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Gee... I sure hope I spelled that right! Anyway, Welcome to this new Yahoo Group for the casual experimenter in Vacuum or High Vacuum (from now on Vac or HiVac). Searching the web I've found a few places for more experienced vacuum workers that seem to really get into the Physics of what and how the molecules do what they do under low pressures. I've made a few requests on some of those lists and I either get a full-blown snow- job or an offer to sell me just the right do-dad for only a few thousand dollars. That kinda leaves me without a place to chat with folks that have some knowledge and are willing to share it. I am interested in HiVac in order to put together an Aluminizing chamber for telescope mirrors. I've been gathering parts for several years in order to build my system and have a barn full of goodies but was still looking for an 18 inch Bell Jar until last week when I found a surplus 24 inch SYSTEM. I will be travelling to Eastern PA this weekend to pick it up and will keep a running description on here (assuming there is any interest and/or members). I've seen Aluminum vaporized onto glass before and "it ain't rocket science". It's a fairly simple process but there are things to be aware of and to watch out for. So... Let's get together and have some friendly discussions on what works, what doesn't, things to watch out for, things to sell, trade, etc. I'm moderator only in the sense that I've started this group. I'll pretty much leave the daily running to the members but will step in if I'm asked or if I see a need... other than that, it's your group to use. Have fun, be kind, learn, teach, participate. Ken Hunter

Hi Guys... I've posted some photo's to the group in a folder named "Ken's junque shop". There's one of me and a SILO top that I have been lugging around for a while, a few of some vacuum valves, diffusion pumps and condenser baffle units as well as one of the 20 inch baseplates I have been trying to find an 18 inch bell jar for. There are also 4 photo's of the vacuum system that I'll be picking up in Pa this coming week. It is a 24 inch bell jar with all the valves, turbo pump etc. Only thing missing is a roughing pump. I have a HyVac that I think will work but it might be a bit under-rated for the turbo. I'll just have to see how it does. Now it's your turn... Open up a folder and post your photo's then give us a description of what you're doing or would like to do. Personal photo's are nice to have also so we can see who we are chatting with. Have fun! Ken Hunter

I've added James Lerch's web site link to the Group Links. If you have a web site that you'd like to add... please do! Ken Hunter

Hi... It's been a while since anyone (me) posted. We now have 12 members, but not much participation. Should I keep the Group open or let it die? I've returned from Eastern PA with a vacuum coating system on the back of the trailer. Unfortunately, I contracted a bad cold during the loading of the equipment and have been bedridden for most of the last few days. It's still where it was parked Wednesday and I haven't been outside since that time. There will be a lot to do to make the system operational. Originally it was a wafer handling and coating chamber for making Integrated circuits. Most of the wafer handling equipment, gauges etc were taken off the rack before I purchased it but I was able to retrieve the electronics necessary for making the gauges and turbo pump work. I'll need to dis-assemble and clean everything as there is no way of knowing what kind of toxic materials may be lurking in the thing. A complete re-wiring will also be necessary as the original machine was controlled by computer. So, I have my work cut out for me. What are you up to these days? Ken Hunter

Hi Andy... Welcome to the Group. I'm sure that your expertise can be of help to some of us as we muddle through. Where are you located? I'm thinking Australia for some reason. (Am I close?) Tell us more about what you do at work and please post a photo of yourself or favorite project or both in the sections to the left. If you have access to surplus gauges, parts or supplies, let that be known also... Let's see if we can keep this thing going. Do you work on Gauge Controllers as well as the gauges? What models do you handle and recommend? There's a lot of folks that use Vacuum pumps, gauges, etc for making Neon signs and other projects that may have some needed information or may be able to pick some up here as well. You never know who will show up or what they will bring with them. Ken Hunter

