Air compressor question

[jtillery]

I have had a oilless craftsman 26 gallon 5 horsepower compressor for about 3 years (I cannot remember the exact SCFM rating but it is 5 &

90psi). It recently starting tripping the breaker within seconds of flipping the power switch. I was told that the motor would need to be replaced to fix the problem since individual parts are not available. I was quote $175 for the repair. I am having a hard time justifying the repair since I paid $250 for the compressor originally.

I am now looking for a replacement compressor. I would like to keep the cost down as much as possible, but don't want to scrimp and regret it again.

My plan was to replace it with a tank with at least the same, but I was at home depot last night and saw a Ridgid OL50135. It is oil lube 3HP peak/1.5 running with twin tanks (cap 5 gallons). It delivers 4.8SCFM @90 psi.

I will not be using the compressor very often, right now we are remodeling the house so I will be running nailers a few times a week for a couple hours at a time. Once that is finished, it will go back to my normal use of using to work on my cars and motorcycles. The most frequent use would be one full day per weekend, but it is more likely half a door every couple weeks. I typically run a few air ratchets and impact wrenches. Once every few months I run a d/a sander or sandblaster. My d/a sander and sandblaster both require about 5 SCFM.

Obviously the Ridgid would run alot more when I was using a sander or sandblaster than my craftsman did, but it still would be able to deliver the same volume of air, correct? The recovery time for the Ridgid is less than 15 seconds, couldn't find the spec for my craftsman, but I would say it is at least 30 seconds - 1 minute. Space is limited in my garage, so the small size of the ridgid would be a nice benefit.

Should the Ridgid deliver the same amount of air as my crafstman, but just run more frequently, or do you thing the air delivery will be lower while it is recovering? Do you think I will damage the Ridgid, by having it running alot while using a d/a sander and sandblaster?

Any other suggestions on a compressor? I would like to keep it under $400 if possible, but if I get a solid benefit for spending more, I will likely do it.

Thanks

[Richard J Kinch]

The specifications are fantasies.

Buy the biggest piston type you can afford.

[SQLit]

Who tested the motor? Are you sure that the breaker/gfci outlet it is attached to is not part of the problem?

I am having a hard time justifying

[jtillery]

It was a friend that tested the motor, he is retired now, but was a maintenance technician for most of his career. He thought he could rig it to get it working but it definitely would not be a permanent fix. I cannot remember the name of the part that needed to replaced, but it is the component controls the start capacitor that is messed up. He checked Sears and some electrical supply shops and was unable to find the part. Sears wanted $175 for a new motor, he thought I might be able to find one alittle cheaper, but didn't know if it would be worth it to replace it. I don't want to buy a new motor, then have the exact same thing happen to me again, he thought it definitely was a design flaw, so I am not sure if they have fixed it or not.

[jtillery]

Also, I tried it on 2 completely different circuits, and got the same results, both circuits had run the compressor with no problem in the past. 1 day it seemed to be working fine, and the next day, I had the problem.

[Edwin Pawlowski]

It will deliver 4.8 as stated. If you use 5 cfm, the tank will run down.

No, it will deliver what is rated and no more. If you take out more that the compressor can put in, you eventually lose pressure at the too. If yo give it time to recover, it will run the sander again from the resevoir that is build up.

Do you think I will damage the Ridgid,

Running the crap out of a compressor wears it out faster than one that has higher capacity. The 4.8 cfm is going to struggle while an 8 or 10 cfm is just coasting. If you had to drive up a steep hill that was 25 miles long, would you do it in a big V8 powered car easier than a Fiat? Which would last longer?

[jtillery]

Thanks for all the help. I think he was talking about the starting contacts, it was a more technical name for them, but I cannot remember what it was. I will ask him and get some more info. I am out of town on business right now, should be back tomorrow, so I can get the specifics on the motor model number.

I was actually wondering if it could be rewired to 220v, after reading the article on compressor power ratings that was posted above, it made me wish I had a 220v compressor. I am not sure if it would solve my problem, but I would rather try that then buy a new compressor. I have only had it for 3 years and have used it very little, I definetly was planning on getting more use out of it.

I saw a Husky 7hp 60 gallon oil lubed 220v compressor at homedepot.com it is $429. It looks like that would be better than the ridgid I saw before. I would much rather repair the Craftsman though..

