The cutting edge

. dinsdag 29 maart 2011
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After reading some more on vacuum technique, the soldering of the RVS didn't look like such a good idea anymore.
If I want to bake-out a chamber, the melting point of the solder is just too low.
So I tried heating the whole RVS hemisphere in a coalfire (pumped with a leaf-blower).
The temperature was ok to almost melt the 60-40 SnAg solder (600 deg.C), but it didn't flow.
So after that experiment failed, I tried the grinding machine, after making an edge I continued with sandpaper, whetstone and then polishing.
It worked! I now have a smooth edge and I can use a standard viton ring.

stainless steel soldering

. zondag 20 maart 2011
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Did some cleaning of the stainless steel hemispheres, they look much better now, I really had some luck finding them.
Exept for one hole each, they have the right edges for standard viton rings.
The opening without the right edge is also damaged, so I will solder a copper ring on it, to solder stainless steel (I think it's 304, but it might be 316, can anyone tell my how to see the difference?) I used lead-free solder (SnAg, 3.5% Ag), and S39-rvs/inox.
Soldered it with a small torch, the soldering was ok, but a bit slow, My torch didn't have enough power.
Next step will be pre-heating the whole thing with a fire and then do the soldering.
Here is a picture, with the soldering halfway.

Spherical vacuum chamber

. donderdag 17 maart 2011
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Today I finally had the time to visit the dump where I saw the two spherical plugs which I plan to use for the vacuum chamber.
I had to spend 2 hours lifting heavy stuff and had to dismantle the plugs, all very heavy work, had some help from two very friendly polish men. My back hurts, but I'm very happy!
They are perfect!
The big connection between the two halves has exactly the right edge for a copper ring, there are openings for a viewport and current feedthrough openings, just great, fantastic and very cheap :)
I will have to to a lot of work to make it into a vacuum chamber, but it's a good start, the inner diameter is 28.5 cm and each half is about 30 kg inox.
The plugs were originally used in an oil refinery.
Here is a picture:

5.4E-5 mbar

. zaterdag 5 maart 2011
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Got 5.4E-5 mbar in about 10 minutes!
Seems my setup works, I didn't use any heating yet because I want to setup the cooling of the turbopump first.
Here is a picture:

Turbo pump

. vrijdag 4 maart 2011
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A picture of the turbomolecular pump:

On the right there is the TCP121 controller, and in front a bottle of alcohol, have been cleaning the setup yesterday.
The open side on the right will be connected to a cold cathode ion gauge, but the connecting piece showed some kind of strange black crust. Seems to be mixed with iron-oxide. Hope I can get it clean, one of the vacuum commandments is "thou shall not use iron".

vacuum chamber

. donderdag 3 maart 2011
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Went to the metal scrap dump a few times this week, but didn't had a change to get my hands on the big spherical plug valves I saw. They were moving tons of steel around with big magnets, so it was too dangerous to disassemble the valves there.
They are big valves, about 40cm wide, used by an oil refinery, I will try next week, two of them would make a wonderfull vacuum chamber.

Vacuum setup

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Got the equipment for the vacuum setup!
Had a crash course in vacuum technique last friday from a very helpful Pfeifer & Balzers technician, and got a very good deal on some equipment.
He worked on the vacuum equipment used by FOM for ITER material research. What a coincidence!
Pictures following soon :)