My used 7x14 surface grinder appears to need a new motor, or maybe just new
bearings. The spindle is belt driven and is currently fitted with GE K163,
1HP, TEFC, 3450 rpm 3-phase motor. The motor is being driven with an
Hitachi L-100 VFD from a 220 VAC single phase line.

With the belts off the motor makes some noise on startup that sounds like it
could be bad bearings. A cup of water sitting on the spindle housing
(spindle belts still removed) has some standing waves at full speed and the
wave amplitude varies with speed. I'm assuming that the motor itself or
perhaps just the motor the bearings should be replaced.

Is the GE motor a good choice for a surface grinder or should I be looking
at other brands? If so, replacement bearings should be pretty cheap. If
the GE motor is wrong for this application, Baldor and Leeson motors with
the same specs above can be had for around $150 on-line.

Also, is it necessary to have a motor specially balanced for a surface
grinder? If so, is this usually specified when the motor is ordered or
should it be done after receipt with the belt pulley in place? Dreisilker
has a service center fairly close to me and would probably be my choice for
balancing should it prove advisable.

TIA, Mike

My used 7x14 surface grinder appears to need a new motor, or maybe just new
bearings. The spindle is belt driven and is currently fitted with GE K163,
1HP, TEFC, 3450 rpm 3-phase motor. The motor is being driven with an
Hitachi L-100 VFD from a 220 VAC single phase line.

With the belts off the motor makes some noise on startup that sounds like it
could be bad bearings. A cup of water sitting on the spindle housing
(spindle belts still removed) has some standing waves at full speed and the
wave amplitude varies with speed. I'm assuming that the motor itself or
perhaps just the motor the bearings should be replaced.

Is the GE motor a good choice for a surface grinder or should I be looking
at other brands? If so, replacement bearings should be pretty cheap. If
the GE motor is wrong for this application, Baldor and Leeson motors with
the same specs above can be had for around $150 on-line.

Also, is it necessary to have a motor specially balanced for a surface
grinder? If so, is this usually specified when the motor is ordered or
should it be done after receipt with the belt pulley in place? Dreisilker
has a service center fairly close to me and would probably be my choice for
balancing should it prove advisable.

TIA, Mike


I don't claim any working knowledge of VFDs. I did look into them a few years
ago when I was hooking up my 3 phase horizontal mill. I eventually decided on
a static phase converter, which meets my needs.

One of the claims made about the VFDs was that the current they supply is not
true 3 phase, but has some harmonics or secondary oscillations which can cause
problems with some older motors. This seems to be rare, but might be your
problem.

Before you dump the motor, you might try driving it with a static or rotary
converter.

John Martin

"JMartin957" wrote in message
...

My used 7x14 surface grinder appears to need a new motor, or maybe just
new
bearings. The spindle is belt driven and is currently fitted with GE
K163,
1HP, TEFC, 3450 rpm 3-phase motor. The motor is being driven with an
Hitachi L-100 VFD from a 220 VAC single phase line.

With the belts off the motor makes some noise on startup that sounds like
it
could be bad bearings. A cup of water sitting on the spindle housing
(spindle belts still removed) has some standing waves at full speed and
the
wave amplitude varies with speed.

snip

I don't claim any working knowledge of VFDs. I did look into them a few
years
ago when I was hooking up my 3 phase horizontal mill. I eventually
decided on
a static phase converter, which meets my needs.

One of the claims made about the VFDs was that the current they supply is
not
true 3 phase, but has some harmonics or secondary oscillations which can
cause
problems with some older motors. This seems to be rare, but might be your
problem.

Before you dump the motor, you might try driving it with a static or
rotary
converter.

John - that thought hadn't occurred to me. The noise on startup seems
indicative of bearing problems, though, so I'll check that first as soon as
I get the current project off the work bench so the motor can be looked at.

The motor installed (GE K163) still seems to be in production so it may be
OK with a VFD. It looks like it was a recent addition on the grinder,
though, and that is part of the reason why I'm asking about brands for
potential replacements. Maybe it's just not a good motor for a surface
grinder.

