Progress Reports on the ETF Rebuilding Project
 

I plan to post periodic reports on our progress here.

First, I'd like to say that we view this as a long term effort - probably years before we can produce rebuilt tubes in any quantity. And, of course, we may never get there.

Our goal is to have a non-profit, self supporting operation that rebuilds tubes for collectors.

We have been making slow but steady progress toward this goal. First, we got the equipment from Hawkeye when they shut down and transported it to Hilliard. This gave us most of what we need to rebuild tubes.

This year we built the room where the equipment will he housed. Volunteers at our convention completed the drywall finishing, and the equipment will be moved in soon.

Recently we raised $8,500 to purchase and ship to Ohio phosphoring and aluminizing equipment from RACS. It should arrive this summer.

We have been accumulating stock of guns, glass, etc. as we find it. I think there is a considerable amount of this stuff out there that we will eventually get.

Our hope is that this year people will use the facility to experiment with rebuilding.

We also hope that by next year we will have a funtioning, active committee in place to oversee the operation. This group would work on the problems:

1. A business plan. Which tubes can we rebuild at a price that collectors can afford? How do we manage the facility?

2. How do we deal with the long term problem of guns? We will have a sufficient stock to do some tubes (who know how many, but maybe 100 late 40s black and white tubes and 50 color roundies), but we will need to find guns, stems, glass tubing, getters, etc. for an ongoing operation.

Very cool, thanks for the update !

Stems and guns: I found this on E3ay this afternoon. The vendor states they have many in stock. Looks like a color gun.

http://www.ebay.com/itm/Steam-Punk-A...item51ba004a98

Can an inline color gun like that even be a good parts donor for the monochrome and delta-gun color types that are worth the effort to rebuild?

At one time, the discussion turned to trying to broaden the types of tubes that could be rebuilt. If they posted an inline gun, and they stated that they have others, there could be delta and monochrome guns in the stash as well.

A tube like M48AAW00X is an example that is popular and priced high enough to warrant a rebuild attempt for those who need them.

Progress Report, July 12, 2014:

Walls and ceiling of the CRT rebuilding room have been painted. Next is the floor. We will schedule a day sometime this summer for volunteers to install the equipment and finish the construction.

We are still waiting for details of a quote that RACS received for shipment of their stuff to Ohio. We expect that shipment will happen this summer.

I can't wait until this happens.. I'm going to put a tube aside to wait and have rebuilt..

Progress report - September 8, 2014

www.earlytelevision.org/crt_project.html

Steve-

I am very happy to hear of the progress at the ETF. If I was nearby, I would want to help with the museum/foundation's efforts. Thank you for the ongoing work and for posting the update.

Take a look at our project page. We have made a great deal of progress:

http://www.earlytelevision.org/crt_project.html

That is great.

Thank you for the update and the pictures.

super! Thanks for the updates.

Very good to see the Oven coming together. Has a decision been made as to a make/model of thermostat and if it will just have one temperature probe or multiple?

Is the sheet metal uncoated or is there a coating on it that might out gas when heat is applied?

Matt

This is the controller we are going to use:

http://www.amazon.com/JLD634-Setpoin...oak+controller

There will be a single temperature probe. I think the convection fan will keep the temperature uniform.

The sheet metal is galvanized. I'm sure there will be plenty of nasty fumes when I first fire it up - oil, etc. and probably something from the insulation. Over a few hours it will probably all be burned off. During the tube baking it doesn't matter because the inside of the tube is sealed via the O ring on the diffusion pump.

How hot is the target temperature in the chamber during bake-out?

775 degrees F

That could be an issue. "Galvanized steel is suitable for high-temperature applications of up to 392 °F (200 °C). The use of galvanized steel at temperatures above this will result in peeling of the zinc at the inter metallic layer."

Oops. I should have checked that. I assume that means that the steel is still structurally OK, just that the galvanized coating will separate. If that is true there isn't a problem. It will just look bad and maybe rust.

Zinc oxide - Iron oxide - not a problem ? Stuff flaking off into an environment
where extreme steps are being taken to keep from poisoning a new cathode....
Not a problem....?

Remember that the CRT is completely sealed when it goes in the oven. The only opening is the stem, which goes into the diffusion pump and is sealed with an O ring. Any contaminants that are in the oven never get into the tube, where the gun is.

I don't think the nickel coating, or potential rust, will be a problem.

OK,

I am sure it will smell lovely during the first few times of operation :)

I like that temperature controller, I would personally also opt for the 25A solid state relay since the internal relay is only a 3A.

