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.
MatthewL
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Progress on my fusor

Post by MatthewL »

Hi all,

It took a little longer than anticipated, but I now have most of the parts for my fusor assembled and I feel like I am at a stage where I should make this update.
IMG_1004.PNG
I had my power supply working for awhile but when the output exceeded 20kv I had an arc over in the tank (luckily not between the windings). I had to move some wires around to avoid the arcing but I then got an oil leak in the tank, which was a large diameter PVC pipe with two .5 inch acrylic lids (I used this instead of a bucket because I didn't want an implosion under vacuum). To avoid leaks I just got a bucket with as thick a plastic I could find from McMaster (still imploded at 3/4 atmosphere, but I did get the bubbles out from the windings). With primary ballasting I can get to just over 40kv DC.
IMG_0985.JPG
My chamber is a four way reducing cross with two 6 inch CF flanges and two 2 3/4 inch CF flanges.
IMG_0998.PNG
IMG_1001.JPG
My grid is made from tungsten and is 1 inch in diameter
IMG_0986.JPG
IMG_0989.JPG
My foreline pump is an Edwards EDM12 pump that I have tested to 30 mTorr. My secondary pump is an Edward's Diffstak 63, which I haven't been able to test yet because I don't have the oil drain plugs or dipstick assembly. I have tried different sized acorn nuts both metric and customary but the size must be unique to Edward"s. I have ordered plugs from Edward's but they are out of stock with a lead time of 7 weeks, if anyone has any other ideas for what I could use in the mean time that would be greatly appreciated. For pressure measurement I am using an Instrutech convection enhanced pirani gauge which measures only to 10e-4 Torr. I hope to also use a an ion gauge (hot or cold cathode) if I find I good deal on Ebay.
IMG_0984.JPG
I am using D2O electrolysis for my deuterium gas source, I haven't fully completed building this part yet.
IMG_0988.JPG
For neutron detection I am using 2 BTI bubble dosimeters. If my neutron flux is high enough I will also be doing some activation experiments.

I need to do a little more work, but in the next few days I should be able to perform a demo test.

-Matthew
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Progress on my fusor

Post by Dennis P Brown »

Looks good; have you considered making your own for the DP? Edwards could tell you the thread type and maybe you could then machine (lathe) your own? You don't show a detailed image of what you need for the DP so can't really know what it is that you are missing - I assume it is a "cap" for that part on the lower section of the DP in the photo?
MatthewL
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Re: Progress on my fusor

Post by MatthewL »

I recently completed doing a demo run of my fusor an got these photos:
IMG_6586.PNG
IMG_6585.PNG
I don't know if this is enough to be admitted into to the Plasma Club, because the plasma is not centrally confined as I would like, that is probably because the pressure in my chamber is just under 800 mTorr (with a voltage in the first photo of 6kv and the second 8kv). My mechanical pump that I spoke about in the previous post can get down to 30 mTorr but didn't this time because I later realized that one of the CF flanges wasn't fully tightened. My pump was working smoothly, but after the first 3 minutes of the run the pump stopped working. I let the motor cool off and I tried it again, it begins to pump correctly for the first few seconds of the run but it then begins to stop pumping and start pumping.......until it stops and makes a quit humming noise. It also draws a lot of current enough to flip a breaker. My guess is that there is a short somewhere. If anyone has had a similar problem or knows what this might be I'de appreciate the help. If not I may end up finding another roughing pump to use.

Also Dennis, here is a closer photo of what I was trying to find a plug for:
IMG_1007.JPG
I will call Edward's on Monday and ask about the thread size and if the lead time on the plugs and dipstick is still 7 weeks, If so I may have to machine my own. I don't own a lathe but I will see if any machine shops around me will help and are not unreasonably priced.

Thanks,
-Matthew
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Progress on my fusor

Post by Dennis P Brown »

This type of pump startup issue happens to one of my pumps when 1) starts at near atmospheric pressure and 2) hasn't been run two weeks or more (which likely means it is near atm pressure since that might be the leak rate for that system ... .) I just make sure to run it once a week until I get a few milli-torr (microns - is the unit we tend to use here) before I shut it down and seal off the system.

