Axiom Home Page Forums General Discussion Home Theater Lets plan a theater space

Great. Thanks for that. Second look makes all the difference.

yeah, bit different looking at it with pics as well. Also the fact they are running mids out of phase, i thought you went right off the rails at first LOL. I had no doubt you would have it right, i see you do your homework . How are the cabinets coming along?

Yeah, building the brain was a part I wanted to be sure on so I paid close attention. Plus, there are a few builds out there where people messed up so I had the opportunity to learn from them.

So everyone can follow along if they want to here are the build plans.

http://www.speakerdesignworks.com/Statementsautocadlayout.pdf

Yesterday we got busy making circles with the Jasper Jig. This thing is a must have and my build pal was sure to run away with it at the end of the day. It is just great. We're taking our time to make sure all angles are covered and making it a buddy project. More fun that way. Time to stop and smell the MDF. mmmmmmmm.

Anyway, here is where we are at. The panels are all cut and marked out for holes. We might hold off on the baffle cutouts; not wanting to rely on the shop drawings being 100% accurate.

Here are the lower base cutouts to accommodate the bottom firing port. Part D on sheet 4 of the drawings. We cut out the back to allow the port to breath better so sitting high off the carpet wasn't an essential thing to do.



Here is the upper base section where the port mounts. Part E in the drawing. The port mounts in it and passes up through part G into the cabinet. Nice flush mount. Where there is space behind between the port plastic and cutouts should I fill with resin or something? Foam?



And here are the shelf braces, Part H. We decided to double the thickness of them and router the top and bottom edges. The idea is to beef up the longest span of cabinet without altering the plan or volume too much. Part L is shown in the pic as well. The woofer facing edge is rounded on these braces.



Now to lightly sand all the edges to de-burr before dry fitting everything. Almost time to glue these monsters up. To save time and sanity we are going to glue, clamp and air nail these suckers so we don't have to make gluing a lifestyle for a couple weeks.

Today is a holiday so I might get started on building the spike feet. Pics on this later.

MDF --- Mega Dusty Fiberboard!

Fun project for sure. Heck, I liked building my larger 4cuft sub, and it wasn't nearly as involved as this. You will surely have a sense of accomplishment when you first fire these things up.

Trev, i dont want to sound like an F'n knowit all but one thing i thought about when you talked about cutting the holes that really pissed me off on my first build was that when i sanded the fronts around the cutouts i didnt use a long enough sanding board and it rounded the edges over just slightly and the end result did not look as good as it could. Just a long random thought . LOL

Someone mentioned online they glued a piece of 1/4" glass to a chunk of wood to use as a block. Thats dedication. I'm wondering if a palm or orbital sander is a no no once past the primer stage? Also, the front baffle will be faced with maple and ebonized. Can I sand the standing grain down after the initial stain before lacquer? Getting ahead of myself perhaps.

The whole purpose of the primer with MDF is to seal the compressed wood cells to slow the absorption. The most common mistake in finishing MDF is that you don't leave the primer enough time to dry.

Sanding, use either 180 or 220 and you are just trying to knock of any nibs or bumps that will have raised on the surface. You are not trying to remove and sand back down smooth. Over sanding will likely do you more harm that good.

I would suggest that you put on at least 2 coats of primer onto MDF with 4 hours between the first and second coat. Then give it a good 12 hours before you start to apply any finish over the primer. Are you using a HVLP sprayer to apply the finish?

As for sanding. You need to know your palm or orbital sander to know if you going to get a problem. It is the stroke of the sander that you really need to know. This is the amount of displacement the sander pad has off center. I have had several sanders. If its crap work that I am doing then I'd grab my Ridgid sander as it is quite aggressive and had a large stroke.
For my finer work i use my Festool sanders. I have a large ES150-5 with a 5 mm stoke that is used to flatten and remove material. I also have an ES125-2 with a 2mm stoke that is purely for finishing. It removed very little material but needs to be moved around with a light touch so not to get burn in swirls.

I use Abranet - Mesh Sanding rather than sand paper. with my Festool it picks up about all of the dust particles and gives a much smoother finish. Again, don't over sand.

Thanks Matt. I hear MDF is a bear to finish so my works cut out. I have a lemmer airless but thats more for painting large scale stuff and the seals cant do lacquer. Fences, exteriors, ceilings etc. I was honestly thinking rattle cans might be the cheapest way to go. About $150 is what I would hope to spend on material for the paper, masking, stain, paint and clear coat. No idea if thats doable.

When I painted my subs I used all automotive finish's. High build primer then basecoat/ clearcoat. Its the only way to get that high gloss finish unless you have the time and patience to do a lacquer paint job which requires a ton of sanding painting and waiting . Even on the speakers I veneered I used automotive clear coat. As for the question about sanding the front. If you want a shiny clear coat smooth finish you need to sand as smooth as you can or it will take many coats of clear with sanding in between coats to get it level. Stain will cause the grain to swell and become uneven as well, i have never sanded after staining so you on your own there. The finish is the hardest part of the project by far. I am in the automotive sector so I have friends at the local parts store and I have picked up paint that was mixed incorrectly for free a few times but the rest I pay for myself and even with my discount it can easily top 300 bux. I tried the urethane from a hardware store and it just doesn't dry quick enough and spraying it is next to impossible .

If you have sanded properly to begin with (on wood) then the amount of sanding you need during the finishing stage isn't so bad.

My point with MDF is that most of the surfaces on the MDF are press heat rolled flat. The case hardening on the smooth surface will still give a bit of absorption but not too much. You don't want to sand back to the point that you break through the hardening and start to expose the fine particles below. Then you have a dogs breakfast to deal with.

The cut sections you need to seal first. I would even look into coating them with a waxless shellac. Zimmer might be good but I would look into getting some flake from either Lee Valley or WoodEssence. Have not played with Target waterbased shellac. If you give WoodEssence a call and explain the project they are great in the advice department of what will work best for you. You can use shellac as a primer for the whole thing. Start with a heavy cut coat and then built it up from there. I would also recommend that you seal the inside of the box as well.