My new setup

How to get to vacuum, what the classes are, and what is needed for what job.

My new setup

Postby Jerry » Wed Feb 12, 2014 1:38 am

Picked this up tonight from Portland State, a new vacuum system. 26" workable diameter in the bell jar, set up for doing thermal evaporation with up to 3 different sources. 6" Varian with a 2hp roots blower and a leybold roughing pump. Has an inficon thickness monitor and a lesker ion gauge readout. Fun!

Another item for my ex-Tektronix collection.

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Jerry
 
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Re: My new setup

Postby Jerry » Fri Feb 14, 2014 1:24 am

I have found most of the manuals already. I still dont know who made the blower, I have not looked very hard. This system was being used up to the very minute I told them I was going to get it. They decided to get rid of the system because it was just too big. By the time the thing got pumped down time was up for the class, so they are building a smaller system.

I hope to get it running this weekend, well, at least the pumps. I messed up the o-ring putting the bell jar back on and made some nice nicks. I was expecting the rings to cost a fortune but nope, $4 each.

I do have some electrical issues to sort out. I immediately noticed they were running 120v equipment in it yet there were only three wires going to the 240v plug, they were using the ground as a neutral. I am going to install a small 240-120 transformer to isolate that. I also need to install a bucking transformer to drop the 240 to 208 for the RG generator I am installing.

I got out the good camera and took more pics, in the first you can see a couple of the filaments.

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Jerry
 
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Re: My new setup

Postby Jerry » Sat Feb 22, 2014 3:26 am

Got the RGA installed with the inficon pressure reducer, basically a valve with an orifice that will allow me to sample up to 150mtorr and is pumped down by another small turbo. I have a couple of those turbovac 50 pump that were on ebay a couple years ago. I never tried one, hope one works.

I did find out what the blower is, it is a Leybold Ruvac WA-150, it is the smallest one they make at 108cfm.

I got the o-rings for the bell jar this week and fired everything up. After a few hours it got down to 2x10^-5 and the RGA showed it is just full of water vapor. I installed a power feedthrough and am going to put a 1200w quartz halogen lamp in the chamber to get things warmed up a bit.

I also got a couple turbos from a friend. Both are Seiko Seiki mag lev pumps, the "small" one is 1000l/s and the large one is 2000. Freeking massive, weighs 60kg. I have the controller for the small one but I need to get four 12v lead acid batteries for the internal power backup for the mag lev. This one is also pretty dirty. The inside is stained kind of a purple color. I tried some methanol and it didn't do much, it seems to be really in the grain of the metal. Any idea what it could be? These were used in semiconductor processing so maybe it was a part of an etch cycle. Both pumps are rated for corrosive conditions.

The 2000l/s one is in pristine condition. I found a drive for it on ebay, $1200. The one that I got with it was for a Osaka Vacuum turbo. Think I might try to sell that one off and buy the right drive.

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Jerry
 
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Re: My new setup

Postby Doug Coulter » Mon Feb 24, 2014 5:45 pm

Nice looking stuff! I'd definately replace that oil diffusion pump with a turbo, a turbo-drag if possible, and get rid of one of the forepumps too - I kind of doubt you need both with a modern turbo. For reference, my own big tank only "needs" 512 l/s to be fine, even that is probably excessive once you get way down there. The issue is that in molecular flow, vs viscous flow, the O rings leak more than happens to find its way into the pump intake by random collisions with the walls, without getting up to viscous flow pressures, and at that point, only things like sublimation pumps and so on have much effect - you just need more square feet of absorbtion ability.

Viton leaks water, but not air. Nitrile the other way around. Why someone hasn't yet invented a dual-seal approach using both, I dunno - I might have to, or you.
If something's been up to STP/shop air conditions for a long time, it takes awhile to get back down there - it looks like that's your situation - tight, but wet (viton, perchance, too?)

In fact, earlier this month, during the very worst solar conditions ever, I turned off my turbo, which I rarely do, for a few days, and even with the forepump valve closed, and mostly CF (copper) but some viton (door and a couple tubing couplers) it went up to e-1 mbar in 3 days, and a week+ later (and a very moderate hour bake) - still isn't back to its normal base pressure, about a factor of two high.
Didn't check - my Pfeiffer mass spec is offline, but you just know it's all water, since the only possible intake is through viton. I can let it up to shop air for an hour and it not take anywhere near this long to get back to base pressure. I can get back on the same day if I take it up to STP using argon or nitrogen instead of shop air, and don't open the door much while I replace a grid or something.