Also, one should not run a system at nearly a full torr and expect a pump to work well; Do you not have a gauge that reads a few torr? Not a big deal with you don't but can be helpful. In any case, 30 microns, which is ok for a DP is rather high for a good two stage pump - maybe the oil is bad?

My next guess is that your pump struggles against near atmospheric pressure due to leaks; certainly leaks will not just cause a difficult start up but will also make the pump work very hard (large current load) as it pumps against the incoming air. A good system should have only "wall out gassing" (a micron or a few microns per second but the system should remain under ten torr or so for the day.) Maybe consider opening the pump body and cleaning it out (if you suspect contaminate build up. I've done this to pumps that have visible contamination in the sight glass. A rebuild kit might be needed - I've done it without but when the main body gasket broke, I had to use a "gasket sealant" to fix that - a kit, allows one to replace all gaskets and other critical parts that tend to wear out. Does require some skill. Not for the novice that isn't ready to learn by getting dirty ... .)

Also, (but not necessarily likely) is that the oil could have some water in it (allowing for a rapid rise in system pressure) but that can be removed if the pump has a built in purge valve; if so, allow the pump to run (with the inlet closed off) and allow the oil to heat up (5 minutes) then open the special valve (if the pump has one) allowing a controlled amount of air to "purge" the oil of water for a few hours. If this feature isn't available, might try replacing the oil (once you are sure all leak issues have been addressed.)

Others may have more/better ideas.

That cap design for the DP could be machined if you have access to a lathe - also, the tread size/type looks a lot like some lecture bottle hardware I've seen (not that that is very helpful with one does not have access to such hardware ... .)
Last edited by Dennis P Brown on Mon Jun 26, 2017 5:08 am, edited 1 time in total.
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Progress on my fusor

Post by John Futter »

Matthew
Any local fitting and turning shop will be able to make your Nut in half an hour. you will need to take the pump to them so as to measure the thread parameters
But that nut had a dipstick attached that gave you the oil level.
These pumps need the o-ring replaced top and bottom on that oil level / drain every year or better still every six months of continuous running otherwise the o-ring goes hard and jams the dipstick down the hole. The service guy then uses a large slipgrip wrench and F#$#$$cks the nut and dipstick. We have around 30 of these pumps at work and replace the viton o-rings six monthly.
MatthewL
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Re: Progress on my fusor

Post by MatthewL »

I disassembled my entire roughing pump and cleaned out everything that needed to be cleaned. I assembled it and changed the oil and it can now run continuously without over heating. My pump can only pump the chamber down to 70 microns with a leak rate of around 1 micron/second. It may be that the rubber tubing I use to connect the pump to the chamber outgasses too much; I will be trying some different tubing to see if there is any change.
I called a machine shop and gave them details for the threaded end cap I need machined and they said it would cost a couple hundred dollars and recommended that I find a place that sells metric sized threaded caps. I will see if there are any other machine shops that could do it for less, or I will look into the lecture bottle hardware that Dennis recommended.
I just completed doing another demo fusor run at 100 microns and 8kv and got much better results than the first run I did at 800 microns:
Screen Shot 2017-06-28 at 12.40.57 PM.png
Screen Shot 2017-06-28 at 12.40.57 PM.png (91.75 KiB) Viewed 7287 times
Screen Shot 2017-06-28 at 12.40.11 PM.png
Screen Shot 2017-06-28 at 12.40.11 PM.png (74.44 KiB) Viewed 7287 times
I have a few more things I need to accomplish before I can achieve real fusion, but I hope to do so within the coming month.

Regards,
-Matthew
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Progress on my fusor

Post by ian_krase »

At that level I suspect you have a real leak. Glow discharge plus Dust Off can tell you much.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Progress on my fusor

Post by Dennis P Brown »

First, glad you cleaned the pump and it runs far better; besides better operation, you've learned a great deal about pump maintenance and have a better understanding of the pump. Your leaks don't appear serious if you see 1 micron/sec. That can be out-gassing from contaminated walls - your pump was rather dirty after all. Maybe clean the chamber. Do you have an anti-back flow system for the vacuum pump between the pump and chamber? If not, than likely a lot of dirty oil vapor got into your system. Use as close to absolute alcohol that you can obtain (Isopropyl or ethyl; never methanol!)

