Need air compressor

What! The woman wants to buy her man an air compressor, and a sand blaster, and who knows what next, and you're trying to discourage her!? Have you been dropped on your head? :)

Reply to
Dave Lyon
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I would not be very happy if my wife bought me a wrong compressor... I would appreciate her efforts and good wwishes, but it is not fun to be stuck with a bad compressor.

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Reply to
Ignoramus30651

That depends a lot on how crusty the workpiece is. My wild guess would be about a pound per minute but it's been a while since I did any blasting from a bucket. "Lava sand" is cheap grit that is pretty aggressive, considerably better than silica sand without the silicosis hazard.

Reply to
Don Foreman

I'd bet that the motor you are about to install did not come as part of a compressor from a compressor manufacturer. Motors intended for compressor service are often capacitor-start capacitor-run -- two lumps on the motor. Cap-run motors have better power factor, hence draw less current for same power output and motor efficiency.

As said before, reading the nameplate on the motor is more reliable than rules of thumb or the advice of others.

Reply to
Don Foreman

Hear hear! Just about every shop guy who ever bought a small compressor has eventually replaced it with a larger one. 10 to 12 CFM at 90 PSI is enough for most of us. We might have agonized for months before getting a respectable compressor, but few who have had ample air for a while would hesitate a minute to fix or replace it if it fails.

Reply to
Don Foreman

I was going by Table 430.148 in the NEC, which is required when sizing branch circuit overcurrent protection and conductors. Motor starter overloads are sized according to nameplate FLA. I never noticed the spread between the table and real motors, which for some reason is much wider for large motors. The 5HP motor on my compressor is indeed 22A on the nameplate.

"Note: Any motor application shall be considered as continuous duty unless the nature of the apparatus it drives is such that the motor will not operate continuously with load under any condition of use."

That doesn't help much, does it?

Ned Simmons

Reply to
Ned Simmons

Hey, I'm guilty of upgrading video cards to the tune of a couple hundred bucks to make a cheap game play that wouldn't without it. Buy the compressor, as big as you can, you won't regret it, you'll wonder how you managed without it.

Reply to
Tom Gardner

Sounds good, I think that I will buy that sand blasting gun. I believe that HF sells lava sand.

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Reply to
Ignoramus30651

I am taking it out of a Bullard EDP-50 air pump. These motors are widely used on many compressors also. The top of the line compressor from Harbor Freight uses a Baldor motor suspiciously similar to my 5 HP motor from Bullard pump, also 184T frame IIRC, but advertised as

7.5 HP.

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Reply to
Ignoramus30651

Which is why you have them keep the receipt.

Reply to
Dave Lyon

Compressed air IS a "guy thing".

Reply to
Tom Gardner

Isn't pumice lava sand? If so I have a few small boxes of it never opened. I think it often used by rock tumblers .

Reply to
daniel peterman

It might be, but what I referred to is black stuff of maybe 80 or 100 mesh. It might have another name like volcanic slag or something. It is very inexpensive at HD, Menards and the like, a very few bux for a

20 lb bag. It works quite well for paint and rust removal on steel though it'll distort thin sheetmetal. It's more aggressive than sand at about the same cost or less.
Reply to
Don Foreman

And for air, he needs a compressor, and the entire discussion makes a great big circle and comes back to exactly where we started. >_<

Imagine that... :-)

You want to do something productive, ask her what size and brand of angle grinder her hubby has, and give her a good deal on an assortment of knot and crimped wheels and cup brushes sized for rust removal.

Oh, and a few of the impact brushes too, since he'll have air, and he can pick up a cheap air chisel anywhere...

90% of the rust can be removed much faster with brushes, it's getting that last 10% that's the real pain in the *** where you need to sandblast it out of the deep corners.

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Reply to
Bruce L. Bergman

7.5 HP, 29 amps. Baldor motors are honestly rated. 5/7.5 of 29 amps is 19.3 amps. QED. A rather wide variety of motors are made on 184T frames, motors that look alike aren't necessarily alike in performance or ratings. Motor mfrs make many different models tailored for specific apps. Motor and compressor designers excluding third-world really do know what they're doing and they put accurate ratings on nameplates. Feel free to second-guess them at your risk, but I wish you wouldn't suggest by inference or otherwise that others do so. You do them no service.

I'll say again, the nameplate tells the tale. Make the circuit so it can supply the current that the motor requires.

Reply to
Don Foreman

Narrows it down just fine fer me. If it stops more than once per motor lifetime then it isn't continuous. Stopping once a day is well within that definition so running 12 out of 24 hours is light duty.

Reply to
Don Foreman

And it's also why we're trying to make sure she makes a properly informed choice in the first place, and using only small words and clear concepts to properly inform her. (Or explaining what the $5 Words mean if we have to use them.) So she buys a good one on the first try, no returns needed.

Farther up-thread she mentions that they had already discussed that he needs to get a compressor, so the surprise won't be anything that he has "no use for"...

Hell, I'm about ready to ask if she has any single sisters. ;-)

Of course, with a surprise of this magnitude Flybaby is setting the bar high. This means Dearest Hubby is gonna have to work REAL hard to top this one on their next anniversary.

And when he appears stumped, send him here. Ideas, we've got 'em.

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Reply to
Bruce L. Bergman

Google "Black Beauty" - it's graded coal slag.

Myself, I stick to a blast cabinet and medium glass beads, most of the stuff I do is cleaning up small parts for paint prep.

Haven't needed bigger, or I'd already have a pressure-pot blaster.

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Reply to
Bruce L. Bergman

Ladies like pretty salad. I won entre to continue pursuit of melady by making pretty salad. There was entrenched competition but he didn't know shit about salad. I didn't either, but I got excellent advice from a lovely fellow shopper. Pretty lettuce kept me in the competition.

Been together 25 years now, stil enjoying each other's company every single day so I think we're good for the duration.

Carrots and carats both work well...

Reply to
Don Foreman

Not necessarily - after you get it together get an Amprobe and look while it's running. You'll have the big start surge, and then it'll settle down to running amps. If it averages under 24A at the pressure switch cut-in setting, you're at the 80% Load for a 30A circuit.

Or bump it to a 40A breaker - #10 THHN 90C Copper wire is good for

40A, because you are running fixed permanently wired equipment. (No, I'm not going to look it up...) Unless this is a long run to the panel where voltage drop will be an issue, you'll be just fine.

As pressure builds in the storage tank, if the pulley ratio has the motor fully loaded you'll see that 28 amps "Full Load" for only a short time right before the pressure switch cuts off.

If you are repowering an existing compressor, you need to do the load check anyway - if the motor goes over the Nameplate Service Factor Load rating, you will need to get a smaller motor drive pulley to reduce the load. Or watch it burn up...

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Reply to
Bruce L. Bergman

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