Archived - Fusor progress, info & photos

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
Daniel Firth
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Re: Archived - Fusor progress, info & photos

Post by Daniel Firth » Thu May 10, 2012 6:39 am

Andrew, Carl,

Thank you for bringing up your concerns & criticism in a constructive way.

Mr. Wiederhold has offered a replacement chamber to me, free of charge. There were a few problems with mine, being the very first 6" chamber constructed there, and had I simply waited another week, you all would be seeing photos of the new one and this fiasco would have been avoided entirely.

I just ask to withhold judgement until the replacement arrives, or refer to the photos John Taylor posted.

swiederhold
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Re: Archived - Fusor progress, info & photos

Post by swiederhold » Thu May 10, 2012 1:29 pm

***
Note: Off the cuff trashing and inflammatory remarks will be ignored by me as they are counterproductive and I have no interest in engaging in forum flame wars. Personal attacks on me or my business are not warranted or appropriate. A large number of assumptions have been made based solely on a few pictures. I was of the belief that this is a scientific forum and that issues were weighed on the facts and not unfounded bias. I have a thick skin, but I won’t encourage the ridiculous.
***
First, I offer a bit of background on the mechanical design of our chambers. The design is such that the flanges rest on a machined flat surface area of the hemisphere. The purpose of this design is for added safety as it reduces the stress on the welds. Pressure loads are shared by direct contact of the flanges to the hemisphere and the weld beads. The intent is that a failure of a weld would be less likely to be catastrophic as the flange (and anything bolted to it) would still be supported by the hemisphere. This is one of the reasons that the flanges are welded directly to the hemisphere and not configured as half-nipples.
In regards to Mr. Firth's chamber, I will be the first to admit that the weld quality is the poorest example of my work. As Mr. Firth has already stated, his was the first run on a 6" chamber and the 1.33" flanges presented a new challenge. The weld current was higher than I would have preferred, but was necessitated by the initial design of the flange to hemisphere mate. The design has been further refined, and the weld current requirements are now much lower. Furthermore, Mr. Firth discovered an issue with the 2.75” flanges, and those were removed and replaced. The photos showing his partially assembled chamber are of the re-worked welds.
In answer to Andrew’s questions: I am using a Lincoln Electric Precision TIG 225 welder with a rotary table. The welds on Mr. Firth’s chamber were with a 3/32” 2% ceriated electrode, 125A on the 2.75” and 90A on the 1.33”, 100% Ar @ 15cfh.
I live in the Detroit area and have many friends that are certified welders with career long experience in vacuum and pressure vessel welding. They have personally examined (not just looking at a couple pictures) the welds on Mr. Firth’s chamber, and the welds on many of my other chambers, and deemed them adequate. I am not a hobbyist making side money. This is a business and shipping a product that would be prone to failure would place me at great risk of liability. I have no interest in losing everything I have worked for – and I would never ship something without being certain that it is safe for its intended purpose.
I have included a few additional photos of recent chambers highlighting the welds. I stand behind my work and offer my customers 100% money back if they are unsatisfied for –any- reason. I have shipped 18 vacuum chambers worldwide since February of this year, and I have not had a single customer complain to me about quality or performance. Many of those customers are registered users of this forum.
Thank you to the users with constructive comments. I'm happy to answer any questions from the community and look forward to hearing suggestions for improvement of my products from its experienced and knowledgeable members.
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Richard Hull
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Re: Archived - Fusor progress, info & photos

Post by Richard Hull » Thu May 10, 2012 3:51 pm

This thread really went south. My original posting advising moderation seems to have not made anyone more forgiving. I would have run the original chamber which looked more than acceptable to me.

I never TIG welded in my life until I built fusor III and IV. No rotary table, just hand work on all the ports. No filler metal, just pushed the thin walled tubing in about 1/8-inch and used the molten lip metal to fuse to the chamber shell. The welds were not flawless to say the least, but none leaked significantly and no touch up welds were ever needed. That is the bottom line here. Rancor like that which has been presented here is more akin to "look at how pretty my stomach lining is". Who cares? As long as it digests, it's an OK stomach! Man! What a bunch of babies.

It's another matter for a professional welder to be proud of his work. However, no real structural strength is demanded and, after all, pride don't run no fusor. A simple seal is all that is required and only against 14.7 PSI max inward pressure. This thing ain't takin' no folks down into the Marianas Trench to watch tube worms near hydrothermal vents.

Oh, and a bad weld with a pin hole isn't a virtual leak, it is a real leak. Virtual leaks are outgassing crud or tiny gas volume traps, all of which go away with use, but are minimized by a good cleaning and de-greasing. A virtual or real leak of 2 microns/minute on a valved off chamber is a fine candidate for a fusor. We are working under continual exhaustion in a continual fuel flow regime. Fuel is hissing into the chamber all the time. Such a leak, real or virtual, would not impede the fusion process. My valved off fusor suffers an 3-5 micron/minute leak and I can hit two million fusions per second. Most solid fusioneers here have witnessed it in person. (HEAS) The folks who know vacuum and have done fusion here know this to be the case.

