Old Sears/Craftsman air compressor value?

[Jeremy]

Runs on 220V, which makes it problematic to use since those outlets are difficult to come by in a typical garage. Vintage would be late 60s or early 70s. It was found on the side of the road, burnt out from the connection between the tank and compressor blowing out while the thing was unattended, which caused the unit to overheat and destroyed the compressor rings. My dad and his friend found it, got the parts from Sears, honed the cylinders and re-ringed it.

It has seen usage on and off over the past 40 or so years in our household. It never got regular use due to the issues associated with not having a 220V power outlet in the garage.

It's entirely in working order right now, no issues. Anybody have any idea what the value on something like this might be? It's obviously no collector's item, but it's a tool and it works, so I figure it must have some sort of value. There's no space for it at the moment, so it's got to go even though I'd much rather sell the cheapo upright compressor that dad has in the garage now, but that's another story.

Jeremy

EDIT: Changed the picture to the actual compressor in question.

[mooseheadm5]

Capacity? When was the tank last checked?

[Jeremy]

Capacity? When was the tank last checked?

I'll roll down the storage unit tomorrow and get some pictures, I don't recall off the top of my head. Define "tank checked" for me. It held air the last time it was used.

[lilpoindexter]

Find a 110 V motor from a surplus store or something, and use it up.

[a]

Mildly interested, will it support tools?

[tsmall07]

I'd probably pay $40-$50 for it.

[Jeremy]

Mildly interested, will it support tools?

"It depends". Plenty of pressure/flow for burst-type air tools like an air chisel or impact wrench, but it won't support a paint gun or die grinder being used non-stop. BTDT on both counts, that's how the cheapo diaphragmatic upright came into the garage. I had a regulator on it to bring the line pressure down to 90psi, I don't recall what the max tank pressure is.

Maybe I should drag the thing home and run it in the basement (our only 220V outlet) to find out.

Find a 110 V motor from a surplus store or something, and use it up.

That an interesting thought, but how would I know that the motor could supply the torque needed to work the compressor? Besides, when looking around briefly, those motors don't appear to be inexpensive.

[Xenocide]

I like the idea of replacing the motor, I'd estimate based on the HP rating on the motor on the compressor now. Many 220 VAC motors can be run on 110 as well, it may be worth taking a look at the motor for a diagram. When the hell did AC motors get so expensive?! I remember when you could buy a 3 HP AC motor for like 50 bucks at sears, and I'm not exactly old! I've got a drill press and jointer both run off the same 3 HP sears motor, they were both kits that my grandfather put together in the 60s, you may be able to find something like that and rob the motor.

[tsmall07]

Do you have an electrical panel in the garage? (A lot of places have at least a sub panel in the garage) If so, just install a 2-pole breaker and have 220v to use the compressor in the garage. If not, (depending on the proximity of your garage to the house panel) it wouldn't be very expensive to run a 220v recep to the garage.

If you don't have any spares in your house or garage panels, ignore this post.

[Paul in N FL]

Extremely weird, but I searched compressor on my local CL and found this...
http://jacksonville.craigslist.org/tls/2857577242.html

[Jeremy]

I'll get the specs/pictures on mine tomorrow. In the meantime, would a step-up transformer be a viable option in this case or is the compressor likely to draw more watts than a reasonably priced unit could provide?

[Mike W.]

I'll get the specs/pictures on mine tomorrow. In the meantime, would a step-up transformer be a viable option in this case or is the compressor likely to draw more watts than a reasonably priced unit could provide?

I haven't priced them, but I suspect one rated for continous duty for 2 -3 HP would be expensive. Not to mention big and heavy.

You could always run it off 120 with a new motor. You might have to change pulley sizes so as to not overload the motor, but in all likelyhood it could be done.

[Jeremy]

Well, it appears that a motor would be $150-200+ whereas a step up transformer might be in the $50-75 range. I'll know more tomorrow when I have all the actual specs, but it was a thought.

[Patrick McHugh]

You can probably reconfigure the wiring in the electrical box and run it off 110.

[Jeremy]

You can probably reconfigure the wiring in the electrical box and run it off 110.

Could you elaborate? 220V and 110V AC motors are built differently internally based on what I've read, and the input voltage determines the operating rpm of the motor. The unit had no power cord on it initially, so we tried 110V before we read the labels. It would run, slowly, until the pressure started to build in the tank, at which point it would kind of peter out slowly until it stopped.

[Duke]

Could you elaborate? 220V and 110V AC motors are built differently internally based on what I've read, and the input voltage determines the operating rpm of the motor.

