Printer Friendly Forum Posts - how perfect are your boxes?

For those of you who build your own sub boxes, I'm just wondering how accurate you are with making your boxes. Cuts perfectly straight? everything lining up perfectly?

I just ask because I've spent some time putting my boxes together, and tried to be accurate as possible, but even as close as I am, there are still some very minor imperfections, and I'm wondering how they could affect things.

So, when you guys build your boxes, how perfect do you insist they be, and how do you go about ensuring such perfection? best ways to cut, attach etc.

Build a large table for your table saw, cover it with formica, and purchase
One of these

When I make a box I usually get within a 1/32", sometimes 1/8" on a bad cut. It doesn't have to be perfect unless you are doing complex angles or something where accuracy is key. With a little bit of sanding and some sealant it all works out.

I don't have a really nice table saw either. Just a pretty cheap one and I use a circular saw a lot of times anyways.

I would just make your cuts like 1/8" big and then sand them down til the joints fit well.

i am an idiot wrote:

Build a large table for your table saw, cover it with formica, and purchase
One of these

AWWW you #@$%@. You would have to show me that!! lol. Now my credit card's getting abused again... btw, don't tell my wife.

sucks that I won't be using it very much anymore.

If you do not want to spend money on one, DO NOT USE one, You will have to have one.

P-E-R-F-E-C-T. I accept nothing less. Accuracy is never sacrificed to time for me. If it is going to be complex enough that I can't handle it on my tablesaw, I pay a buddy of mine to cut all my parts. He and his sister own a sign shop, and his shop has a router table that will hold a full 4X8 sheet of MDF.

If it's worth doing, it's worth doing right.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

I just use a piece of 1x3 with quickclamps as a guide...all you need is a pencil, square, rule, circular saw and sawhorses and you're good to go. I'm consistently within 1/32" and almost never off by more than 1/16" (unless I straight-up measured wrong).

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2003 Chevy Cavalier coupe

haemphyst wrote:

P-E-R-F-E-C-T. I accept nothing less. Accuracy is never sacrificed to time for me. If it is going to be complex enough that I can't handle it on my tablesaw, I pay a buddy of mine to cut all my parts. He and his sister own a sign shop, and his shop has a router table that will hold a full 4X8 sheet of MDF.

If it's worth doing, it's worth doing right.

I dont have this luxury :),

my dads table saw is messed up, so I was stuck using this other one he had, that Im fairly certain was made somewhere in 1930. The straight cuts are straight surprisingly, and even the angled cuts on my baffle boards are straight, except I messed one of them up pretty bad and have a 1/8" gap about 5" long on the left side of one baffle boards where I tried to sand the angled part.

Im considering either recutting it, or using the PL premium I have to fill the gap..... it will fill a 9.5mm gap and this stuff is ridiculously strong.

But how do you sand on an angled edge perfectly straight without a planer ?

If it is not perfect it is not right...........set your standards high..........A table saw with a great fence is essential, also a great table like megaman stated build a table around your table saw covered with formica so one man can cut and handle a full sheet.

Or you could just do what Remy does on Unique whimps.....take the sander to it, grind it down to "kinda square" and fill the gaps with glue!!!!

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It all depends on the application for me. My inwall speaker boxes for my home theater weren't as "perfect" as a box I would build that would be highly visible in a car. If you are going to finish the box with carpet (or not finish it at all) accuracy (within reason) isn't a big deal. If you are going to paint or vinyl the enclosure then things needs to line up a bit better. For a 1/8" gap I would fill it with white glue and mix in some sawdust until it was a pretty thick consistency. I would then seal the inside of the box with a construction adhesive (like liquid nails) although almost any adhesive that comes in a paper caulking tube should seal it well enough.

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Kevin Pierson

I learned a trick from a professional cabinet maker that works wonders when the wood seams are going to be visible (not covered in carpet). What you do is on the side that you will be able to see the edge of the board, cut that piece 1/4" larger than you want. When assembling the enclosure, make sure those pieces stick out further than the adjoining piece by 1/8". Then when you are done, take a flush trim router bit to those edges and you will end up with an edge that sits perfectly flush.

Here is a picture of a project I did using this technique with solid oak:
posted_image

Every single one of my enclosures is absolutely perfect. At least it is after liberal use of wood putty and silicone sealant. posted_image

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Depends on the amount of fibreglass odours in the shop area.....

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Top Secret, I can tell you but then my wife will kill me.

lol @ forbidden.

My box is pretty damn perfect, it just seemed to be a little bit off after the application of glue (PL Premium.... this stuff is invincible)

It's just the one baffle board that has a gap, but its a gap that PL Premium is capable of filling, and it should have no problem holding up to what a speaker can throw at it..... if you have ever used the stuff you will know what I mean.

Steven: how did you do the angled pieces at the top of those boxes? how did you measure/mark/cut the angles etc ?

bigjohnny wrote:

Steven: how did you do the angled pieces at the top of those boxes? how did you measure/mark/cut the angles etc ?

