Skip to main content

Vacuum Fittings... Lab Work!!!

I had  lot of ups and downs in the lab yesterday.  The kids, (Jr. aged 3, and Sam aged 1), and I went out ot Bryan Hose and Gasket and picked up our new vacuum hose yesterday.  They had the hose ready and waiting for us and they had the free popcorn machine up and running, so the kids got popcorn.  So, that was cool.  The hose looked a bit small though.

After taking the kids out to visit Blinn College for lunch with their physics professor mom and then returning them to daycare after their mini-adventure, I made it back into the lab.  Sure enough, the hose was too small to fit over our vacuum fitting.  It had seemed like a good idea to cut the old hose behind the fitting to get a better measurement, but I hadn't really thought about the pipe that someone had jammed into one end to permanently expand it so it would fit over the fitting.  The 'jam a pipe in' expansion technique worded fine for red rubber vacuum hosing I'm replacing because its stretchy.  Unfortunately, it won't work at all for our new tubing.   There's a metal coil running through the center of the new tubing to keep it from expanding or collapsing, consequently, the hose is not at all stretchy.  So, that was a bummer.



The net result of all this was we needed new hose, which takes a week or so to get, or new vacuum fittings which I could build in a few hours.  That might sound like it could be a bummer, but it's not.  It means I got to play in the machine shop!!!  I like the theoretical aspects of physics, it's fun to play with the math and especially with the geometry, but I love getting to play around in the lab and the machine shop.  I guess at heart that makes me an experimentalist.  I'm not sure yet, and I'm definitely not ready to decide, but man I love playing with equipment.  To build new fittings, I had to start out with the two blank flanges shown below.  They had to be drilled through to provide a path for air to flow.  Next, a beveled bottom had to be added so the pipe would have something to sit rest on while it was being soldered into the flange.



Using the machine shop lathes, I bored out a hole in each flange, the same size as the inside of the brass tubing that would fit into the new vacuum hose.  Then, I using a boring bar I carved out the bezel that would fit the pipe.



The next step involved playing with the acetylene torch!  I cleaned the pipe and the flange using emery cloth in preparation for the application of soldering flux.  Wikipedia has the best most concise explanation of flux I've seen recently, so here goes:
"In high-temperature metal joining processes (welding, brazing and soldering), the primary purpose of flux is to prevent oxidation of the base and filler materials. Tin-lead solder (e.g.) attaches very well to copper, but poorly to the various oxides of copper, which form quickly at soldering temperatures. Flux is a substance which is nearly inert at room temperature, but which becomes strongly reducing at elevated temperatures, preventing the formation of metal oxides. Additionally, flux allows solder to flow easily on the working piece rather than forming beads as it would otherwise."[1]
Here are the fluxed parts


The next step?  Get the torch to light.  This is a bit simpler than it seems...  You'll see:


The whistling towards the end is my nervous habit when I think things are about to explode.  All was well though.  The issue turned out to be that the gas nozzle was dirty.  After a little cleaning, the torch lit right up.


A few minutes later, (ok, more like half an hour), I had two new fittings.





Comments

Anonymous said…
Here is a great place to purchase vacuum products and the following.
UHV Wire
Vacuum Burst Disc
vacuum components
Vacuum Components
Vacuum Feedthorugh
Vacuum feedthorugh connectors
Vacuum feedthroughs
Vacuum Fittings
Vacuum Flange
Vacuum Flanges
Thank you and I hope it helps all the vacuum enthusiasts out there.
Chris

Popular posts from this blog

Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems, there seem to be fewer explanations of the procedure for deriving the conversion, so here goes!

What do we actually want?

To convert the Cartesian nabla



to the nabla for another coordinate system, say… cylindrical coordinates.



What we’ll need:

1. The Cartesian Nabla:



2. A set of equations relating the Cartesian coordinates to cylindrical coordinates:



3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system:



How to do it:

Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables.

The chain rule can be used to convert a differential operator in terms of one variable into a series of differential operators in terms of othe…

Lost Phone

We were incredibly lucky to have both been in university settings when our kids were born.  When No. 1 arrived, we were both still grad students.  Not long after No. 2 arrived, (about 10 days to be exact), mom-person defended her dissertation and gained the appellation prependage Dr. 

While there are lots of perks attendant to grad school, not the least of them phenomenal health insurance, that’s not the one that’s come to mind for me just now.  The one I’m most grateful for at the moment with respect to our kids was the opportunities for sheer independence.  Most days, we’d meet for lunch on the quad of whatever university we were hanging out at at the time, (physics research requires a bit of travel), to eat lunch.  During those lunches, the kids could crawl, toddle, or jog off into the distance.  There were no roads, and therefore no cars.  And, I realize now with a certain wistful bliss I had no knowledge of at the time, there were also very few people at hand that new what a baby…

Lab Book 2014_07_10 More NaI Characterization

Summary: Much more plunking around with the NaI detector and sources today.  A Pb shield was built to eliminate cosmic ray muons as well as potassium 40 radiation from the concreted building.  The spectra are much cleaner, but still don't have the count rates or distinctive peaks that are expected.
New to the experiment?  Scroll to the bottom to see background and get caught up.
Lab Book Threshold for the QVT is currently set at -1.49 volts.  Remember to divide this by 100 to get the actual threshold voltage. A new spectrum recording the lines of all three sources, Cs 137, Co 60, and Sr 90, was started at approximately 10:55. Took data for about an hour.
Started the Cs 137 only spectrum at about 11:55 AM

Here’s the no-source background from yesterday
In comparison, here’s the 3 source spectrum from this morning.

The three source spectrum shows peak structure not exhibited by the background alone. I forgot to take scope pictures of the Cs137 run. I do however, have the printout, and…