Wait!
Micheal and others about to build tables, don't resort to the pvc or cans just yet. I've got a source here in St. Louis that has some hexcel so sell by the pound!
Its surplus from Boeing Aircraft that is available in a few different sizes.
I built my 4'x8'x8" table using three big chunks with one milimeter cells. I epoxied the chunks together with aircraft epoxy from Wicks Aircraft in Illinois.
I then ran out of epoxy before I got to doing the top and bottom skins with series 400 stainless. That damn epoxy was thirty-five bucks a pint and I could'nt afford any more nor did I have the patience to save the money required so I just grabbed some Liquid Nails to finish the job! Ok, well that was'nt by best idea because its taken a number of months for all of the L.N. to set up hard.
Its stable enough to make bright silver holograms, ten inch by ten inch, transmission, and is light enough for two guys to carry it.
Saturday I'll have time to post pictures and give more acurate description of whats available and for how much!
Metal Hexcel is nice stuff for tables though a bit awkward to work with. ( easy to cut along cells boundaries, a pain to face cut. ) You can get it in a variety of formats from Hexcel ( www.hexcel.com )if you've got deep pockets. You can also order it skinned with various materials. For example, commercial aircraft floors are 1/2" phenolic hexcel with a fiberglass skin on both sides.
If you have access to industrial surplus ( Boeing uses a lot of it for "filler" in composite structures here in Seattle and in St.Louis ), you can often find the phenolic and aluminum versions in several cell sizes and thicknesses. I've seen 4" thick aluminum material with 1/8" aluminum skins on both sides in 4'x8' sheets.
Most commercial optical tables are steel honeycomb construction with 1/4" steel skins. Not sure if the core is a Hexcel product but mine is pretty light and very rigid.
Hopefully this works this time.
I've just started a website where I can upload some photos (finally).
If this doesn't hot link just click. http://indimensionn.com/page4.html
Gary, first of all thanks for sharing your ingenious set up. It looks great and is shows you have put a lot of time and thought into fabricating it.
By the way, your photos must be huge because it takes a very long time to load them when viewing your page. Of course my 56k modem doens't help either. It took about 30 minutes for the entire page to load. But after the first image loaded it captivated my attention.
Your draft exclusion is done very professionally and the gantry looks very stable. Where did you get the material for the gantry? Is it the stuff found in large walk-in refrigerators/freezers.
Is there a reason you did not paint the top skin of the table black? I am not real familliar with trying to paint stainless steel. Is it possible?
I like your combination of sand and inner tube tires for vibration isolation.
I can't wait to see your photos of some holograms you have made.
Well I was afraid that if I painted the stainless that it would get all scratched up from scooting magnets and bumping steel pipes into it all the time.
Do ya have some kind hotrod primer that would resist that kind of scratching?
I used Krylon Ultra-flat black. I put a very thin coat down. I find it pickups stains but it is very scratch resistant. Theraml grease is the worst ofender. Since the paint is so cheap I figure I can re-spray the table when needed.
Ah, yes I remember the old paint-scratch-repaint technique from a few years ago when I dicided to paint my 79'chevy impala station wagon flat black to defeat the cops' laser radar. It worked fine and it cost about 20 bucks to paint the whole thing, windows and all.
I'll give it a shot on a test portion of my table.
No sweat about the name John.
The Material for the gantry is just schedule 40 steel 2" pipe with Keeklamp connectors ( also Cheeseborough clamps from the staging industry), which can be expensive for the large sizes and I've probably gone overboard by using such a large system its just that it felt so good to be totally hardcore!
The draft exclusion is the same as that described by Saxby in the 2nd edition and yeah its the walkin freezer stuff. My basement is a really dusty enviroment and it has now a coating of dust that does'nt seem to want to seal like it used to and for that reason I might reconsider this draft exclusion technique for one that lowers a box over the table.
Next time that is. Right now I only have an inch or so clearance above my gantry system.
As far as the water in the last pic; that's where I wash the film. Its just a plastic tray I've got at an angle that I clip film to while I run water over it.