My table saw electric motor can be wired for 110 or 220. Would you like a pic of the diagram?

[Patrick McHugh]

Some motors have the option to run both ways effectively depending on how you wire them. My shop compressor is this way, I choose to run it on 110, but all it takes is a different cord and perhaps moving a jumper to switch to 220

[1st 5er]

Some motors have the option to run both ways effectively depending on how you wire them.

My table saw electric motor can be wired for 110 or 220. Would you like a pic of the diagram?

If he wouldn't, I would.

[Mike W.]

There is often a small wiring diagram on the inside of the plate covering the wiring connections, or sometimes on the motor itself, but they aren't always the same, so you either need it or do a search on that make and model of motor. I would say "most" 220 motors can be wired for 110. But not all, and not necessarily the other way around, some can, but not most.

Jeremy, as far as a transformer for 50-75, you need to know the motor rating, my guess is it's about a 2 or 3HP, which old style will be something like 3Kva. Plus some for starting and headroom.

[Jeremy]

So yea, it appears the only thing that will make this usable in my current environment is to get 220V out to the garage somehow.

The compressor, built sometime around 1970, tank is probably about 25 gallons. The label doesn't mention tank size unfortunately. Peak pressure I remember being about 135-140 psi, tank is rated for 150 psi.





The tag on the side of the tank.



The plate on the motor.



230V times 12 amps = 2.76 kW of peak power usage. 3 kW step up transformers are available for ~$80-$100 to satisfy that, but it would need to be plugged into a 25 amp circuit. The same would be true if I could re-wire it to 110V I believe, correct? Half the voltage means double the amperage when/if rewired? Since the motor plate doesn't list any 110V values, I wonder if re-wiring is even possible.

It's built like a damn tank and parts are still available for it from Sears. These compressors only seem to fetch about $80 used, if you can find one. I think I need to see if I can find a place to hide it away until I can either get 220V in this garage or get my own workspace again.

[Mike W.]

230V times 12 amps = 2.76 kW of peak power usage. 3 kW step up transformers are available for ~$80-$100 to satisfy that, but it would need to be plugged into a 25 amp circuit. The same would be true if I could re-wire it to 110V I believe, correct? Half the voltage means double the amperage when/if rewired?

Correct, except more like 30A minimum especially given that there is a 80% rule, ie you shouldn't load a circuit over 80% of it's rated load by design. Not to mention 25A breakers are beyond rare.

Since the motor plate doesn't list any 110V values, I wonder if re-wiring is even possible.

Correct, if it was 120-240 it would be listed that way.

It's built like a damn tank and parts are still available for it from Sears. These compressors only seem to fetch about $80 used, if you can find one. I think I need to see if I can find a place to hide it away until I can either get 220V in this garage or get my own workspace again.

And or keep an eye out for a 2HP 120 motor on Craigslist or the like. Either gear it down so to speak with a different size sheave or find a 1725RPM motor so it's not working so hard. Compressors are hard work for a motor, especially on startup and there are even compressor rated motors.

[Jeremy]

Thanks, Mike. 2 hp instead of 3 hp? You think a more modern 2 hp motor would be sufficient, or is that a typo?

[Mike W.]

Thanks, Mike. 2 hp instead of 3 hp? You think a more modern 2 hp motor would be sufficient, or is that a typo?

No, a 2HP rigged in such a way the compressor isn't using more than 2HP. Now I don't know how linear the load is by RPM, but assuming it is, if you mount a sheave, ie pulley, say 2/3 the size of what's on there it will only turning the compressor 2/3s the speed and be doing 2/3 the work. Again, if it's a linear load. Or if you get a 2HP motor with 1725 as the rated speed, it will only be turning the compressor half as fast as with a 3450 motor, which the current 3HP is. Of course wouldn't have the same capacity, but it would enable you to use it without a 240V circuit.

[Jeremy]

Problem solved. The home garage needed some electrical work, and I managed to convince parents that what they REALLY wanted out there was an electrical sub-panel rather than doing these electrical projects piecemeal one at a time. Now I have a 30amp 220v outlet to play with.

I brought the compressor home, cleaned and oiled the air filter, tossed a dash of MMO into the cylinders, changed the crankcase oil, and it runs like a charm. WAY quieter than the oil-less model, and a more pleasant tone to the noise as well. It sounds like a little engine chugging away under the counter.

Now we just need to figure out what to do with the oil-less one.

[L_N_Love]

Happy...

[alijonny]

Now we just need to figure out what to do with the oil-less one.



Out by the curb is one good idea... Or on craigslist for the next sucker.