Greetings All, To stimulate a little conversation, I thought I'd recount a few of my more "Exciting" moments during a few recent coating runs :) Good Times #1 Things were going well, but perhaps it was a little cold for Florida (~40f). So I'm in the process of evaporating some Al, actually I was almost done. Anyway I've got my eyeball right next to my 1/4" thick viewing window, watching the 'Magic' as the coating forms, when I hear a LOUD "TINK" followed by a hissing noise!!!!!!!!!!!!!! After quickly turning my head away from the chamber and stepping back a few paces, I waited for the chamber to implode :) Thankfully it didn't, but ya never know.. After a few seconds I regained my courage and started looking around to see what was going on. In one smooth motion, I scanned the chamber and mirror inside, both of which appeared to be in one piece still. Next on the list were the pressure gauges, which were rising rapidly! I quickly killed the evaporative power source, Cold trap power and Diff-Pump power, and started closing the Diff-Pump valve as fast as possible, still not sure what was going on! After venting the chamber, I started investigating. First the mirror coat looked pretty funny, with odd waves going across it. After a little more investigation, I found the culprit. The 2" diameter 1/4" thick plate glass electric pass thru for my heater power had fractured!!! The odd waves on the mirror coating were caused as the air streamed into the chamber, past the evaporating Al, and onto the mirror. The glass appears to have fractured from thermal imbalance caused by the "Cold" chamber and the rather hot bolt conducting the high current into the tungsten heaters. OOpps :) I've since replaced the 1/4" thick piece of glass with a nice big square piece of 3/4" thick scrap I had lounging around (BTW, a diamond wet saw cuts glass like butter!!) No problems since then. One good thing I learned from this is just how tenaciously my two part Silicone weather strip adhesive holds the glass the steel! I thought I could just 'peel' the glass off the chamber with a razor blade, WRONG. In the end I used a hammer to pulverize the glass into dust, which STILL stuck to the chamber like no tomorrow! In the end I had to use a 4" grinder to grind the silicone and remaining bits of glass of the steel chamber. Good Times #2 I'm with a friend, demoing the 'Junkyard Coating rig', things are going really smoothly. We just finished the fascinating glow discharge light show and had starting evaporating Al, onto the mirror. Next thing I know the lights are out and everything is QUITE! Ahh HELL the breaker TRIPED! Fortunately I was smart enough to use a electro-pneumatic valve on the Diff pump fore line, So I know when the power went off the valve would have snapped shut protecting the hot oil in the diff pump. UNFORTUNATLY I wasn't smart enough to turn the switch controlling the valve off PRIOR to resetting the breaker! (WHOOPS!) Since it took a few minutes to blindly find my way to the breaker box, AND my rough pump won't hold a vacuum when its turned off. The moment I flipped the breaker the diff pump fore line valve snapped open, exposing the diff pump to the much higher than normal fore line pressure. As you can guess this made a NASTY mess inside the chamber, as the high pressure wave went backwards thru the diff pump and blew hot oil all inside the chamber! NOTE TO SELF, its time to install that relay and a pair of push buttons to control the fore line valve!!! Worse part is I had considered doing this during the build, but never got around to it :( The ideal mechanism would be a push button that would trigger a relay, the relay would in turn power itself AND power the fore line valve. To close the valve a second push button would interrupt the power to the relay, allowing it to turn off, thus powering down the relay AND closing the fore line valve. In the event of a power outage, when the power came back on the valve wouldn't instantly snap open making such a horrendous MESS! :) I guess we'll chalk this one up to a little "On the Job Training"

Greetings All, Thanks to Peter Baird, I've added the option in my simulation code to support multiple evaporating rings. An interesting result from this experiment shows that it should be feasible to construct a 12" diameter by 5" tall chamber. The downside of course is the need for 19 separate tungsten evaporating coils! While this might not be feasible for such a small chamber, when constructing my next chamber (20-30" diameter) it might just be worth the effort! The main benefit of such a short chamber would be the reduction in chamber volume, thus allowing the use of smaller pumps and faster pump down time! To implement such a wiring nightmare might be interesting, but I'm wondering if I might be able to mass produce some Ceramic electric pass throughs. Something that would just require drilling a hole in the chamber, then drop the pass thru in, and seal with an O-ring.. (still working out the details :) Anyone ever seen anything like this? new Near Field Evaporative Simulator code is available from here: http://lerch.no-ip.com/atm/NearFieldSim2.zip (8.6KB) Take Care, James Lerch http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)

James, In my photo folder I have added something you might want to consider. It is a common item found at most any Hardware store and it's called a "wellnut". They come in various sizes and I imagine that it could be used as a cheap feedthrough for electrical purposes. I don't have an assembled system yet to test the idea but you do! It would work just like the botttom plug on a small boat. Put it into a hole, pass a bolt through and tighten it up. The rubber will compress sealing against the smooth shoulder on the bolt and the (hopefully smooth) sides of the hole. The pass-through bolt becomes the conductor. Ken Hunter wondering throughs. then drop details