That's one nice transformer too. I re-wound a harbor frieght spot welding transformer with some taps on the secondary for use here, with a variac and a solid state relay - it's a working thing I can count on. I noticed in my own evap work that most of what you might evap - I messed with Al, Ti, Pd and Cu - is a decent "getter" itself. It's why some pro lashups have a "shutter" over the source. You preheat the stuff you're going to evap, maybe even evap a little - and it eats all the contaminants itself - only then do you do the deposition, after the evap source itself has cleaned things up. Kind of like a sublimation pump for free. Al and Ti are particularly effective at this, and especially with water. I accidentally coated much of my tank innards with Al on my first try at all that - and I believe it is better than stainless at not having water stick back onto it later on. It ruined all my insulators, of course - I had to do a teardown and clean them all again - but it went back to base pressure a lot faster....hmmm. I may have to do a more complete job of that coating.

I'm surprised maglev needs a backup power source. My Pfeiffer thingie makes enough back emf to run the controller for 15 min or more in a power failure, if there's no leak. It's almost freaky how low the ratio of friction to stored energy in that rotor is. It only draws about 35-40W to run the entire mess at base pressure.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: My new setup

Postby Jerry » Wed Feb 26, 2014 11:41 am

You can't run a roots without a roughing pump and the roots brings the chamber down so much faster. Also roots blowers have one other benefit, they eliminate back streaming from the rotary pump since they run dry. If I can get one of these turbos running that means I will basically have a dry system.

The newer version of these turbos do use the regenerative power of the turbo to maintain the mag lev of the rotor. This design dates back to at least 95. The drive inverter weighs about 80lbs.

I was having an issue with getting the system below -5 torr and it did not match up anywhere near what the rga was telling me. I hooked up a couple other ion gauge controllers and found that they all read a decade less than this one. Some digging through the manual revealed that the setting for the gauge tube were totally out of whack. Now with a bake out I am getting down to 5x10-7. Not bad.

When I vent the incoming air goes through a drierite canister to strip out some of the air. It slows it down quite a bit. Takes at least 5 minutes before the lift will open it.
Jerry
 
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Joined: Sun Jul 18, 2010 12:07 am
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Re: My new setup

Postby Doug Coulter » Thu Feb 27, 2014 2:07 pm

Yeah, e-7 mbar is definitely way into "not bad". I know roots are quick - the largest one I've seen was in a pair that did the air conditioning for an enourmous church in Vienna VA - the assembly was about 30 feet on a side, including huge motors to run it all.

You can get some oil backwards through one if you're not careful - they are quick, but do have a little clearance or they die young.
Personally, I like roots for this:
http://youtu.be/EXnkTsU3bsA


There will be more of this if Vice ever gets around to airing the piece they did on me last fall, when this was taken. Their cameraman, though brave and strong, could not hold his camera during a 0-100-0 run in half a mile - he got great footage of the sky and his feet, though.
The car (I helped build this, a little, for my good friend John) has nearly 2hp/lb. Yes, it's very fast. Getting sideways at 100 as you cross old railroad tracks in an industrial park was, well, a bit exciting - not bad. Heeeeeeeeeerrrrres Johnny!
JohnRod.jpg
Context


On a more practical note, the ability to just pull the entire tank off what you're doing there is a MAJOR advantage. Making it easy to try stuff means you'll do it - and improve whatever process you're trying to do a lot quicker and easier.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: My new setup

Postby Jerry » Fri Mar 07, 2014 2:45 am

Well, the smaller turbo is dead. Looks like a short somewhere in the mag-lev side in the pump. It pulls the power supply way down when you hook it up and errors out. About $6k to repair it. I think I am going to try to sell the drive and pump as well as a Osaka drive I have and try and buy a drive for the big one.
Jerry
 
Posts: 561
Joined: Sun Jul 18, 2010 12:07 am
Location: Beaverton, OR

Re: My new setup

Postby Jerry » Mon May 19, 2014 1:47 am

I got another turbo pump this last week, this time a complete set, pump and controller. It is an Osaka Vacuum TG2003 rated for 2000l/s at 24,000 rpm. It is mag lev like the other pumps I had been trying to get going but a little more friendly. I plan on keeping an eye out for another controller for the other 2000l/s pump I have.

ImageUntitled by macona, on Flickr

So, to get this thing on the system is going to take quite a bit of modification. The rotary pump/blower package is going to come off the frame to get the vibration isolated from the turbo. I am also installing a stepper driven gate valve from VAT with a adaptive pressure controller. The gate valve mounts directly to the ISO250K flange on the turbo and receives feedback from a capacitance manometer on the vacuum chamber. The controller can be set for a pressure and the controller with open or close the gate valve to maintain the set pressure in the chamber. Pretty handy for sputtering and plasma processes that work above the high vacuum range.
All of this needs to mount where the diffusion pump was. That was mounted to the system through a 6" port with a ASA flange and a 6" pneumatic gate valve in between. I am leaving the gate valve in place, it closes very quickly and will be useful to cut off the turbo in case of a high pressure event. The stepper driven valve won't be of much use for this, it takes up to 10 seconds to close.