Mike

On 12 Dec 2004 18:29:33 GMT, (JMartin957) wrote:

One of the claims made about the VFDs was that the current they supply is not
true 3 phase, but has some harmonics or secondary oscillations which can cause
problems with some older motors. This seems to be rare, but might be your
problem.

This is indeed quite true. Until I got my 5hp rotary..I was running
all my (then, very few) machines on a single 5hp VFD. Oddly enough the
old Clausing 6525 would leave a slight herringbone pattern on one
direct drive speed setting. I had assumed it was something worn in the
headstock. When I went to the RPC..the pattern vanished. I then
swapped back and forth and indeed, it was the VFD. None of the other
machines exhibited this phenom, including the surface grinder, which
gives the same finish either way.

A cautionary note...if you were to power up your surface grinder via
vfd,..be damned sure..that you set the maximum rpm rating to less than
that of the max rpms of wheels. IRRC 3600 rpm. It would be very
possible to over spin a wheel and have it catastrophicly disassemble
itself..which will result in a grenade going off on your grinder.

Gunner

"To be civilized is to restrain the ability to commit mayhem.
To be incapable of committing mayhem is not the mark of the civilized,
merely the domesticated." - Trefor Thomas

"Gunner" wrote in message
...
On 12 Dec 2004 18:29:33 GMT, (JMartin957) wrote:

One of the claims made about the VFDs was that the current they supply is
not
true 3 phase, but has some harmonics or secondary oscillations which can
cause
problems with some older motors. This seems to be rare, but might be your
problem.

This is indeed quite true. Until I got my 5hp rotary..I was running
all my (then, very few) machines on a single 5hp VFD. Oddly enough the
old Clausing 6525 would leave a slight herringbone pattern on one
direct drive speed setting. I had assumed it was something worn in the
headstock. When I went to the RPC..the pattern vanished. I then
swapped back and forth and indeed, it was the VFD. None of the other
machines exhibited this phenom, including the surface grinder, which
gives the same finish either way.

Odd - I haven't seen that on my VFD-powered 5914, but then I rarely use the
VFD for speed control and it's almost always at 60 Hz. Does the 6525 have
the hydraulic vari-speed system (like the 5914) or step pulleys?

A cautionary note...if you were to power up your surface grinder via
vfd,..be damned sure..that you set the maximum rpm rating to less than
that of the max rpms of wheels. IRRC 3600 rpm. It would be very
possible to over spin a wheel and have it catastrophicly disassemble
itself..which will result in a grenade going off on your grinder.

Good point - I leave the VFD at 60 Hz and only use it to convert single
phase power to 3-phase.

Mike

Actually, VFD's do provide true 3-phase. While the phase voltage waveform
has high harmonic distortion, the phase current waveform is sinusoidal, with
a little ripple(not enough to matter); the current waveform is what counts.
I think what you saw was a mechanical resonant condition excited by a small
unbalance. Because motor rpm can be infinitely varied using a VFD, resonant
conditions can show up when the speed is just right. Using a step pulley
or even a mechanical variable speed drive can completely miss those
resonances, especially if a single-phase motor is used. I have one on my
13x36 lathe (at about 600 rpm(spindle) that was invisible using the original
single-phase motor because the none of pulley steps were precisely the right
speed. When I switched to VFD drive, it appeared on one particular pulley
step @ 40 Hz drive output.

Randy


"Gunner" wrote in message
...
On 12 Dec 2004 18:29:33 GMT, (JMartin957) wrote:

One of the claims made about the VFDs was that the current they supply is
not
true 3 phase, but has some harmonics or secondary oscillations which can
cause
problems with some older motors. This seems to be rare, but might be
your
problem.

