I _may_ have an opportunity to pick up a compressor a bit "too large"
for my needs at reasonable cost (depends on the bidding).

GRANTED (wanna bet some people ignore this part) that doing so will
provide less air than the compressor is rated for, and GRANTED that I
don't mind that, what actual problems would be encountered by running a
5 or 10 hp compressor on a 2 or 3 hp motor AT REDUCED COMPRESSOR SPEED
(larger pulley on the compressor, or a jackshaft) such that the 2 or 3
hp motor is not being overloaded.

In engine service, lower speed is a good thing, so 3600 rpm motors wear
out much faster than 1800 rpm motors.

What, other than reduced air output that I'm willing to accept, are the
actual downsides, if any, of running a compressor slower than it's
"supposed" or rated to run?

Lack of fan action from the pulley is easily compensated by putting a
fan on it, and heat production will be lower at a lower speed anyway.

Not enough "splashing" for splash lubrication? Something less obvious I
can't think of?

While I could always harvest the large tank and try to flip the big
motor and compressor for a smaller one, the less stuff I'm trying to
swap, the better, generally.

--
Cats, coffee, chocolate...vices to live by

Without getting into mechanical calculations, your premise sounds like it should work ok. I
questioned the logic until I came to the part about "larger pulley on the compressor, or a
jackshaft" in order to avoid overloading a motor of lesser hp. Others, better versed in compressor
design, may have different ideas but my "knee jerk" is that you will be ok.

Bob Swinney

On Feb 6, 10:36*am, Ecnerwal
wrote:
I _may_ have an opportunity to pick up a compressor a bit "too large"
for my needs at reasonable cost (depends on the bidding).

GRANTED (wanna bet some people ignore this part) that doing so will
provide less air than the compressor is rated for, and GRANTED that I
don't mind that, what actual problems would be encountered by running a
5 or 10 hp compressor on a 2 or 3 hp motor AT REDUCED COMPRESSOR SPEED
(larger pulley on the compressor, or a jackshaft) such that the 2 or 3
hp motor is not being overloaded.

In engine service, lower speed is a good thing, so 3600 rpm motors wear
out much faster than 1800 rpm motors.

What, other than reduced air output that I'm willing to accept, are the
actual downsides, if any, of running a compressor slower than it's
"supposed" or rated to run?

Lack of fan action from the pulley is easily compensated by putting a
fan on it, and heat production will be lower at a lower speed anyway.

Not enough "splashing" for splash lubrication? Something less obvious I
can't think of?

While I could always harvest the large tank and try to flip the big
motor and compressor for a smaller one, the less stuff I'm trying to
swap, the better, generally.

--
Cats, coffee, chocolate...vices to live by

The big down side is the slower motor will run forever to pump up to
the same pressure the faster motor gives.

Paul

At a speed below minimum, lubrication systems of compressors may not
work properly. Splash lubricated compressor have little spoons that
"splash" the oil around, and at low speed they would not be able to
fling oil far enough. I am not sure about pressure lubed compressors,
but they too have a minimum speed.

You can call the manufacturer and find out.

i

On Feb 6, 1:31*pm, Ignoramus20464 ignoramus20...@NOSPAM.
20464.invalid wrote:
At a speed below minimum, lubrication systems of compressors may not
work properly. Splash lubricated compressor have little spoons that
"splash" the oil around, and at low speed they would not be able to
fling oil far enough. *I am not sure about pressure lubed compressors,
but they too have a minimum speed.

You can call the manufacturer and find out.

i

Good point Ig...I would not have thought of that.

That and the compressor under pressure will require a certain starting
torque to run are the two issues I can think of.

The speed to pump up seems to be not an issue with the OP.

TMT

On Feb 6, 9:01*pm, Too_Many_Tools wrote:

That and the compressor under pressure will require a certain starting
torque to run are the two issues I can think of.

The speed to pump up seems to be not an issue with the OP.

TMT

Should have the same starting torque with a lower HP motor turning the
compressor at a slower speed.

Dan

I don't know if you're concerned about efficency but the larger
compressor will have more friction loss than outputting the same CFM's
with a smaller compressor because of larger piston contact area,
larger bearing area ETC.
Also there is more power loss compressing air into the inevitally
larger space above the piston that must be pressurized before the
outlet check opens.

