Just an interested lurker here so far... But I am interested in how you are
going to heat it red hot then cool it quickly, this 7 ft long thing weighing
heavens knows how much? It wouldn't exactly fit in my kitchen oven ;-)

Hans

$50 as opposed to $500. This isn't a little BBQ grill tank I am talking
about. It is 36" in diameter and 7 feet long.

On Friday, January 9, 2004, at 03:52 PM, Jerry B. Hillman wrote:

Okay,
I have been told that I either can't use the propane(used) tank due to
absorbed hydrocarbons, or I have to find a way to remove said hydrocarbons.

What's wrong with buying a brand new (empty) one that hasn't yet contained said hydrocarbons?
They aren't that expensive.

I am neither a metalurgist nor a chemist but it amazes me that steel can
absorb enough propane to be a problem,

It takes only very tiny amounts of anything to be a problem when one is talking about
high vacuum.

However, I think I can remove it with heat.

Heat, vacuum and patience, yes.

Say enough heat to turn the tank red hot, then rapidly cooled to
restore temper. I can generate and maintain this type of heat easily.
Am I still wasting my time?

I think you'd be better off just finding a tank that hasn't yet been put into service.

Okay,
I have been told that I either can't use the propane(used) tank due to
absorbed hydrocarbons, or I have to find a way to remove said hydrocarbons.
I am neither a metalurgist nor a chemist but it amazes me that steel can
absorb enough propane to be a problem, However, I think I can remove it with
heat. Say enough heat to turn the tank red hot, then rapidly cooled to
restore temper. I can generate and maintain this type of heat easily.
Am I still wasting my time?
Jerry

Guys,
Just ran into this link @ dartmouth:



These guys took apart their evaporator - which is 90% the same as
mine.

The site contains some interesting teardowns on the vacuum valves
and of their large diffusion pump.

-Bill

--- In VacuumX@..., "jbhillman2004" <JBHillman@e...>
wrote:

Okay, so since Ken invited me to join, I'll start asking

questions. I

am about to purchase a propane tank. I intend to cut each end off

and

I can see why you need to cut off one end (to create an o-ring
flange etc) but why the 2nd end?

build a vacuum chamber from it. Finished size should be better

than

30" in diameter and I am thinking about 30" tall from round bottom

to

round top. The seal will be in the center where the two halves

join.

OK so the seal will be in the center, or 'beltline' of the tank. I
would suggest just leaving the original ends on the tank unless you
have some requirement for removing them. The original ends are
spherical and will deflect less than - say - flat ends...

The brand new tanks are (at least around here) filled with dry
nitrogen prior to first filling. Thus you shouldn't have problems
with hydrocarbon load soaking into the steel. If you are using a
used tank then yes you will have to attempt to get that stuff off of
or out of the surface of the steel, or else your vacuum pump will
take a week to pull it down the first time (and you will contaminate
the pump oil in the process).

For used tanks I think the primary problem source is the mercaptain
odorant additive in the gas - which seems to condense or otherwise
form a waxy film inside the tank. Some souls have used alternate
washings of weak water + Drano (sodium hydroxide), followed by
detergent to chemically remove this gunk. Please do not forget that
the vapors of this waxy residue are also flammable, and in the
proper ratio with air - explosive. I discovered this the hard way
one day!

The metal is about 1/4" thick.

The '20lb' type BBQ propane tanks which I have dealt with are less
than 1/8th inch thick steel (except at the seamed/welded beltline).

Any reason why this won't work. The tank only costs $50.
Next question. Can someone point me in the direction of a used

vacuum

Ebay. Welch 1397 and 1402 pumps run for $200-$300.
I'm glad to hear about your experiments. Keep us all informed!
-Bill

On Thu, 2004-01-08 at 16:12, jbhillman2004 wrote:

Okay, so since Ken invited me to join, I'll start asking questions. I
am about to purchase a propane tank. I intend to cut each end off and
build a vacuum chamber from it. Finished size should be better than
30" in diameter and I am thinking about 30" tall from round bottom to
round top. The seal will be in the center where the two halves join.
The metal is about 1/4" thick.
Any reason why this won't work. The tank only costs $50.
Next question. Can someone point me in the direction of a used vacuum
pump. I have considered building my own out of a small gasoline
engine and turning the engine externally by the crankshaft but there
is probably a reason why this won't work. Any comments.
Enough for now. Jerry

Greetings

No reason it can't work but there are some potential problems.