To mount the pump/valve to the existing valve I need an adapter that will go from the ISO250K on the stepper valve to the ASA 6" on the pneumatic.
First step is to make a ASA 6" non-threaded to non-threaded flange. To make this I used a 11.25'x2.25" disc of aluminum with a 4" hole in the center I found on ebay. I chucked it up in the lathe and faced one side and then flipped it over and faced the other. I then ran into a problem. I do not have enough travel in the cross slide to cut out the aluminum to create what would be the flanges. I decided I would figure out a way to do that on the mill. Putting that aside I cut the two grooves for the o-rings that will seal this to the valves. If all possible you always want to cut o-ring grooves with a lathe or a trepanning tool, the scratches in the cut will be with the length of the o-ring and create a better seal, milled o-ring grooves can leak. To cut this I used my threading tool holder with a 1/8" wide grooving insert.

ImageUntitled by macona, on Flickr

With that done I put the ring on parallels on the mill table and secured it with a stud to the table. I used the mill to clean up the perimeter of the disc to 11" and then drill eight 27/32" holes for bolts.

ImageUntitled by macona, on Flickr

To cut the flanges out I put the disc on edge on the table and use the shortest 1" cutter I had and milled out the groove 1.55" in from the edge at each bolt hole. Finally I clamped it back down to the table and programmed a tool path to cut out the remaining material in the center of the ring which finished this part. Next will be to make another adapter, this one will go from the ISO flange to the ASA flange, but I need more aluminum for that. Making this part has really stretched the limits of what I can make in my shop, Barely enough Z travel on the mill and just fitting on the lathe.

ImageUntitled by macona, on Flickr
Jerry
 
Posts: 561
Joined: Sun Jul 18, 2010 12:07 am
Location: Beaverton, OR

Re: My new setup

Postby Jerry » Fri May 23, 2014 1:54 am

I got a piece of aluminum from a friend for the next part of the adapter, this was an lid from an old plasma etcher. Its a piece aluminum about 14x14 and 1.25" thick. Pretty perfect.

Image6" ASA to ISO250 pump adapter by macona, on Flickr

I decided to leave it square, no reason to make it circular in the greater scheme of things. Milled out the chunk in the center leaving the core for the base for the telescope. Spotted and drilled all the holes, 7/16" on the small ones and 5/8" on the large ones. Had a little fun with the 7/16" ones, had a bit explode on my when I lost coolant. Oops.

The 5/8" holes were cleaned up with a mill and then thread milled to 3/4"-10. This was my first attempt at thread milling, one goof and a $80 bit is toast. But it all worked out and had nice, straight threads in a blind hole all the way to the bottom.



Image6" ASA to ISO250 pump adapter by macona, on Flickr

After that I cut a groove for the centering ring/seal for the ISO side. I had ordered some new o-rings, 3/4" threaded rod, and half nuts from mcmaster which arrived today. I cut up the rod on the lathe and bolted it all together. Here's hoping it does not leak!

Image6" ASA to ISO250 pump adapter by macona, on Flickr

Image6" ASA to ISO250 pump adapter by macona, on Flickr


Next up is to clean up the gate valve that is going to hang off this adapter and then hand it. Both the gate valve and the turbo are 150lbs each so I need to figure out a way to get them up in place. I am thinking a hydraulic motorcycle lift.
Jerry
 
Posts: 561
Joined: Sun Jul 18, 2010 12:07 am
Location: Beaverton, OR

Re: My new setup

Postby Jerry » Sun May 25, 2014 1:24 am

I installed the valve today, it was a total mess on the inside. There was a layer of rust coating the inside of the valve body which just should not happen. The entire thing is made from stainless. It must have been from whatever was being pumped in the system. I disassembled everything and scrubbed it down with scotchbrite and it cleaned up pretty well. I do need to get a new bearings for the gate, they are in pretty sad shape.

I borrowed a hydraulic motorcycle jack to lift the valve in place. Worked rather well. I did have to turn the other gate valve 90 degrees to clear the big valve's mechanism.

Tomorrow I need to run down and pick up some longer bolts. The one I have were just barely long enough to reach. I also need to tie the valve into the frame of the system, there is going to be significantly more weight hanging off there than what was there in the past.

ImageVat gate valve by macona, on Flickr
Jerry
 
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