Engineman

On Feb 6, 11:31�am, Ignoramus20464 ignoramus20...@NOSPAM.
20464.invalid wrote:
At a speed below minimum, lubrication systems of compressors may not
work properly. Splash lubricated compressor have little spoons that
"splash" the oil around, and at low speed they would not be able to
fling oil far enough. �I am not sure about pressure lubed compressors,
but they too have a minimum speed.

You can call the manufacturer and find out.

i

"Ecnerwal" wrote in message
...
I _may_ have an opportunity to pick up a compressor a bit "too large"
for my needs at reasonable cost (depends on the bidding).

GRANTED (wanna bet some people ignore this part) that doing so will
provide less air than the compressor is rated for, and GRANTED that I
don't mind that, what actual problems would be encountered by running a
5 or 10 hp compressor on a 2 or 3 hp motor AT REDUCED COMPRESSOR SPEED
(larger pulley on the compressor, or a jackshaft) such that the 2 or 3
hp motor is not being overloaded.

In engine service, lower speed is a good thing, so 3600 rpm motors wear
out much faster than 1800 rpm motors.

What, other than reduced air output that I'm willing to accept, are the
actual downsides, if any, of running a compressor slower than it's
"supposed" or rated to run?

Lack of fan action from the pulley is easily compensated by putting a
fan on it, and heat production will be lower at a lower speed anyway.

Not enough "splashing" for splash lubrication? Something less obvious I
can't think of?

While I could always harvest the large tank and try to flip the big
motor and compressor for a smaller one, the less stuff I'm trying to
swap, the better, generally.

--
Cats, coffee, chocolate...vices to live by

Is it splash lubed or oil pumped? Bigger pumps usually have an oil pump. I
run my Quincys way slower than max, they will last forever. I think you
will not only NOT have a problem, you will LIKE the way it runs quiet and
cool.

On Sat, 06 Feb 2010 11:27:18 -0800, wrote:

On Feb 6, 10:36Â*am, Ecnerwal
wrote:
I _may_ have an opportunity to pick up a compressor a bit "too large"
for my needs at reasonable cost (depends on the bidding).

GRANTED (wanna bet some people ignore this part) that doing so will
provide less air than the compressor is rated for, and GRANTED that I
don't mind that, what actual problems would be encountered by running a
5 or 10 hp compressor on a 2 or 3 hp motor AT REDUCED COMPRESSOR SPEED
(larger pulley on the compressor, or a jackshaft) such that the 2 or 3
hp motor is not being overloaded.

In engine service, lower speed is a good thing, so 3600 rpm motors wear
out much faster than 1800 rpm motors.

What, other than reduced air output that I'm willing to accept, are the
actual downsides, if any, of running a compressor slower than it's
"supposed" or rated to run?

Lack of fan action from the pulley is easily compensated by putting a
fan on it, and heat production will be lower at a lower speed anyway.

Not enough "splashing" for splash lubrication? Something less obvious I
can't think of?

While I could always harvest the large tank and try to flip the big
motor and compressor for a smaller one, the less stuff I'm trying to
swap, the better, generally.

--
Cats, coffee, chocolate...vices to live by

The big down side is the slower motor will run forever to pump up to the
same pressure the faster motor gives.

Paul


But that's exactly what you'd get with a smaller compressor run at a
higher speed.


--
www.wescottdesign.com

Is it splash lubed or oil pumped? Bigger pumps usually have an oil pump.
I
run my Quincys way slower than max, they will last forever. I think you
will not only NOT have a problem, you will LIKE the way it runs quiet and
cool.

Now HOW do you know they'd last any longer? A Quincy will last forever
anyway.

But, I think the OP has a good idea. gear it down to the smaller motor.

Karl

Not many motors or compressors like starting under load.

I've known of people (like me) to use refrigerator
compressors as air compressors. There are a few technical
things, like change the oil. A quiet running refrigerator
compressor works nicely, if you start it with zero back
pressure.

A compressor out of a HVAC unit might work, also.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Buerste" wrote in message
...


