Tag Archives: Woodworking

Quick TV Pillar Mount Project.

early assembly with TV

Now that Maximum Baby is crawling I wanted to get our huge tv off of the rickety cart it was sitting on. Sam had a tv fall on her as a child and one is enough for us.

The tricky thing here is that we wanted to mount the TV on a concrete pillar.

Trying to attach a flat thing to a curved thing is tricky.  My solution was this:

  1. Got a 2×8 of Douglas Fir from my local Home Depot. They usually have crappy wood, but I managed to find a piece that looked quarter-sawn, so that’s good.
  2. Cut it to length based on the height of my TV, the height of my soundbar and allowing room for attaching some shelves later.
  3. At the base trim each side 45°, then angle the saw blade to 45 and make a cross cut. Makes a nice beveled end instead of a dramatic right angle.
  4. Use some of the scrap at the top to increase the depth so the TV mount screws get a lot of purchase depth. I used wood glue and 8 screws.
  5. Prime and paint.
  6. Attach hardware.
  7. For attaching it all to the pillar I decided to go with a friction mount. I ordered 3 endless loop ratchet straps and ratchet them tight against the pillar.

Using a friction mount is a dicey thing. Materials have two kinds of stickiness – or friction coefficients. One is how sticky two things are when they are at rest (static friction coefficient) and the other is how sticky two things are when they are moving (kinetic friction coefficient). Friction works great right up until you overcome the static friction coefficient and then it works very poorly because the kinetic friction coefficient is always lower than the static friction coefficient.

Good news is we can calculate how much force our friction mount should support! Friction is dependent on the pressure between two surfaces (the normal force) and the stickiness between them (the friction coefficient). The frictive force is going to be our normal force times the static friction coefficient.

How much normal force do we have? I’m estimating that I can ratchet around 150lbs of pressure on one of those ratchet straps. Let’s cut that a little bit because I haven’t been working out and I am an optimist. Let’s call it 120lbs. I’m using 3 ratchet straps so that adds up to 360lbs of pressure.

There’s a table on that page with friction coefficients for common materials. Looks like they say the static friction coefficient between wood and concrete is 0.62. 360lbs * 0.62 = 223.2lbs.

I’m around 175lbs – I should be able to do a pullup on this!

me doing a pull up on a ratchet strapped wood.

And I CAN!

My TV weighs 50.8 lbs, the tv mount weighs 8lbsmy shelves weigh 11lbs and they can support 22 lbs per shelf. I forget how much my soundbar weighs. Let’s call it 10 lbs.

50.8 + 8 + 11 + 22 + 22 + 10 = 123.8 lbs. I’ve got around 99 lbs of spare capacity before we hit the limit of  my static coefficient of friction!

I feel like I can trust this not to drop on Max for a while!  How long until Max might hang off of this and make it drop? Hmmm – when is he likely to be around 100lbs? Wolfram Alpha tells me a 10 year old American is around 94lbs. I should be able to teach him not to do it by then or get another ratchet strap.

Secret Project D – a Custom DIY Dresser

Secret Project B has been so on my mind that I totally forgot to write up my Secret Project D!

thin_hudson_dresser

Sam had been talking about wanting a dresser, but none of the ones we found really fit where we wanted to put one. We liked West Elm’s Hudson dresser. Clean modern style, but it was too deep to fit our space. Sounds like a job for me!

Screen Shot 2013-07-03 at 5.57.12 AM
I made measurements and decided that the best way for a nerd like me to proceed would be to make a sketchup design. I found a sketchup model of the thin hudson and made my dresser model based on that.
I started working on this last August on nights and weekends.

Screen Shot 2013-07-02 at 1.26.10 PM

Screen Shot 2013-07-02 at 1.27.52 PM

Afterwards, I dropped by a West Elm to see how they put theirs together. That’s when I realized that I didn’t have to make the stretchers in the carcass solid – I could make them a frame and they’d be just fine. Also – less weight in the furniture will be helpful when we move it around.

Then life gets in the way – the project was on hold for months. After figuring out what I wanted to do I bought tools, and got started in December.

I decided to go with a furniture grade plywood. Not all plywood is crappy – some looks really nice. I went with Baltic Birch. It’s good looking, the beveled edges on the drawers have a sweet pinstripe on them and I could get it nearby at the Brooklyn Dyke’s Lumber1.

bevel_drawers

Plywood has a couple of other sweet properties for small apartment woodworking. The cross-grain layering of plywood makes it very stable with regard to moisture. This means I don’t have to have a jointer or planer to flatten the wood. In addition, the sheet of plywood has a continuous grain veneer – so you cutting the drawer fronts from one sheet of plywood preserves that grain across the drawers.

drawer_fronts

When you buy lumber, you have to know how to order it, and you need to know how much you want. The sales folks are used to dealing with people who order very large amounts, so not knowing makes you an irritant. You won’t get what you need. Fortunately, if you build your model in Sketchup first, there’s a handy plugin that calculates how much lumber to buy and gives you a cutlist based on your model. It even gives you a plan on how to get the most out of the wood with the least waste. That’s so helpful!

Armed with my cutlist, I grabbed a truck from zipcar and brought back three huge 4’x4′ sheets back to my woodshop in the sky.
wodshop_in_the_sky

After many nights and weekends of cutting, swearing, panicking, gluing, screwing, sanding and shellacing I got the dresser done. My woodshop in the sky has turned into a baby room, so I’ll have to find a new place to make any future furniture. If any folks are interested in either how I made it or what I’ve learned about small apartment woodworking, I could write more about that.

1ks-see-ya-later

  1. I cannot imagine the creepy search terms those folks find in their server logs  (back)