Petrochemicals soak into even steel during long term storage. If your
tank is used you may have to come up with a way of removing the gassed
into the steel propane. The reason for caution - propane makes a very
nice boom when the conditions are right!!

Darald

开云体育

All of the components you speak of will contain hydrocarbons which will outgas for years. This contamination will only be evident in the poor quality of the coating. I am sure a used air tank might be as available as a used air compressor will be available too. Don't start with insurmountable problems. Vacuum coating has enough secrets without adding some obvious problems! Good Luck.......Bill Lang

Okay, so since Ken invited me to join, I'll start asking questions. I
am about to purchase a propane tank. I intend to cut each end off and
build a vacuum chamber from it. Finished size should be better than
30" in diameter and I am thinking about 30" tall from round bottom to
round top. The seal will be in the center where the two halves join.
The metal is about 1/4" thick.
Any reason why this won't work. The tank only costs $50.
Next question. Can someone point me in the direction of a used vacuum
pump. I have considered building my own out of a small gasoline
engine and turning the engine externally by the crankshaft but there
is probably a reason why this won't work. Any comments.
Enough for now. Jerry

I appreciated the invite, Ken, and am glad to be a member. The
Strong article is a great one, especially for the telescope crowd.

Kevin

--- In VacuumX@..., "Ken Hunter" <atm_ken_hunter@y...>
wrote:

Hi Kevin...

Thanks for taking my invitation seriously and becoming an active
member of the VacuumX Group! Your posts have been well received

and

I'm sure that your information will be an important part of our
archives for those who come along in the future.

In fact... Your posting of John Strong's article has already
answered several questions that have been asked of me lately.
Somewhere I have the Amateur Scientist book but have recently

moved

so I can't lay my hands on it so quickly.

I'm also sure that there will be members taking you up on your

offer

to post the TIPS articles as well as a few incidental sales of
coating supplies.

Again...

WELCOME!

Ken Hunter

Hi Kevin...

Thanks for taking my invitation seriously and becoming an active
member of the VacuumX Group! Your posts have been well received and
I'm sure that your information will be an important part of our
archives for those who come along in the future.

In fact... Your posting of John Strong's article has already
answered several questions that have been asked of me lately.
Somewhere I have the Amateur Scientist book but have recently moved
so I can't lay my hands on it so quickly.

I'm also sure that there will be members taking you up on your offer
to post the TIPS articles as well as a few incidental sales of
coating supplies.

Again...

WELCOME!

Ken Hunter

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the VacuumX
group.

File : /strong.pdf
Uploaded by : toglman <inky@...>
Description : Strong metallizing article

You can access this file at the URL



To learn more about file sharing for your group, please visit



Regards,

toglman <inky@...>

Thanks.

Stranding is really a continuous operation, difficult to do in batch
fashion, with a fair amount of scrap generated during the initial
setup to get the pitch correct and regular. you might be able to do
it with a lathe and torch if you create the right type of "die".
You will probably be able to do a few feet at a time that way, but
expect the first few inches to be trash.

We have a 3 x .015 strand that would fit your requirment well. We
can supply it as a continuous length or in precut pieces for about
the same cost. The precuts are easier to ship and save you the
hassle of trying to cut tungsten (not an easy task) Let me know
which you prefer. As for winding, we do this under high heat to
avoid splits and microfractures. This yields longer life. I don't
know how much of an issue this is for you.

Kevin

--- In VacuumX@..., "James Lerch" <jlerch1@t...> wrote:

Greetings Kevin, Welcome to the group!

Any tips on winding stranded tungsten? I have three 60" pieces of

0.01" solid

wire, I've been trying to devise a method to wind them into a

single strand.

