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Making sawdust on some CJD RS150 MTM's

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  • Making sawdust on some CJD RS150 MTM's

    after a few "preliminary" projects, i've finally gotten around to starting the project that i began diy speaker building for: new l/c/r for my dedicated theater. i've chosen to do cjd's rs150 mtm's, with the 27tdfc tweeter, and the seas generic on-wall crossover version. these will all be vertically oriented at the same height, with their backs right up against the front wall of the room, behind a spandex AT screen (which i have yet to build - too many projects, too little time), hence the on wall version of the crossover. since these will see about 80% movie use, and space was a concern, i've chosen to go with a sealed cabinet. i shrunk cjd's sealed dimensions just slightly, for dimensions of 7.5"w x 20"h x 12"d. i'm the weird OCD type and i like numbers like "20" and "12" better than "21.5" and "12.5". i kept the baffle width the same, since we all know thats the one that counts. in some simulations i did, when crossed over at 80hz, the smaller cabinet (as compared to cjd's dimensions) barely changed the low end any, if at all.

    one new thing i've done in this build that i didn't do in any of my previous, was to use the cutlist program to generate my cut sheet, then print that out and mark and number each cut i intended to make, in the order i intended to make them. this made for a foolproof way to end up with the largest possible pieces of scrap, and more importantly, to make all cuts without ever having to set my fence more than once for a given dimension. that, combined with replacing my 6 year old stock 40t table saw blade with a new freud diablo 60t, has resulted in the most accurate and consistent panels i've ever made. another thing i plan to do for the first time on this build is to use biscuit joinery to help align my panels for (hopefully) more consistent overhangs, resulting in squarer boxes after flush trimming.

    haven't made a final decision on finishing yet, but they'll definitely need to be something black since they're going behind an AT screen. the ebonized ash used in this khanspire build kind of caught my eye, as i much prefer veneering to painting, and i thought it might be cool to show the real version of what all the crap in big box stores are trying to look like. the only drawback is that i'd hate for it to turn out "not better enough" that the untrained eye couldn't differentiate it from said crap. i've also thought about some more "industrial" type finishes (rolled on bedliners, undercoatings, and the like), but as i'm intending this to be my best build yet, i feel that they deserve better than that.

    but there's still plenty of time for all that. as of right now all i've done is cut all my panels. none-the-less, what would a build thread be without some pictures...




  • #2
    Re: Making sawdust on some CJD RS150 MTM's

    nice way to tackle the project. keep us informed.
    " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

    Quote Originally Posted by hongrn. Oct 2014
    Do you realize that being an American is like winning the biggest jackpot ever??

    http://www.midwestaudioclub.com/spot...owell-simpson/
    http://s413.photobucket.com/albums/pp216/arlis/

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    • #3
      Re: Making sawdust on some CJD RS150 MTM's

      made some more progress over the last couple days. don't have last nights shots uploaded yet, but here's some from tuesday. the biscuit joining is working great. i spent a lot of time measuring and thinking through, practicing, and refining the method i would use. and for once i was conscientious to take pictures showing each step, so maybe someone can benefit from this in the future. here goes...

      first, transfer "side to side" lines from the top/bottom cabinet pieces onto the side pieces. note that these do not have to be exact, as biscuits don't hold things firmly in place in this direction.


      and here's a shot of the successfully transferred marks


      next, for the "depth", i pulled a tape from the side of the board i just transferred marks onto, and made a mark to show where i wanted top (front, when turned vertical) of the biscuit joiner to be. in my case, i measured the height of the joiner with a caliper to be 4.125". i wanted to have a 1/16" lip, and needed to add a little more to account for the fact that the slots in the ends of my top/bottom pieces are not completely centered vertically in the edges of the boards. 4.125 + .0625 + a little bit = 4.25"


      then, set my square/fence at the mark i just made, so that it will be square to what will be the baffle mating surface (in other words, square to the front of the speaker).


      clamp that down, and we're ready to go


      a shot of the joiner standing vertically, with it's top/front against the fence


      same thing, different angle


      after both spots have been plunged with the joiner


      showing how the two boards to be joined match up


      goes together perfect, nice and square to the face




      and with a nice consistent lip and no movement up and down, glue up should be a snap


      and finally, a dry fit of the finished product


      one more just for the heck of it...