And, the head will be unloaded...I assume.

It's likely that the manufacturer offered different models with the same
pump on them, but with different HP motors (and outputs).

A pump that's used on a 5HP model may be the same one used on a 7.5HP model,
with the 7.5HP model having a slighly larger motor pulley diameter.

A pump used on a 10HP model probably isn't the same one used on a 5HP model.

I will probably be more difficult to find a larger pump pulley, than to find
a smaller motor pulley.
A motor pulley that's too small could have a tendancy to slip at startup if
the belt contact area with the pulley is too small.

The pump manufacturer may provide minimum and maximum pump speed
recommendations. Proper lubrication is probably the only vital issue with
reducing the pump speed.

Reducing the upper pressure limit cut-out is another option, in conjunction
with a slower pump speed. The upper end of the cut-out limit is where the
highest power demand is involved.
Reducing an original upper limit of 175psi to 150psi, for example.

--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Ecnerwal" wrote in message
...
I _may_ have an opportunity to pick up a compressor a bit "too large"
for my needs at reasonable cost (depends on the bidding).

GRANTED (wanna bet some people ignore this part) that doing so will
provide less air than the compressor is rated for, and GRANTED that I
don't mind that, what actual problems would be encountered by running a
5 or 10 hp compressor on a 2 or 3 hp motor AT REDUCED COMPRESSOR SPEED
(larger pulley on the compressor, or a jackshaft) such that the 2 or 3
hp motor is not being overloaded.

In engine service, lower speed is a good thing, so 3600 rpm motors wear
out much faster than 1800 rpm motors.

What, other than reduced air output that I'm willing to accept, are the
actual downsides, if any, of running a compressor slower than it's
"supposed" or rated to run?

Lack of fan action from the pulley is easily compensated by putting a
fan on it, and heat production will be lower at a lower speed anyway.

Not enough "splashing" for splash lubrication? Something less obvious I
can't think of?

While I could always harvest the large tank and try to flip the big
motor and compressor for a smaller one, the less stuff I'm trying to
swap, the better, generally.

--
Cats, coffee, chocolate...vices to live by

On 2010-02-06, Wild_Bill wrote:

The pump manufacturer may provide minimum and maximum pump speed
recommendations. Proper lubrication is probably the only vital issue with
reducing the pump speed.


One more issue is that if the pump does not get hot sometimes, then
there could be condensation in oil (water in oil, milky oil).

i

Ecnerwal wrote:

I _may_ have an opportunity to pick up a compressor a bit "too large"
for my needs at reasonable cost (depends on the bidding).

GRANTED (wanna bet some people ignore this part) that doing so will
provide less air than the compressor is rated for, and GRANTED that I
don't mind that, what actual problems would be encountered by running a
5 or 10 hp compressor on a 2 or 3 hp motor AT REDUCED COMPRESSOR SPEED
(larger pulley on the compressor, or a jackshaft) such that the 2 or 3
hp motor is not being overloaded.

In engine service, lower speed is a good thing, so 3600 rpm motors wear
out much faster than 1800 rpm motors.

What, other than reduced air output that I'm willing to accept, are the
actual downsides, if any, of running a compressor slower than it's
"supposed" or rated to run?

Lack of fan action from the pulley is easily compensated by putting a
fan on it, and heat production will be lower at a lower speed anyway.

Not enough "splashing" for splash lubrication? Something less obvious I
can't think of?

While I could always harvest the large tank and try to flip the big
motor and compressor for a smaller one, the less stuff I'm trying to
swap, the better, generally.

--
Cats, coffee, chocolate...vices to live by

I certainly wouldn't want to run a splash lube compressor too slow. I
pressure lube one shouldn't have a problem at any speed.

Ecnerwal wrote:

GRANTED (wanna bet some people ignore this part) that doing so will
provide less air than the compressor is rated for, and GRANTED that
I don't mind that, what actual problems would be encountered by
running a 5 or 10 hp compressor on a 2 or 3 hp motor AT REDUCED
COMPRESSOR SPEED (larger pulley on the compressor, or a jackshaft)
such that the 2 or 3 hp motor is not being overloaded.

I'm running a compressor underpowered but at specified speed.