This is indeed quite true. Until I got my 5hp rotary..I was running
all my (then, very few) machines on a single 5hp VFD. Oddly enough the
old Clausing 6525 would leave a slight herringbone pattern on one
direct drive speed setting. I had assumed it was something worn in the
headstock. When I went to the RPC..the pattern vanished. I then
swapped back and forth and indeed, it was the VFD. None of the other
machines exhibited this phenom, including the surface grinder, which
gives the same finish either way.

A cautionary note...if you were to power up your surface grinder via
vfd,..be damned sure..that you set the maximum rpm rating to less than
that of the max rpms of wheels. IRRC 3600 rpm. It would be very
possible to over spin a wheel and have it catastrophicly disassemble
itself..which will result in a grenade going off on your grinder.

Gunner

"To be civilized is to restrain the ability to commit mayhem.
To be incapable of committing mayhem is not the mark of the civilized,
merely the domesticated." - Trefor Thomas

In article ,
Mike Henry wrote:
My used 7x14 surface grinder appears to need a new motor, or maybe just new
bearings. The spindle is belt driven and is currently fitted with GE K163,
1HP, TEFC, 3450 rpm 3-phase motor. The motor is being driven with an
Hitachi L-100 VFD from a 220 VAC single phase line.

With the belts off the motor makes some noise on startup that sounds like it
could be bad bearings. A cup of water sitting on the spindle housing
(spindle belts still removed) has some standing waves at full speed and the
wave amplitude varies with speed. I'm assuming that the motor itself or
perhaps just the motor the bearings should be replaced.

To me, it sounds like a mixture of problems. The standing waves
are most likely from an imperfect balance of the combination of the
motor and the pulley.

The noise during startup could be bad bearings -- or it could be
the vibration from the imbalance passing through resonance with some
structural feature of the grinder.

Since you have a VFD, try starting the motor very slow, and
stepping the speed up a little at a time. If it is a problem with
balance and resonance, you will find one speed at which it is
particularly bad.

When you find this speed, start touching various parts of the
machine to see where you can damp the vibration. If you can't damp it
with pressure anywhere on the machine, then it is more likely to be the
bearings.

However, if you do find such a speed, you might try removing the
pulley (and its key, to keep that from flying away at speed). If you
have similar vibration, the motor's rotor is poorly balanced. (Though
the absence of the key will introduce a bit of imbalance.) However, if
it is much better without the pulley, then the pulley itself is the
primary candidate for balancing. Ideally, the pulley and motor rotor
should be balanced as a unit, probably after doing as good a job as
possible on the motor's rotor first. I believe that a proper job of
balancing calls for specialized equipment.

It is bad news to run a motor under load at low speeds from a
VFD for very long (without augmented cooling from an external fan), but
for the time of this test that should be within reason.

Is the GE motor a good choice for a surface grinder or should I be looking
at other brands?

I suspect that you can get many grades of motor from *any*
maker. The trick is finding someplace to get ones of the quality which
you need from whatever maker you choose. Most GE motors are sold for
appliance applications, or machine tools where the balance is less of an
important factor, so you may have to search more to get what you need.

If so, replacement bearings should be pretty cheap. If
the GE motor is wrong for this application, Baldor and Leeson motors with
the same specs above can be had for around $150 on-line.

Trace down where the vibration comes from. It may be that the
pulley was balanced for a different motor, and simply needs to be
re-balanced for this one.

Also, is it necessary to have a motor specially balanced for a surface
grinder?

Since vibration in the surface grinder can negatively impact
surface finish, I think that I would consider it to be more important
than for a big horizontal mill.

If so, is this usually specified when the motor is ordered or
should it be done after receipt with the belt pulley in place? Dreisilker
has a service center fairly close to me and would probably be my choice for
balancing should it prove advisable.

Run the tests which I suggested, and go to them if balance of
the motor/pulley assembly turns out to be the problem.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Sun, 12 Dec 2004 16:13:25 -0600, "Mike Henry"
wrote:

This is indeed quite true. Until I got my 5hp rotary..I was running
all my (then, very few) machines on a single 5hp VFD. Oddly enough the
old Clausing 6525 would leave a slight herringbone pattern on one
direct drive speed setting. I had assumed it was something worn in the
headstock. When I went to the RPC..the pattern vanished. I then
swapped back and forth and indeed, it was the VFD. None of the other
machines exhibited this phenom, including the surface grinder, which
gives the same finish either way.

