Author Topic: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup  (Read 16304 times)

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Offline pcmeiners

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Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« on: August 10, 2013, 07:42:19 pm »
Edwards E2M12 vacuum pump rebuild / overhaul / cleanup .....

Many pumps are very similar, including other brands, so this will cover many makes\models. Pardon my rambling, I ramble better then write.

Link to pictures of a different model (same design) pump I rebuilt...

http://s852.photobucket.com/user/pcmeiners/library/Edwards%20E2M2%20Vacuum%20Pump%20overhaul?sort=3&page=1

Task difficultly..
Once past your own fears, which is the most difficult part of the project (or life), overhauling one of these pumps was surprisingly simple, yet detailed as to cleanliness. The engineering of these pumps is very good. Parts are few and most only fit one obvious way; that is not the norm as of late. As a perspective, overhauling a pump like this is slightly more involved then doing a automobile disc brake job involving replacing the rotors and a hydraulic cylinder. If you done this, you can rebuild a vacuum pump; this is also a lot more fun then a brake job.
In the following, part numbers and descriptions are as referred to from the Edwards parts list PDF.

My pump's background.....
From it appearance the pump had been used very little, I speculate it failed within very low hours of use. After preliminary cleaning and flushing the pump failed to produce any appreciable vacuum, I purchased a major maintenance kit (all seals/o-rings/vanes). Little did I know, I could have gotten the minor kit, same components of the major kit without the vanes ( a good bit cheaper), because the original vanes were in good shape.
Likely issues with my pump were partially seized vanes, possible worn shaft seals and a spring support (part 47) which was totally loose, worn/destroyed from wobbling.

Purchased a major clean and overhaul kit (37001800)  from A&J Vacuum Service, one of the lowest priced dealers, delivered it quickly. Prices for minor/major repair kits vary tremendously, from reasonable to ridiculous. For the major kit, on the low end $ 200, high end $800 (same exact kit). Minor kit $65 to $300.  P.T. Barnum could have take a lesson from some of  parts dealers out there..

Lower priced parts dealers...
http://www.ajvs.com/
http://www.capvac.com/

If you intend to reuse the seals/O-Rings/gaskets be very care as to solvent used for cleaning, paint thinner is safe, carburetor spray maybe safe but there was a warning as to seals and O-ring being affected by certain solvents. I had one of the old seals and O-rings soaking in carburetor cleaner, seemed to have no affect. I highly recommend purchasing the minor maintenance kit at minimum, it has all the seals, o-rings, gaskets, springs, filters etc. Vanes can be purchased separately if needed.
If you have another make/model which has ball bearings which are sealed or shielded , do not use any solvent near them. My unit just has solid bearing surfaces, no ball bearing to worry about. I  am in the habit of replacing ball bearings automatically if the equipment has been well used, has vibration issues or has been contaminated for any length of time. It is not necessary to get the exact bearing brand, but get the same size/type. The bearing info will most likely be stamped on the bearings. Make sure you get the same clearance, most likely "C3", as heat is involved in vacuum pumps. SKF or Japanese brands are good bearings, do not use no-name or Chinese brands. It is not necessary to get them via a vacuum parts supplier, unless you enjoy premium prices, I get most of my bearings off Ebay.

Tools needed...
hex keys
paper towels, 1 roll
dental pick if you have one
tweezers
Locktite 242 blue for the Allen bolts, sold at Autozone
Permatex Threadlocker green ( Locktite 290),  only for one of the shaft seals,  AutoZone
Wet/dry 1500 sand paper, 1 full sheet minimum, small piece of 2000,  AutoZone.
1 gallon paint thinner ( if you pump is really dirty), 2 qt minimum, Home Depot .
1 qt Lacquer thinner, a more aggressive cleaner, Home Depot.
2    14-16 oz spray cans Carburetor cleaner, AutoZone
An old 6203 bearing would be handy to remove/install the outer pump seals, but not required.
Snap ring pliers, a must have tool, as the snap ring in this pump is large/stiff.
A low height plastic container to soak parts.
I skipped gloves, but if your pump is contaminated use them.
Safety glasses due to the carburetor cleaner spray and or contamination.
Download your pump's manual and expanded parts list, both are necessary.
Overhaul kit, either minor for the seals, O-rings, gasket, springs or major with the vanes.
Plastic hammer, a must have tool
Tooth brush  (but not the wife's)
Very thin plastic bristle brush to get into small orifices. Pipe cleaners leave lint .
White cloth, old white sheet to work on, to keep dropped parts visible.
Seal removing tool for the smaller inner shaft seal, about $20, PepBoys , or make it

