posted
I am planning on making a box made only of fiberglass. I plan on making a separate box for each of my subs and I can manage to make the right amount of airspace within each box, but I am wondering about putting ports in. (i'm not by any means a audio expert so bare with me) Now, there are certain specs for the ports that i need to take into consideration? On the Rockford site, it says for my subs:
Ported box -
Recommended Volume (Cubic feet) - 1.00
F3(Hz) - 35
Number of Ports - 1
Port diameter(Inches) - 3
Port Length(Inches) - 13.25
So, can I put my port anywhere i want? what i mean is in a regular MDF box, the ports come very close to the ground, in the box i plan on making, the end of the port probably wont be very close at all the the bottom of the box, also the sub will be in a different position in reference to the port. Will this change anything even if i stick to the 3" x 13.25" port size?
Posts: 60 | From: B.C, Canada | Registered: Aug 2003
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not sure about any of the port stuff. ive never done a fiberglass box and used ports. the reason ive never done this is because while my fiberglass skills are awsome my math skills suck. to do port calculations you need to know exact volumes and if you want to do it right you need to figure in specific info for the subs like Qts, polyfill amounts, placement, etc. with a fiberG box you cant get the exact volume amounts untill the box is done. ive see people who are big SQ freaks make a sealed box just to get volume info then build a new box all over again after taking the port calculations into consideration. thats why i dont do ports with FG.
but one other thing. you said you wanted to make it only of fiberglass but at the same time have seperate chambers for each sub. if this is your first time trying to do this i can tell you from experience its going to be difficult. you have to build the box in two phases. phase 1 would be the bottom half of the box. use wood to make a basic skeleton then glass over your skeleton to get the basic shape of the botton half. then build it up to the thickness you want it. if you need specifics on that stuff let me know. then you need to start working on the top half of the box. after you determine where you want the subs to be, you gotta put in MDF panel/s that will make the chamber wall/s. its hard if youve never done it before. the best way is to take a piece of cardboard and start chopping away at it to figure the shape of the panel. dont forget the panel has to fit exactly to every contour of the box. after you get the shape you want the panel cut it out on a bandsaw or whatever. then to fix it in place first line it up where you want it then draw two guidlines on each side of the MDF slab so you know where it sits on the box. drill some holes between the guidlines so you can screw the mdf panel to the bottom half of the box. next, step is kind of tricky. cut a long narrow strip of fiberglass mat, mix up a tiny bit of resin and lay the strip along the guidlines of you drew so it sticks out about 3/4 of in inch over each side of the line. then as soon as you can while the resin is still wet screw the MDF panel into the holes you previously drilled. not only will this help seal off the two chambers, but it will also make that panel real sturdy. let it cure. then scuff up the sides of the panel near the bottom edge where it meets the bottom half of the box. you need to seal up the joint better. the best way is to use regular body filler. you dont want it to be more than 1/2 inch thick in any place so itll make a nice cure. just spread it evenlly in the joint all the way around on both sides of the panel. then after it cures scuff it up again with some 40 grit sandpaper and lay down some resin and mat. go about 5 inches over each side of the joint. out two or three layers on it. now you got yourself a sealed and strong joint.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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So how about if i were to make the two boxes for my subs out of MDF except for the front panel. I Could cut out 5 1' x 1' pieces, glue them together, then the front panel is FG. This would make the box very close to specs. Also, i was wondering if FG adheres to MDF? like if i were to do this, then FG over the mdf part of the box just for looks, would that work? And another Q, to strengthen the long flat parts or FG, i've heard you lay pieces of rope down and simply FG over them? and if i do this, i assume i simply leave the pieces of rope within the FG.
Posts: 60 | From: B.C, Canada | Registered: Aug 2003
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quote:Originally posted by Cdn_Cory: So how about if i were to make the two boxes for my subs out of MDF except for the front panel. I Could cut out 5 1' x 1' pieces, glue them together, then the front panel is FG. This would make the box very close to specs. Also, i was wondering if FG adheres to MDF? like if i were to do this, then FG over the mdf part of the box just for looks, would that work? And another Q, to strengthen the long flat parts or FG, i've heard you lay pieces of rope down and simply FG over them? and if i do this, i assume i simply leave the pieces of rope within the FG.
yeah you can build put 5 peices of wood like that together to make a box then make the front panel out of fiberG. i have some pictures of a box like that that i built...
first cut the five panels that make up the sides and screw them together using pilot holes. put sealant between the boards before you screw them down. then run sealant around the joints after its screwed together...
then cut the mounting ring for the sub and attach it to the box however you can to hold it firmly in place...
then stretch fleece over top of the box a by stapling it to the four side panels and to the speaker ring...
then soak the fleece with resin and let it dry. when it drys cut out the holes for the sub and sand away the resined over fleece so the sub can mount onto a bare MDF surface. drill pilot holes before mounting the sub. also, after the fleece is dry you need to add 3 or 4 layers of fiberglass mat to make it strong...
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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quote:Originally posted by Cdn_Cory: So how about if i were to make the two boxes for my subs out of MDF except for the front panel. I Could cut out 5 1' x 1' pieces, glue them together, then the front panel is FG. This would make the box very close to specs. Also, i was wondering if FG adheres to MDF? like if i were to do this, then FG over the mdf part of the box just for looks, would that work? And another Q, to strengthen the long flat parts or FG, i've heard you lay pieces of rope down and simply FG over them? and if i do this, i assume i simply leave the pieces of rope within the FG.
ive never heard of anyone putting rope in there glass. seems like it would make air bubbles and cause other probs. dont waste your time. just make it thicker using more layers of glass. and also remember. the bigger you cut the peices of mat, the stronger they will be.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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posted
and yes you can glass over the rest of the box to give it that smooth look. you will need to use 3/4 inch mdf though because youll have to sand down the joints to make rounded edges. then just glass it over with a layer of mat and then cover it with body filler and sand smooth.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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It looks to me that when soaking cloth with resign it makes a smoother surface than laying down mat, would it be a bit less finishing work if i were to add the extra layers on the inside, like make the face of it a separate piece, strengthen it, THEN attatch it?
