FUJ-219 Magnetically Assisted Ionization fusor

[Richard Hull]

Maciek, once again, super quality work. The last image of you with your creation is great! Thanks for all the images as you proceed in your efforts. Pictures are always worth a thousand words.

I love the old dial phone in your image. Rare in the U.S. now. 100% of the phones in our home are rotary dial phones still on the 'twisted pair"! To call for services or the government, we have to use our cell phones to push the myriad of routing command button presses forced upon those in need. At a monthly HEAS meeting, one time, a young girl brought by a visitor had to call home. I pointed to the wall mount rotary in the lab. she had no clue of how to use it. Her dad went over and instructed her how make a call on it. Later I heard that she excitedly told her mom about using the "really old telephone".

Richard Hull

[Maciek Szymanski]

Once I was very involved with photography. Then, when the digital cameras and especially phones with camera become popular I’ve given it up - I’ve feeling that there is so much photographic images everywhere, so there is no sense for me to take one more. But lately I’ve realized, that most of the photos are made quickly and absently thus very often are useless afterwards. So for some time I’m trying to do high quality photographic documentation, take care for proper lighting, background etc. I’m really upset, when at my work I see illustrative photos in publications taken with a smartphone camera with a dirty lens, crooked, with a photographer’s shadow on the subject and random junk in the background.

The phone is connected to the twisted pair and operational. This is first telephone my parents had.

[Richard Hull]

I will say I did a lot of wet photography back before digital. (3 Nikons with many lenses. and 2 4X5 sheet film cameras.) It forced a bit of discipline on me due to costs, even though I developed and printed 100% of my own photos back then. I waited until 1997 to leave wet photography as the digital cameras were, at that time, of sufficient resolution for casual photography. I feel you still must have a formal digital camera of good quality to call yourself a photographer. I have never and will never use my 15 year old flip phone to take an image. For one thing, I don't know or care to know how to even use it. I have two digital cameras and I use my oldest Sony camera set on 1024 X 768 for all fusor images posted to keep them under 1 mega byte. My latest super Canon camera can be used for insane resolution images. I rarely use it because it is rare I see something I want or need to use it for. Adequate is good enough for me here at fusor.net, but I do use a real camera.

Richard Hull

[Maciek Szymanski]

Today I’ve chance to use the big TOS lathe, so I’ve finally started to build the main chamber. The flange was made from a laser cut blank, which was machined from both sides. On the inner hole a shoulder was machined to accept the straight tube segment. Then the whole thing was TIG welded: first all parts were stitched in four points from the outside, and then a tight weld was made from the vacuum side in few centimeter increments (four seams 90 degrees apart, then another four in between and in the third pass the gaps were filled to complete the seam). For just aesthetic reason I want to do also the outside weld between the cap and the straight tube.

Practical remarks for those planning machining and welding stainless steel parts. SS is not easy for machining. I’s best to use the carbide cutters for SS. The chips tends to be extremely sharp, hot and springy. Always wear the eye protection! When cleaning machine from the chips it’s good to wear heavy leather gloves - the long chips have razor sharp edges that can cut deeply through your hand without notice.
Welding SS with TIG is not difficult as long as you have in mind it’s very high thermal expansion. Welding by small evenly spaced increments with some cool down between consecutive operations helps to minimize deformation.

Machining of the o-ring mating surface:

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Flange ready for machining the inner shoulder. The triangular wire holds three textolite spacers between the chuck and the part:

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The upper shell parts ready for stitching:

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Apparently a bowler’s hat:

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The parts after first two passes of welding:

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The seam between the flange and the straight tube finished:

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[Richard Hull]

Yes, tack welding with TIG is a must with all standard thin or low thermal mass metal items. Then, longer seams can be made after cooling and checking for dimensional stability. Your flange looks relatively thin and surely must remain flat and sound.

This is why conflat flanges and most all manufactured flanges of ISO or other standards are so incredibly thick. This allows for total, full, one pass, machine welds without the possibility of warping or misalignment of critical vacuum sealing.

Richard Hull

[Maciek Szymanski]

After break for other issues and return to normal work schedule I’ve finally returned to the construction process. Today I’ve machined the flange for the lower part of the chamber. What is left is the groove for the sealing o-ring.


Machined flange after the lathe was all cleaned up from all the chips.

Cutter ground for machining the o-ring groove.

[Richard Hull]

Nice, big, serious lathe. I am glad to see you back at work on your fusor. You are doing it the "hard way", from scratch. This is how I made fusor III. It was difficult, a nightmare, but totally successful and the first fusor that I made that did fusion. It used indium wire as a gasket. I actually learned how to use a milling machine which I purchased used on fusor III. Great work and far better finished than my fusor III effort.
You are obviously a first rate machinist and have the big tools at hand to do the work. I love seeing such work being done by skilled hands.

After fusor III, I swore I would use standard conflat and ISO fittings for the rest of my life to avoid needless work. I figured I worked for about $1.12 per hour as a machinist, versus purchasing a proper set of 8-inch conflat rings at full list price which were ready to accept the 6" SS hemispheres that would be used for fusor IV. Cheaper and faster in the long run.

I attach an image from 1999 fusor III labors. It was stupid, in hindsight, but I wouldn't trade the learning experience at my milling machine for cash money. Learning due to the "hands-on-imperative".

