e8a translam bass bins

[Black300zx]

At the beginning of the summer I decided that I wanted to put my new router table to good use, so I designed a pair of translam enclosures for the pair of Elemental designs e8as that I had laying around. They'll be paired with the CSS/Dayton Bookshelf speakers I built a couple years back (which are still in progress :P ). I'm planning to cross them over around 80hz, and they'll be driven by the front channels of my old Kenwood 5.1 receiver (100rms per channel @ 8ohms).

They'll make their home underneath these speakers, taking the place of the wobbly folding tables. Sorry for the terrible picture:


CAD Rendering of the design:


Specs

1.3cf
~11.5 sq in of port area (combined between the two ports)
Tuned to ~27hz iirc
47 layers of 3/4" MDF per cabinet
~3.5 sheets of MDF will be consumed

Over the course of the summer a few other projects took precedence over this, but I finally started making sawdust a couple weeks ago.

Templates cut out from 1/2 MDF. The left most template is for the bottom two layers of the enclosure, where the drivers will mount. The center was left intact to allow me to transfer the center point from the paper template (which I printed out from an AutoCAD file) to the MDF template, and then to the first layer. The next template to the right was used to cut out the internal cavity of the cabinets. To the right of that is the template for the bracing, which will be placed every 10th layer. The final template is for the 5 top-most layers.


After ripping the first sheet of MDF down into 7 strips, I traced the first template onto the MDF and roughcut the outer perimeter and port with a jigsaw to make 28 'blanks'.






The first blank for each enclosure was attached to the template and trimmed flush on my router table. This first layer then served as the template to which I trim the next layer. This method will be used throughout the whole build so that I don't have to precisely align each piece.

First two layers:




Driver holes routed out in the first two layers, the third (which is actually the bottom-most layer) attached, and the holes for the speaker spikes drilled:


Third layer trimmed flush, sub test fit:


T-Nuts pressed in for the spikes:


Fourth and fifth layers attached, and ready to be trimmed flush tonight.


I'm hoping to get 4 or 6 more layers added to each this weekend.

[ThomasW]

Nice job.... :T

Since this project is being spread out over a period of time, you might think about sealing the individual layers so the MDF doesn't change size with changes in humidity..

[Black300zx]

Nice job.... :T

Since this project is being spread out over a period of time, you might think about sealing the individual layers so the MDF doesn't change size with changes in humidity..

Good idea, especially since the Home Depot near me only carries the low quality MDF that likes to swell alot. Do you think I should seal the end grain, faces, or both?

[Hdale85]

Wow those look like they are going to be fantastic! Love the design.

[ThomasW]

Do you think I should seal the end grain, faces, or both?

All surfaces will absorb water

[Curly Woods]

Good idea, especially since the Home Depot near me only carries the low quality MDF that likes to swell alot. Do you think I should seal the end grain, faces, or both?

Don't mean to laugh, but its MDF. It does not have end grain or face grain :B
Seal it all. Shellac would be a good finish for the interior of the boxes. Most people do not think of finishing the interior of their boxes, but it makes sense to a woodworker to seal all surfaces! Moisture wil get in anywhere that it can. Shellac will not have undue smells after it cures either, that is why it is used for a finish for the interior of drawers a lot of times. Dries quickly too.

[Black300zx]

Don't mean to laugh, but its MDF. It does not have end grain or face grain :B
Seal it all. Shellac would be a good finish for the interior of the boxes. Most people do not think of finishing the interior of their boxes, but it makes sense to a woodworker to seal all surfaces! Moisture wil get in anywhere that it can. Shellac will not have undue smells after it cures either, that is why it is used for a finish for the interior of drawers a lot of times. Dries quickly too.

Yea, at the time, I couldn't think of a better way to refer to the ends of MDF board that weren't the face. Perhaps "the cut face" would have been more appropriate:P

Next trip to home depot I'll grab some shellac.

[Black300zx]

13 layers down, 33 to go. I ran out of MDF yesterday, so I'll need to get to home depot to get another sheet before I can continue.

[jbateman]

Are you trimming each layer to the preceding layer? Any flush trimming bit I've used had a bearing about .005" smaller than the cutter diameter. Multiply by 30 layers and the top layer will be about 1/8" bigger than the bottom.

This may not matter for what you are doing...but it might. You could reduce that by 1/2 if you "start" at the middle of the stack.

[Black300zx]

Are you trimming each layer to the preceding layer? Any flush trimming bit I've used had a bearing about .005" smaller than the cutter diameter. Multiply by 30 layers and the top layer will be about 1/8" bigger than the bottom.

This may not matter for what you are doing...but it might. You could reduce that by 1/2 if you "start" at the middle of the stack.

Yes I am trimming each layer to the preceding layer, however I'm pressing the enclosure firmly against the bearing so that it makes a slight impression into the MDF. Hopefully this impression will make up for the difference between the bearing size and the actual cutter size. Regardless, I'm not too concerned if it grows. I'm more concerned with avoiding as much sanding as possible at the end. The one area it could cause problems is in the port.

After I route this layer flush I'll take a quick measurement to see if the layers are growing at all.

[Hdale85]

Are you going to cover them in resin or something and then sand?

[Black300zx]

Are you going to cover them in resin or something and then sand?

I'm not exactly sure how I want to finish these yet. I hate painting bare MDF with a passion. I might veneer them, and I've also considered covering them with some sort of laminate, which I would then prime and paint. That should provide a nice base for a high gloss black paintjob.

[evilskillit]

Those things look pretty awesome. Its a darn ambitious undertaking. I envy everyone who has the time and money to do a project like this. Not only would it be hard for me to come up with the time but it uses SO much more wood that I just can't usually justify the cost vs just building a box.

[gmed]

Yes I am trimming each layer to the preceding layer, however I'm pressing the enclosure firmly against the bearing so that it makes a slight impression into the MDF. Hopefully this impression will make up for the difference between the bearing size and the actual cutter size. Regardless, I'm not too concerned if it grows. I'm more concerned with avoiding as much sanding as possible at the end. The one area it could cause problems is in the port.

After I route this layer flush I'll take a quick measurement to see if the layers are growing at all.

Speaking from experience, it does grow a bit. I used this process on one of the speakers I built and at the end I realized one end was about 1/4"larger than the other all around, but looking at it, you cant even tell, so don't sweat unless you grab a ruler and measure!

[Black300zx]

I actually read through your build thread once or twice since I've started this build. I did measure, and it'd definitely not growing .005 per layer. I think since you used a harder wood (baltic birch), the bit didn't sink into the edge of the wood as much as in my case. Each time I route a layer, you can actually see the indentation the bearing made in the edge of the mdf. I'll do a final measurement just out of curiosity.

As for an update, it rained almost all of last week so I didn't get a whole lot done. Early in the week I picked up sheet #2 of MDF, cut it down to size, and over the weekend I cut out another 28 blanks. This week I hope to get those 28 layers added so that I can grab the third sheet at the end of the week.