Jason Rodgers builds a vacuum clamping system

[Chuck Tweedy]

Good stuff Jason.
As I've said before - That really sucks!!

[Jason Rodgers]

Built a simple, quick-and-dirty hold-down clamp to carve on a solidbody this weekend. Just a couple circles of foam weather strip on a square of plywood. The pump ran non-stop, but it was strong enough to withstand all sorts of aggressive chisel, plane, file, and scraper work. I'm really happy with this setup, and I've only begun to play with it!

[Randy Roberts]

If the pump ran non-stop then you had a fair amount of leakage, probably either the plywood or the wood you were working.
If you seal the plywood well with a few coats of polyurethane, and give the mating face of the wood you are working a good wash coat of shellac, I'll bet it will solve the problem.

[Jason Rodgers]

Oh, I know it had some leaks. The guitar in question has a red alder core, which was quite fuzzy with tool marks. The clamp base, on the other hand, is a nice chunk of prefinished, veneered plywood. The weather strip probably isn't great, either, but I'm surpirsed at how strong it holds the work. I was whacking a chisel to hog material out of the belly cut on the back and it didn't budge.

[Jason Rodgers]

Erm... I think I killed my pump. Left in on overnight for a vacuum bagging droptop glueup, and came back to find it not running. Snap.

[David King]

Check Craigslist, there always seem to be good candidates on there. Otherwise look for a used Gomco medical aspiration pump on ebay. It's what they use in Dr's offices to remove beans and pebbles from noses.

[Jason Rodgers]

Well, if you read back in this thread, it came to me without much lubrication, and I didn't add any. I haven't put a whole lot of hours into it, but it's always run quiet and cool. First thing I'll do is pull the intake hose and pour in some mineral oil. If that doesn't work, I'll pull it out from beneath the bench and see if there's anything else that's obviously buggered. Then I'll start shopping around. Stupid on my part.

[Jason Rodgers]

I think I figured it out. This description of the "click-buzzzzzzz-click" is what my compressor is doing. Looks like I need a new 3-in-1 starter (or at least start with checking that).

I'm posting all of this because it might be a common issue for folks using fridge compressors in their vacuum systems, especially if they are older motors and we're pushing them a little harder than what they're designed for.

http://www.appliancerepair.net/refriger ... air-5.html

[Randy Roberts]

Jason,

I think it might be quicker to just replace the pump rather than try to find specific parts and try to repair it. The lubricant is in there to lubricate and especially to cool the whole thing. If you ran dry I would worry that the insides may be damaged from excessive heat, and your repair time not being worth the effort.

I burned out my first one by doing the same thing and running it dry.

Once you are up and running, get some Zerol 150 Alkylbenzene Refrigeration oil.
Fill the pump until it just starts spitting out oil, and the new one will probably run forever. It will take a fair amount as the rotor inside is basically immersed in the oil, with a kinda propeller shooting the lubricant up through the center of the rotor to bathe the upper parts with lubricant.

I wish to God I could find it again, but years ago there was a U-tube from a guy in Australia who had cut the top off a refrig. pump (no small task) to show how it worked, and as he's standing there looking down into it, had someone turn it on. The lubricant went flying all over, shooting way up in the air and soaked the guy. The best part as I remember was the cameraman wouldn't shut it off.

I went to try and find it to put a link here to it but couldn't find that particular one. There are a number of videos on there that show the insides with the pump running that are worth taking a peek at but I don't have the chops to get a link to them posted here. (unfortunately they all seem to have emptied the lubricant first, which eliminates most of the fun of watching <g>)

[David King]

There is something called a hard start capacitor which you can buy for $15 but your disconnected compressor would be starting with no load when there's no vacuum present so it's toasted and seized up probably if it won't turn on at all now.

The Zerol oil sounds good but I'd think straight up compressor oil would be fine and a lot cheaper/easier to get. I'd also worry about anything with benzene in it not being in a sealed system.

[Jason Rodgers]

Thanks, guys. Yeah, the no/low oil level has been gnawing at me for a while. My dad jumped a fence after hours at the local dump to yank this compressor from a fridge.

I'll know more when I pull it out from beneath the bench and look under the electronics shield. One site I read said you might open it up and find some burned up pieces of the starter. But if it's fried inside, I won't go to heroics to get it running again. I'll report back.

[Jason Rodgers]

I pulled the compressor out and plugged it in alone, to make sure it wasn't something up the line causing the problem. Same funny "click-buzzzz-click." While I was out and about this morning, I stopped by an appliance store off 217 and Canyon in Beaverton and bought another one. $50, which is about what they're going for on ebay, give or take $10, and I don't have to mess with shipping. Free is better, but I don't want my dad going on any more covert ops into the dump.

It took a little convincing to get the guy to sell it to me. He made me promise that I wasn't going to put it in any refrigeration unit and run freon through it! I told him about the vacuum system and he'd never heard of such a thing. Anyhoo, I'll get this guy plumbed in and be back on my merry sucking way.

[Randy Roberts]

David,

I agree that normally the term benzene in most contexts is a big red flag to me too.

Apparently if you tie up all 6 carbons in the benzene ring, it doesn't have bonding sites to do harm?

Here's the pertinent parts of the MSDS sheet on the Zerol, and it's cheap as well.