Richard Hull

[Maciek Szymanski]

Making custom vacuum components is part of my job at Institute. With my fusor chamber I’m hoping to test some tricks and solutions for vacuum systems I can use later in other projects. But machining SS can be a nightmare.
Looking at your photo I’ve realized that I’ve never worked on the “Bridgeport style” milling machine - they are quite rare in Europe as we tend to use “Deckel style” tool room milling machines instead. The global world is not as global as it seems at first glance.

BTW - is theat small round object on the post on the left side of the rotary table a fan for blowing the chips? A brilliant idea indeed!

[Richard Hull]

Yes, it is a small high CFM fan for chip removal and a tiny amount of forced air cooling. I applied oil every so often as well. SS machining is all about sharp tools and critical speed control. The work was tedious and time consuming. After two solid steam fittings being hollowed out, I just threw the high speed cobalt steel tool in the trash and bought a new 1/2-inch replacement tool. It gave its life for fusor III.

In the image, I have already cut out the solid center disk, ( a nightmare), and am cutting the weld lip to receive the 6 inch hemisphere retaining it for welding where the lip, itself is the source of welding fill. No SS rod feed needed.

Richard Hull

[Maciek Szymanski]

Today I’ve welded the lower part of the chamber. It needs some seam backside cleaning an all the ports can be fitted.



Lower half of the chamber:

Detail of the flange with the o-ring groove:

Chamber halves fitted together. The back sides of the seams will be ground and the additional outside seam added.

[Maciek Szymanski]

Today I’ve cleaned up the back side of the seam (outside of the chamber) and placed the back seam on both halves of the chamber. I’ve also layed out the positions of port holes according to the drawing and prepared the flange for the diffusion pump connection.
Now I have to find the way to swap the milling machine table with the double pivot universal one for boring the inclined holes.


Laying out the chamber centerline:

Laying out the ports:

Chamber with back seam placed an the diff pump flange:

[Richard Hull]

Doing major machine mounting changes can be tough and time consuming to do one particular job. Finally, you realize you have to put the machine back into the "normal" manner of use once you are done. More trouble and hassles. But, it has to be done to proceed. Thanks for the continued updates and discussion on what you must do to keep moving on in the effort.

Richard Hull

[Maciek Szymanski]

After quite a long break (I’ve to do some work at my apartment, move my lathe form friend’s workshop to my garage and spend a week in Prague setting up the measurement system for a p-b laser fusion experiment.) I’ve returned to building the fusor. Finally the simplest tools proven to be the best. A hand drill,a cold chisel and some good files made the work faster than messing up with mill setup. Tomorrow I hope to weld the lower part and pump down the bare chamber.

Drilling out the opening perimeter with a hand drill may look very tedious in the times of 3D laser cutters and water jets, but if you have an old, heavy, high geared drill and the cobalt drill bit for stainless steel it takes half an hour including cleaning up with a good sharp file.

Lower part of the chamber with all the ports ready for fitting and alignment before welding.

Upper part with cathode installed. The shielding of the cathode stem is not in place yet.

Cathode as seen through the viewport:

The look along the magnetic ionization line.

[Richard Hull]

Your effort and reporting are quickly becoming the finest amateur fusor implementation and presentation ever seen over the 22 years of Fusor.net! Your abilities are many! The admission that common tools are often the best or a last resort for those not immediately equipped or have access to top level machining is important to others here. Falling back on common tools is no disgrace and often the only way to be sure of special fittings via careful attention to detailed work.

Thanks for keeping us updated on your amazing effort. We all look forward to your doing fusion with your device. Going slow really shows in the beauty of the finished product.

Richard Hull

[Steven Sesselmann]

Makiek,

Beautiful work and photography, well done on trying something new.

Steven

[Maciek Szymanski]

Than you very much for your kind appreciation. Personally I’ve much more reserve to this design and expect quite rough road ahead. Anyway I’ve finished welding and assembled the thing with all the ports blanked so the leak hunt can start:

By the pure luck an old x-ray scattering fixture was disassembled at my workplace and it’s chassis turned to be a part of a series production vacuum pump unit SP300E form Unitra Unima:

The chassis was few times modified and incomplete but originally it housed a vacuum system identical to the one I’m using, so I was able to put my system into the chassis giving a very neat and clean setup:

The vacuum system consist of:

• BL8 rotary vane pump,
• oil vapor trap,
• two foreline solenoid valves for diff pump and bypass pumping,
• vacuum canister (so the backing pump may be turned off for at las 30min with diff pump running),
• PDO300 water cooled diffusion pump,
• water cooled baffle (with provision for LN cooling),
• electromagnetic 100mm gate valve,
• electromagnetic vent valve,
• two TC senders (for forevacumm and main chamber),
• ionization sender,
• BS100 control unit,
• PW12 high vacuum meter.

The control unit allows manual control of pumps and valves, has meter to read two TC vacuum gauges (and cold cathode high vacuum one - known to be unreliable, so I’m using the external hot cathode unit) and has a bunch of TTL circuits to provide interlocks (i.e. turns off the diff pump when there is no flow of cooling water) and allows fully automatic operation with set points adjusted with potentiometers inside the unit.


So let the leak hunt begin!

[Richard Hull]

Luck and slow builds often allow for great opportunities to unfold as one builds a fusor system. This is a nice looking cabinet for your fusor!
Good luck with the leak tests. These are always a bear to get through.

Richard Hull