Molding/casting? — Totseans

Molding/casting?

fagfag Regular
edited December 2011 in Life
Say one wants to make a guitar body out of acrylic resin..What would be the best thing to make the mold out of? SWIM hears plaster of paris is a bit bittle, and can easily break. It has to be something able to capture fine detail, be not brittle, and not chemically reactive with acrylic resin. Any ideas?

Comments

  • RogueEagle91RogueEagle91 Regular
    edited November 2011
    Try mdf. To my knowledge, the resin wont adhere to the mold.
    You'll likely have to build up multiple layers and rout/sand the interior to make it work properly.
    Do some research on that one first, as I'm not 100% on it.

    Past that, if you have any questions on guitar building, feel free to pm me. Building and repair is where I make a good chunk of my income.
    Good luck!
  • chippychippy <b style="color:pink;">Global Moderator</b>
    edited November 2011
    Resin sticks to MDF like shit to a blanket. You need to seal the mold if using MDF and spray it with a release agent.
  • RogueEagle91RogueEagle91 Regular
    edited November 2011
    I stand well corrected.
    Go chippy.
    Thought wax paper beneath might work, but that'd create some...interesting textures on the resin itself.
  • fagfag Regular
    edited November 2011
    Probably won't be using MDF. I don't really have the tools to shape it. I asked around, and it turns out I have a friend who is a personal friend with the the ceramics instructor here. I think she would be able to make a badass mold for me. Then I'll just find out what release agent is best for acrylic, and go ahead and cast the body. Making a copy of an Ibanez JEM body, if anyone cares. Mated up with an RG550 neck, I think it will kick major ass. :D
  • RogueEagle91RogueEagle91 Regular
    edited November 2011
    Are you going to do an SRV style monkey grip on the body?

    Best of luck with it.
    Be sure to post pictures when you're done!
  • fagfag Regular
    edited November 2011
    Are you going to do an SRV style monkey grip on the body?

    Best of luck with it.
    Be sure to post pictures when you're done!

    With any luck, it will be an exact replica of the JEM Im copying, complete with monkey grip and cool trem cavity. Also, I think you're thinking of Steve Vai, not Stevie Ray Vaughan.
  • RogueEagle91RogueEagle91 Regular
    edited November 2011
    Haha.
    So I am.
    Son of a bitch.
    I should probably stop responding to these things when I'm fucking exhausted.
    Very cool project, regardless.
  • fagfag Regular
    edited December 2011
    Haha.
    So I am.
    Son of a bitch.
    I should probably stop responding to these things when I'm fucking exhausted.
    Very cool project, regardless.

    Im pretty excited to start working with acrylic. Lots of stuff I want to experiment with. I would also like to build an electric cello, as I think one monolithic casting of acrylic could constitute the entire instrument, save for the tuning pegs and electronics.

    Also want to try making an acrylic ice scraper:
    urdefense_2183_12286568

    This is supposedly a CIA crafted weapon. 13 grams of metal-detector evading, vertebrae-detaching, bone-crunching, flesh lacerating polymer. Oh-so-easy to conceal, and easily extracted from the back pocket. It's already a stealthy implement, but imagine if it were transparent..It's likely under the stress, your enemy, nor bystanders would even see the weapon.
  • RogueEagle91RogueEagle91 Regular
    edited December 2011
    I've been thinking about doing acrylic for a while now, after seeing a custom shop that does the same thing with different shades of transparent resin.
    Very sharp looking pieces.
    Biggest reason I haven't looked into it is I've been exploring the effects of certain exotic woods and construction techniques on tone and sustain.
    Despite the overwhelming amount of tone that comes from your pickups, I am finding some species that I really enjoy the sound of.
    Also, I've made a chambered body design that all but eliminates the need for a reverb pedal (for those who need it) without any of the feedback issues some people experience with full or even semi hollow bodies.

    The cello seems like it'd be a bitch to mold.
    Luckily, if it's solid, you do eliminate the other major grievances with orchestral instruments.
    No sides to glue, no back and top to carve, no soundpost to set.
    I've seen some violins done in a similar manner.
    Very cool shit.

    If you're feeling experimental enough, check around for transparent dyes.
    Think you'd have some fun with those.
  • fagfag Regular
    edited December 2011
    Maybe the guitar could be cast with phosphorescent/fluoroscent stuff in the mix. Something like this, perhaps...Some electric celli are very simple shapes..

    DV020_Jpg_Jumbo_463028.008_brown_R.jpg


    I've never actually heard a synthetic guitar being played. I think it's a bit rash to assume that it will sound sterile, just because it's a synthetic material and not made from the flesh of another lifeform. It may be possible to change the resonant characteristics by embedding certain objects in the acrylic, or by forming resonant cavities..
  • RogueEagle91RogueEagle91 Regular
    edited December 2011
    I'm sure it'll have its own unique tonal properties, especially if you add any sort of density pockets in the mold.
    I'd think you could add some natural reverb by carefully adding air pockets, as well.
    I'm just having my own fun with wild woods.
    Whatever lights your creative fire, and all that, man.

    Didn't even think of casting a cello like that.
    Very streamlined look. I dig it.
    There is definitely a wide avenue to explore as far as design for the instrument goes with the acrylic.

    Also, food for design thought.
    Inject phosphorescent/fluorescent pinstripes.
    Whatever design, imagine a dark stage where the only thing you can see is a solid, glowing portion of your guitar.
    It would definitely turn heads.
  • fagfag Regular
    edited December 2011
    I'm sure it'll have its own unique tonal properties, especially if you add any sort of density pockets in the mold.
    I'd think you could add some natural reverb by carefully adding air pockets, as well.
    I'm just having my own fun with wild woods.
    Whatever lights your creative fire, and all that, man.

