Polycarbonate - off topic


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    Cool Polycarbonate - off topic

    All;

    I know this isn't really a Tormach question, but I don't post on that many forums, and this is about as close as I could get.

    I need to place some small magnets ( 3/8") into bores in polycarbonate, and I'm looking for advice as to the best way to do it.

    My initial thought is a light press fit, but I have very limited experience with polycarbonate, and I'm concerned that this may cause micro cracks to develop over time and lead to failure.

    Is this a valid concern? My next thought was to epoxy the magnets in place.

    Any advice would be much appreciated.

    Terry

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    I use lots of small magnets in 3D Printed Assemblies.

    I find that a snug fit, as in finger tight with water thin ACC adhesive works very well. I would share your concerns with a press fit.

    I also print polycarbonate, makes very durable assemblies.


    Gary

    Quote Originally Posted by MFchief View Post
    All;

    I know this isn't really a Tormach question, but I don't post on that many forums, and this is about as close as I could get.

    I need to place some small magnets ( 3/8") into bores in polycarbonate, and I'm looking for advice as to the best way to do it.

    My initial thought is a light press fit, but I have very limited experience with polycarbonate, and I'm concerned that this may cause micro cracks to develop over time and lead to failure.

    Is this a valid concern? My next thought was to epoxy the magnets in place.

    Any advice would be much appreciated.

    Terry




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    Default Re: Polycarbonate - off topic

    Thanks Gary, I like your approach, think that I will try that first.

    I am milling one part that will be held in place magnetically to another one that I had planned to print in PLA. I've never used a polycarbonate filament before. Any advantages over PLA? I assume that the poly filament will work with standard printers, temps, diameter, etc.

    Terry



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    Default Re: Polycarbonate - off topic

    Have you considered epoxy?



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    Default Re: Polycarbonate - off topic

    I have, that was my second thought after the press fit.

    I just finished milling the first piece and the fit of the magnet in the hole is very close, I suspect I will have better luck on this one with the CA, because I don't believe I can get enough epoxy between the magnet and the poly to create a decent bond.

    Terry



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    Default Re: Polycarbonate - off topic

    Quote Originally Posted by MFchief View Post
    I have, that was my second thought after the press fit.

    I just finished milling the first piece and the fit of the magnet in the hole is very close, I suspect I will have better luck on this one with the CA, because I don't believe I can get enough epoxy between the magnet and the poly to create a decent bond.

    Terry
    CA does not bond well to smooth surfaces. see this article.

    https://www.starbond.com/tutorials/w...dhere-well-to/



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    Default Re: Polycarbonate - off topic

    Fractures usually start around drilled holes. I use a propane torch to melt the edges of acrylic or plexiglass to head off later fractures. Lexan has a very fine point between melting the edge and burning. I don't know if any type of glue will prevent this.

    Rough drilling and boring may give a better surface finish that will not fracture.

    Dave



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    Default Re: Polycarbonate - off topic

    I have read various accounts that most common adhesives don't play well with polycarbonate, CA's and epoxies included. The stress relief of the torching sounds like it could help.

    I have room to put a plug behind the magnet, and plan to leave a small thin lip in front of the magnet to keep it from pulling out to the other magnet it faces. I hope that will do the job, it's not a super critical situation, so I think that will work.

    Terry



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    Default Re: Polycarbonate - off topic

    I haven't glu3e to PC, but I have glued to that really-slick stuff: acetal!

    The adhesive that works there is "show goo," which is made to waterproof hiking shoes. But ... it also bonds pretty well.

    Sounds like you have something that works, but if you need to experiment more, I'd recommend that!



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    Default Re: Polycarbonate - off topic

    CA will work just fine, just make sure you don't over-do it, as it will make a mess of ANY surface it touches. Gorilla brand "Super Glue" is, by FAR, the best I've found for gluing to Acrylic and PolyCarbonate, and is thick enough to fill any small gaps. Many others will not stick at all. Applied to a machined surface, you will never be able to get the magnets out, without destroying the Poly.

    Regards,
    Ray L.



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    Default

    PC prints well but requires much higher temperatures. Usually 260 to 300 C for me but it is good stuff, about the same or a little better strength than nylon BUT more difficult to print.

    PC prints well on a PEI bed with the bed temps between 100 - 120 C.

    PC absorbs water and must be throughly dried. It also wants t
    o shrink and curl up on the bed. Requires planning and good design but it is good stuff for strength.

    Quote Originally Posted by MFchief View Post
    Thanks Gary, I like your approach, think that I will try that first.

    I am milling one part that will be held in place magnetically to another one that I had planned to print in PLA. I've never used a polycarbonate filament before. Any advantages over PLA? I assume that the poly filament will work with standard printers, temps, diameter, etc.

    Terry




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    Default Re: Polycarbonate - off topic

    Thanks for the tips Gary, I'm going to get some and play around with it.

    I have some Gorilla brand CA, that's what I plan to use, I'll let everyone know how it comes out. It will take a few days, Cura says it's going to take 20 hours to do the print I need, and I'm still fiddling with the CAD for the part.

    Terry



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Polycarbonate - off topic

Polycarbonate - off topic