I bought an old Atlas Copco 3-stage, 400PSI compressor with a 10 HP
3450 RPM motor. I put a 3 HP 3450 RPM motor (previously on a seawater
pump) on it. Connected to an 80 gal. 600 PSI-rated Halon tank, I get
150 PSI of air okay. Sluggish starting.

Upgrade: Replaced the 3HP with a 5HP 3450 RPM motor from a large fan.
Somewhat better starting.

PROBLEM: Starting torque is okay with either motor in warm weather.

For either motor, at winter temps (say, 20F to 0F or lower) I
have to turn a propane salamander on the compressor for maybe
15 minutes in order to start it. Once started, and with
medium air use, its own heat keeps it warm enough to restart
in the cold.

Bonus question: Anybody have a manual, exploded parts diagram or parts
list for an Atlas Copco model "KT 630 A1"? (The company doesn't
admit to ever having made this old (50 yrs?) model.) Email me if you do.

--
Mike Spencer Nova Scotia, Canada

(Remove bells and whistles)

In article ,
Mike Spencer wrote:

PROBLEM: Starting torque is okay with either motor in warm weather.

For either motor, at winter temps (say, 20F to 0F or lower) I
have to turn a propane salamander on the compressor for maybe
15 minutes in order to start it. Once started, and with
medium air use, its own heat keeps it warm enough to restart
in the cold.

Does it have unloaders? If not, perhaps electrically unloading it would
help to start it. Then again, gearing it down might also help -
particularly if it already has unloaders.

Sketch of an electric unloader:

Compressor out======+======checkvalve====tank===piping to shop====
| |
| |
Electrically operated valve to air

Set up where the valve is operated by a time delay relay such that the
valve is opened for the first 10-15 seconds each time the motor starts.

--
Cats, coffee, chocolate...vices to live by

On Feb 6, 3:10*pm, " wrote:
On Feb 6, 9:01*pm, Too_Many_Tools wrote:

That and the compressor under pressure will require a certain starting
torque to run are the two issues I can think of.

The speed to pump up seems to be not an issue with the OP.

TMT

Should have the same starting torque with a lower HP motor turning the
compressor at a slower speed.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Dan

I have seen some compressors not run because the compressor was under
pressure.

Some manufacturers make stupid design decisons to save a penny.

TMT

Ecnerwal wrote:

In article ,
Mike Spencer wrote:

PROBLEM: Starting torque is okay with either motor in warm weather.

For either motor, at winter temps (say, 20F to 0F or lower) I
have to turn a propane salamander on the compressor for maybe
15 minutes in order to start it. Once started, and with
medium air use, its own heat keeps it warm enough to restart
in the cold.

Does it have unloaders? If not, perhaps electrically unloading it would
help to start it.

Yes. The unloader works fine. It's just a very clunky old compressor.
Three pistons and crank with cold oil. Probably *should* have a
special motor designed for prolonged starting load.

Then again, gearing it down might also help - particularly if it
already has unloaders.

I use it so little in very cold weather that it's not worth the cost
of the pulley or the trouble or the reduced pump-up time in warm
weather.

The object of the post was to offer a possibly useful data point for
the OP who was thinking of gearing down in a similar situation,
i.e. that I get by without reducing speed except for extra bother in
cold weather.

--
Mike Spencer Nova Scotia, Canada

In article ,
Mike Spencer wrote:

The object of the post was to offer a possibly useful data point for
the OP who was thinking of gearing down in a similar situation,
i.e. that I get by without reducing speed except for extra bother in
cold weather.

I am the OP, so that's fine and appreciated. Of course, you're also
using a 400 psi compressor at considerably lower pressure, so that
probably helps to keep your load down from the original design load. I
won't really know until I get to inspect things exactly what I'm looking
at, but I would guess they are typical shop air compressors aimed at
150-175 psi, which I probably can turn down to 110-120 for my purposes
just fine and gain some that way, but I suspect I'll still need to slow
whichever one I get (if any - never can tell with auctions, and I'm not
going into a bidding frenzy) down some to run it on a motor I can
actually run without ticking off my electric company (rural line, single
phase, motor HP limited).