Current stumbling block is how to heat the wire to the ductile

transition temp

while at the same time winding them together. :)

Heck, can you quote a price on bulk stranded wire? I'm currently

consuming

about 600 inches of 0.032" solid wire a year for my amateur

needs. If stranded

wire is more durable (I'm discarding the solid filaments after

each firing) I'm

afraid my consumption will probably decrease.

If you can quote on bulk stranded wire, I'm in the market for 60"

or so lengths

with an overall diameter of 0.03" (+/- 0.005" or so) formed from 3

or more

strands. BTW, I have been, and probably will continue, forming my

own filaments

from the bulk wire.

Thanks in advance, and again "Welcome"

Take Care,
James Lerch

I just added another3 articles to my website.
wwwvacuumlab.com. That makes a total of 34 articles on
practical vacuum technology.
Phil Danielson

Guys,
Stumbled into the following groups:



Both groups are into high vacuum experiments - mostly towards
achieving inertially-confined fusion of deuterium (!) .

Looks like quite a bit of research, personal sagas etc related to
high vacuum technique on those pages. SOme characters seem to be
developing amateur ion beam rsources.

I wonder if one could produce his own e-beam evaporation scheme for
the bulk or continuous evaporation of aluminum etc?

-Bill

Greetings Kevin, Welcome to the group!

Any tips on winding stranded tungsten? I have three 60" pieces of 0.01" solid
wire, I've been trying to devise a method to wind them into a single strand.
Current stumbling block is how to heat the wire to the ductile transition temp
while at the same time winding them together. :)

Heck, can you quote a price on bulk stranded wire? I'm currently consuming
about 600 inches of 0.032" solid wire a year for my amateur needs. If stranded
wire is more durable (I'm discarding the solid filaments after each firing) I'm
afraid my consumption will probably decrease.

If you can quote on bulk stranded wire, I'm in the market for 60" or so lengths
with an overall diameter of 0.03" (+/- 0.005" or so) formed from 3 or more
strands. BTW, I have been, and probably will continue, forming my own filaments
from the bulk wire.

Thanks in advance, and again "Welcome"

Take Care,
James Lerch
(My telescope construction,testing, and coating site)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "
Calvin Coolidge

The answer to both questions is yes. Multi-tranded tungsten of any
type is generally better than single-stranded wire since the multi-
stranded has a wicking action which wets the aluminum across the
filament and minimizes balling and dripping of the aluminum.

Aluminum cored wire improves both of these qualities. The aluminum
core "prewets" the filament. Commerical metallizers use their
filaments for more than one shot so on subsequent shots the open
strand which is left is bettter able to wick and hold molten
aluminum that a non-core strand. The tradeoff is that the open
structure is weaker than a tight strand and will probably not last
for as many shots.

In both aluminum core and non-aluminum core versions additional
aluminum is placed on the filament. The core itself is not usually
considered as the primary evaporant. This means that the first shot
from a cored filament deposits a bit more aluminum than subsequent
shots.

As far as explosive evaporation, that was one of the earliest
methods of deposition. However, the amount of deposited material is
smaller and there is a problem with spatters of molten material
contaminating the surface.

Kevin

One thing I would be interested in is knowing if anyone has
tried tungsten with aluminum core for making mirrors. For that
matter, has anyone considered just skipping the tungsten
altogether and just using aluminum filament like a fuse?

Dominic-Luc Webb

Greetings to all members of the group. My name is Kevin
Anetsberger. I would like to offer my assistance to anyone who
might find it helpful. I am the General Manager of Midwest Tungsten
Service, a company that manufactures vacuum evaporation sources of
all types. Ken Hunter has contacted me regarding some things that I
might be able to do for the group, and I am more than happy to
oblige. I am the author of MTS's "TIPs Newsletter" which provides
layman language coverage of many metallizing issues. I will be
posting them gradually to the files section here. I have personally
visited hundreds of metallizing operations for troubleshooting
purposes, so perhaps I can be of assistance answering some questions
or locating sources of supply for various items.

Glad to know you all.

Regards,

Kevin