Progress on my fusor

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.
John Futter
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Re: Progress on my fusor

Post by John Futter » Sat Jul 01, 2017 6:12 am

Matthew
I might add that diffs pumps have to be mounted vertically not horizontal as per your photo

If you are having trouble sizing your photos and manipulation of said same you need
irfanview a free photo manipulation program
You resize resample your photos to 1024 x 768 pixels and this comes out perfect on this site

MatthewL
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Re: Progress on my fusor

Post by MatthewL » Sat Jul 01, 2017 6:22 pm

IMG_1013.JPG
Here is the photo in the correct orientation. You can, of course, click on the photo and it will show it correctly oriented.

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Re: Progress on my fusor

Post by MatthewL » Thu Jul 20, 2017 8:40 pm

I called Edward's about two weeks ago and found out that thread for the dipstick and oil drain plug is a 3/8 inch British Standard Pipe Straight Thread. I found the correct thread tap and drill bit and I got some hexagonal aluminum bar stock to make the caps. It won't have the dipstick, but it should work until I get the real ones from Edward's whenever that may be (the lead time keeps extending). I ultimately had to get help from a machine shop but it wasn't nearly as much money as they had said it would be before I had all of the supplies for it included. My original idea was to just use a my drill press to make the threaded plug but the drill bit shank was 15.25mm in diameter and my drill chuck can only hold a .5 inch diameter shank so I found a machine shop that would help me make the part and they ended up using a lathe on it and got much better results than I could have with a drill press and a hack saw.
IMG_1022.JPG
IMG_1023.JPG
The plugs can't fit the Viton O-rings that are from Edward's so I will be cutting out some small circles out of Viton gasket material to seal the oil drain.
I completed my D2 generator and I attached it to my chamber using stainless steel tubing, and my leak rate has gone up from 1 micron per second to almost 10 microns per second and I can now only achieve just over 150 microns of vacuum. I have a Swagelok metering needle valve in-between the generator and the chamber, and I have suspicions that when I fully close the needle valve it is still allowing a small amount of air through. I may buy a Swagelok shutoff valve to go between the chamber and needle valve to see if anything changes unless this is a problem that someone else has had and the would be willing to share their solution.
I have another question that isn't necessarily fusor related but I figure most here might know something about it. I am looking into purchasing a bench top metal lathe and I was wondering if anyone has had any experience with a Shereline lathe and would recommend it or not. I want to try and stay clear of the Harbor Freight and Grizzly etc. mini lathes that are 7X14 and 7X12 as they are all made by the same manufacturer in China and have plastic gears and tend to eventually break down (as I have read in various reviews). I would like to have a lathe that will last and if it does break down I would like to be able to get a hold of a real person if I need to order a replacement part.

Thanks,
-Matthew

ian_krase
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Re: Progress on my fusor

Post by ian_krase » Fri Jul 21, 2017 3:50 am

I think that many needle valves are not supposed to turn all the way off, or at least are not very good at it.




I have never used a sherline lathe. AFAIK they are very high quality but they are so tiny that you might have a hard time with the kinds of stuff normally found in vacuum systems. Especially what with all the stainless.

The 7x12 or 7x14 lathes can do a lot with a little money (though IIRC they are much more expensive than 8 years ago). Though gears are a problem. What might be worthwhile is an "8x14" lathe, which weighs about 4 times as much as a mini lathe and is quite durably built with no plastic gears. IDK if it is still available.

You might want to check out the "HiTorque" offerings from Little Machine Shop such as http://littlemachineshop.com/products/p ... 1271799306. They also sell the upgrade parts to change a mini lathe to 100 percent metal gears.

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Richard Hull
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Re: Progress on my fusor

Post by Richard Hull » Sat Jul 22, 2017 7:37 pm

When choosing a lathe the question comes back to what is the largest item you might wish to turn in future, how much you are willing to invest. I will ultimately attach images here of the lathes I have and use. I have acquired them used and new. Will you be working on a lot of long items on the lathe? Waht about big diameter stuff?

99.5% of all of my lathe work is right at the headstock, (chuck). This is when you are turning an item under 2" long. It is an almost never event where I am turning a 12" long item.
Thus for me, a lathe with a 14" bed is overkill. I just seem to never work between centers! Yet, due to lucky buys I have 2 lathes with 24 inch beds. What is more important to me and my work is a really good chuck and an over bed clearance to the center line of at least 6". Even this is not needed for 90% of my work. This is why I have 4 lathes in the lab.