Downloads sources....

http://www.gasflovac.com/GASFLO_DOWNLOADS.htm

Exploded Parts diagrams

http://www.idealvac.com/downloads/explodedviews/Edwards_E2M2_to_E2M12_Exploded_Views.pdf

E2m12 Manual...

http://www.ajvs.com/technical_library.php?tlcPath=0_34&man=7

Empty the oil into a low pan, I  used a large tray which had a 1" lip. Tilt the pump with a block of wood or similar item under the motor to drain the oil remnants, I let it drain overnight.

I used paint thinner to flush out the remaining oil which makes it much easier to work on the pump. This pump does not have sealed ball bearing which could be affected by solvents, if your pump has sealed bearings, do not flush the pump with solvent. On the other hand if your pump has open bearing (no covers or contained grease), you can flush as described below.
 
Flushing...
Reinstall the oil plug, fill the pump with paint thinner, 3/4 full, and added some to the inlet port of the  pump, I turned on the pump for 4 seconds only. With the pump off, rock the pump sided to side to get the solvent around the inside, let it sit for a while, turn the pump on again for 3 seconds; if you have the time, let it sit over night. Empty the paint thinner/oil solution into a container. Turn on the pump for 1 second only to clear the pump stages; in all this basically cleans out approx. 98 % of the oil.  You will get a 1/4 cup of  pure oil from the area of the main pump seal (closest to motor area) upon dis-assembly, so be prepared with paper towels. Without using paint thinner to solvent out the oil, overhauling is one messy procedure.

Do yourself a favor, remove the motor from the pump body first. On my pump, I needed to remove the plastic side covers, loosen the Allen set screw from the motor coupler, then remove 4 Allen bolts. Be careful the motor does not drop, as it could damage the plastic fan blade;  I removed the two bottom bolts first, wedged my sneakers to support the motor , then removed the top two bolts, slowly backing out the motor. With the motor removed the pump assembly weighs little; trust me with the motor in place working on the pump is a tough. Remove the motor shaft key if it does not stay with the motor coupler.
To make it even easier remove the base plate (part 14), 4 Allen bolts. This way the pump is light and the pump body can be rested  standing vertically, much easier to disassemble/ assemble, and can be easily worked on in any position. In the vertical position, o-ring will remain in place during assembly.

Next remove the main pump housing cover (oil box assembly, part 90), 4 Allen bolts. Clean up the oil box interior of  metal particles/gunk.
 
Remove the exhaust baffle (part 108), remove clamp (part 48).

Remove the plate which covers the first pump section, referred to as the  rear cover (part 94). Remove gas ballast tube assembly (part 5) by gently but firmly pulling up, while twisting slightly after the bolts are removed from the end plate, and plate is lowered by about 1".

Remove the LV vanes . The vanes in my  pump are phenolic material, rather hard material  but do not even think of using anything near these which could scratch their smooth surfaces.
To get these out of the LV stage, I could not grip them with my fingers as the space is confined,  I used a dental pick (sharp angular point) to grab them on the surface which does not need to be perfect, where the vane springs are, they slid out easily; you could use a small hook tool to hook around the springs if you are using an overhaul kit, as the springs will be replaced. A sharpened piece of thin hard plastic could be used as a wedge between the stator wall and vane. Do not use a screw driver, pliers etc, you could damage the vans or pump walls. Both the LV and HV vanes have a tendency to fly across the room if you do not hold them, I had a set fly 10 feet, finding the springs and pins was loads of fun, especially on a dark floor.
Another method, Loosen the bolts connecting the LV stage to the HV stator, as described in the next paragraph. Once the LV stator has a separation of  approx 1/2" from the HV stator, carefully push or tap the LV stator back to it's original position. The vanes will likely not go back to their original position, at this point you should be able to pull them out with you fingers.
Another method but untried. Cut two strips of  wet/dry sand paper, 1"x6", oil the back of the paper. Push a vane in with you finger nail or a thin wedge, slip the sand paper under the vane, abrasive side towards the vane, do the other side. Now pull both pieces of paper at the same time.