Just my $0.02

Matt

Bob beat me to the punch on the Zinc issue...(Actually I went to bed after posting.) But he was thinking along the same lines.

Just a heads up, you do NOT want to inhale zinc fumes. https://en.wikipedia.org/wiki/Metal_fume_fever

Mild or Stainless. The choice depends on if you can live with rust and/or have the budget for stainless...

Your target temperature is just high enough that you wouldn't catch me in the same enclosed space without an apparatus for breathing.


Squirrel Boy also helpfully points out that anything hot and galvanized around virgin cathodes is a very bad idea. The vapor *will* travel, and produce fine granules of zinc, which *will* get into/onto everything. If you want a practical demo, just break open a bottle of laser toner in the rebuild lab. You'll be finding it everywhere for MONTHS afterwards no matter how carefully you think you managed to clean it up.

I was not going to say this, but I do believe that at that temperature
zinc would be a bad idea. Its probably not a health risk, but would be at
100 degrees hotter.

I would break down and change to 300 series stainless steel. For
a system that small it does not have to be thick.

This is advice from a person who has done tons (literally!)
of vacuum stuff involving electronics and heat.
At that temperature even stainless will be strongly oxidized and
turn brown, but it will not flake.

In many cases of even slightly larger ovens than yours brick
is normally used, but since you already have it, go to stainless.


Doug McDonald

I asked a friend of mine at MIT who works with high vacuum systems as part of his research on nuclear fusion. He strongly agrees with the prevailing opinion that zinc in the rebuilding room is a bad idea:

I am happy to chip in to help pay for the cost of stainless and strongly suggest that we should go ahead and replace the galvanized.

-Matthew

Thanks for your comments. I think I'll fire it up and run it for several hours (It is in a large warehouse - I'll do it when there are no people in the room and have good ventilation) and see what happens. If there appears to be an issue I'll go the stainless route.

Matt, I've ordered a 40 amp solid state relay and heat sink. The heating element is 8400 watts.

You know the zinc doesn't just flake off nice and neat, it powders off and it does make
extra stinky nasty gases..... Why risk getting that crap all over the building....?
That little fan in there, you gunna run that on yer test....?

And no laser printers in that building either......

Please, think about things before proceeding. Getting zinc everywhere is not a good idea. It could damage things in the museum. (Do you want metal powder settling on open-bobbin flybacks?) Not to mention the whole "Well we have a 30% failure rate on rebuilds after 100 hours of use and we can't figure out why?" issue of poisoned cathodes that awaits.

If you're not willing to take 7jp4-guy's offer of financial assistance to change up to stainless, at least consider buying a $16 pail of refractory cement at the hardware store and 'spackling' the entire exposed galvanized inside with a thin coating to minimize the zinc exodus. As a bonus this will add a bit more thermal insulation to the whole apparatus, plus because it is white it will reflect more heat back into the oven than metal would and thus increase systemic efficiency, which lowers your cost per tube.


Yes, I'm sure there were many one-man rebuild operations run out of terrifyingly dirty garages and basements. I'm also sure that they produced working rebuilds. What nobody is sure of is what the lifespan of these mom-n-pop back-alley rebuilds was compared to say an NVC rebuild. If people are going to pay you to rebuild a tube, I think they're hoping (like me) to get a rebuild that exceeds all original specs, because we have 60+ years of knowledge, tech, and tools to do the job.


I've refrained from posting the following observation/thought because I wanted to wait for more news from ATF on which way they were leaning toward, but it kind of goes hand-in-hand with the current topic of discussion.

Regarding re-phosphoring or just re-gunning.

If I'm budgeting to have a rare or significant tube rebuilt, much like a car there's things that you just do while you have it torn down because it is cheaper and easier to replace parts that you have easy access to. So if I'm going to have a tube refreshed, I'd feel better about stripping the jug and re-phosphoring and aluminizing. There will come a point where bent-guns are no longer an option, and if you can't aluminize a tube, then all it will be good for once re-gunned is short demos in a dark room or you're just going to wind up with a big goose-egg ion burn up front, and then it's really pooched because there's nobody to re-phosphor it, even if the gun is good for another 8k hours.


The solution to all of this is to determine the haz-mat disposal fee related to the wet-process of re-phosphoring a tube, and declare that up-front to the customers in the same way that you have to pay a haz-mat fee to dispose of tires and automotive fluids. The actual bench process can (and should!) be heavily revised to significantly reduce the volume of haz-mat produced at the increase of labor and/or in non-hazardous alternative consumables.