Odd - I haven't seen that on my VFD-powered 5914, but then I rarely use the
VFD for speed control and it's almost always at 60 Hz. Does the 6525 have
the hydraulic vari-speed system (like the 5914) or step pulleys?

Nope..its a gear head with a two speed motor and 4 speed gear box. I
believe the top speed is direct drive.

The 1501 I replaced it with is hydraulic vari-drive, with 3 gear box
speeds, the top speed being direct drive.

Gunner

"To be civilized is to restrain the ability to commit mayhem.
To be incapable of committing mayhem is not the mark of the civilized,
merely the domesticated." - Trefor Thomas

Also, is it necessary to have a motor specially balanced for a surface
grinder? If so, is this usually specified when the motor is ordered or


I have a Rockwell "toolmakers" grinder which is a cross between a
surface grinder and a tool/cutter grinder. The manual states that
the motor is a special balance and is also dynamically balanced with
the pulley in place. They stress that changing the motor requires
the motor and pulley be rebalanced together.

Now, does that still apply to motors made today? I thought I read
here that today's motors are much better balanced than the motors
of yesteryears; even to the point that production motors are as
good as specially balanced motors of the past. I have no idea if
this is true or NOT.

I will say that the old Rockwell motors on my mill definately have
annoying resonances when ran at certain speeds with a VFD. The worst
one is the 1/2HP 1140RPM motor on the rockwell vertical head. This
motor has numerous resonances with just the pulley. However it runs
very smooth at high RPM.

My new VFD rated 2HP Leeson motor is perfectly smooth at all frequencys
with or without the belt running the spindle of the mill/drill. However
I have also have a 2HP leeson motor on my rockwell lathe and it
is smooth except below 15Hz where the drive system has some kind
of resonance. I believe this is a resonance in the big flat drive belts
used for the mechanical variable speed and it not directly related to
the motor. The drive belt is difficult to remove so I have never
tested this theory.

I have also noticed that older motors seem sensitive to carrier frequency.
Some of mine are quite noisy with low carrier frequencies. I have not
experimented to determine if the resonances are different with
different carrier frequencies. I try to use a low carrier freq with
older motors because I THINK high carrier freqs can cause motor heating
and I think the high freqs stress the winding harder. The leeson motors
run very smooth and quite with a high carrier freq (7.5-10K) There is
more noise from the motor with lower freqs but I don't remember
any resonances when I was experimenting in the past.

Mike, I have a static phase converter if you want to try running
your grinder with it.
chuck

"DoN. Nichols" wrote in message
...
In article ,
Mike Henry wrote:
My used 7x14 surface grinder appears to need a new motor, or maybe just
new
bearings. The spindle is belt driven and is currently fitted with GE
K163,
1HP, TEFC, 3450 rpm 3-phase motor. The motor is being driven with an
Hitachi L-100 VFD from a 220 VAC single phase line.

With the belts off the motor makes some noise on startup that sounds like
it
could be bad bearings. A cup of water sitting on the spindle housing
(spindle belts still removed) has some standing waves at full speed and
the
wave amplitude varies with speed. I'm assuming that the motor itself or
perhaps just the motor the bearings should be replaced.

To me, it sounds like a mixture of problems. The standing waves
are most likely from an imperfect balance of the combination of the
motor and the pulley.

The noise during startup could be bad bearings -- or it could be
the vibration from the imbalance passing through resonance with some
structural feature of the grinder.

Since you have a VFD, try starting the motor very slow, and
stepping the speed up a little at a time. If it is a problem with
balance and resonance, you will find one speed at which it is
particularly bad.

When you find this speed, start touching various parts of the
machine to see where you can damp the vibration. If you can't damp it
with pressure anywhere on the machine, then it is more likely to be the
bearings.

