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Continuum Speakers Using my Trench Method on the MDF Seams

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  • #31
    Re: Continuum Speakers Using my Trench Method on the MDF Seams

    The Epoxy is thinner than the 2K primers so more coats are required. If you must use a 2k primer for filling use it after the epoxy primer.
    Coat the inside if the box to really seal it.
    Etching primer is for METAL ONLY. Nasty stuff do not use!!!!

    Comment


    • #32
      Re: Continuum Speakers Using my Trench Method on the MDF Seams

      Originally posted by djg View Post
      The Dupont self etching primer I am familiar with is for metal.

      http://www.pc.dupont.com/dpc/en/US/h...19303_615S.pdf
      I thought etch primer was etch primer? I am no expert but I have used it on mdf.

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      • #33
        Re: Continuum Speakers Using my Trench Method on the MDF Seams

        Etch Primer has an acid that etches into the metal for adhesion!
        Nasty stuff ! V.O.C is off the charts!

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        • #34
          Re: Continuum Speakers Using my Trench Method on the MDF Seams

          For those who do not have a compressor and paint guns try www.rotdoctor.com
          Paint it on with a brush then sand :-D

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          • #35
            Re: Continuum Speakers Using my Trench Method on the MDF Seams

            Originally posted by bigfishe View Post
            Etch Primer has an acid that etches into the metal for adhesion!
            Nasty stuff ! V.O.C is off the charts!
            We use etching ink in the factory for marking parts. You don't want to be anywhere near the stuff if you're in an enclosed space. Not only is it corrosive, it is some nasty smelling stuff.
            Click here for Jeff Bagby's Loudspeaker Design Software

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            • #36
              Re: Continuum Speakers Using my Trench Method on the MDF Seams

              What he said^

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              • #37
                Re: Continuum Speakers Using my Trench Method on the MDF Seams

                Originally posted by lucasa.miller View Post
                Can you give details on your paint setup? What do you use to spray the paint?
                I personally use a Binks 2001 with a 66SD tip. Only because I bought it over 20 years ago and from what I've been told there is no reason to replace it. I checked into an HVLP gun ,which I've used in the past, and was told if I'm not spraying a lot that it's really not worth spending the money for what it would save me in paint.
                I've also gotten use to the cup on the bottom and found it a little awkward with the cup on top. It does have the advantage of not spitting when the paint gets low but on the other hand it's hard to spray underneath something.

                I have a C-Air compressor. 5hp 17cfm @ 175psi. Upright with an 80 gallon tank. I use a toilet paper filter system. So for what I do I don't run the compressor hard enough to have water issues.

                Since I spray in my wood shop I made up a piece of 1/4" x 3' long copper tube adapted to a fitting that plugs into my air hose. The tip of the tub is slightly pinch. I use this to blow all the dust out of my shop. Works great to get down between tools and around objects. Spraying something like these speakers that I want a real nice job I'll put up a plastic curtain around the project to insure a cleaner environment. I also wet the floor for dust control. In this weather I open the garage door about a foot and the service door at the other end about 6" and that gives me a pretty good air flow.

                Dave
                http://www.pellegreneacoustics.com/

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

                Comment


                • #38
                  Re: Continuum Speakers Using my Trench Method on the MDF Seams

                  I absolutely agree with you. Why make it so complicated to begin with?
                  I think we all endeavor to find a way that will work best for us, and when we do, we stick with it. Regardless of the difficulty.
                  Trenching seems silly especially since there are other ways to achieve the same results. But joints are already the worst as it is, both structurally and cosmetically. In the cabinet industry, it's all about production and making a fast buck, so they use simple but joints.
                  What other ways will achieve the same results? If you mean miters, they do show the seam less but in my experience will still show through. On the stands I used a miter joint to build the post thinking if it shows a little it's not as critical as on the speaker itself. I still used body filler on the round over to fill in the end grain. I left a build up of filler so the MDF didn't show through and so far no seams. This makes me wonder if rounding the corner off more then you want and then filling it back in might just prevent the seam from showing. I hope to get paint on these next week so we'll see.
                  I may do some test pieces with filler and see how they hold up. The movement is less then a b u t t seam so maybe it won't take as much filler.


                  Dave
                  http://www.pellegreneacoustics.com/

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

                  Comment


                  • #39
                    Re: Continuum Speakers Using my Trench Method on the MDF Seams

                    Back to my stand post problem with the primer soaking in.

                    I sanded the posts with 180 grit which broke through the hard surface exposing the pits in the MDF.



                    This is how the 2K primer went on. It soaked into the pits and after sanding the pits where still there. I recoated with primer again and still had pits.