As noted above.....What will you want to do with your lathe in future??

A new lathe, a small one, even from China that is worth having will be about $500. Grizzly has many good lathes with metal gears and a new one from them will start at $1000 and go up fast.

A used lathe can be a fanastic bargain or one of the worst decisions of your life. I purchased a classic K9 South Bend lathe (the best of the best) made in the late 40's for $200 I knew what I was getting, too. The three jaw chuck was shot. The bed ways and cross slide were all in good order. The large 4 jaw independent chuck was rusty but like new, otherwise.
4 jaw independents are used on a basis of 1 job with it to 250 jobs with a 3 jaw. This ancient lathe uses a 1-inch wide flat, tensioned belt on stepped, domed pullies so it could be driven in an old factory from overhead drive spindles. Such lathes were commonly found 20 in a row driven from the ceiling on one long shaft driven by a single multi-horse motor, not having their own motor.

Luckily, South Bend has an industry standard chuck thread and I purchased a new, fabulous 6" diameter, 3 jaw chuck from Grizzly that screwed right onto the old Southbend for $250.00. This lathe is now used for all of my "big" work and when I am cutting screw threads.

I would say that 95% of my work is under 2" long, under 2" in diameter where I need to do a smooth cutoff or just "skin" a part down to a precise diameter, bore a precision hole or internally thread a short item. Really, most of my work in under 1-inch in diameter. The largest diameter I have ever worked is about 4-inches and the longest about 10-inches.
I just don't do big stuff.

You must know what your material limits are and what you are planning on doing in future or you will over spend on a big machine, whose capabilities will never be used or live to regret you didn't buy a bigger lathe as larger work comes along.

Many of my hobbies from model railroading to fusion work just needs lathe work on smallish items. I have lathes made for "pin work" 1/4" diameter and smaller all the way up to machining short 4" diameter pipe sections.

My Lathes.......

K9 South Bend.... Big work and odd ball screw cutting 3-jaw and 4-jaw chucks. Belt speed selection
Kennedy combination lathe (Grizzly) giant 9-inch over center swing (18" diameter) with a 6-inch, 6-jaw chuck....Larger materials and large diameter disk skinning. Belt speed selection
Micro-Lathe.....Pin work can't chuck over 1/2" diameter pieces. Model Railroading, tiny work. Belt speed selection
Harbor freight Chi-Com lathe..... 3-inch three Jaw. 12" bed, only 8" of which is usable. 1.2 inches is the largest diameter it will support. Electronic speed control. Plastic gears

I bought the harbor freight lathe when it was $495.00 a couple of years back. It is now $569. I used a Sunday only 25% off coupon and paid a bit under $400.00 after taxes.
A really sweet little lathe for little work.

Which lathe sees the most action? The little Harbor Frieght lathe. Why? it is the perfect size and I can set the speed precisely to secure the fastest cuts with the least tool wear.
Next would be the Kennedy mostly due to its fabulous 6 jaw centering chuck. Grizzly said it couldn't be done, but I mounted their 6-jaw chuck on my own custom made face plate.
Next the South Bend. Really big stuff!
I rarely use the pin lathe except for really fine and tiny work. (Although the harbor freight lathe has taken a lot of work away from the pin lathe.)

Again, if you buy a used lathe, buy it from a machinist. They know their stuff and have probaly maintained it well.

I might put this in a FAQ in Construction.

Photos below.

Richard Hull
Attachments
micro-Lathe.JPG
It may be small but is extremely useful for tiny work on small parts, pin stock. Mostly used on free turning brass, aluminum and mild steel
South Bend.JPG
Ugly, needs paint, but a classic, great lathe. Used or larger light work and screw threading....South Bend = Quality!
6 Jaw Kennedy.JPG
My go to lathe for bigger work. the chuck is fabulous! This lathe came with a small 4" 3 jaw chuck. Adding the 6", 6-jaw made it a really useful lathe (Grizzly)
Harbor Freight.JPG
This is now the most used lathe in my lab. Just perfect for the bulk of what I do here. (Harbor Freight)
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.

ian_krase
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Re: Progress on my fusor

Post by ian_krase » Sat Jul 22, 2017 8:51 pm

Used lathes are a bit of an odd thing -- the ones you're likely to find for cheap are the really big ones while ones of a size you probably prefer (and have space for) are often very expensive, because everybody else has space for and prefers them as well.