VI - HEALTH HAZARD DATA
EFFECTS OF OVEREXPOSURE (Medical Conditions Aggravated/Target Organ Effects),
A. ACUTE (Primary Route of Exposure): EYES: Applications into the eyes of rabbits produced slight membrane
irritation without corneal injury. SKIN: Product may cause skin irritation on prolonged or frequently repeated contact.
Application onto the skin of rabbits produced moderate erythema and edema. INGESTION: Not expected to be
acutely toxic. (ORAL LD50 Rats >5g/kg). INHALATION: Not acutely toxic.
B. SUBCHRONIC, CHRONIC, OTHER: No available information was found.
C. MEDICAL CONDITIONS AGGRAVATED BY OVEREXPOSURE:
VII - EMERGENCY AND FIRST AID PROCEDURES
INHALATION: N/A
EYES: Flush eyes immediately with fresh water for at least 15 minutes while holding eyelids open. If irritation
persists, see a doctor.
SKIN: Wash skin thoroughly with soap and water. See a doctor if rash or burn occurs. Launder contaminated
clothing.
INGESTION: If swallowed, give water or milk to drink and telephone for medical advice. Consult medical personnel
before inducing vomiting. If medical advice cannot be obtained, then take the person and product container to the
nearest emergency treatment center or hospital.
VIII - SPILL OR LEAK PROCEDURE
Spill Management: Stop the source of the leak or release. Clean up releases as soon as possible. Contain liquid
to prevent further contamination of soil, surface water or ground water. Clean up small spills with absorbent
material and remove contaminated soil. Report and respond to larger releases.
Waste Disposal Methods: Place contaminated materials in disposable containers and dispose of in a manner
consistent with applicable regulations. Contact local authorities for approved disposal.
IX - PROTECTION INFORMATION/CONTROL MEASURES
Respiratory: None normally required
Eye Protection: Safety goggles Gloves: Rubber gloves
Other Clothing and Equipment: Wear impervious clothing.
Ventilation: N/AV
X - SPECIAL PRECAUTIONS
Precautions to be taken in Handling and Storing: Do not weld, heat or drill container. Residue may ignite with
explosive violence if heated sufficiently. CAUTION! Do not use pressure to empty drum or explosion may result.
Additional Information: Read and observe all label precautions.
NFPA HMIS RATING
Health Hazard ...........: 0 Health Hazard..............: 0
Fire Hazard................: 1 Fire Hazard ..................: 1
Reactivity ..................: 0 Reactivity.....................: 0
Specific Hazard ........: Personal Protection.... : X (Sec. 9)
Revision Date: 8/6/2004

[Jason Rodgers]

Gaaaaaaaahhhhh!!!! This new one doesn't work, either! It does the same thing: hums for a bit, then the overload trips. I have tried wiring both directly to a plug, the same way the first was wired, and worked, for a couple years. Black into the overload circuit (plugs into the top of the three pins) and white into the #2 lug on the relay (spans the bottom two of the three pins). Searching the interwebs confirms this is correct. WTF?!

[Michael Lewis]

Better go tell the guy you want one that actually works. Maybe there is a secret wiring code that "any fool" should know about. I find electrons and their activities mysterious.

[Randy Roberts]

Look in the yellow pages under commercial refrigeration ( yeah, I know nobody does that any more - it's a big thick book that has lots of names and numbers in it ).

Tell the guy what you are doing, and my guess is they will pull one for free, they probably have to pay to get rid of them out there in Environmentland.

Commercial might be a little sturdier also?

[David King]

Is it missing it's start capacitor? It won't start without that. Refrigerator motors have a lot of extra gizmotry to make them failsafe and reliable. Then again when an old fridge stops working it's usually the motor that's gone south so getting a junker isn't going to be a sure bet by any means.
Why not pickup an actual vacuum pump off Craigslist for $50? Then hopefully you won't have to deal with the oil fumes contaminating your wood and air generally.
Here's a monster that normally costs about $900 http://portland.craigslist.org/clc/tls/5018538321.html These can pull about 27"Hg when the vanes are in good shape.

[Jason Rodgers]

So, this is what I've got. The doo-hickie with the grey (black) hooked in is the overload, connected to the top pin. The thingamabob with the white wire is the relay, which spans the bottom two pins.

My original compressor ran just like this. But you're suggesting there is a third component I need? And that's a start capacitor? Sooo, like, for example, this is the third piece of a "3-in-1"?

EDIT: One of these puppies? http://www.amazon.com/Supco-RCO810-STAR ... B00A8O0E5Y

[David King]

That would be the "Hard Start" cap I mentioned above. It needs to be sized for the motor HP. I make no promises that it will work but it just might. I know I have one in my fridge after it failed to run one day.

[Jason Rodgers]

Ok, I can get one of those easily enough. I'll be sure to double-check the specs to get the right one. I can even get two.

Here's my question, then: why did the original compressor, the one my dad plucked from a fridge in the dump, turn over and work so well from the get-go, but now may need a starter capacitor? Is there some internal start circuitry that fails, and so requires an external nudge to get going? And is that why this second compressor needs help?

Well, on the upside, if a 3-in-1 is the solution for either of these compressors, I'm back in business. If it's the solution for both, I'll plumb them both into my system!