Announcement

Collapse
No announcement yet.

ABS Wave Guide

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • ABS Wave Guide

    I've been reading the wave guide threads and was thinking about how I've been heating plastic pipe to bend it. Once you get the plastic hot enough it's almost like rubber. Just for fun I took a piece of 2" abs and cut it 7 1/2" long, put a slice down the side of it on my table saw. I then took my heat gun and heated the pipe hot enough to open it up to a flat sheet. I cut an 1 1/4" dowel rod an 1 1/2" long stood it on end then laid the abs sheet over top of it. I cut a 4" piece of abs pipe a couple inches long and laid it over top and pushed down on it until it touched the table. I held it there until it cooled enough to hold the shape. so it ended up an 1 1/2" deep with a diameter o
    f 4". It makes me think you could buy sheets of some sort of plastic and have an inner and outer mold made up that you could heat the plastic and sandwich it in between the two molds.
    The whole process took about 10 minutes.



    Dave
    Last edited by davepellegrene; 10-27-2012, 03:08 PM.
    http://www.pellegreneacoustics.com/

    Trench Seam Method for MDF
    https://picasaweb.google.com/101632266659473725850

  • #2
    Re: ABS Wave Guide

    Dave you are truely a renaissance man, or mad scientist, whichever title you prefer.

    Comment


    • #3
      Re: ABS Wave Guide

      Great idea! I saw someone do something similar by heating a smaller diameter ABS tube itself and at the same time, pressing it down over a 1 gallon glass wine bottle.
      Audiophiles listen to the equipment, not the music.

      Comment


      • #4
        Re: ABS Wave Guide

        I've been thinking of a similar process, using a male mold and a type of plastic suited for heat shaping. A matched male/female set would probably be even better, but the female half would have to be undersized in every dimension to correspond to the male form (this sounds a bit like an old Biology lecture:o). Plexiglas is readily available at home improvement centers -- I know it will become pliable with heat, but there are probably more suitable materials available.

        This process will unavoidably result in stretched material, causing thinned areas -- some perhaps too thin. I'm thinking that a guide made by this process would benefit from reinforcement on the back side, accomplished by pouring in a "moldable" material such as plaster of Paris.

        For me, the question is the shape/contour of the wave guide. Is there a consensus of opinion about an optimal size and shape? Dave, yours looks almost perfect.
        Tritrix HT:http://techtalk.parts-express.com/sh...d.php?t=222519
        Dayton 12" Subwoofer: http://techtalk.parts-express.com/sh...d.php?t=222930
        Overnight Sensations: http://techtalk.parts-express.com/sh...d.php?t=223751
        Cerberus sub: http://techtalk.parts-express.com/sh...hlight=cerebus
        Duellatis: http://techtalk.parts-express.com/sh...d.php?t=224943
        NTN's: http://techtalk.parts-express.com/sh...d.php?t=227902

        Comment


        • #5
          Re: ABS Wave Guide

          It's called "drape molding", and a google search will get you lots of hits.

          "drape mold acrylic" might be especially useful, since you can by acrylic sheet in many thicknesses at Tap Plastic . . . and you can solvent and/or thermal weld gussets, mounting plates or additional shapes with ease. ABS obviously works too . . . as do a number of artist's molding clays, like Sculpey.

          Pick a profile, shape the plug (mold), and you're in business . . .
          "It suggests that there is something that is happening in the real system that is not quite captured in the models."

          Comment


          • #6
            Re: ABS Wave Guide

            Dave - do you know how hot you're getting the ABS? I could make a male + female mold pretty easily from glass filled nylon, but it starts to move at about 140C. If the ABS is not quite that hot when you're working it, it should work great. This could be the answer to cheap waveguides we've been looking for.

            Dan
            _____________________________
            Tall Boys
            NRNP Computer Sub
            The Boxers
            The Hurricanes
            The Baronettes
            Conneccentric
            UX3

            Comment


            • #7
              Re: ABS Wave Guide

              Originally posted by Soundslike View Post
              For me, the question is the shape/contour of the wave guide. Is there a consensus of opinion about an optimal size and shape? Dave, yours looks almost perfect.
              As usual there's not really any such thing as optimal, and even if there was there wouldn't be any consensus. It all really depends on your goals and what you are trying to achieve. But these are really just small horns and can be modeled with any program that can simulate horns.
              Don't even try
              to sort out the lies
              it's worse to try to understand.

