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Thread: Machining/Routing Celluloid

  1. #1
    Registered User Max Girouard's Avatar
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    Default Machining/Routing Celluloid

    Anyone have any experience machining or routing celluloid? I'm planning on making some pick guard / finger rests out of some celluloid sheet and want to try cutting it with either a CNC or on a router table. Normally I'd just jump in and experiment, but due to the nature of the material and the risk of burning down my shop I'm approaching this with a little more caution!

  2. #2

    Default Re: Machining/Routing Celluloid

    I once set a celluloid tele pickguard on fire routing it for a pick-up. I'd be hesitant to use a router/laminate trimmer on one again.

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    Default Re: Machining/Routing Celluloid

    I've done several Loar replica guards and have a pin router template and jig that I use. I take several smaill bites and keep the material moving pretty quickly as it's cutting. I haven't seen any indication of overheating doing it this way.

  4. #4

    Default Re: Machining/Routing Celluloid

    10,000 rpm, single-flute (o-flute) cutter, 100ipm (assuming .020" passes with a 1/4" cutter), and blast it with a 20-30psi air blast. If it doesn't get hot, it won't catch on fire.
    If it got hot enough for it to be a problem, it would be too hot to be cutting nicely.. so it's really the same as any other plastic. You want the heat to leave the part in the chip. The part itself shouldn't get hot. That's why you use a low spindle speed and a high feed rate with a large flute volume cutter. Don't heat up the part, heat up the swarf, then get rid of it. You shouldn't smell hot plastic when you're machining, regardless of the polymer. But I bet your shop will smell nicely of camphor for a few days... :-)

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  6. #5
    Registered User Max Girouard's Avatar
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    Default Re: Machining/Routing Celluloid

    Thanks everyone for the input. Thanks Marty for the details on machining. I'm going to have to get myself one of those cold air guns before I give this a try.

  7. #6
    Registered User Frank Ford's Avatar
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    Default Re: Machining/Routing Celluloid

    Quote Originally Posted by Marty Jacobson View Post
    10,000 rpm, single-flute (o-flute) cutter, 100ipm (assuming .020" passes with a 1/4" cutter), and blast it with a 20-30psi air blast. If it doesn't get hot, it won't catch on fire.
    If it got hot enough for it to be a problem, it would be too hot to be cutting nicely.. so it's really the same as any other plastic. )
    That's right, and little weenie guys like us don't have celluloid fires and explosions because the stuff we work on is so small, and because we use so little at a time. Obviously, a build up of celluloid bits, particles, and dust would be asking for a problem - that's sloppy factory kind of behavior. Belt sanding celluloid can generate enough heat to start it burning, and I do that all the time with little pieces, making elevated pickguards and such. If it catches fire, I simply hold it up, puff it out like a single birthday candle, and get back to work.

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    Registered User David Houchens's Avatar
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    Default Re: Machining/Routing Celluloid

    Using a heat gun to soften for bending, you generally see it start to disappear right before it blazes. Very frustrating when I'm fitting at a body point.

  10. #8
    Registered User Max Girouard's Avatar
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    Default Re: Machining/Routing Celluloid

    Quote Originally Posted by Frank Ford View Post
    Belt sanding celluloid can generate enough heat to start it burning, and I do that all the time with little pieces, making elevated pickguards and such. If it catches fire, I simply hold it up, puff it out like a single birthday candle, and get back to work.
    Yep! That is where I run into all my "small shop fires". I'm so paranoid about burning my shop down that I give the shop a very thorough cleaning and do not use my dust collector when sanding those pieces. I'm worried that a smoldering ember might get sucked up into the collector and ignite the dust in the bag. I've also had the bandsaw cause it to puff up in smoke while I was cutting that 15th fret cross piece to size. I always have a portable fire extinguisher right next to me whenever I'm working with the stuff.

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  12. #9
    Registered User crooksj's Avatar
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    Default Re: Machining/Routing Celluloid

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    Had a scare trimming binding on my router table. Small fireball while pulling binding across the table. Done this a dozen times before, but today I was “blowing out birthday candles” on my router table. Maybe time to replace a dull carbide downshear bit?

  13. #10
    Adrian Minarovic
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    Default Re: Machining/Routing Celluloid

    You can also do a test piece out of PVC sheet and see how the cut edges behave, if the chips fly away and leave clean surface it is ok if they remain fused to the edge by the heat you are going too slow or RPM is too high for your bit.
    Adrian

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    Formerly F5JOURNL Darryl Wolfe's Avatar
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    Default Re: Machining/Routing Celluloid

    Max, I do this all the time. On a router table, with pattern bit, template and carpet tape. The trick is to work the celluloid down close to the pattern you are using via a spindle sander. This way you are not over gouging the bit teeth which leads to snags and vibration. I've got my binding jig on right now, but this is the bit I use, and here are some of my patterns. I also traced the A5 guard

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    Darryl G. Wolfe, The F5 Journal
    www.f5journal.com

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  17. #12
    Teacher, luthier
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    Default Re: Machining/Routing Celluloid

    I have always roughed them out with a coping saw or bandsaw, followed by touch up on a belt sander, and finishing them off with hand tools. My shop space is limited. I don't have routing tables or CNC.

  18. #13
    Registered User amowry's Avatar
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    Default Re: Machining/Routing Celluloid

    Yes, it's probably time to replace the bit. Like Adrian said, if the bit is sharp and the celluloid is still getting hot, you can increase the feed rate or decrease the cutter speed. The idea with any machining is that the shavings carry away the heat, so you should be feeding the material fast enough to produce plentiful shavings. I machine a lot of celluloid, and I find it one of the nicer plastics to work with. It doesn't melt as easily as acrylic, and it isn't stringy like nylon, so it tends to cut very cleanly.

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