Loosen the Allen bolts from this pump stage (LV stator, part 20) a few turns (1/4"). If your lucky, by tapping around the LV stator (plasic hammer), the stator will loosen from the next pump stage (HV stator part 9) easily. Go slow here, the matting of parts here are very close tolerance, especially the shaft to stator clearances; so tight they provide a partial seal between the LV and HV pumps. The are two small détentes where you could tap a hard plastic, wood, or aluminum wedge, to separate the stator (on the sides of pump stages), DO NOT use a steel screw driver, a sharpened wood wedge or a piece of  sharpened aluminum is soft enough to use. The stator must separate from the next stage evenly,. Once you see a separation develop, keep tapping with the plastic hammer evenly around the separation ( top, side, bottom, side of the LV stator). Once it is loosened, remove the Allen bolts, very carefully pull the LV stator off, do not pivot the LV stator or it will jam due to the close tolerances; do not use excessive force, it is not required. Do not use a metal hammer on any part, all parts in the pump are hardened but very little.

Once the LV stator is removed, the next stage's internals are visible (HV stator), again you will need to remove a set of pump vanes. On the e2m12, you need to carefully  remove the entire pump rotor assembly (Part 113), which is now free, slowly pulling forward with the fingers; if a bit tight, lightly tap the shaft from where the motor connects to the pump with a plastic or rubber hammer; this should require very little force . Go slow as the vanes have springs which will shoot the vane assembly across the room if you are not compressing them together as the shaft is removed. Make sure the shaft key was removed previously before removing.
Be extremely careful with all these machined parts; drop them or knock them together producing a dent and your in trouble; seriously dent a bearing surface and the part is lost and VERY expensive.

Next, remove the Allen bolts which hold the HV stator to the pump body rear plate (part 6 adapter? (where the outer seal resides)) . As the stator comes off, there is about 1/4 cup of pure oil between it and the rear seal , no appreciable amount of solvent could get in here, so have paper towels handy.

There is a pressed in solid metal bearing  in the E2M12's LV stator, leave it be. I do not see a number for it so if damaged I assume you would need to purchase the entire stator body. Likely it was milled once it was press installed in the stator.

Cleanup time. If you plan on reusing the seals, use a non aggressive solvent. My advice is at least get new seals/O-Rings (available kits); after all this work, you do not want to pull the pump apart once reassembled to reseal.
If you get a kit, then use paint thinner first then Carburetor cleaner  or even more aggressive solvents to initially clean the parts (Lacquer thinner works great). You will need to clean all surfaces a number of times. Initially soak everything in paint thinner, cleaning everything with a tooth brush and pipe cleaners (skip the Q-tips). For the final cleaning, with new seals and gaskets in place, play it safe and use a mild solvent such as paint thinner  What you are after most is the microscopic metal particles, secondly the gunk.

The following is NOT recommended by vacuum pump manufacturers. Personally I somewhat polished the LV and HV stator surfaces which the vanes contact. With 1500 wet/dry ( with some oil on it), on a hard rubber backing pad I sanded the surfaces lightly. Mine had a couple tiny metal flecks embedded in the surface, just enough to be felt on the finger tips.  I sanded enough to smooth the surfaces slightly, but not enough to create a polished surface. Lastly I used a PVC 3/4" pipe wrapped with 1500 to sand, so the sanding marks were perpendicular to the vanes, as were the original milling marks. I did not want to polish the surfaces, so surfaces  absorbed oil better; if the surfaces are highly polished, oil will not cling as much. Hard to explain, I was looking to knock of very rough areas, making it all consistent . With 1500-2000 grit you can get a fairly high polish, as in you can see details of your face, this was not what I wanted. I spend roughly 20 minutes sanding total on both stages, this included cleaning often, and feeling the surfaces with my finger tips, and I was not moving fast...basically not a terrible amount of sanding. Sand with oil or paint thinner or the 1500 paper does not cut. Personally I would not use a courser paper, it would cut to much.  If the stators have scoring, it is not possible to remove it by sanding without negatively affecting the pumps vacuum ability, leave scoring alone.