The bottom of the tray rests in the sink where the water drains ( I'll get better photos of that next week). I dont have filtered water but I always rinse in deionized before and after such a wash.
Bill
Well the responce for the Hexcel was good enough to justify buying the whole stack so as of this morning I own all fifteen pieces of the "type 1" stack (as refered to on my website <indimensionn dot com>). I'll gladly sell them cheap to holographers.
For each sheet I will charge $30.00 plus shipping.
Shipping is probably going to cost you a lot more because of the bulky size. That'll have to be quoted on a case-by-case basis but you could figure around $150 to $300 depending on your proximity to St. Louis.
...........However!............
On Tuesday March 9th the day job has me driving a box truck from St. Louis to San Diego and I'll deliver to anyone along the way for free.
the route I'll take is as follows:
I-44 through Joplin,
69 to Dallas,
I-20 to I-10,
I-10 to I-8
I-8 to San Diego
Those of you who have already contacted me please do so again so that I may get your address for a shipping quote.
Bill McGarvin
bmcgarvin@imagetechnologies dot com
Ok, Bill dropped off the Hexcel last night. I've got three 3.5' x 6.7' x 1.4" sheets to work with and Andres bought two. After talking holography (and drinking beer) for a while with Bill he left for his hotel and Andres and I seriously lamented the fact that we had to work the next day and that the local hardware stores weren't open at 12am.
For those more familiar with the material, what would you recommend for skin material and size, adhesive and final panel thickness? I've sent an email off to Hexcel with the specs from the box the sheets came in (ahh, five sheets of nearly pristine hexcel) and I hope to have some specific information on what material the sheets are made of. It appears to be aluminum and Bill was guessing that it's aircraft grade since it came from Boeing.
I'm thinking of cutting my sheets into 3.5' x 5' sheets so that I can end up with four layers, using 16ga steel for the skins and either PC7 or JB-weld epoxy.
It's slightly possible that I could use the full-length panels and end up with three layers rather than four but that would take a serious re-design of the layout of my office.
---------------------------
If someone says it can't be done but they haven't tried it, don't believe them. http://www.dragonseye.com/Holography
Well, if their responsiveness is any indication Hexcel is a good company to work with.
The material that Bill acquired is CR III 5052 & 5056 Corrosion Resistant Specification Grade Aluminum 1/8 4.5lb core. The PDF is available in the first row on the following page
So your shear modulus is 70,000 on the long axis and 31,000 on the short axis. Which makes it's lower shear modulus than blue foam. Run the math for the table stiffness.
Something doesn't quite add up (I hope). I'm using the basic LEOT calculations and values and substituting my numbers (shear of 70K, width 3.5', length 5', pane thickness 0.11667) and end up with a deflection of 2186.484 wavelengths.
If I simply expand the pane thickness to my final estimated 6" I end up with a deflection of 495 wavelengths.
---------------------------
If someone says it can't be done but they haven't tried it, don't believe them. http://www.dragonseye.com/Holography
That is what got as well (well I got a little different because I did not look up the exact thickness of 16 ga steel). We both neglected the steel in between the sheets but they don't contribute as much as the skin. We could derive the equation for the added steel but it would take me a whole evening as my math skills aren't the best. Figure it is only the caps and the next layers in of steel that helps. When you see the large honey comb tables they are steel and have very thick honey comb papers. If you look at the pdf you reference you will see even in Al the parameters are very different based on cell geometry.
The inner skins are 2.8" apart and that alone will give you some stiffness. But not as much as doubling the outer-skins so that give you a limit on how much the can contribute.
No, Michael and I just mis-read the hexel data sheet. However, I have been thinking about your data. What is the width of your metal compared to the width of a single can?
I have been very interested lately in how to build a better optical table and this thread and others have been very helpful.
I found this article that might be of interest to some of you, it helped me understand a little better what to expect when using honeycomb composite materials like hexcel
BTW, Bill, it was nice to meet you and thank you very much for talking the trouble of delivering the hexcel right to my garage! Hopefully I can soon share some of my holograms using the new table.