Well, I tried your suggestions and am a bit perplexed. The gradual ramp up
revealed that the vibration (or rather, wave amplitude) was worst at about
51 Hz and somewhat smoother at 60 Hz. Applying force at various locations
didn't seem to make a difference until I started to fiddle with the motor
mount. The mount has a rigid plate cantilevered off the back of the column
to which a hinged plate is attached. The motor mounts to the bottom of the
hinged plate (motor is upside down) and there is a spring-loaded bolt to
adjust the angle of the hinge, and presumably the belt tension between the
motor and spindle pulleys. The standing waves all but disappeared as soon
as the adjusting bolt was, er, adjusted. No amount of re-fiddling could
bring the standing waves back.

Put the belts back on and cranked up the grinder to 60 Hz - no standing
waves. A test grind with some 12L14 and a blue 5sG46-IVS Norton wheel
produced passable results.

Tried to call KO Lee today but got put on automated hold and gave up before
a live voice responded. I'll try them tomorrow and see what they say about
motors. I also need to find out what sort of tension the belts are supposed
to have.

snip

On Tue, 14 Dec 2004 23:33:18 -0600, "Mike Henry"
wrote:


"DoN. Nichols" wrote in message
...
In article ,
Mike Henry wrote:
My used 7x14 surface grinder appears to need a new motor, or maybe just
new
bearings. The spindle is belt driven and is currently fitted with GE
K163,
1HP, TEFC, 3450 rpm 3-phase motor. The motor is being driven with an
Hitachi L-100 VFD from a 220 VAC single phase line.

With the belts off the motor makes some noise on startup that sounds like
it
could be bad bearings. A cup of water sitting on the spindle housing
(spindle belts still removed) has some standing waves at full speed and
the
wave amplitude varies with speed. I'm assuming that the motor itself or
perhaps just the motor the bearings should be replaced.

To me, it sounds like a mixture of problems. The standing waves
are most likely from an imperfect balance of the combination of the
motor and the pulley.

The noise during startup could be bad bearings -- or it could be
the vibration from the imbalance passing through resonance with some
structural feature of the grinder.

Since you have a VFD, try starting the motor very slow, and
stepping the speed up a little at a time. If it is a problem with
balance and resonance, you will find one speed at which it is
particularly bad.

When you find this speed, start touching various parts of the
machine to see where you can damp the vibration. If you can't damp it
with pressure anywhere on the machine, then it is more likely to be the
bearings.

Well, I tried your suggestions and am a bit perplexed. The gradual ramp up
revealed that the vibration (or rather, wave amplitude) was worst at about
51 Hz and somewhat smoother at 60 Hz. Applying force at various locations
didn't seem to make a difference until I started to fiddle with the motor
mount. The mount has a rigid plate cantilevered off the back of the column
to which a hinged plate is attached. The motor mounts to the bottom of the
hinged plate (motor is upside down) and there is a spring-loaded bolt to
adjust the angle of the hinge, and presumably the belt tension between the
motor and spindle pulleys. The standing waves all but disappeared as soon
as the adjusting bolt was, er, adjusted. No amount of re-fiddling could
bring the standing waves back.

Put the belts back on and cranked up the grinder to 60 Hz - no standing
waves. A test grind with some 12L14 and a blue 5sG46-IVS Norton wheel
produced passable results.

Tried to call KO Lee today but got put on automated hold and gave up before
a live voice responded. I'll try them tomorrow and see what they say about
motors. I also need to find out what sort of tension the belts are supposed
to have.

snip

If it doesnt slip, and it doesnt flap around like a flag in the wind,
and your water glass test (a very good one btw) is smooth..the belt
is tight enough.

Gunner




"If I'm going to reach out to the the Democrats then I need a third
hand.There's no way I'm letting go of my wallet or my gun while they're
around."

