@Kornbread said:
Had good luck with Gorilla glue, or poly glue for plastic to wood. With a double wall, I like to router a step maybe half way into the wall so the pvc can be butted up against that and glued in place. After the glue dries, router a roundover in the outer layer of ply.
Have not tried Gorilla or poly glue, will check into this. Does the Gorilla or poly glue stay soft when it cures? Or does it harden and become brittle? I know 100% silicone does not work well gluing foam type rubber material. I peals off easily. But it stays soft and sticks pretty good to PVC, especially if I rough the PVC up with sandpaper before application and then let it cure out for several days.
I agree. But I would need to find an epoxy that is thick and and will stay in place as it cures. I cut the holes so that they have an approximate 1/64 to 1/32" gap all the way around the PVC coupler. The silicone will fill the gap and then stay in place as it cures to form a fairly rigid bond.
I never use silicone on or near anything I'll be applying paint or a finish to. Around the bath tub or shower wall, ok. On speaker projects, no.
If you have a small gap mix up a 5 minute setting epoxy and let it sit for almost 2 minutes before applying it. That has always worked well for me when gluing in PVC ports.
I would just tape the the front and pour the epoxy from the back. I also use mdf dust to thicken epoxy on some occasions, but not in a situation such as this.
Will have to use the slow cure type epoxy, giving it plenty of time to fill the long, thin gap. The gap will be .05 inches all around. 5 minute epoxy might set up too fast. Will mix it up without flour or thickener. Maybe use a small toothpick to agitate the gap a little bit to eliminate bubbles and/or air pockets. And a few small alignment shims to keep the gap consistent all the way around.
If you sand the opening into a slight funnel shape, it will be easier to pour, and with epoxy the strength isn't compromised, it's stronger than the surrounding wood.
I routed a 3 1/8 x 3 1/8" recess 3/4" deep into the lower back and then glued a small 30 degree beveled piece of hardwood (maple) to the upper edge of this recess. A dual banana jack mounts to the bevel, providing easy access for bare wire, spade lug, or banana plug type connections.
I squared up the top two corners of the recess with a chisel, then clamped and glued the hardwood in place:
Project is done. @jhollander - John, as suggested, a flare/no flare test, see spreadsheet below. @6thplanet - Eric, thanks again for your donation to the cause of high power chuffing experimentation.
I know this is a sub that will be low passed fairly low, but it would be interesting (at least to me) to see near field port measurements with and without the low pass filter applied. A port that long must have a significant resonance.
Anywho those boxes look great Bill! The tall phallic ports not so much. You should build a tall pair of shallow MTM's to set on top of them and sort of hide the big black shafts
Well, I hope everyone is getting their jollies at my expense, but the commentary totally misses the point of using an external port system. If I was really interested in the aesthetics, I would have used real wood veneer instead of peel & stick. I was going to leave the boxes completely unfinished, but I had a big roll of peel & stick laminate left over from another project, just sitting on the shelf, so I decided to use it up before the adhesive went bad. Even so, if you look closely at the pictures, you can see air bubbles in several places where the adhesive is giving way. The only way to get rid of the bubbles is to place a large foam backed board over the bubbled up area and clamp the board firmly in place for several hours.
Anyhow, the point of using an ugly looking external port is so that I can hot swap port lengths while playing music, adjusting the length for the best satellite blend. I currently have 10 different port lengths that I am experimenting with. Can't do that with an internal port! I also want to experiment with an external trapping system to kill the 1st or 2nd port/box resonances. Again, can't do that with an internal port.
In addition, because I used a coupler instead of a closet flange, I can easily convert to a fixed length internal port system later on, should I choose to do so, after I get done experimenting.
With vinyl wrap bubbles another alternative is puncturing followed by rolling using your rubber veneer roller. Use the smallest point you have.
This is how the professionals do it on automotive wrap. The pin hole is not visible afterwards. You may need to create a couple three on each bubble depending on how the air pocket behaves.
Bill, I hope you weren't offended. I admire your ability to do these tests and share the data. Sometimes pictures just hit a funny bone, it's not personal.
I did some testing on a subwoofer once with a box that was too long. I was testing various tunings to see how it sounded in room. It probably wasn't accurate as I started with a box about 3 feet long with a port on the end.
After measuring nearfield and taking impedance sweep, I would play a variety of music and take notes.
Then I would cut a certain amount off of the box on one end and glue a new end plate in, cut hole and install port. Tedious and not sure I learned anything other the end plate should have been removable and the port should have been mounted on the outside. Might have saved a lot of time and even some math.
Bill, I am truly sorry if I offended you. That was not my intent. I was just fun'n around. Thanks for your contributions to our wonderful hobby/addiction!
Comments
Roger that, 2 units coming acha.
Have not tried Gorilla or poly glue, will check into this. Does the Gorilla or poly glue stay soft when it cures? Or does it harden and become brittle? I know 100% silicone does not work well gluing foam type rubber material. I peals off easily. But it stays soft and sticks pretty good to PVC, especially if I rough the PVC up with sandpaper before application and then let it cure out for several days.