              Comment


              • #8
                Re: ABS Wave Guide

                Originally posted by diy speaker guy View Post
                As usual there's not really any such thing as optimal, and even if there was there wouldn't be any consensus. It all really depends on your goals and what you are trying to achieve. But these are really just small horns and can be modeled with any program that can simulate horns.
                So to achieve the potential acoustical benefits of a wave guide, each one must be individually tailored for the system it will be used in. I guess I've assumed that since a wave guide could be fashioned from MDF, using a lathe, or chucked up in a drill press, and since the discussions I've read here about wave guides often focus on methods suitable for producing a bunch of them rather than using more common one-off methods, that the goal is to turn out a bunch of them that would produce some benefit for a variety of speakers...
                Tritrix HT:http://techtalk.parts-express.com/sh...d.php?t=222519
                Dayton 12" Subwoofer: http://techtalk.parts-express.com/sh...d.php?t=222930
                Overnight Sensations: http://techtalk.parts-express.com/sh...d.php?t=223751
                Cerberus sub: http://techtalk.parts-express.com/sh...hlight=cerebus
                Duellatis: http://techtalk.parts-express.com/sh...d.php?t=224943
                NTN's: http://techtalk.parts-express.com/sh...d.php?t=227902

                Comment


                • #9
                  Re: ABS Wave Guide

                  PE sells ABS sheets so you could start with something flat.
                  http://www.parts-express.com/pe/show...number=265-948

                  Comment


                  • #10
                    Re: ABS Wave Guide

                    It would be interesting to go from the 3" hole size in the plywood to a 5" hole keeping the depth the same and see how different it measures.
                    Dave
                    http://www.pellegreneacoustics.com/

                    Trench Seam Method for MDF
                    https://picasaweb.google.com/101632266659473725850

                    Comment


                    • #11
                      Re: ABS Wave Guide

                      Originally posted by Soundslike View Post
                      So to achieve the potential acoustical benefits of a wave guide, each one must be individually tailored for the system it will be used in. I guess I've assumed that since a wave guide could be fashioned from MDF, using a lathe, or chucked up in a drill press, and since the discussions I've read here about wave guides often focus on methods suitable for producing a bunch of them rather than using more common one-off methods, that the goal is to turn out a bunch of them that would produce some benefit for a variety of speakers...
                      Well... there's nothing wrong with trial and error but if you want to move quickly to a decent result it pays to do some quick simulations. The waveguide will affect every aspect of the driver's performance. The depth and shape of the flare will affect directivity and the frequency range the waveguide is useful for, power handling, frequency response, basically everything. Using a waveguide without simulating is kind of like picking a box for a driver without knowing t/s specs. It might work well... it might not.
                      Don't even try
                      to sort out the lies
                      it's worse to try to understand.

                      Comment


                      • #12
                        Re: ABS Wave Guide

                        What if you use an aluminum cone from a woofer as a buck to heat form the ABS to? The cost of say a Dayton RS 8" woofer would be minimal if the profile of the cone worked out as a WG form.
                        A mains
                        The Ventures
                        Open Invit8tions
                        RSR
                        Sound Troopers
                        Acorns
                        442
                        DGBG's
                        The Monuments

                        Comment


                        • #13
                          Re: ABS Wave Guide

                          You can also use acetone to melt ABS plastic pieces into a workable paste, which hardens into one piece as it dries.

                          http://www.mp3car.com/fabrication/45...se-them-2.html

                          Comment


                          • #14
                            Re: ABS Wave Guide

                            Originally posted by 6thplanet View Post
                            the profile of a WG
                            It is easy to turn any profile you want in plaster or clay on a potter's wheel, and not that much harder to do it by turning a pattern (instead of the workpiece) on a drill press. Both (plaster and clay) harden temperature resistant and plenty strong to allow even vacuum assisted forming.
                            "It suggests that there is something that is happening in the real system that is not quite captured in the models."

                            Comment


                            • #15
                              Re: ABS Wave Guide

                              Assuming you've got a spare stove in an area where you won't give yourself chemical poisoning you can do amazing things shaping polycarbonate plastic, you just need mold pieces that will withstand temperatures to around 200f. The possibilities are quite endless, simple bends can be made quite easily with a heat gun and some practice as well.

                              Comment

                              Working...
                              X