[Mark]

was it the centrifugal switch?

Mark

[Dave Jefford]

I bought a new similar SCFM compressor a few years back and it trip off every time it restart. I rewired it from 110C to 220V and haven't encounter tripping ever since. Further, most compressor with the exception of Inglesoll Rand, the rated HP are all bull shit.

He should rewire it to 220V or get one of his neighbour to do for him and save the few hundred bucks.

[Terry]

Not much info to go on; however from your quotation of your friends comment it sounds as though it might be the 'start' contacts. Typically these are closed when the motor is at rest; when the motor gets up to speed the contacts open and disconnect the starting winding and/or capacitor etc. These contacts can wear out; the more often the motor starts the quicker the wear.

One way to test that it 'might' be the start circuit is to release all pressure; switch on and carefully spin the motor manually (mind your fingers)! If it then runs it 'may' be the said start circuit.

I guess a new/replacement 5 HP motor will not be cheap? But if you published the motor type/number/rating/ etc. here you might get some good advice as to where new contacts (if that is indeed the problem!) could be obtained.

If it was mine and it was/is the non replaceable? starting contacts, I would probably devise a starting circuit, probably using a relay of some sort (kinda similar to pressing that start button on some models of) clothes dryers but doing it automatically when the pressure falls. But it would depend on the motor circuitry. It is possible this is what your technical friend is mentioning as a possibility?

Locally friend/neighbours say that some so called 5 HP compressors are inadequate for the demands placed on them! e.g. Recently someone was sanding a fibreglass boat repair using an air tool. The 5 HP compressor ran almost continuously!

[lp13-30]

Look in your Yellow Pages under "Electric motor repair" and see if you can find one that can replace the centrifugal switch in your motor. If the rest of the motor is ok, it should be able to be repaired for probably $50 or less. Larry

[PaPaPeng]

Try running it off a very short extension chord to see if the compressor still trips. On a long extension chord there is a voltage drop and the compressor trips at the slightest provocation.

[Bob]

When I decided I needed more compressor than my origional "5HP" Craftsman, I was convinced by talking to "real" compressor shops to buy a used "commercial" cast iron compressor. The 5HP 2 stage compressor I ended up with delivers way more pressure and volume than the one it replaced, and the sound is way more bearable. I was told it would last way longer than any of the cheap compressors I could get at local "home inprovement" stores.

Bob

[jtillery]

To answer a couple of the questions above. The compressor is not plugged into an extension cord, the cord that came on it from the factory is about 4' long, and I have that plugged directly into the outlet.

The part was the centrigufal switch. I will try to call some shops around to see if I can get it replaced. I did look at Northern Tools and Grainger for a replacement motor, they did not have the exact replacement, and most of the ones I saw that were close were more expensive than the Sears motor. My concern with using a different motor, is the pump, actually mounts directly on the shaft of the motor, and bolts into the motor case. It is not the design, where there is a pully and seperate pump. I don't know how standard the mounts and the shaft sizes are, so I would need to be real careful and make sure I got a compatible unit.

A used commercial compressor is definitely an option, one of my customers rebuilds and sells commercial compressors, most of the units are much larger than what I would need, but I will check to see what he has.

Has anyone had experience with the Husky Pro compressors? I believe the one I am interested in is actually made by Cambell Hausfield and sold through Home Depot. This is the one I am interested in:

Thanks

[Stormin Mormon]

Couple thoughts. First, if you get the smaller compressor, you may be able to plumb it in, and use the larger tank as a ballast tank. Hook the air hose to the larger tank.

Second, try Froogle for 5 HP motors. Or Ebay.

Motors are also available at places like Northern Tools, and Grainger. Might be less expensive than the Sears motor. If you get the same direction, and V-belt configuration, the compressor shouldn't know the difference.

[rbrittne]

i have the OL50135 ridged for a few months now..and have run into a problem. When pressure builds up i hear a leak coming from the pressure regulator knob. I took it apart but found nothing wrong that i could tell. Then i read in the manual that you shouldnt turn the knob when pressure is at peak in the regulated pressure guage as it may cause malfunction of the pressure regulator. Well i did just that. Now when i g oto use it the pressure goes down very fast and the back up tank isnt very fast to re pressurize the tank i'm using. Does anyone have any idea how i can fix this? Thanks in advance.