James, I've added a photo to my folder that might be what you are asking for. It's a common item found at hardware stores and is called a "wellnut". I imagine it would work like the hole plug at the bottom of a small boat. You drill the hole, put in the wellnut, insert the bolt and tighten. The rubber compressess and tightens against the sholder on the bolt and the sides of the hole. The bolt becomes the conductor. It's available in various sizes. Ken Hunter wondering throughs. then drop details

Changed the Group photo so you wouldn't have to chase down the photo of the Feed-Thru idea I have... If you have any photo's that you would like to submit to the Group, please do. I'll rotate all submitted photo's through the Group's home page as time permits. Ken Hunter

Hi Guys... It's been 2 weeks since we have had any input to the Group, There are 2 new members this week but no message activity. Should we close down the group or keep it open? I'd like to see more activity here... I'd also like to see some warmer weather so that I can get out to the garage and start work on the vacuum station sitting out there. Last night we had whiteout blizzard conditions just above zero F, snow drifts 4-5 feet filled up the 75 foot driveway. Luckily we have a 4 wheel drive vehicle and made it across the yard between drifts to the road when we needed to get out this morning. I can post some photo's if anyone's interested. Let's get something going here... I challenge each of you to invit ONE other person to join the Group and get them to participate. I know there is interest out there and I'd like to see this become a useful place to meet and discuss various things about your pet projects. If we don't have any improvement in a couple of weeks I'll close the Group down. No sense writing this down for myself, I don't need to compile a journal for others to read. OK, now get typing! Ken Hunter

I just found this group as I was looking for info on vacuum stuff. I am a machinist that now owns his own shop. I like to make things, and my mirror needs recoating so...Hmm guess I'll make a chamber! I'm going to weld up an eight sided chamber out of 1/2 inch alum. plate. It will be around 20 inches across and 12 to 20 high. Check out yarde metals drop zone for good prices on metal. www.yarde.com As for the cold trap, I have an old window unit that stoped cooling. I brazed on a valve to fill it, R22 was the refridgerant, propane is a drop in replacement so thats what I used. It is still low on propane, but I saw -31F on the cold side with the blower off. Max would be -41F, after that propane makes a vacuum. If you want to replace R21 use 80 percent propane and 20 percent isobutane. I have a rough pump and a gauge, but lack a oil diffusion pump still, if you guys have any leads I'll check them out. As for feed thru's will spark plugs work? How many amps can they pass? I also plan on trying to cast mirror blanks with a honeycomb back. Thats a big project so well see how it goes. To support that project I want to make grinding and polishing machines...like I said I like to make things :) Take care Les

Hi Gang, It's now official... I have been selected to be the new Electronis Systems Analyst (ESA) at the National Weather Service Office in Amarillo, Texas. My report date is 5 May but Rose and I will probably be on the road for a few days prior to that and unavailable (not that you'd miss me). If I seem scarce in the next few weeks, it's got to do with the move and finishing up some projects that have been neglected before the movers show up. Tons of stuff to do... Ken Hunter

Hi gang Hi to Ken / James / Les Congrats to Ken I just found your group I haven't started to put together a vacuum system yet but it is on my list and I'm collecting info. I am an ATM guy I have ground polished and destroyed 2 mirrors a 12" and a 16" I purchased both at the same time from ASM they were supposed to be ceramic low expansion and all of that and the price was great. Both were laminated from ?" thick pieces of black glass. the 12 " I ground ok but it was astigmatic so I reground it and was polishing on a machine, the power went out in my shop and the mirror stuck to the tool and when the power came back on $$%^&*( oh well. When I saw how the glass was laminated together I know why it kept bending on me. When I ground the 16 "F4 I didn't have any problem with astigmatism but I ground thru the first layer of ?" glass there were a lot of voids in this blank from not being fused properly so it was an ugly mirror. I had a lot of problems with scratches I think from the pieces of glass chipping up from the void areas. When I finally got the scratches under control I couldn't repair a bad zone at the transition area between the laminations it was as if the glass bond area had stress or was harder than the surrounding glass. Because the glass was black I couldn't check it with polarized light The best I got to was 1/3 PV. Would have been 1/8 PV if I blacked out a big doughnut in the bad zone area After way to many hours of playing with this blank I decided to cut my losses. I threw out the glass so I wouldn't be tempted to play any more. I just finished building a furnace so I can fuse my own glass blank. The furnace cost me about the same as a good 20"blank. I fired it up yesterday for the first time. I'm waiting for a controller to come in for it. The next projects will be: A trepan setup to cut glass disks. A new grinding machine, An interferometer the testing is almost done I need to make a 20 " Plano mirror and a 4" spherical un coated f2 reference a beam splitter and all of the hardware to hold it all together. And then a vacuum setup. Oh yea, let's not forget an awesome telescope: Later Ron PS Ken do you know how I could do a 50% transmission silver coating for the beam splitter.

