hey im about to start building a box for my DD 2512, and my local hardware store (mitre 10) wont cut the mdf sheets to size for me! so im stuck with the task of doing it myself...

now if im making a box i need edges that will fit FLUSH, i dont want bad-fitting pieces...

the only tools i have are...a normal wood saw, a jigsaw, and an angle grinder. i am thinking the only way to do it is with the jigsaw, but im just worried that i wont be able to cut it straight enough....is there any ways i can make the jigsaw cut straight and square? or does it just come down to keep trying until i can cut it straight....

any tips would be appreciated.

you could try turning the speed rite down and going very slow, or using another piece of timber as a guide, thats how i did my box and it came out square and fitting flush.

good luck.

Tip #1 - buy a cheap circ saw
Tip #2 - buy a piece of aluminium or similar to use as a rip guide

speeds up box building by a factor of ~60

also jigsaw + guide doesn't tend to work so well because the jigsaw blade is fairly flexible = not a square cut.

i just found out that my dad has a circ. saw, but the blade on it is bent, i will probably do that...

is a jigsaw ok to use for the sub hole and port hole?

is normal PVA glue ok to use? with some ~25mm screws? ive read the enclosure tute but not sure on glue+screws

Jigsaw is fine for port and sub holes.
PVA is what you would use for MDF.. but for extra grip and also to work as a sealant... Liquid Nails wouldn't be a bad thing to use.
PREDRILL before you screw into MDF and screws to use? 40mm is fine... 50mm if you are paranoid... and drill straight!

yeah i was going to use sikeflex i think its called, ive heard its pretty good for sealing.

ill have a look for some screws, might go with 50mm to be safe, i always predrill whenever im screwing into wood...learnt that the hard way.

should i just run a bead of PVA along the join? whats the best way do do it? i think the tute said to drill it then screw the join up tight, then undo it so theres ~5mm gap there then put the glue in then screw it back up...does that sound right?

Why double screw?
Apply the glue along the piece that you are drilling in to and then screw the panel to it... tight.

Depending on how much luck you have, sometimes you may screw away and it's left "spinning" in the wood and the head of the screw is not flush with the panel, you can always countersink it so it grabs that little bit further into the wood and it finishes either flush or slighty sunk in.

Instead of running a thin bead along the join, smear it over the join so it covers more surface area, you will have a stronger join that way.

Happy Building.

Even after the join is made, ensure the seal by using the sikaflex or whatever and run your fingers along the inside of the join to make sure it's airtight.

I'm sure you knew that one already though...

yeah i was planning to countersink the screws so theres nothing to scratch stuff too much. and yeah the finger thing with the sealer is the way to go.

im not sure what port length i will need but ill PM DD phil as he knows plenty about DD subs and enclosures.

thanks heaps for the help guys\girls

(takes hat off)
Anytime dude. That's what we're here for

surely u know somebody with a factory and or bandsaw would make it simple and easy depending on quality of the equipment, no way would i waste money on mdf by cutting with a jigsaw

well believe me if i knew someone with a bandsaw i would take advantage of it. i have a small one but it wont fit the 320mm of width that i need so its useless to me.

as it has been said above, the only cutting ill be doing with the jigsaw is the sub and port holes, im using a handheld circular saw to cut the panels...and the wood is costing me zilch so yeh..

Whats so wrong with using a jigsaw? Using a peice of timber as a guide you can get it pretty straight.

i know someone that cuts mdf with a jigsaw
strait as and thickness of an inch with out a trouble
just goto use the right blades to do it

Bah I typed out a reply and it got too big, so here it is in the Tutorials & Technical forum:

http://www.caraudioaustralia.com/forums/in...showtopic=59226

If you have a strip of wood and 2 clamps, clamp the wood down onto your mdf as a guide to run the jigsaw along.

Mitre 10 is about useless for anything i've found, metric bolts, nup, decent tools, nup, small drill bits, nup, decent headlight globes, nup ......

