Friday, December 23, 2011

Simple optics: I'm still doing it wrong

I did some approximate calculations and picked the really nice (expensive) laser lenses I needed.

I drilled out some plates to mount them on since they were both super fucking small. A little super glue and they were on there perfectly without messing up the light-transmitting surfaces or even having to touch them with human hands.

Then I disassembled the laser gun and used little stand up clamps to hold them in approximately the right places.

And it totally didn't work. The light was more or less collimated but it was so out of focus it just kind of spread out on it's own. It is clearly not going to work this way. But I didn't know for a while why it wasn't working.

I noticed that the website I bought lenses from also sold duplets (just two lenses affixed to each other). I also noticed that these duplets, which I'd gotten one of in the scope and one in the original projector, seem to work far better than any other lens I have. But when I look at diagrams of how they bend the light it doesn't seem to be any different than any other lens.

So I did some root investigation. I bought some simple 5mW lasers and shined them through the duplets.

It seems like the real strength of the duplets to me is actually their tolerance for poor placement. When you shine a light through them at not quite 90 degrees and centered the lens on the far side just corrects the odd angles the lens on the near side made.

In the case of the laser, it came through clear even when I was off by a bit. Using a single lens or a lens duplet I placed myself it would always be skewed out of focus because my placement wasn't just-fucking-right.

By contrast the manufactured duplet always focused the laser on the other size like one would expect even when I did it at a bad angle or offset from center.

At least that's my theory. So I did some more approximations and bought a duplet that I think will be better for this than the ones I have.

Sunday, December 18, 2011

My table has 99 problems. None of them are related to women because it's a table.

For starters, I've got the main shelf structure together. A few problems I've run into:

I didn't consider that the welded-on shelves would get in the way of the rollers. They do. I noticed after I'd only put on a few of them. A little angle grinding solved the ones I had on there. For the others, I just had then stick out the back a bit instead. This caused them to block the cross bracing in some areas. More angle grinding and some hack-saw.

The shelf that slides up and down needs to be put on by sliding it underneath the shelf structure. Unfortunately each side of the shelf structure weighs about 90lbs. They're just within my limit to easily maneuver. I believe I'm too weak to safely tilt a constructed setup backward so I can put the movable shelves on. I also don't believe the cross bracing would survive this. The shelves must be put on and then the main structure assembled. That's a bitch.

The cross bracing is generally too weak for how much the structure as a whole weighs. There's nothing that keeps it from bowing out. It'll have to be replaced with cut angle iron.

I've mounted the motor on the moving shelf. It does run but it makes a terrible racket. I need to run it more and investigate what exactly is being so damn loud.

During some light stress testing I also had one of the pegs for the rollers just fall off. It looked the welds were bad. I took an old piece I'd done as a test before doing this one and took a hammer to the pegs. They all bent instead of broke off. From that experiment I concluded that this piece was done badly but the process in general was good. I re-welded all the pegs on the existing piece and attached a new one in place of the one that fell off.

I've mounted the winch on the top piece. This just sits across both shelves. There's nothing particularly wrong with it except that I had to make pieces that kept it from tipping over and I didn't make them long enough the first time because I wasn't thinking.

Saturday, December 3, 2011

The new workspace: Submitted plans to the city.

Google docs link to plans

There's a process called 'intake' in which the city reviews the plans with you waiting there so they can assure you have at least all the documents and basic data you need and they can reject you right away if you're totally effed it.

During our intake, the woman reviewing our plans actually brought over her manager just so he could marvel at how ridiculous it was.

The planning phase alone was about $15k-20k. The city's share of that for permits and reviews was around $7k. We'll just have to wait and see if our plans are accepted by the city. If so, construction will begin around April. I'll still need to give more information about interior before we'll have a quote on how much the whole thing will cost.