I also sanded the matting surfaces where the pumps stages come together (flat surfaces) by placing 1500 paper on a perfectly flat surface and rubbing the matting surfaces on it, again you need liquid on the paper, again do not sand a great deal.
Check the shaft surfaces where the oil seals contacted it. I  polished this area slightly with 2000 wet/dry paper. If you have considerable wear/pitting on the shaft due to the seals, you are suppose to use a spacer shim washer, so the seal contacts the shaft in a different area.

After sanding, clean everything again . Every orifice needs to be cleaned out.

The are two shaft seal to be replaced, remember the direction they are installed; the Edwards parts pictorial is not that clear.  I will not go into great detail but what ever tools/method used to remove/replace the seals do not scratch the surfaces they go into; your vacuum/oil depends on those surfaces. The inside oil seal (part 55) is a royal pain to get out, I had to create a tool to pull the old seal out. If you have a metal shop, you could easily make a tool for it. I made one from a 3/16 bolt, creating a hook on the end of it by hammering the tip to flatten it, bending the flattened tip  >90 degrees, sharpening on a grinding wheel; a Dremel rotary tool would do it.  After the fact, I found a seal puller at Pepboys, shaped like the letter J with a small bent up hook.
Installing the replacement seal part 55, you need something close to the outside diameter of the seal to push it into place.  I used a common washer, slightly larger then the seal's OD. I sprayed the seal and the housing with Teflon spray ( Borden's Teflon Spray or Remington's (dry powder)) before pressing the seals into the housing; aligns flush with the back of the stator body, do not push further or leave seal a bit above the surface; when you install the rotor, a couple of light taps to the rotor end will seat the seal at proper depth, which is VERY IMPORTANT.
I used a bit of Locktite 290 on the outer seal, after it was installed, as it is very easy to remove/install. On the outer seal I used an old, clean 6203 bearing to push out the old seal and install the new one (with a bit of grease on it); this seal should be easy enough to remove and replace without the bearing; perhaps a properly sized large metal washer would be a help.

Refer to the parts list and disassemble the distributor valve assembly (part 14), clean or replace the distributor rubber (part 40), clean all parts, reassemble.

Cleanup the vanes, spring, pins, if to be reused. If the vanes are very lightly scored. sand with 1500 paper on all side. If highly scored, chipped or worn. replace them. The minor/major kits have new vane springs/pins.

Do a final cleaning,  When your parts are clean enough, your solvent soaked white paper towel will remain white after wiping parts; I spent more time cleaning then disassembling/reassembling. Remember, go after the gunk in the pump ports and orifices.

Reassemble in the reverse order, referring to the downloaded parts list, ensuring all O-rings, springs,  button valves etc are replaced, oiling all parts before assembly, including the shaft seals. During the reassembly, check the main shaft turns during each stage of assembly. Turning the shaft gets a bit tough after both stages are assembled with the vanes in place.

As far as torque on the Allen bolts... snug fit seems to be OK, do not super tighten. Personally I used a small amount of Locktite 242 for each Allen bolt (let fully cure), I would not full coat the bolts with Locktite, they are rather long, longer then necessary (over engineered), so using a full coat just makes it more work for the next person working on the pump. Locktite 242 releases with normal tools, it is medium strength; DO NOT use a high strength Locktite  (such as Locktite red 271), under any circumstances. High strength Loctite  requires high temperatures to release which would affect metal hardness, no less even with heat it is difficult to disassemble parts assembled with 271; basically you will ruin your pump.
 
I have super magnets from computer hard drive activator arms; really strong magnets. I placed one on the bottom portion of the oil box upon reassembly to catch metal particles suspended in the oil.

The glass oil site area had aluminum/steel particles in the area where you view the oil level, it was difficult to see the level. Snaked a pipe cleaner between the stainless back plate and the glass, with paint thinner to clean the glass.

Replace the oil box gasket, I used a lacquer base spray to tack hold the cork gasket to one of the mating surfaces. Bolt up the oil box, again not super tight, replace the base plate. Bolt the motor on, make sure the key-way key is in place, tighten the Allen bolt holding the shaft to the motor fairly tight, but remember your going into aluminum, which does not withstand high torque .