If you want to prevent this problem and don't want to get such an item, then you either need a valve between the pump/chamber or need to back fill your system to atm every time you turn the pump off. I do all three - I have made a dry air supply, have a valve and anti-back flow device (which was surplus so I cleaned it out. Dirty at first but it was cheap ... should have just replaced the packing inside ... .)

I assume you are allowing the chamber to operate at 800 microns? If not, is that pressure achieved when the plasma ignites of is your leak rate far above 1 micron/sec? That pressure and your leak rate don't agree. If the pump is running and your chamber remains at 800 um then that is a serious leak and your stated leak rate can't be correct. In which case that sounds like a bad sealing surface like an o-ring or Cu gasket or a similar issue. That high a rate should be audible. So, maybe a picture of your connector system and a better call on the leak rate.

As for the cap, yes, metric might be the issue but that doesn't help unless you know the spec's so that a correct one can be ordered cheaply and fast on line. Having one made will be pricey since labor isn't cheap.
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Progress on my fusor

Post by Richard Hull »

Matthew, I have added your name to the Plasma club listing.

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
MatthewL
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Re: Progress on my fusor

Post by MatthewL »

Here is a photo of the connection made from my pump to my chamber:
IMG_1013.JPG
There is a right angle valve in between the pump and chamber. While my pump is running I am able to get down to a vacuum of around 70 microns, I then close the valve to isolate the chamber and I can then turn off the pump. At that point the leak rate in my chamber is around 1 micron/second. There must be a leak before the valve or the silicone rubber tubing I am using to connect the pump to the chamber outgasses too much (this probably isn't the problem). If I did not close the valve and I turned off the pump my chamber would be brought to about .5 atmosphere, because when the pump stops running air rushes in through the pump outlet (I don't think that is supposed to happen because it doesn't happen on my single stage HVAC pump, it still retains a vacuum when off)
I have been using acetone to clean the inside of my chamber, would the alcohol have the same effect?
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Progress on my fusor

Post by John Futter »

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
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Re: Progress on my fusor

Post by MatthewL »

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.
MatthewL
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Re: Progress on my fusor

Post by MatthewL »

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
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Progress on my fusor

Post by ian_krase »

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.
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Progress on my fusor

Post by Richard Hull »

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
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
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
Ugly, needs paint, but a classic, great lathe.  Used or larger light work and screw threading....South Bend = Quality!
Ugly, needs paint, but a classic, great lathe. Used or larger light work and screw threading....South Bend = Quality!
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)
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)
This is now the most used lathe in my lab.  Just perfect for the bulk of what I do here.  (Harbor Freight)
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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Progress on my fusor

Post by ian_krase »

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.
User avatar
Jason C Wells
Posts: 113
Joined: Sun Oct 20, 2013 7:11 pm
Real name: Jason C Wells

Re: Progress on my fusor

Post by Jason C Wells »

Wait! There's a plasma club? I only thought there was a neutron club.
MatthewL
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Re: Progress on my fusor

Post by MatthewL »

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
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Progress on my fusor

Post by John Futter »

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
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Progress on my fusor

Post by Richard Hull »

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
MatthewL
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Re: Progress on my fusor

Post by MatthewL »