    Didn't even think of casting a cello like that.
    Very streamlined look. I dig it.
    There is definitely a wide avenue to explore as far as design for the instrument goes with the acrylic.

    Also, food for design thought.
    Inject phosphorescent/fluorescent pinstripes.
    Whatever design, imagine a dark stage where the only thing you can see is a solid, glowing portion of your guitar.
    It would definitely turn heads.


    You could even make a hologram of sorts..Like one of those shapeshifting multilayer holograms. Could look like some sort of psychedelic hallucination. But yeah. I wonder if it would be possible to cast an entire guitar out of one piece? Like, neck, fingerboard and all. Hammer the frets directly to the acylic..
  • RogueEagle91RogueEagle91 Regular
    edited December 2011
    I should think you'd be able to.
    You can build your neck as one piece as happens with maple necks with the same fretboard.
    You can build the body and neck as one piece as with neck thru designs.
    Why not combine them?

    From what I've seen, acrylic isn't a great neck material because of its brittle nature, unless you really baby the guitar.
    Saw some suggestions to use glass as a truss rod.
    On the brittle nature, whenever you're doing casting, make a spare block and test out the fretting capabilities.
    Sawing might be doable, but the barbs on the fret tang might cause cracking.

    By the way, just happened across a site that's done the same design that you're doing (I think).
    LINK

    By the way, this whole discussion is making me want to try out acrylic...
  • fagfag Regular
    edited December 2011
    They built it pretty much exactly..I just wonder if an acrylic neck would feel weird. Like if it would be as smooth against your hand as maple, or if it would feel sticky and crappy. Maybe I'll buy one of their acrylic bodies off them, since I already have all the parts needed to make it into a complete guitar..It would probably be cheaper than buying all the stuff to make one, and I will be able to see if the sound of acrylic is even worth messing with..

    acl_1.jpg
  • chippychippy <b style="color:pink;">Global Moderator</b>
    edited December 2011
    An acrylic neck would take some machining. How you gonna drill a 3' hole through it for the torsion bar?
  • fagfag Regular
    edited December 2011
    chippy wrote: »
    An acrylic neck would take some machining. How you gonna drill a 3' hole through it for the torsion bar?

    That is a silly question. You could probably leave a piece of lubricated allthread/really long screw in there when you cast it. Then unscrew it when the guitar is cured. Then again, who is to say a torsion bar(or at least an adjustable one) would even be necessary?

    Either way, Fender figured it out.

    lucitefull.jpg

    Be really cool if the only electronics it had on board was a piezo, and there was a very discreet bridge/tuner. It would practically be an air guitar! Other than weight, of course. Acrylic is apparently 1.2g/cm3. Alder and mahogany drift somewhere around 0.5g/cm3.
  • chippychippy <b style="color:pink;">Global Moderator</b>
    edited December 2011
    It wasn't a silly question. And yes it would need one. I came a cropper building a wooden one when it came to boring the hole. I ruined 3 necks before I gave in and had it done at a workshop with the correct machinery for doing it, and I'm a joiner. Good idea about putting a removable plug in there though. that may work.
  • fagfag Regular
    edited December 2011
    chippy wrote: »
    It wasn't a silly question. And yes it would need one. I came a cropper building a wooden one when it came to boring the hole. I ruined 3 necks before I gave in and had it done at a workshop with the correct machinery for doing it, and I'm a joiner. Good idea about putting a removable plug in there though. that may work.

    You could do it the conventional way..Do an acrylic neck, insert the truss rod, then adhere the acrylic fingerboard..Would the torsion bar need to be adjustable? Why not just use a tempered steel bar or two?
  • chippychippy <b style="color:pink;">Global Moderator</b>
    edited December 2011
    Depends on what strings you use to what tension the neck is under. You quite often have to fine adjust the bend of the neck to get the strings parallel to the frets. It depends whether you want to end up with a good instrument or a great one. And yes I do play. Been playing for almost 40 years now. Been in a couple of bands and used to teach guitar part time.
  • fagfag Regular
    edited December 2011
    I typically run a very low-tension setup. 9's in DGCFAD. But yeah, great guitars are nice. :D
  • RogueEagle91RogueEagle91 Regular
    edited December 2011
    Installing a truss rod isn't a must, but it can be incredibly useful, especially if you're thinking of doing a one piece casting.
    I'm sure chippy could give more insight on the how for this than I, but you could rout the back of the neck fender style and re-fill the cavity with an acrylic strip with a different shading, emulating the rosewood strip.

    fag, your tuning will have a lower tension, but I would personally install the truss rod, anyway.
    Until you actually string it up, you're not going to know exactly how the neck will bow.
    Also, leave yourself open to doing different setups.
    If you ever want heavier strings or to go with Standard tuning, you've got an increase in tension.
    Straight truss=no adjustment to your action.

    If you do cast the neck, don't use allthread.
    You'll get a cavity, but it either wont secure your truss rod properly or it just plain wont go in.
    To give you an idea, block style adjustable (which is much the same as any non-adjustable you'll use), traditional rod, note the washers/stops used for tension, and a final option for non-adjustable carbon fiber.
    You might be able to get away with two smaller CF rods run parallel and not have to worry about future tuning choices.
    Best thought, if you want to do one piece, use a squared metal rod you can coat with something that wont adhere.
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