Specifically, I'm looking at the HFA based stripping process. You can strip the phosphors off with a weaker acid and some mechanical scouring action. (Put the tube on a rotary-shaker table with some water+acid/base and soda-lime marbles or even just a cup of lead-free birdshot for a few hours.) This way you don't produce many many gallons of water+HFA+barium/lanthanum/etc haz-mat like RACS did. You will still produce, say 1.5 gallons of non HFA haz-mat containing just the phosphors and weak acid/base, and then you do the final rinse/clean of the inside with the HFA process only once for the desired surface prep, using significantly less than a quart of acid solution, and probably being able to re-use the same acid two to five more times before it becomes exhausted since it isn't eating up ALL the phosphor and aluminum, it's just putting the final polish on.

We have now potentially reduced the haz-mat disposal requirements by an order of magnitude or more in volume, but we've added some extra processing time via the shaker-table. I'd wager the extra time is cheaper than the bulk haz-mat disposal rate, though.


Hell, I'm pretty sure that 24 ounces of bismuth bird-shot, an inch of warm water, and a pint or maybe 20 fl oz of regular old lye on a shaker-table will strip the face of all aluminum and the phosphor in 60-90 minutes. You'll have to put it on a tilt lathe or roller table to de-aluminize the rest of the bell, but still entirely feasible. Even if someone had to go in and 'bottle-brush' the neck and bell, lye will eat that aluminum right up. (Yes, I know, fumes. I'm pretty sure you're going to have to install a fume hood at some point to comply with OSHA, but that's an infrastructure cost over time, not a consumables cost.) On the up-side, the effluent produced is low-grade hazmat, only because of the phosphor compounds. The lye is just "caustic" and you can neutralize that on-site rather cheaply. I'm also fairly sure that there's a non-hazardous way to strip the dag if that somehow survives the caustic assault.

Again, instead of washing it all off with copious HFA and H2O, you can use something slightly more tame than HFA with a bit of mechanical assistance to do the real dirty work, and only unleash the HFA in a smaller dose to achieve the final ultra-clean surface that is required in re-phosphoring the face.


Go find an undergrad student majoring in inorganic-chemistry at your local edifice of higher education and ask how he(or she!) would solve the problem of cleaning glassware that has phosphor and a few microns of aluminum stuck to it. (CRTs are just very large erlenmeyers when it comes to "I need to clean this filthy thing extremely thoroughly.") Actually, even an org-chem major can provide workable solutions. They have all kinds of fun gloop stuck to their apparatus that they need removed entirely, too! They also probably know more about exactly what waste products are and are not classified as haz-mat these days and can advise the best way to minimize reportable waste while still achieving the necessary final result. They're also happy to be paid in beer, food, or fuel, if not for free just because someone finally asked them to help solve a real world problem with their knowledge even though they don't yet have that shiny degree on the wall. Grads want a budget and a notch on their resume, while post-grad students can only afford to consider problems that have grant-money attached to them. Undergrads aren't fully jaded like that, yet...


You folks at the ETF have come a long way towards the goal of rebuilding CRTs again, but don't scuttle the whole project with an avoidable mistake or by limiting your potential at only providing palliative care with a new gun shining onto old phosphor. If I have a tube that went to air in 1968 because the socket came loose, I really do not trust the phosphor coating to behave properly no matter how much you bake it out. If it was aluminized then it will certainly require the full service process to obtain an acceptable result. In 44 years with access to the atmosphere, those few microns of aluminum have become mostly aluminum oxide with just a tiny bit of actual aluminum underneath. Remember that AlO2 is an electrical insulator, and that alone is enough to result in an inferior finished product. I'd also put good odds on the AlO2 flaking off the face/bell and falling into the gun assembly during pump-down and bake-out, much to the detriment of the finished product from that side of things.

Thanks everyone for your comments. I will replaced the galvanized metal to avoid the zinc issue.

As for re-phospohoring and aluminzing, we have the equipment to do that coming from RACS later this year. We also have a person who visited RACS for two weeks and learned the process. At some point we will deal with the issues of getting this equipment converted to operate on US power standards and with the environmental issues.

The vast majority of the dud tubes out there are still under vacuum, so the existing phosphor is most likely OK.

Bent guns are not available now - we plan to replace the heater and cathode in existing guns.

Well, I think that Steve is working very hard to get a really terrific thing off the ground.
I'm beginning to think that each step, and every little item may need to be looked at by
more people just so something can be avoided like short life tubes after a rebuild. Like
NoPegs said above. Not that Steve and the people at the museum are not doing the best.
But more along the lines, that an overlooked item may mean a hundred tubes will
possibly have a short life due to something no one realized.