Fill with oil to just below proper level, add some oil to the pump intake . Turn on the pump for a couple seconds, check the oil level, add oil if necessary. Turn on the pump for a few seconds, check for unusual noises.
If the pump has no unusual noise or vibration, let the pump break in by letting it run for hours without attachments.
« Last Edit: September 30, 2013, 08:27:31 pm by pcmeiners »
 
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Offline M. András

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #1 on: August 11, 2013, 06:41:56 pm »
pictures? :)
 

Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #2 on: August 11, 2013, 06:51:16 pm »
Pictures of a very similar Edwards E2M2 pump have been posted, the original E2M12 pictures were lost due to corruption. If you download the pump part list, it shows the parts.
« Last Edit: September 08, 2013, 05:17:48 pm by pcmeiners »
 

Offline SeanB

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #3 on: August 11, 2013, 07:07:39 pm »
Nice with the magnet to trap metal fines, I did that with a bigger compressor, it keeps the oil very clean. I just used a ferrite bar magnet, and put it in the filler plug, which is made from turned nylon, and held it in place more securely with 2 part metal epoxy. Generally has a thin black ferrous wear particle smear on it on the checks. Keeps the expensive synthetic oil very clean, as they do not have any oil filtering and use splash lubrication.

I might do that with my vacuum pump, but the oil in that is changed regularly as it becomes water contaminated and refrigerant contaminated quite fast. I do not like to leave it in there so long that it becomes black.
 

Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #4 on: August 11, 2013, 08:49:56 pm »
Yes the magnet catch the particles well. I also throw them in any rebuild that has an oil lubrication sump. On this pump I had flushed the oil really clean before initial testing, I ran the pump for only 10 minutes before deciding on a rebuild. I had placed a super magnet hanging off the baffle plate after flushing, two days later when I took off the oil box cover, the magnet was covered with metal particles, particles smaller then the strainer mesh Edwards uses. On my truck I place 4 on the oil filter and a couple on the oil pan, not as good as epoxying to the oil plug, but it works, especially with the thin metal of the filter.
« Last Edit: August 12, 2013, 05:40:36 pm by pcmeiners »
 

Offline robrenz

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #5 on: August 11, 2013, 10:47:32 pm »
Very nice write up and welcome to the forum. I enjoyed reading all the excellent detail :-+

Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #6 on: August 12, 2013, 02:35:18 pm »
Thanks..
Bit long, but expensive mistakes monetarily/time wise can be made, so I detailed it as much as I could.
 

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Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #8 on: August 13, 2013, 01:49:30 pm »

Another writeup by T J Nelson on a similar pump...

http://www.randombio.com/e2m30.html
 

Offline SeanB

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #9 on: August 13, 2013, 06:57:03 pm »
Yes the magnet catch the particles well. I also throw them in any rebuild that has an oil lubrication sump. On this pump I had flushed the oil really clean before initial testing, I ran the pump for only 10 minutes before deciding on a rebuild. I had placed a super magnet hanging off the baffle plate after flushing, two days later when I took off the oil box cover, the magnet was covered with metal particles, particles smaller then the strainer mesh Edwards uses. On my truck I place 4 on the oil filter and a couple on the oil pan, not as good as epoxying to the oil plug, but it works, especially with the thin metal of the filter.

I have some sacrificial hard drives, must take the magnet assembly out of one and stick it to my car. Should be interesting.
 

Offline PedroDaGr8

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #10 on: August 13, 2013, 10:47:10 pm »
Hey mate good to see ya here.

Here is a tear down/repair I did on an Edwards RV8

http://www.instructables.com/id/RepairingCleaningUnsiezing-Edwards-RV8-vacuum-pu/
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Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #11 on: August 13, 2013, 11:31:09 pm »
Hey, I had a link to yours but I had to cut the novel by a 1/3 to post it, regretfully you got cut; amyk linked you though   :D

Another vane pump tear down source...

http://www.idealvac.com/files/ManualsII/Leybold_A_Series_Pump_Service_Manual.pdf
« Last Edit: August 25, 2013, 05:39:46 pm by pcmeiners »
 

Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #12 on: September 07, 2013, 06:55:39 pm »
Edwards RV3 overhaul photos...
Picked up 3 Edwards RV3 pumps to overhaul/sell. Some seals in the RV series are partially silicone rubber, once solvent is introduced into the pump, and parts disassembled, the seal become unusable, so be prepared to purchase a minor overhaul kit at minimum; RV3 kits approx $ 125.00. If you only disassemble the oil, LV, and HV stages, there are no silicone seals involved, other then the oil box seal which may or may not involve a silicone seal. Kind of a scam by Edwards to use silicone, basically forces you to buy an overhaul kit if you totally disassemble the pump for cleaning. After rebuilding any vacuum pump, using any solvent, do not expect any great gauge reading until the solvents are out-gassed, which could take days of vacuum pump use. Also pump need to run a while so tiny particles seal microscopic leaks on metal to metal sealing surfaces, before testing.