First off, welcome Ron [now I'm not the new guy :)] I won a diffusion pump on ebay, but it is not here yet. It holds 100ml so I will put Santovac 5 oil in it. That 100ml of oil costs about $140 but should give little to no back streaming with no baffle, cold cap, or cold trap. Yesterday I welded up the sides of my chamber, and the top ring. It is half inch plate, about 18 inches wide and 17 tall. After I get the pump I'll machine the port for it and weld on the bottom. Then mill the top flange flat and mill the Oring groove. Then I get to make 7 covers for the ports. Why so many ports? It is easyer to make the port in each side piece before it was welded together, so I'll just block off unused ones. I plan on two windows and a power feed through port. Later I may use the chamber for a glove box to weld titanum in an argon atmosphere, so there goes two more ports for gloves. I'll post pics of it now. Ken... look on the bright side, moving gets rid of stuff ya dont need. Les

There is a crapy photo of the tester I made. I wanted to share the cam idea that rocks the knife edge in and out. It is on the right side and can raise and lower about 3/16 of an inch, It works very well. Later I'll put in better pics. Les

Don't buy your SantoVac oil yet... I have a small container that came with my 24 inch chamber (Turbo pump) plus I have a half gallon of 704 somewhere... Let me see if I can find it. Ken

Hi, This is an imteresting group. I have been involved in thin films for about 20 years. We have 3 E-beam systems, utilizing cryo-pumps for deep vaccum. Other equipment includes spectrometers, photometers, and spectralradiometers. We use crystal monitoring for thickness monitoring. We are now placing and optical monitoring system for improved accuracy. The E-beam power supplies are 2 10KV an 1 14KV system. We feed these power supplies with 3 phase 220V at 100Amp. Two of them are air-cooled. The 14KV system is water cooled. I usually design and make interference filters. This weekend, I coated 12 mirrors from 6" to 10" in size and about 50 diagonals. I found an interesting combo of layers that I really like. It starts with about 20nm of Chromium, followed by 130nm of Aluminum and finished with 4 layers of Tantalum Pentoxide(Ta2O50) and SiO2 for enhancement and protection. I get about 94% reflectivity with this combo. I find that very few people use Ta2O5. I found that the thin Chromium layer all, but eliminates pinholing. The Ta2O5 is an extremely adherent material and combines very well with SiO2. I have silver mirrors that I coated the same way. I have one mirror in my MN56 that is over 3 years old and is still like brand new. The reflectivity of that mirror is about 97%. Al M

If you can do it a stack for a silver mirror that is reported to be highly stable is: Glass - NiCrNx (8?) - silver (1200?) - NiCrNx(2-8?) - SiNx (100?) [146a]. The NiCrNx seems to act as a nucleating layer for both the silver and the SiNx protective layer. 146a. J.D. Wolfe, R.E. Laird, C.K. Carniglia and J.P Lehan, p. 115 in Technical Digest OSA, Optical Interference Coatings Conference (1995); also P.D. Fuqua and J.D. Barrie, "Optical Properties and Corrosion Resistance of Durable Silver Coatings," p. 85 in Properties and Processing of Vapor-Deposited Coatings, edited by R. Johnson, W. Lee, M. Pickering, B. Sheldon, Material Research Society Proceedings, Vol. 555 (1998) Regards, Don Mattox ____________________________________ Donald M. Mattox Technical Director Society of Vacuum Coaters 71 Pinon Hill Place NE Albuquerque, NM 87122-1914 Telephone 505/856-7188 FAX 505/856-6716 E-mail donmattox@... WebSite http://www.svc.org

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