I used to have to throw a blanket over my lathe to keep the heat in and
put a lightbulb under it to get it to start in the winter, since it was
in an unheated shed. I wonder if there's synthetic compressor oil, and
if so, if that would help any.

--
Cats, coffee, chocolate...vices to live by

On Feb 7, 6:01*am, Ecnerwal I wonder if there's synthetic compressor
oil, and
if so, if that would help any.

--
Cats, coffee, chocolate...vices to live by

There is synthetic compressor oil. Should help. WW Grainger lists
some in their catalog.

Dan

"Karl Townsend" wrote in message
anews.com...

Is it splash lubed or oil pumped? Bigger pumps usually have an oil pump.
I
run my Quincys way slower than max, they will last forever. I think you
will not only NOT have a problem, you will LIKE the way it runs quiet and
cool.

Now HOW do you know they'd last any longer? A Quincy will last forever
anyway.

But, I think the OP has a good idea. gear it down to the smaller motor.

Karl



In 35 years, I have had to replace 2 wrist pins, 1 HP piston, numerous valve
bodies, a bunch of valve disks, 3 sets of rings, various oil pump rebuilds
and a boatload of gaskets. But, that's on four pumps and mostly due to the
"Run em till they die" maintenance program. Now, we actually keep them
clean so they cool better, run them slower, change the oil using synthetic
and keep up on the leaks.

Don't forget I need a ship-to address if you want some 9mm cast.

wrote in message
...
On Feb 7, 6:01 am, Ecnerwal I wonder if there's synthetic compressor
oil, and
if so, if that would help any.

--
Cats, coffee, chocolate...vices to live by

There is synthetic compressor oil. Should help. WW Grainger lists
some in their catalog.

Dan
*******************

Very good stuff!

Don't forget I need a ship-to address if you want some 9mm cast.

Thanks for the remind. I was a bit very distracted when you first offered.
You got email.

Karl

"Karl Townsend" wrote in message
anews.com...
Don't forget I need a ship-to address if you want some 9mm cast.

Thanks for the remind. I was a bit very distracted when you first
offered. You got email.

Karl



There's plenty of load info on the web but if he needs any more, I've got
plenty of books. I'm still working my loads for my 9's, I use IMR 700x,
most people don't. But so far, I like the projectile though it's not the
easiest to cast, probably because it's so small.

It seems like anytime I need Gunner's wisdom, the *******'s out of town!

"Karl Townsend" wrote in message
anews.com...
Don't forget I need a ship-to address if you want some 9mm cast.

Thanks for the remind. I was a bit very distracted when you first
offered. You got email.

Karl



Will do.

On Sun, 7 Feb 2010 23:44:47 -0500, "Buerste" wrote:


"Karl Townsend" wrote in message
tanews.com...
Don't forget I need a ship-to address if you want some 9mm cast.

Thanks for the remind. I was a bit very distracted when you first
offered. You got email.

Karl



There's plenty of load info on the web but if he needs any more, I've got
plenty of books. I'm still working my loads for my 9's, I use IMR 700x,
most people don't. But so far, I like the projectile though it's not the
easiest to cast, probably because it's so small.

It seems like anytime I need Gunner's wisdom, the *******'s out of town!

Son...the phone is close to your hand. Use it

805-732-5308

Just keep in mind Im living on PST...and dont do "early" very well, but
I live in "late". G

Gunner

Whenever a Liberal utters the term "Common Sense approach"....grab your
wallet, your ass, and your guns because the sombitch is about to do
something damned nasty to all three of them.

"Gunner Asch" wrote in message
...
On Sun, 7 Feb 2010 23:44:47 -0500, "Buerste" wrote:


"Karl Townsend" wrote in message
ctanews.com...
Don't forget I need a ship-to address if you want some 9mm cast.

Thanks for the remind. I was a bit very distracted when you first
offered. You got email.

Karl



There's plenty of load info on the web but if he needs any more, I've got
plenty of books. I'm still working my loads for my 9's, I use IMR 700x,
most people don't. But so far, I like the projectile though it's not the
easiest to cast, probably because it's so small.

It seems like anytime I need Gunner's wisdom, the *******'s out of town!

