Aluminum Can Tables - what's new?

This is a forum to share experiences and ideas about holography.
Locked
Tony

Aluminum Can Tables - what's new?

Post by Tony »

Thought I'd try to resurrect this great thread on the new forum. I'm about to start building a 2x2' can table. I'm interested in what new info others may have come up with!
John Klayer

Aluminum Can Tables - what's new?

Post by John Klayer »

I'm still working on the 2 can high 8 by 18 inch breadboard. It is taking a lot more time than I ever expected it would. The single can high boards were nothing like this much trouble. It may have just been good luck putting those boards together that the heights of the individual cans were about the same. I never thought to measure them, I just assumed that they all would be the same. When I blindly epoxied a batch of double cans together is when I noticed the variations. So I tried measuring a lot of cans and matching them so all the heights of the pairs would be equal.
Guess what - the tops and bottoms are not exactly parallel. I used a sleeve to align the pairs of cans for glueing.
Tonight I finally got to glueing the first pair onto the bottom plate of my breadboard. I hope to work on the rest of them tomorrow night.

When this double height board is done I want to set it up next to my single height board and put identical interferometers on each one to see if the double board is better.
Tony

Aluminum Can Tables - what's new?

Post by Tony »

John et al-

Last night I finished my single layer can table. Still waiting for the epoxy to cure before I put an interferometer on it. It is a single layer of cans with 2x2' sheets of 16 gauge steel on top and bottom. I used mostly all the same brand of cans and didn't have any height problems, except for a few mogrel flavors that crept in. Seems very stiff, can't wait to set up the interformeter on it! Took me about four evenings plus one Sunday to assemble...
John Klayer

Aluminum Can Tables - what's new?

Post by John Klayer »

Tony,
Great! I'm glad someone else is trying this. Did you leave the tabs on the cans or remove them? Did you glue the cans on the sides too or just the top and bottom? What epoxy did you use? I pressed mine between 1/4 inch glass plates with a lot of bricks to make the sheet metal flat. As soon as I get home this evening I'm going to work on finishing the double height breadboard. I like what you're calling it - hexcan.
Tony

Aluminum Can Tables - what's new?

Post by Tony »

I removed all the pull tabs as they stuck up above the tops. I used West System 105 epoxy with the 205 hardener. I sanded the cans on the sides in six places and epoxied them to each other at the contact points. Seems very stiff - though no interferometer results yet.
Tony

Aluminum Can Tables - what's new?

Post by Tony »

I completed my hexcan table this week and have made some tests and one hologram on it. So far so good, but:

It is definitely not as rigid as my previous tables. One was 1x2' cast concrete; the other was 2 layers of patio block stacked offset, glued with concrete block cement (smelly stuff in a tube), and topped with two marble squares and then a layer of 16 ga steel epoxied on top. Note that the new table is 2x2 so my interferometer on the new table has much longer legs. I can press down on the corner of the table and get a subjective measure of the rigidity of the table. The hexcan is definitely less rigid. With these longer legs I am now experiencing much more drifting of fringes due to air currents as well.

The new table is also much lighter. For this reason I had to add a layer of four patio blocks under it to lower the resonant frequency.

I did an A/B test by making a hologram on the old table and the new table in the same environment. Both were split beam transmission holos of my futuristic porcelain cat, a plastic R2D2. The exposures were only 6 seconds long and both came out equally very bright.


I'm going to continue testing and making holograms on it. I'm going to make a good H1 master on a glass plate, then try to do an H1/H2 reflection copy. That will be the acid test, when the fringes get smaller.

In general, I need this idea to work, as I have no other ideas how to build a table this size in concrete or concrete blocks, such that I can move it by myself (out of the basement) or take it apart. Every attempt I've made at building a table out of blocks where they aren't glued together has been a failure, like a wet noodle, they flop in the middle!

I also learned something cool about inner tubes. I'll post that separately.
John Klayer

Aluminum Can Tables - what's new?

Post by John Klayer »

I just finished glueing the top 16 ga plate on my 2 level hexcan breadboard with JB Weld. I need to let it cure over night then compare it against the one level board.

Even if the two level shows significant improvement over the one level, I'm not going to build a bigger one the same way I did glueing the pairs of cans together. Instead I'd do one level, add an intermediate sheet metal then build the second level on top of it.
Tony

Aluminum Can Tables - what's new?

Post by Tony »

So far I've made 7 holograms on my 2x2' hexcan table. The last was a reflection copy, 15 second exposure. No hints of vibration problems. So it seems the hexcan idea works!
John Klayer

Aluminum Can Tables - what's new?

Post by John Klayer »

Tony,

What kind of vibration isolation are you using?
Tony

Aluminum Can Tables - what's new?

Post by Tony »

From the bottom up:

-Basement floor
-Indoor/Outdoor carpet
-Cheapo folding table (!)
-3/4 inch plywood
-20" bicycle inner tube, very soft
-3/4" plywood with vent hole
-4 1x1' concrete patio blocks ~1.5" thick
-1 layer 3/8" bubble wrap (just so the table doesn't rock on the blocks
-single layer 2x2' hexcan table 16 gauge steel

the latest exposure was 34 seconds long, an H2 copy. still no vibration problems.
Locked