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      • #4
        Re: Making sawdust on some CJD RS150 MTM's

        Well done.

        CenTech rules!
        My projects
        https://picasaweb.google.com/112307725038877176664

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        • #5
          Re: Making sawdust on some CJD RS150 MTM's

          Originally posted by ckmoore View Post
          CenTech rules!
          heck yea. harbor freight FTW. save money where you can, so you can spend it where it counts!

          here's last nights progress. top, bottom, and sides of the first box put together. glue up is definitely easier with the biscuits setting the overhang and holding everything in place. decided to go with dowels for braces to make it easier to maneuver the crossover and stuffing through the woofer holes, rather than a shelf brace or two like i was originally planning, which would have made all that quite difficult. tonights progress looks about the same, except its the second box instead of the first. i also got the first box flushed trimmed after gluing and clamping the second box, but i didn't feel that merited a picture.

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          • #6
            Re: Making sawdust on some CJD RS150 MTM's

            Awesome! My dad bought a biscuit joiner and used the crap out of it! Did you leave the bit on the ends so you could route it smooth or is that aesthetics?

            रेतुर्न तो थे स्रोत
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            • #7
              Re: Making sawdust on some CJD RS150 MTM's

              Originally posted by greywarden View Post
              Awesome! My dad bought a biscuit joiner and used the crap out of it! Did you leave the bit on the ends so you could route it smooth or is that aesthetics?
              for flush trimming. i always go an eighth big vertically on the sides, and both ways (vertically and horizontally) on the baffle and back.

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              • #8
                Re: Making sawdust on some CJD RS150 MTM's

                Originally posted by absolootbs View Post
                for flush trimming. i always go an eighth big vertically on the sides, and both ways (vertically and horizontally) on the baffle and back.
                Looking good so far, and +10000000 on the flush trim bit idea - wish I had heard about that three years ago.
                Don't listen to me - I have not sold any $150,000 speakers.

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                • #9
                  Re: Making sawdust on some CJD RS150 MTM's

                  had a busy weekend, so i didn't really get anything done saturday or sunday. but i did make some progress last night. all three boxes now have four sides and braces, and are flush trimmed. on all three boxes, i managed to get everything glued, set, and clamped before i realized i'd forgotten the braces. on two of the three i was able to unclamp, pull a side off, put the braces in, add a little more glue, and put the side back on. on the third the glue had set too much already and i had to slide the braces in. despite not having as much glue on them as i would have liked, as a result of the sliding, they seem to be holding fine. how i managed to mess that up not one, not two, but THREE TIMES is beyond me.

                  also got a start on the baffles. i don't wanna jinx myself, but assuming i follow my layout lines, this will be my first ever build where i've made the baffles symmetrical from the get go, rather than getting them all finished, realizing they're identical, and having to re-do one of them.

                  here's how things currently stand. i didn't get any pictures with them sitting up against each other with straight edges/squares on various sides, but i did check all of that and they are very very close. two match each other pretty much exactly and are as close to square as you can get without being dead on. the third leans forward ever so slightly. still, i'd say the biggest variance from one box to the next, or out-of-square, is less than 1/32". certainly nothing to gripe too much about.









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                  • #10
                    Re: Making sawdust on some CJD RS150 MTM's

                    This is my first post around here. I must say it's a little intimidating as you guys make it all look so easy!
                    Now accepting submissions at Homebuilt Hi-Fi website

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                    • #11
                      Re: Making sawdust on some CJD RS150 MTM's

                      this is not his first build. it would seem he is a woodworker and a clear thinker. this helps alot.
                      " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

                      Quote Originally Posted by hongrn. Oct 2014
                      Do you realize that being an American is like winning the biggest jackpot ever??

                      http://www.midwestaudioclub.com/spot...owell-simpson/
                      http://s413.photobucket.com/albums/pp216/arlis/

                      Comment

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