I think it's worth noting that 8 by 17, 9 by 20, etc are kinda typical, traditional ratios of swing-over-bed to distance-between-centers. Some of the Chinese lathes are significantly shorter like the 7x12 and the 8x12 or 8x14. This takes up less bench space but on these small sizes of lathes it can get a bit awkward and limiting when you consider the stackup of chuck+chuck jaws+tailstock extension+tailstock chuck+drill bit+length of workpiece that the drill needs to withdraw out of. So to effectively work with something 12 inches long you need a bed that's a lot longer than 12 inches. In particular don't buy the "7x10" Chinese lathe, it is really closer to 7x8 or so and there are much better options. And be careful about the distance-between-centers and length-of-bed: they are very much not the same thing.

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Jason C Wells
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Re: Progress on my fusor

Post by Jason C Wells » Sat Jul 22, 2017 9:17 pm

Wait! There's a plasma club? I only thought there was a neutron club.

MatthewL
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Re: Progress on my fusor

Post by MatthewL » Sun Jul 30, 2017 4:45 pm

I have been working on getting my vacuum system down to a better vacuum, but with little success. I have completed everything that I should need for my vacuum system. I have placed a Swagelok ball valve in between the needle valve and the chamber, and I have put the end caps that I just had machined on the diff stack sealed with Viton gaskets. I cleaned everything with acetone and assembled the chamber. I lit a plasma at only around 2.5kv at 80 microns and let the grid get red hot (I did this to plasma clean the system if there was anything that the acetone did not clean). Now I can shut the foreline valve, turn off the mechanical pump, and the chamber will have a much improved leak rate of around one micron every seven seconds. The issue I am having now is that the best vacuum my pump seems to be able to pull is 78 microns. There is no leak after the foreline valve and I doubt that there is a leak in the foreline as there isn't really anywhere that it could be. The tube that connects my chamber to the pump is 1 inch in diameter and 2 feet long. My suspicion is that there is a leak in the pump itself. One thing that I find a little counterintuitive is that when I pump down the chamber with the gas ballast valve on the pump open I can achieve the vacuum of 78 microns but when I close the gas ballast valve the pressure will immediately increase to 110-120 microns and the gas ballast intake is still drawing in some air; it doesn't seem like this should happen, but it could be may lack of experience in vacuum systems and this is a normal occurrence. Everything else with the pump seems normal, it sounds normal when running and it does not get hot until it has run for about 15 minutes (even then only warm to the touch). If there is anything that sounds like it could be the problem in what I stated in my above explanation I would appreciate the help.

I appreciate all of the responses on the lathe. I decided to go with the Shereline (3.5"X 17") mainly because of space limitations that I will have and because I plan on doing many projects that will require me to turn small, precise parts, mainly from aluminum, brass, mild steel, and possibly some stainless. I will definitely look into the website that Ian suggested, http://littlemachineshop.com/default.php, when I consider getting a mill or CNC mill.

Thanks,
-Matthew

John Futter
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Re: Progress on my fusor

Post by John Futter » Tue Aug 01, 2017 7:32 am

Matthew
A rise like you say when the gas ballast is closed usually menas there is a lot of water vapor in the pump oil.
Time to go back a couple of steps
disconnct the diff pump and use your pirani on the backing pump and line that would have gone to the diff pump.
run the gas ballast open in this configuration for a least an hour and remeasure vacuum levels ballast open ballst closed, pump off and pressure rise rate
and report back

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Richard Hull
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Re: Progress on my fusor

Post by Richard Hull » Wed Aug 02, 2017 2:50 am

John mentions what I mention in a vacuum FAQ. Water in the oil, if the oil is know good and free of other garbage, can be got out of the oil through gas ballasting for hours. Once the water is out of the oil...(usualy put there by stupidly running the pump and sucking in outside air), you should be able to close the ballast and pull down to at least 20 microns on any pump worth its salt. 10 microns or less if the pump and, or, the oil is new. I have ball valves on both the exhaust and inlet of my Precision 5CFM belt drive Ideally, you don't want any part of your system to have to see or pump outside air ever again.

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.

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