Son...the phone is close to your hand. Use it

805-732-5308

Just keep in mind Im living on PST...and dont do "early" very well, but
I live in "late". G

Gunner


You're just saying that 'cuz I woke you guys up at some ungodly hour on a
Sunday morning. I STILL feel bad about that! I keep forgetting about that
pesky time-zone thing.

OK, I think I have an extractor problem on my 1911. I bought it used with
what the guy said had only 100 rounds through it. Everything points to that
being the truth except the extractor looks like somebody attacked it with a
file. With factory ammo, it gets 5% FTF. I have yet to get my reloads to
feed right with a 200gr. SWC Keith. On the web and in my books, I see all
different kinds of OALs. What specs do you use for this bullet? What
should I do about the extractor? I'll try to get some pix with my new,
WAY-COOL, USB 200 power video/still microscope.

I do have my .38 load dialed in! I put 100 rounds through a 1" hole from a
rest. 3.0 gr. 700x 148gr. DEWC. I use 1 part Alox in 6 parts mineral
spirits and it looks like thin wood stain. It's hardly noticeable on the
bullets and dries hard. It WORKS! No lead, no smoke, no residue!

On 2010-02-09, Buerste wrote:

"Gunner Asch" wrote in message
Just keep in mind Im living on PST...and dont do "early" very well, but
I live in "late". G

I am the same way.

You're just saying that 'cuz I woke you guys up at some ungodly hour on a
Sunday morning. I STILL feel bad about that! I keep forgetting about that
pesky time-zone thing.

My solution to pesky early morning phone calls, is that I installed a
"whole house phone switch", and when I flip it, landlines are turned
off. (and for those wishing to lecture me on safety, we have cell
phones)

i

Ignoramus30280 wrote:

(and for those wishing to lecture me on safety, we have cell
phones)


Who cares?


--
Greed is the root of all eBay.

On Tue, 9 Feb 2010 01:04:29 -0500, "Buerste" wrote:


"Gunner Asch" wrote in message
.. .
On Sun, 7 Feb 2010 23:44:47 -0500, "Buerste" wrote:


"Karl Townsend" wrote in message
. octanews.com...
Don't forget I need a ship-to address if you want some 9mm cast.

Thanks for the remind. I was a bit very distracted when you first
offered. You got email.

Karl



There's plenty of load info on the web but if he needs any more, I've got
plenty of books. I'm still working my loads for my 9's, I use IMR 700x,
most people don't. But so far, I like the projectile though it's not the
easiest to cast, probably because it's so small.

It seems like anytime I need Gunner's wisdom, the *******'s out of town!

Son...the phone is close to your hand. Use it

805-732-5308

Just keep in mind Im living on PST...and dont do "early" very well, but
I live in "late". G

Gunner


You're just saying that 'cuz I woke you guys up at some ungodly hour on a
Sunday morning. I STILL feel bad about that! I keep forgetting about that
pesky time-zone thing.

OK, I think I have an extractor problem on my 1911. I bought it used with
what the guy said had only 100 rounds through it. Everything points to that
being the truth except the extractor looks like somebody attacked it with a
file. With factory ammo, it gets 5% FTF. I have yet to get my reloads to
feed right with a 200gr. SWC Keith. On the web and in my books, I see all
different kinds of OALs. What specs do you use for this bullet? What
should I do about the extractor? I'll try to get some pix with my new,
WAY-COOL, USB 200 power video/still microscope.

I seat em with about 1/16" of lead bullet shoulder showing at the mouth
of the case.

5%?.....tried changing recoil springs? Go down a couple pounds. The
weapon was set up to be a combat arm..and if you are loading target
velocity ammo..feed problems are likely.


I do have my .38 load dialed in! I put 100 rounds through a 1" hole from a
rest. 3.0 gr. 700x 148gr. DEWC. I use 1 part Alox in 6 parts mineral
spirits and it looks like thin wood stain. It's hardly noticeable on the
bullets and dries hard. It WORKS! No lead, no smoke, no residue!

Noted! Thanks!!

Gunner

Whenever a Liberal utters the term "Common Sense approach"....grab your
wallet, your ass, and your guns because the sombitch is about to do
something damned nasty to all three of them.