http://s852.photobucket.com/user/pcmeiners/library/Edwards%20RV3%20vacuum%20pump%20after%20final%20cleanup?sort=2&page=1
« Last Edit: September 30, 2013, 08:30:48 pm by pcmeiners »
 

Offline bigJim1

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #13 on: January 09, 2014, 04:35:47 pm »
That is really a helpful post. Thanks a lot for sharing this!

I also bought a vacuum pump (E2M5) and now I want to clean the oil box before using the pump. I removed the 4 Allen bolts, but I still cannot remove the oil box from the pump.

So is there a "magic" trick in order to remove the oil box or shall I use "controlled forces"?
Could it be that the gasket ring is glued with the oil box and pump?
 

Offline SeanB

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #14 on: January 09, 2014, 04:45:53 pm »
Gentle tapping with the wooden shaft of a hammer normally will unstick those sticking parts. Use the wooden back of the hammer, not the head, and it should pop off easily.
 

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #15 on: January 09, 2014, 05:08:32 pm »
I might do that with my vacuum pump, but the oil in that is changed regularly as it becomes water contaminated and refrigerant contaminated quite fast. I do not like to leave it in there so long that it becomes black.
Unless you work with very low pressure refrigerants (R11 and the like), any refrigerant that gets in would evaporate almost immediately. That's especially true for HFCs that do not dissolve in mineral oil.
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Offline SeanB

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #16 on: January 09, 2014, 05:20:58 pm »
I still buy R141B........

R22 till next year or so.
 

Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #17 on: January 09, 2014, 11:17:09 pm »
"So is there a "magic" trick in order to remove the oil box or shall I use "controlled forces"?
Could it be that the gasket ring is glued with the oil box and pump?"

As Sean recommends or plastic faced hammer, do not even think of using a metal faced hammer. Yes all the metal to metal contact points have oil contaminates between them so they can take a bit of force to separate. If your lucky the seals are reusable, clean with mineral spirits or paint thinner. If you plan on getting a seal kit, use lacquer thinner, cleans much better/faster but may destroy the seals/o-rings; also lacquer thinner should be used with good ventilation, and NO spark or flame producing devices, Lacquer thinner can easily get you a Darwin award in a flash.

"controlled forces"....... the forces one uses until the item just breaks, often associated with expensive learning experiences and four letter words.  :P
 

Offline meggerman

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #18 on: May 24, 2014, 11:34:25 pm »
Re. Edwards E2M2 pumps:
Excellent write up, very useful.
To get the oil box off you can use two blocks of wood between the oil box fins and the adaptor/manifold section and use a large screwdriver to prize the two apart. This worked for me on a real tough, glued to gasket, oil box. The result was some of the gasket was left stuck to the adaptor/manifold section.

One issue I have is the rotor is weeping oil out of the outer spiro seal onto the base plate.
There is some minor pitting on the shaft that I could try to rub down - my next job.

At the moment I get a vacuum of 9.7 x 10^-3 mBar (0.0097 mBar), just into the x 10^-3 (tested on Edwards APG-L pirani gauge).
But getting it any better is a real struggle - the original spec. of 1 x 10^-3 mBar seems a real challenge.
New blades, new seals and finally new oil.
Some of the seal seats have microscopic pitting.

One thing that puzzles me is the oil distributor design has been changed in the lifetime of the E2M2/5/8 and I think at a later date they added the wave washer and cap to the distributor.
But to adapt/convert  an old distributor into the new style you need a new brass weight because the old brass weight does not fit the wave washer.
Has anyone got some pictures of the wave washer type distributor?
I have been trying to "tune" the spring tension on the standard distributor by making an adapter piece to reduce the spring tension.
In the hope that more oil gets pushed into the HV section.
But I need to perhaps try with less oil going into this section by increasing the pressure on the distributor weight.

The ball bearing in the bottom of the ballast valve seems to prevent the spring from grinding into the softer aluminium of the adaptor. Having the ball stuck in the bottom would not appear to be an issue but what ever I try, I cannot remove it.