Before I had gotten either of these responses I had decided to change the oil. I have already done one oil change before when I disassembled the pump to clean it. When I did the first oil change, the oil was black (It was light yellow when I had originally put it in). The black color of the oil and the fact that the pump was not working is what drove me to disassemble the pump to clean it. The inside of the pump was very dirty and all I had done was wipe down most of the black residue that was covering a lot of the pump with a cloth. I then reassembled the pump filled it with new oil and that is how I have been using it up to now. Before I had gotten the responses I drained some of the oil to see what color it was, and it was the same black color as before. I thought maybe I did not clean the pump well enough, so I did some searching on the internet and read some websites on rebuilding rotary vane vacuum pumps and realized that I other people where using a solvent like acetone or petroleum ether and wire brushes and steal wool to get all of the parts very clean. So I just spent yesterday completely disassembling my pump and thoroughly cleaning it. I didn't have quite enough oil left to test it so I ordered some more and it should be here on the fourth. August 4th also happens to be my birthday so I will not be achieving fusion as a fourteen year old as I had wanted to (although it was not very important to me). I cleaned the pump as if I was doing a rebuild, but I did not have a rebuild kit to replace any O-rings or gaskets. I would like to do a rebuild at some point in the future, but I can't find a rebuild kit for this model in particular (Edward's EDM12). In fact I can't find much information of any kind on this pump besides the few for sale on eBay and LabX. If any one knows anything about it or knows of a rebuild kit for it I would be interested knowing about it. If there is no rebuild kit for this model I would still like to change the main gasket that seals the oil within the body of the pump, as the gasket is fragile and very slowly will leak a couple drops of oil. The gasket appears to made out of cork, but before I order a sheet of cork gasket material and cut out the correct shape I am curious if maybe it is a particular kind of cork for these pumps, or if maybe there is a completely different material that is even better?
This is the oil that I have been using: https://www.duniway.com/part/mpo-190-1. I chose this one mainly because it was the least expensive, but there where some other options. If there is a better oil to use, and it is not the ridiculously expensive oil like fomblin, I might want to switch.

Thanks,
-Matthew
Rex Allers
Posts: 570
Joined: Sun Dec 30, 2012 3:39 am
Real name:
Location: San Jose CA

Re: Progress on my fusor

Post by Rex Allers »

Matthew,

When I read that you had an Edwards EDM12 I thought it might be a typo. I have an E2M12 pump. With a bit of web searching I see that the EDM is an older version. Looking at the Edwards site I don't see my E2M12 being sold now but there is no mention of the EDM. One link I found was this one, which seems to indicate parts for EDM pumps are hard to find...
http://vacuumandlowpressure.com/oldEdwardsParts.html

So, my Edwards E2M12 had major problems when I got it that started with not very good vacuum and moved to a pump that wouldn't spin. I managed to get most of my purchase price back and used it to buy a total rebuild kit. A lot of work followed. I know that there is a small score on one of the rotors now but it does pump down to ~5-10 mTorr.

Problem came because it was used to pump for fiberglass molding and sucked many bad things through it. Actually this was second pump with this bad life... 1st yet to be saved, maybe never.

So it is unlikely that you can find parts to rebuild yours. Hopefully any problems can be fixed with the cleaning or something simple. If not, I don't think I'd try to get into the internal pump unit without documentation or rebuild parts. That may make a marginal pump a boat anchor.

So, on your first questions, I think the oil you used was fine. Part of the blackening of the replaced oil may be what was still in the pump mechanism itself. Hope things are better on your second pass. Duniway does sell a flushing liquid that is cheaper than the real oil if it comes to that, but probably not worth it if 2nd try is still bad.

So more important, I think, is that the symptoms you described earlier sound odd.

On my OK working E2M12, here's how it works. As I start it up it gurgles a bit as it pulls down a vacuum. When the vacuum is settling in the pump itself is pretty quiet. The motor obviously makes noise but I'm talking about sounds out off the pump section. Let's say I have a vacuum gauge on the pump and it gets to 20 mTorr at lowest. Now I might open the ballast a bit. This lets air into the pumping chain in the pump. While the ballast is open the sound will be gurgling a bit and the exhaust will have more oil vapor. The vacuum gauge will go up a bit (less vacuum) while the ballast is open. Normally you would run with the ballast open for a long time, then close it. Pump should stop gurgling. If the ballast cleaned anything out of the oil, the pressure should go lower than before.

Your description of what your ballast valve is doing does not sound right. You said your maximum vacuum was with the ballast open. That's not normal. You said with the ballast closed the pressure went up and you could hear the ballast drawing air. Both of those are wrong indications. Can you provide any info on the sounds (gurgling, quiet, etc.)?