I also think that as for the bent guns not being available, the best solution I think is to
rebuild the bent gun, and not mess with a good screen. Re-coating the screen should
only be done after rebuilding bent guns is tried and failed repeatedly.

It's just my thoughts that disturbing something that you are not sure you can replace
with long term reliability should not be jumped on quickly and without long term testing
first.

Username1, thanks for you comment. We are not doing this project without a lot of expert help. Several of our members have participated in rebuilding tubes at Hawkeye and RACS. One of our members spent two weeks in France at RACS learning the process. Scotty at Hawkeye and Phillipe at RACS are available to us to help when we need them. Nothing we are doing is new - guns have been rebuilt before, and the process of rebuilding tubes is well understood and documented. I don't think we will have a problem with tubes having short lives.

I understand you guys are knowledgeable on this, but you were not there to build
the equipment at RACS, or at Hawkeye. You are however, building some new equipment
at your location. What I am saying is that if you don't look into even the smallest
details on the items you use, proper procedures may not make a difference, you could
innocently introduce something unintended and have problems.....

Believe me, I do wish you luck on this project.......

Keep up the good work Steve and I wish you total success! You can count on a tube or two from me when the time comes. If I lived local to you I would be there helping all the way to a finished product.

Gregb

Since the galvanized was not used, what metal is now being used?

I'm using bare steel for now. At some time in the future I may replace it with stainless. The Hawkeye oven was full of bare steel, so i think it will work fine.

Krylon makes a spray-on high temp paint, good to 1200 deg. F. What do you think of spraying the steel with it?

http://www.homedepot.com/p/Rust-Oleu...specifications

Unless you're only planning on firing the oven up during the full moon, I think you're over-thinking things. Blacksmiths don't paint their anvils or tools for the same reason. Once the surface rust happens, it won't progress much further unless it goes unheated for long periods in wet weather. I'd loop back to the "Well, what are the potential side effects if it flakes off or outgasses etc?" line of thought and just go with "Steel."

Untreated steel is the best option. High heat keeps rust from progressing to the
point it will become a problem. And if the oven remains unused for any period of
time, heating it and or wire brushing it down will remove any rust.

You can keep a dehumidifier in the room to keep humidity levels down and
keep the bare steel from forming any oxide from becoming a problem.

I believe in time you guys will have no choice but to rethink how you will rebuild
tubes. And I am thinking the gun, stem, and pinch off will be changed because spare
items will not be available. I think in the future, guns will be rebuilt, and the neck
will have to be rewelded to the old tube envelope at the point that use to be the separate
stem, and the entire oven may need to be under vacuum.... Just thinking about how things
will have to be done when new guns complete with through wires and stem/pinch off's as
a finished assembly are not going to be available.... For that reason, you may well
begin to think about a really clean oven...

.

I am sure they are think about this, this is the first revision of the oven. The reason for the experimentation is that this is retrofitting an existing oven and enlarging it so that very large (30BP4) tubes can be rebuilt with relative ease.

I am glad to be seeing a large amount of progress being made in this effort rather quickly as of recent,

Lets bootstrap things here and start with a laminar flow hood for the gun reworking process area. Someone keep an eye open on the local used markets and pick one up for a song and store it until needed. The vacuum kiln will come in time...


I'm going to regret saying this, I'm sure...

Hawkeye was a master artisan of tube doctoring, he used tried and true methods and equipment to re-gun tubes with a high rate of success and had a very solid understanding of the fundamental processes involved. RACS were a bit more cavalier about their process, but knew a lot of tricks and reliable methods, especially for Pyrex jugs. However, their bench methods were just a bit on the scary side of things. I shudder to think about the lit cigarette accompanying most of the process.(Both for the quality of the rebuild, and from the ingesting all kinds of fun things aspects.) The communal spoon and weighing pans are also up there on the list of crazy stuff. One spoon per compound, and at least use weighing papers... I understand we're not cloning cell cultures or building a space probe here, but just because RACS got away with their cowboy techniques doesn't mean that following their lead is a good idea. (Props to Nick rocking out his E-cig though!)

Again with the car engine analogies: If my mechanic is pulling the head and sending it out to be rebuilt, I'm expecting him to securely cover the open block while it's out for service. I don't want chunks of cutoff wheel and rusty exhaust clamps flung into my open engine from the next bay over. Obviously it will still start and run, but in time all that crap will take a toll on something important and shorten the life.

Along the lines of cleanliness, should we not also try to have the room at a slight positive air pressure, just like they used to do(and maybe still do) in computer centers. The slight positive pressure helps to keep dust from migrating in.