Also, to avoid removing and re-filling with oil each time you change something and try again, you can plug the outlet, remove motor and then remove the oil box bolts and lift the whole assembly out of the oil box, hold and tilt it to get most of the oil out before putting it on the bench.
I use plain lining paper (wallpaper) to put on the kitchen type worktop/bench to soak up the oil.
Always try to wear rubber gloves and old cloths, also put a thick rag on the floor (in case you drop and damage a part).
Always keep any bits you replace.
Removing the seals on the ballast pipe are really tough, so I cut them off with a robust plastic knife to avoid damaging the brass connector.

 
 

Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #19 on: May 25, 2014, 05:34:04 pm »
" that I could try to rub down"
I rubbed out some scoring on one of my pumps shafts, another couple I purchased  shaft sleeves (rear, $40 each ).

"But getting it any better is a real struggle - the original spec. of 1 x 10^-3 mBar seems a real challenge"
Yes, I have a couple pumps where most parts were replaced recently, still can't get to specs, with no pitting.  I am getting between 20 and 35 microns on my rebuilds.

The only pics of the wave washer assembly I have found are the typical Edwards downloads which are not the most detailed.

Did you find documentation about "tuning" the distributor?

As to oil weeping, the rear oil seal  almost always needs replacement ( $20 ?).
 

Offline meggerman

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #20 on: May 25, 2014, 08:49:19 pm »
Hi Pcmeiners,
I already have a new outer spiro shaft seal, I think its the slight pitting on the shaft where the seal sits that is causing it to weep slightly.
I need to measure the drops of oil per hour of run time, but I expect its probably a just a small amount but more than it should be.

For the tuning of the distributor, there is no documentation but its key in the supply of oil to all the sections.

From what I can make out in the design of the oil pump and distributor, some oil goes directly into the top of the HV section, some into the rear spiro seal section, and the rest comes out the top of the distributor, floods the HV flap valve pool, then cascades into the LV button valve pool, then finally cascades into the oil sump. Its like a water feature but filled with oil.
The oil in the HV section gets pushed into the LV section by the HV vanes and lubricates the shaft/solid bearing at the same time.

Take the round rubber disc off the dist. and check for the smoothness of the aluminium rings in the base of the distributor, if they are rough, use some fine wet/dry paper 1600/2000 grit + oil and a flat block to get a smooth machined like surface. This helps the vacuum hold level after the pump is switched off and should also help with the ultimate vacuum.
After the pump is switched off for 10 minutes you should be able to hold a vacuum of between 2 to 9 mBar for a gauge sitting on the inlet (even less if you have a large bellows pipe connected -- because of the extra volume).
For tuning, I found that it you just screw the bolt down onto the spring (light finger tight) then back it off a quarter of a turn, it does not compress the rubber so hard into the distributor base and "may" allow a different amount of oil flow into the various sections.
To hold the bolt in place you can bend the oil baffle plate slightly so when you screw in the end plate of the LV section the baffle plate presses down on the top of the bolt. You have to lift the top edge of the baffle plate over the head of the distributor bolt when you screw the last two bolts in.
It may be that you baffle plate is already like this.
Also put some vacuum grease on the ballast pipe seals if the seats are slightly pitted/scored or corroded.

Somewhere on the net it mentions that vacuum grease on seals causes them to become permanently distorted/compressed over time, but I am not sure if this is still true today.

You should be able to get 7 microns or better on a good pump with good surfaces.
0.75 microns is the original spec. to aim for but tricky to get to on an old pump.

Checking the hold vacuum after the pump is switched off is key to finding the problems.
Total loss of vacuum indicates that gas is getting past a seal.

Changing to new oil make a big difference too, I found that constantly draining and refilling with the same oil causes it to become grey in colour and filled with air. That is why I recommend lifting the pump out of the oil box and leave the oil in the box.

I keep a diary of all the changes I make and the differences each change makes to the ultimate vacuum and leak test.

I have 2 of the Edwards E2M2 pumps and the first was pumping to 9.5 x 10^-3 mBar and the second pump an amazing 2.0 x 10^-3 mBar and I wanted to get the first pump down to around 5.0 x 10^-3 mBar.
So I decided to start swapping the parts across to find out where the problem was and after swapping almost everything except the main rotor, HV/LV stators, I could not get any improvement, albeit very little improvement.
Then I put the second pump back together and that now shows 8.0 x 10 ^-3 mBar at best, so disturbing the whole pumps and its vanes impacts the ultimate vacuum.

