 20, 2014 2:36 pm 
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Cocobolo
Cocobolo

Joined: Mon Mar 03, 2008 6:51 pm
Posts: 488
http://www.amanatool.com/ingroove/

Yes, they are a V-groove bit. 90 degree bevel. Single flute so there's lots of room to clear chips.

We use downcuts for pickguards to keep from lifting them off the vacuum fixture and because I don't want to have a burr on the top edge of a PG.


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