                    Rather then putting body filler over the primer I picked up some glazing putty. this is basically a thick primer in a tube. It spreads real easy and fills pits and scratches. It also sands easy.

                    This is with the glazing putt sanded with 400 grit dry paper.




                    After a new coat of primer pits gone. I'm going to have to try the glazing putty before any priming on the flat surfaces to see if this may cut down on the amount of primer needed. This may be a good option if you are not working with trenches and don't need to fill anything but pits and end grain.



                    Sanded with 400 dry paper. Seems to have worked well.




                    I have everything ready for paint hopefully I'll get time this week to shoot them.

                    Dave
                    Last edited by davepellegrene; 09-22-2013, 09:30 PM.
                    http://www.pellegreneacoustics.com/

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

                    Comment


                    • #40
                      Re: Continuum Speakers Using my Trench Method on the MDF Seams

                      Originally posted by davepellegrene
                      What I did notice I found interesting is all the ones with a trench has a crack in the center of the piece b u tting against the other piece. All the other samples no mater what finish or method does not have this crack. Originally I thought the body putty was flexing over the seam enough to keep it hidden. Now I wonder if part of what is going on is the putty is stopping the moisture from coming through the surface but still allowing it to get in and out through the back side. So the shrinking and expansion is now in the middle of the piece. If you look at my samples above you can see I experimented with a slot cut an 1/8" below the surface. None of those attempts worked.
                      I think the putty layer is rigid enough that it is preventing the longitudal piece to move forward on the outer surface, hence no seam visible from outside. But since the dimensional change still happens from humidity, it causes the crack inside while expanding. This brings the idea that if the piece gets "precracked" with a thin and deep enough slot in the middle like those cracks that happen, it may prevent the seam to show without putty. Basically allowing it to move with expansion. I see that you experimented with slots, but they may not have been at the right place and deep enough. Just an outsider observation and ideas.

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                      • #41
                        Re: Continuum Speakers Using my Trench Method on the MDF Seams

                        Originally posted by feyz View Post
                        I think the putty layer is rigid enough that it is preventing the longitudal piece to move forward on the outer surface, hence no seam visible from outside. But since the dimensional change still happens from humidity, it causes the crack inside while expanding. This brings the idea that if the piece gets "precracked" with a thin and deep enough slot in the middle like those cracks that happen, it may prevent the seam to show without putty. Basically allowing it to move with expansion. I see that you experimented with slots, but they may not have been at the right place and deep enough. Just an outsider observation and ideas.
                        I thought the slot was going to work and I was kind of surprised it didn't.

                        Dave
                        http://www.pellegreneacoustics.com/

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

                        Comment


                        • #42
                          Re: Continuum Speakers Using my Trench Method on the MDF Seams

                          I added the final sanding of the stand post in post #39. Seams to have work well.

                          Dave
                          http://www.pellegreneacoustics.com/

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

                          Comment


                          • #43
                            Re: Continuum Speakers Using my Trench Method on the MDF Seams

                            Finally got a chance to get them painted over the weekend.

                            A couple cell phone pics. I'll get them out in the light with a set of drivers in one for some final pics.

                            Italian sports car orange





                            I did not have any ghosting on the trench seams or on the 45 degree miters I did on the posts. The post miters are covered with a layer of body putty so maybe this will be enough that they won't show through. I'm definitely convinced the way to go is to sand all the MDF with 150 grit and skim with body filler. It seals the MDF without adding any moisture so the primer and paint can be put on without it adding any moister either.
                            Dave
                            http://www.pellegreneacoustics.com/

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

                            Comment


                            • #44
                              Re: Continuum Speakers Using my Trench Method on the MDF Seams

                              THAT COLOR IS SO LOUD

                              but it looks pretty awesome, is that Lamborghini?

                              रेतुर्न तो थे स्रोत
                              return to the source
                              leviathan system thread
                              deadhorse thread
                              shockwave build thread

                              instagram :: greywarden_13

                              in war, victory . . . in peace, vigilance . . . in death, sacrifice.

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                              • #45
                                Re: Continuum Speakers Using my Trench Method on the MDF Seams

                                Originally posted by davepellegrene View Post
                                The post miters are covered with a layer of body putty so maybe this will be enough that they won't show through. I'm definitely convinced the way to go is to sand all the MDF with 150 grit and skim with body filler. It seals the MDF without adding any moisture so the primer and paint can be put on without it adding any moister either.
                                Dave
                                Dave what body putty do you use that goes on that thin? Any special techniques for covering large surfaces before it hardens off?
                                John H

                                Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

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