It would seem that if you allow the vanes to bed in and the seals and seats to become settled in over time then the ultimate vacuum improves.
I think that worn material from the vanes slowly fill in minute pits and gaps.
I always try to mark the vane position and orientation using a marker pen and dots. Two dots for one vane and one dot for the other. Then mark the rotor with the same dots.  Do this as soon as the rotor is removed from the stator.

I am currently writing a C program for a STM32F407 discovery board microcontroller to convert the output voltage signal from the Pirani APG type gauges into mBar/Torr/Microns.
 
I also noticed this evening that depending on whether the Edwards APG gauge is horizontal or vertical effects the output signal and I think this is because of convection of gas inside the gauge.
It helps if you have more than one Pirani gauge as I had what I though was a real pump problem the other day and in the end it appeared to be the stainless steel filter was blocked with oil mist.  Because when I tried a different gauge the pump was working as expected.
After washing the filter in EPA (rubbing alcohol) and replacing it, all was working again.

It might be worth you checking your filter in your gauge - if there is one.


« Last Edit: May 25, 2014, 09:47:04 pm by meggerman »
 

Offline pcmeiners

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #21 on: May 25, 2014, 09:12:58 pm »
"I already have a new outer spiro shaft seal, I think its the slight pitting on the shaft where the seal sits that is causing it to weep slightly"
On the RV series, extra washers are supplied in the kits which can be added to the rear seal casing to move the seal in more, placing the seal area on an unused area of the shaft, I did the same on the EM series pumps with a washer I obtained at a hardware store.

I  may play with the distributor, wish there was more technical info released by Edwards or repair depots...the hidden secrets.
« Last Edit: May 26, 2014, 03:07:46 pm by pcmeiners »
 

Online amyk

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #22 on: May 26, 2014, 12:31:34 pm »
So you're trying to make your pumps suck more... :D
It would seem that if you allow the vanes to bed in and the seals and seats to become settled in over time then the ultimate vacuum improves.
This is what I thought too. The components should wear together and improve the sealing.
 

Offline meggerman

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #23 on: May 26, 2014, 10:44:43 pm »
From a test I did this evening with the distributor bolt shows the changes are very small but noticeable.
With the bolt loose the pump got down to 1.05 x 10^-2 mBar after 15 minutes.
With the bolt tightened to normal tension the value was 1.13 x 10^-2 mBar after 15 minutes.
It takes about 30 minutes to remove the motor + oil box, adjust the bolt tension, grease the ballast pipe coupling and re-assemble it all.

My next test is to try it with the bolt very loose and if it proves to be good then I will apply some some thread lock to hold its position.

The good news is there does not appear to be any more oil weeping from the outer spiro seal, since I wiped away the oil from my previous test the seal shows no oil across the face, so it might have been there from when I put it together.



 

Offline DogsAfire

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Re: Edwards E2M12 vacuum pump rebuild / overhaul / cleanup
« Reply #24 on: April 28, 2015, 05:48:00 pm »
First of all, I would like to thank pcmeiners for making the original post in this thread. The links to the Edwards manuals, especially the exploded diagram, were very helpful

I have disassembled an Edwards E2M8 and am waiting on a part from Edwards before I can begin the reconstruction. In the process, I acquired a copy of the overhaul instruction set provided by Edwards. I will be happy to scan the document, but where would be the best place to post it?

Also, one member had a question about the oil distributor with the wave washer. That is the version that I have. I can take pictures, take measurements, etc. if anyone is interested.

One other rebuild note I might add. Keep in mind that the pump that you're rebuilding might have been previously rebuilt by an idiot. Marking the parts so that you reinstall things in the same direction means that you may be reinstalling them backward because the idiot before you did _not_ mark the parts. Guess how I know this. Also, both of the compression springs (oil distributor and HV valve) were cranked down completely. Not much good to note the adjustment setting.

I know I'm reviving an old thread, but it seemed that it would be better to place my comments here than to start a different thread. If there is anything that I can add from my overhaul/rebuild experience, I would be happy to do so. Again, I am very grateful for the information that is already here.


 


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