Epoxy for the win!
I agree. But I would need to find an epoxy that is thick and and will stay in place as it cures. I cut the holes so that they have an approximate 1/64 to 1/32" gap all the way around the PVC coupler. The silicone will fill the gap and then stay in place as it cures to form a fairly rigid bond.
+1
I never use silicone on or near anything I'll be applying paint or a finish to. Around the bath tub or shower wall, ok. On speaker projects, no.
If you have a small gap mix up a 5 minute setting epoxy and let it sit for almost 2 minutes before applying it. That has always worked well for me when gluing in PVC ports.
I would just tape the the front and pour the epoxy from the back. I also use mdf dust to thicken epoxy on some occasions, but not in a situation such as this.
Thanks! Sounds like a plan.
Saw dust and wood flour to thicken epoxy, but generally I just tape the joint like Nick.
Will have to use the slow cure type epoxy, giving it plenty of time to fill the long, thin gap. The gap will be .05 inches all around. 5 minute epoxy might set up too fast. Will mix it up without flour or thickener. Maybe use a small toothpick to agitate the gap a little bit to eliminate bubbles and/or air pockets. And a few small alignment shims to keep the gap consistent all the way around.
Make a shaker table using the woofer. 10Hz ought to get that epoxy down in the cracks.
A bass transducer will help but don't run it too long or the epoxy will crack as it dries (cures). Also if you do this take pics.
I'll put my camera on a tripod and shoot an automated timelapse sequence of the epoxy pour!!
If you sand the opening into a slight funnel shape, it will be easier to pour, and with epoxy the strength isn't compromised, it's stronger than the surrounding wood.
Any decent YouTube video needs a torch to pop the bubbles in the epoxy pour
Progress report: DIY input cups:
I routed a 3 1/8 x 3 1/8" recess 3/4" deep into the lower back and then glued a small 30 degree beveled piece of hardwood (maple) to the upper edge of this recess. A dual banana jack mounts to the bevel, providing easy access for bare wire, spade lug, or banana plug type connections.
I squared up the top two corners of the recess with a chisel, then clamped and glued the hardwood in place:
Done
Project is done. @jhollander - John, as suggested, a flare/no flare test, see spreadsheet below. @6thplanet - Eric, thanks again for your donation to the cause of high power chuffing experimentation.
Carpet sliders:
Eric's flares attached to coupler:
I know this is a sub that will be low passed fairly low, but it would be interesting (at least to me) to see near field port measurements with and without the low pass filter applied. A port that long must have a significant resonance.
Anywho those boxes look great Bill! The tall phallic ports not so much. You should build a tall pair of shallow MTM's to set on top of them and sort of hide the big black shafts
You had to go there Craig!
Port envy!!!!
Pooooorrrrrt power!!!!!
Nice, Bill! Always glad to help a fellow speaker geek🤘🏼
Post like that make me wish you could hit the WTF and the LOL 😂
Well, I hope everyone is getting their jollies at my expense, but the commentary totally misses the point of using an external port system. If I was really interested in the aesthetics, I would have used real wood veneer instead of peel & stick. I was going to leave the boxes completely unfinished, but I had a big roll of peel & stick laminate left over from another project, just sitting on the shelf, so I decided to use it up before the adhesive went bad. Even so, if you look closely at the pictures, you can see air bubbles in several places where the adhesive is giving way. The only way to get rid of the bubbles is to place a large foam backed board over the bubbled up area and clamp the board firmly in place for several hours.
Anyhow, the point of using an ugly looking external port is so that I can hot swap port lengths while playing music, adjusting the length for the best satellite blend. I currently have 10 different port lengths that I am experimenting with. Can't do that with an internal port! I also want to experiment with an external trapping system to kill the 1st or 2nd port/box resonances. Again, can't do that with an internal port.
In addition, because I used a coupler instead of a closet flange, I can easily convert to a fixed length internal port system later on, should I choose to do so, after I get done experimenting.
With vinyl wrap bubbles another alternative is puncturing followed by rolling using your rubber veneer roller. Use the smallest point you have.
This is how the professionals do it on automotive wrap. The pin hole is not visible afterwards. You may need to create a couple three on each bubble depending on how the air pocket behaves.
Bill, I hope you weren't offended. I admire your ability to do these tests and share the data. Sometimes pictures just hit a funny bone, it's not personal.
Bill, we were just awestruck by the size of your port.
I did some testing on a subwoofer once with a box that was too long. I was testing various tunings to see how it sounded in room. It probably wasn't accurate as I started with a box about 3 feet long with a port on the end.
After measuring nearfield and taking impedance sweep, I would play a variety of music and take notes.
Then I would cut a certain amount off of the box on one end and glue a new end plate in, cut hole and install port. Tedious and not sure I learned anything other the end plate should have been removable and the port should have been mounted on the outside. Might have saved a lot of time and even some math.
Bill, I am truly sorry if I offended you. That was not my intent. I was just fun'n around. Thanks for your contributions to our wonderful hobby/addiction!
I don't think that anyone was trying to be mean spirited.