For those planning guided tours of the inside of their fusor vessels for large numbers of VIPs wandering around inside it that need to be impressed, I guess the foregoing pursuit of perfection is very important. I'm far more interested in doing fusion and proving it to skeptical observers standing outside my fusor.

Attached is an image of fusor III. Not many real vacuum components were used. The flanges were milled out junk steam line flanges, (local scrap yard). The view window was a hand made aluminum and stainless steel affair with a quartz window. The HV electrode was a special spark plug adaptation in a non-standard SS base mount. All hand welded using my large Lincoln TIG welder purchased only weeks before and my first welds were not pretty. Yet, was well sealed and did nuclear fusion with ease back in 1999. Fusor IV did use 100% vacuum rated materials, but still all hand welded by me, again, with less than ideal skill sets. I weld to seal not to impress.

You might say I am operating a nuclear fusion reactor that employs sloppy, non- standard welding techniques all done by an untrained, unskilled, un-certified welder. In this case not a road to disaster, but one to complete success!

Richard Hull
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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Andrew Seltzman
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Re: Archived - Fusor progress, info & photos

Post by Andrew Seltzman » Fri May 11, 2012 3:57 am

Scott, that's a really nice looking weld, and your currents/diameters seem to be just about what I use. I'd buy one with welds like that if I didn't already have a chamber.

With each 8" CF costing $130, each 1.33 CF costing about $15, each 2.75 CF costing $24, and each hemisphere costing about $50 that's $528 in parts for a 6" chamber with 8x 1.33 CF flanges.

With a total chamber cost of $815 with 8x 1.33 CF flanges that's $278 for machining, welding and post weld cleanup. I don't think I've ever seen anyone offering vacuum chamber production at that low a price. I think you may become the standard in fusor.net vacuum chamber production.

I wouldn't worry too much about about the structural strength of the welds, or about not using nipples, there is more than enough overhead in the weld strength. I ran some numbers when designing my chamber since I was particularly worried about the weld strength on my hemispheres due to my design removing the original weld lip in the hemisphere and having the entire force of the vacuum being supported by the weld. My concerns were unfounded though:

For a 6" hemisphere (8" CF) :
28.3 in^2 of area = 415.6 lbs force at vacuum
18.8 in of weld seam length = 22 lbs/in stress on the weld

For a 1.5" tube (2.75" CF):
1.77 in^2 of area = 26 lbs force at vacuum
4.7 in of weld seam length = 5.5 lbs/in stress on the weld

A good weld will have about the same strength as the base metal, which for an 1/8" thick hemisphere will be considerably larger then 22 lbs/in.

I noticed the CAD designed on your website indicate that the chamber is spherical, do you machine down the height of the hemisphere (cutting off how much)? If so, how do you deal with the change in diameter at the weld with respect to centering and mating with the flange lip that is designed for a 6" diameter tube/hemisphere?


Andrew
Andrew Seltzman
www.rtftechnologies.org

David Geer
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Re: Archived - Fusor progress, info & photos

Post by David Geer » Fri May 11, 2012 3:58 am

Scott, I can definitely see the improvements in the welding process in these photos and glad the process was learned and refined through trial and error. This set of photos shows a very high quality and clean set of welds and would gladly pay for this quality of work myself. I apologize for the bashing earlier but those were pretty bad with all the heat stress and overbead.

To Richard's response, I understand that even a amateur weld can be good enough for most things but everything factors into the performance of the unit. Be it, outgassing, surface particle degradation due to temperature and plasmatic cooking and electron bonding. Just everything works better with better materials.

Again, I apologize for negative, unconstructive criticism and bashing/flaming. It was unnecessary and undeserved.
- David Geer

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Richard Hull
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Re: Archived - Fusor progress, info & photos

Post by Richard Hull » Fri May 11, 2012 2:11 pm

This thread is now into Construction issues and not images anymore. Thus, good material is being lost here, buried deep in the replies to some posted images.

I choose to create a FAQ and discuss the machining off of the weld lip on the rings in the Construction forum you can find that discussion at......

viewtopic.php?f=24&t=3203#p12713

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

swiederhold
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Re: Archived - Fusor progress, info & photos

Post by swiederhold » Fri May 18, 2012 1:00 am

In regards to the strength - I never know what people are going to do with them once they leave my control. Better safe than sorry.

I'll follow Richard's lead and jump over to the other thread to respond to your questions about the spherical shape of the chambers.

Daniel Firth
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Re: Archived - Fusor progress, info & photos PLASMA IGNITION

Post by Daniel Firth » Mon May 21, 2012 3:27 pm

I got the new chamber on Saturday, so I assembled everything and turned it on.

The plasma photos were taken with pressure around 125 microns, voltage between 3000 and 4000 volts, current between 10-15 mA.

I had some arcing issues with the ceramic, it's all been removed.

The grid was formed the same way as Andrew Seltzman's:
http://www.rtftechnologies.org/physics/ ... d-grid.htm
By "same way" I mean the way the stainless steel is bent with the slotted pipe. Not the cooling part.
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