I made a sub box the other day. the get the best joints use a circ. saw that you can adjust the angle on. then when you cut each edge, cut at 45 degrees, it makes for a neater finish, and is often stronger then straight edges. Although it is advisable to do this only if you know basics about woodwork. If not, then get some assistance from somebody who does, otherwise the box will be royally screed, as an unfortunate friend of mine found out

cheers, Matt

thanks for the replies ppl, blackice that was a top thread but until i start getting serious and doing real installs(i.e with false floors and all that stuff) i cant afford any of those tools! at the moment im struggling to afford the materials! my uncle has a circular saw thats in a bench kind of thing, im not sure how straight it cuts but i will have a play with it. if its not good enough ill go with the jigsaw or handheld circ saw...the only problem with the circ saw is the blade is bent and it does not cut straight. i think it will be easier to just clamp on a piece of wood and use that as a cutting guide.

im getting the mdf tomorrow, its 25mm packing sheet...about 2400x1200mm so i will let you know how i go.

also how much space should there be each side of the subwoofer when mounted? like the sub's diameter is ~300mm so how much space should be left either side of that? or isnt it that important...im just tihnking from a strength perspective

well alot of SPL guys will mount their woofer as close as possible to the outside walls of the box, simply to maximise the amount of room to be used for ports.


Really it doesnt matter though. unless you have a really big baffle(surface area) and a lack of support in the middle of the box where alot of people would choose when placing a single sub in a box.

hmm, it should be ok, im aiming for 400x250x600mm(inside measurements...and yes i will allow for the thickness of the wood!) which will give about 60L volume. im aiming to use the 400x600 side as the baffle(not sure on mounting depth for the DD sub so may have to check that out before i build). i have a rough design planned but might do a quick draw-up in paint so ive got it all figured out.

For cutting out the port and sub hole i used a router with a jig attached to it so the router would pivot around a hole that you drilled. The hole was drilled in the centre of the box and the bolt placed through the jig and into the hole. Then i set the router to cut to a certain depth, cut a channel in the shape of a circle, adjusted the depth and continued. After a while i cut through the whole thing and a there was a perfect circle. This was really good for the round port cos the tube fit perfectly in their really tightly and doesnt need to be sealed so it can be adjusted.
I suck at explaining things like this but i included a crude drawing to help! I dunno where i got the jig cos its my dads but im sure you could get one from mitre ten for cheap....thats presuming u have a router!
anyway in the pic the red dot is pointing to the router, the blue dot to the slot part of the jig and the orange dot to the bolt. Once the router is set to the right radius a nut is screwed onto the bolt to prevent it from changing its radius while u r cutting.

ok so i got to building the box yesterday, pretty much finished it actually. i just have to cut the hole for the sub and glue\screw the baffle in...

its pretty damn solid...28mm mdf is heavier then i thought it would be.
i do have a router but no jig, so i will just use the jigsaw for the hole i think.

i know its too late but some things you might want to know for next time or for others that wanna help other members out when they ask...

Screws
the lenght of the screw needs to be double the thickness of the material used, so its best to ask what thickness is being used before saying 40-50mm's are fine... as it tuned out 28mm was used so the screws recommended were under rated for the task...

counter sunk holes are highly recommended becasue the hard surface "face" can strip the screw... clearance holes are used to avoid blow outs leaving rubbish inbetween your joint, and pilot holes are used to clear the waste which adds tension when a screw is driven into the hole...

use the correct driver and correct size to match the screw head/slot... adding an even square amount of pressure to the head while driving.... tip- hold your trigger until the head of the screw reaches the face of the MDF then flick your trigger until the head is under the surface (pulls up allot better with less chance of strippin)

Bonding
PVA is your strongest bonding power with MDF, you can get customwood graded PVA.... use a butter tech when applyin the PVA to the edge but using your finger to spread the glue across the whole edge- this covers a larger surface which means a stronger joint!

if you have gaps in your joint i dont know recommend L/nail... here's a tip for all CAA members- use silicone instead of l/nail!! you should still run a bead of silicone around the inside of the enclosure anyway to seal it up completely (if your joints are poor)

Cutting
you can get a square edge off a jigsaw cut but when your cutting a longish line, chances are your blade will bend and run all over the place... how many ppl on here check their cuts will a square?? i bet not many so even tho it looks square i bet your just kidding yourself for a "true" edge your gonna need a solid cutting blade....


anyway its good to see some many ppl giving basic stuff a go on their own!!

ok well ive done most of those...my screws were about 3" long, i pre-drilled, and countersunk them. I cut with a bandsaw then neatened the cuts with a bench sander. PVA glue was used(just standard stuff) there was no gaps but i put a bead of silicone along all joins then ran my finger along it to seal it right up.

and yes my box is square, checked every side with a set square and measured it all with a tapemeasure...



i cant help but feel a bit patronised by that comment...despite your poor attempt at spelling.

dont worry it only means that more and more ppl are giving these projects a go on their own, ppl like yourself will go onto bigger and better projects or help others take that 1st step, which is good for all of us