Not sure how the ballast works on this thing. Can you unscrew it entirely out of the pump and try to figure out how it should work? Maybe something is not sealing or who knows what.

If I remember right from my work on the E2M12, the ballast led to a tube that allowed air into the 2nd pump (lower vacuum side rotor) just for reference of how it might connect.

I wouldn't mess with the case gasket until you decide if this pump is worth more effort. If it is and you can't find one to buy, I'd go to the auto parts store and buy a roll of gasket material. I'd go for one like thick paper rather than cork. With the pump case open, lay the case on the gasket (on a flat surface) and trace around it with a pencil. Measure thicknesses of the case lip and transfer to draw inside lines on the gasket.
Pressing the gasket onto the parts with your fingers may help to find hole locations. Cut with scissors, exacto knives, paper hole punches, or whatever. On the holes, you can make one punch (too small) and then eat it out with more punches or an exacto while on the part. Some ideas. Use your own creativity as you go if it comes to this.

Good luck. Hope your pump is not a basket case. I'd start with trying to figure out why the ballast valve seems weird. Here's a link to what it is supposed to do.
http://www.edwardsvacuum.com/asia/newsl ... sk_en.html
Rex Allers
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Progress on my fusor

Post by John Futter »

We have two of these at work and 4 years ago we did manage to get rebuild kits from Edwards

warning after dissassembly you have to put a little oil down the inlet or you run the risk of seizing the rotors -- we did this once --gets expensive with a second recon kit
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Progress on my fusor

Post by Richard Hull »

I hear a lot of horror stories here about mechanical pumps. I guess I have been lucky. The worst pump I ever bought struggled to hit 25 microns after a good 3 oil change, run for hours, change oil, run for hours, etc.. It was a well worn Welch 1200 which is kind of whimpy to start with. (1CFM). I will admit, I have bought 100% of my pumps locally, finding most of them for sale in our local 7-11 distributed rag, "The Trading Post".
I took a little battery operated, CVC TC gauge with me before I gave up the bread. That helped a lot.

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
MatthewL
Posts: 50
Joined: Sun Mar 05, 2017 7:13 pm
Real name: Matthew Lallinger
Location: Houston, Tx

Re: Progress on my fusor

Post by MatthewL »

After I cleaned the pump I began to reassemble it. After it was fully reassembled I went to turn the motor on, but it wouldn't spin. The motor is definitely working but it is the shaft for the actual pump which won't turn.
IMG_0235.JPG
IMG_0236.JPG
I included an exploded view of the pump so it is easier to understand what I am taking about.
I thought about what could be the problem for awhile, and after disassembling the pump again and trying to spin the shaft with various parts attached, I determined that the resistance is where the shaft (number 5, 12, 13 in exploded view) meets with the area labeled 80 on exploded view. I realized that this resistance is only present only when the bolts are fully tightened.
IMG_0231.JPG
in this photo the bolt is tightened (there are six bolts that go around to hold it in place, I only show one but the same affect happens with all six) and the shaft can not be turned barely at all.
IMG_0232.JPG
I then loosen the bolt a few turns
IMG_0233.JPG
now I can spin the shaft by hand, but there is still a lot of resistance. Oddly, as I spin the shaft it is easier to spin for most of a revolution but at one point per that revolution it becomes even my difficult to turn, and then it goes back to being easier until it reaches that point again.
IMG_0234.JPG
I thought it might have been the shaft seals that where to old so I emailed the person behind the website that Rex provided, vacuumandlowpressure.com, and he sent me a rebuild kit for my pump that also included the manual that had this exploded parts view. I just completed doing a full rebuild of the pump last night and the same problem is still encountered. Also I coat all of the parts in a little pump oil before I reassemble it.
I know that what I am trying to explain is pretty tedious so if something needs to be clarified just ask.
If anyone knows why this problem might be happening I'de appreciate the help.

Thanks,
-Matthew
Post Reply

Return to “Images du Jour”