Posts: 60 | From: B.C, Canada | Registered: Aug 2003
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quote:Originally posted by Cdn_Cory: As to making only the face out of FG:
It looks to me that when soaking cloth with resign it makes a smoother surface than laying down mat, would it be a bit less finishing work if i were to add the extra layers on the inside, like make the face of it a separate piece, strengthen it, THEN attatch it?
no because either way you have to cover the face with body filler to get it smooth enough to paint. and also, itd be a real bitch to lay the mat on the inside of the box. you dont want to make a box in more than one peice unless you have to do it in order to get it out of the car.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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quote:Originally posted by Shane N: Lay the rope on the inside of the box on the backside of the fiberglass once you have your layers done. It'll strengthen it quite a bit.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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posted
So, If i am building the boxes out of MDF, can I port them?
And is it a no, or a yes for the rope? (i heard the FG boxes are weakest on the flat parts and adding rope makes curves and strength)
Posts: 60 | From: B.C, Canada | Registered: Aug 2003
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quote:Originally posted by Cdn_Cory: So, If i am building the boxes out of MDF, can I port them?
And is it a no, or a yes for the rope? (i heard the FG boxes are weakest on the flat parts and adding rope makes curves and strength)
you could probably port it with a rough volume estimate. id ask some porting experts first. and about the rope. its a big no. maybe that would be the thing to do if you had GIANT flat areas but you wont.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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The rope strengthening method does work extremely well. We use it on every glass enclosure we build. Posts: 58 | From: Beaumont, TX | Registered: Jan 2003
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quote:Originally posted by SirRost: The rope strengthening method does work extremely well. We use it on every glass enclosure we build.
yeah i said that then ironically i needed a panel strengthed so i tried it and your rightit did work very well. i mixed a batch of resin 50/50 resin/laquer thinner. then soaked the rope for an hour. then added hardener and layed em out. then glassed over them with 5 layers. brick hard.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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quote:Originally posted by Cdn_Cory: what advantages does putting thinner in resin have?
before i tell you. DONT USE PAINT THINNER. it HAS TO BE LAQUER THINNER.
anyways, it does a few different things. first it make the resin thinner. more watery if you will, so when you lay mat, the mat soaks it up easier. you can also add it to bondo to thin that up, you can actually add thinner to bondo and use bondo like resin. although ive never done that ad added mat to it, ive done tht for a finish coat. another thing you can mix is resin and bondo, if you want a real light weight body filler mix part resin 4 parts bondo and justuse the normal creme hardener for the bondo and youll have a nive finishing layer of bondo.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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quote:Originally posted by Cdn_Cory: what advantages does putting thinner in resin have?
before i tell you. DONT USE PAINT THINNER. it HAS TO BE LAQUER THINNER.
THAT could be a head scratcher! to me, and pretty much everyone i know...those are the same things. and why would you thin bondo with thinner? i'll bet when it evaporates out it leaves a nice brittle material. i've never tried it so i cant say for sure, but it sounds pretty creepy to me.
-------------------- Luke Fidler Posts: 1930 | From: state college, pa | Registered: Sep 1999
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would putting laquer thinner in the resin make a better bond between MDF and FG? (from what i understand the MDF absorbs the resin, making the bond, or am i wrong?)
Posts: 60 | From: B.C, Canada | Registered: Aug 2003
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posted
i dont think it would make a noticable difference. resin bonds to mdf pretty well by itself.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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posted
ok, sounds good. One more thing, as I was in buying my MDF today, the sales person i was talking to, turns out that he builds custom boxes on the side. One thing that he mention that I never considered before was that he lays down quilt batting on the inside of the box, claiming it gets rid of certain unwanted noises, and makes the subs sound better. Anyone here of this, or recommend it? (or recommend against it?)
Posts: 60 | From: B.C, Canada | Registered: Aug 2003
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posted
It's always better to thin bondo with no more than 10% "Strene Monomer" rather than alcohol, laquer thiner, acetone etc. Strene Monomer is the liquid componet of Bondo, and is available from Tap Plastics, and will not adversly affect the strength of the Bondo in the long term.
Posts: 27 | From: Silicon Valley | Registered: Sep 2003
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posted
usually people use polyfill. its the stuff inside your pillow.
-------------------- Need fabrication help? AIM Me at capo don zoni. I have built everything. Don't bother if your completely new to this. I'm not here to baby anyone. If you do your research and still can't figure something out then ask. Posts: 86 | From: Connecticut | Registered: Sep 2003
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Next time ... a nice time saving tip.... Instead of Pre Building the entire enclosure.. leave the Back off, and use Braces to keep the enclosure Square... This will allow better access to the back of the FG Surface... so instead of having to apply the FG Extremly neat, and having to Grind though Half of the Strength u just put on... u can apply it to the back... and just apply a thin layer of Marglass or a Bondo Slurry to the outside... sand it and be done... Also, if u rabbit an edge around ur Rings and staple the cloth in the rabbit, then trim flush with the edge... u will not have to Grind the surface flat... ull have a better seal to the Subwoofer as well. Hope this helps
Posts: 2 | From: NY | Registered: Sep 2003
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