Well the top pieces I just cut with the saw blade set to 45 degrees. I knew how wide to cut them using the formula a^2+b^2=c^2. The front and back pieces didn't have to be perfect because of the flush router bit technique I mentioned earlier. But first I just marked the center of the board. I knew how high I wanted the tip, and I knew how low to start the cut at because it was half the width of the board. So I used a strait edge to mark my line and used a miter gauge set at 45 degrees to make my cuts.

I'm wondering if anybody saw the noticeable mistake I made in those speakers. posted_image

forbidden wrote:

Depends on the amount of fibreglass odours in the shop area.....

There must be a lot because your spelling all "Canadian" again adding all them extra vowels. posted_image

Yes, Steven, the grain runs the wrong way on the peak. Nothing that some carpet can't fix... posted_image

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

stevdart wrote:

Yes, Steven, the grain runs the wrong way on the peak. Nothing that some carpet can't fix...

Good eye. Unfortunately all my experience is with MDF where grain isn't something to take into account when making cuts. I was careful with all the long pieces, but ended up with my leftover wood forcing one of my top pieces to be cut with the grain the wrong way. I think some of Rob's resin fumes were affecting me. posted_image

...but beautiful speakers nonetheless. And you said "fumes". Didn't you mean to say "odouours"?

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

LOL

Could you provide a little more detail about this formula, and what you mean when you say you knew how wide to cut them based on that formula.

My sub boxes have an angled baffle board similar to that, but with a different angle. Even though I have them cut already, I think that formula would be helpful to me if i understood what you were talking about fully :D

That "forumla" is special. It has a name! :)

https://en.wikipedia.org/wiki/Pythagorean_theorem

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Kevin Pierson

bigjohnny wrote:

LOL

Could you provide a little more detail about this formula, and what you mean when you say you knew how wide to cut them based on that formula.

My sub boxes have an angled baffle board similar to that, but with a different angle. Even though I have them cut already, I think that formula would be helpful to me if i understood what you were talking about fully :D

Kevin gave you a great link that should explain how that formula works. It's really basic geometry so you should read that link and learn it. But there are online calculators that will give you angles and sides if you do a search. If you don't have a right triangle in your project, then you venture into trigonometry where the math becomes more complex. But again it is important to know if you plan on doing enclosures with complex angles.

I just use a circular saw...my boxes aren't perfect but they are close enough

1/8" inch or less is my usual.

Here's a calculator that I use: https://www.1728.com/pythgorn.htm

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

I know not all people have access to one, but i use a waterjet to cut my boxes, MDF is actually water resistant enough to cut the wood with the water. After cutting i just let them dry overnight and then assemble next day.

my joints on all of my boxes have been tight from the very first box that i made, but that is thanks to my dad and his carpentry skills, that and my ocd

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97 F150, Sony CDX-M630, Sony XM-2165GTX, JL Audio 12W3D2, Planet Audio VX-602, Memphis 15-MC5.7

Yeah it's a mutt, but mutts make the best dogs!

i have to agree with the ocd, my skill isnt the problem, its the tools i was working with.

All in all the cuts came out pretty well, and the one angled side was the the only problem.

I still have to finish the boxes and cut the tubes etc.

show us pictures of what you mean... a ruler in the picture to show the actuall gaps will help as well

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97 F150, Sony CDX-M630, Sony XM-2165GTX, JL Audio 12W3D2, Planet Audio VX-602, Memphis 15-MC5.7

Yeah it's a mutt, but mutts make the best dogs!

I love math and am good at it. However, when I'm building a box for work, I'm not spending the extra time to calculate the angles that I need. Here's a few tricks that I follow, that are basic and anyone can do them.

One thing I'll do is cut my side peices first that have the angles on them. For example, if I'm building a truck box with an angled front, I'll cut the sides out first. I use the depth measurements for the top and bottom and cut accordingly. If the truck I am cutting for has a top depth of 4 inches and bottom depth of 8 inches, then i'll cut my sides with a top dimension of 2 1/2" and bottom of 6 1/2". That allows me 1 1/2" inches for two thicknesses of 3/4" MDF. Now, the overall depth of the box will be reduced by less than 1/32" which I can live with. Using the cut out side pieces, I can now measure the angle at which to cut the front, top, and bottom pieces and tilt my table saw accordingly. To cut to the specific lengths, it's cut and fit. I'll cut the piece, then fit, and if it's a bit long, trim it up, refit, etc. etc. I do this escpecially for the front since there's two angled cuts.

Another trick I'll do, is actually draw the side profile out in real scale. I can then take my measurements and cut away.

I always cut out my side pieces first becuase all the cuts are at 90 degrees. Then I'll use that as the base for fitting all my angled pieces.

i dont have any pics with a ruler right now, but there are very few, very minor problems.
My biggest challenge is building two identical boxes without the use of some really good woodworking equipment.... I dont have access to anything on a professional level, If i did, my skill would do the rest :)

I'll post some pics in a bit if i remember, Cause I also need help putting in a large piece of sonotube that the sub will mount into.