"Democrat. In the dictionary it's right after demobilize and right
before demode` (out of fashion).
-Buddy Jordan 2001

"Gunner" wrote in message
...
On Tue, 14 Dec 2004 23:33:18 -0600, "Mike Henry"
wrote:
Tried to call KO Lee today but got put on automated hold and gave up
before
a live voice responded. I'll try them tomorrow and see what they say
about
motors. I also need to find out what sort of tension the belts are
supposed
to have.

If it doesnt slip, and it doesnt flap around like a flag in the wind,
and your water glass test (a very good one btw) is smooth..the belt
is tight enough.

That makes sense, but it will give me a good excuse to call and see what
they have to say about motors and balanceing.

In article ,
Mike Henry wrote:

"DoN. Nichols" wrote in message
...

[ ... ]

To me, it sounds like a mixture of problems. The standing waves
are most likely from an imperfect balance of the combination of the
motor and the pulley.

The noise during startup could be bad bearings -- or it could be
the vibration from the imbalance passing through resonance with some
structural feature of the grinder.

Since you have a VFD, try starting the motor very slow, and
stepping the speed up a little at a time. If it is a problem with
balance and resonance, you will find one speed at which it is
particularly bad.

When you find this speed, start touching various parts of the
machine to see where you can damp the vibration. If you can't damp it
with pressure anywhere on the machine, then it is more likely to be the
bearings.

Well, I tried your suggestions and am a bit perplexed. The gradual ramp up
revealed that the vibration (or rather, wave amplitude) was worst at about
51 Hz and somewhat smoother at 60 Hz. Applying force at various locations
didn't seem to make a difference until I started to fiddle with the motor
mount. The mount has a rigid plate cantilevered off the back of the column
to which a hinged plate is attached. The motor mounts to the bottom of the
hinged plate (motor is upside down) and there is a spring-loaded bolt to
adjust the angle of the hinge, and presumably the belt tension between the
motor and spindle pulleys. The standing waves all but disappeared as soon
as the adjusting bolt was, er, adjusted. No amount of re-fiddling could
bring the standing waves back.

Hmm ... perhaps the belt was too loose at first, and flapping
around at the speed in question. Can you find a new resonance point?

Or perhaps there was just enough give to make for resonance at
that speed, and clamping a weight on the plate would shift the resonance
point.

Put the belts back on and cranked up the grinder to 60 Hz - no standing
waves. A test grind with some 12L14 and a blue 5sG46-IVS Norton wheel
produced passable results.

It sounds good to me.

Tried to call KO Lee today but got put on automated hold and gave up before
a live voice responded. I'll try them tomorrow and see what they say about
motors. I also need to find out what sort of tension the belts are supposed
to have.

FWIW -- the manual for my Sanford grinder, which uses a flat
rubber belt says the following:

"Belt tension should be such that the belt between pulleys may
be compressed to within one inch of touching. This is rather
loose, and should be so."

I don't know how this may apply to your machine, as it is a
different size and a different manufacturer.

Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" wrote in message
...
In article ,
Mike Henry wrote:
snip
Well, I tried your suggestions and am a bit perplexed. The gradual ramp
up
revealed that the vibration (or rather, wave amplitude) was worst at about
51 Hz and somewhat smoother at 60 Hz. Applying force at various locations
didn't seem to make a difference until I started to fiddle with the motor
mount. The mount has a rigid plate cantilevered off the back of the
column
to which a hinged plate is attached. The motor mounts to the bottom of
the
hinged plate (motor is upside down) and there is a spring-loaded bolt to
adjust the angle of the hinge, and presumably the belt tension between the
motor and spindle pulleys. The standing waves all but disappeared as
soon
as the adjusting bolt was, er, adjusted. No amount of re-fiddling could
bring the standing waves back.

Hmm ... perhaps the belt was too loose at first, and flapping
around at the speed in question. Can you find a new resonance point?

Or perhaps there was just enough give to make for resonance at
that speed, and clamping a weight on the plate would shift the resonance
point.

I've no clue on what changed unless maybe the grease in the motor bearings
suddenly re-arranged itself for more complete lubrication. The grinder was
bought used from a dealer and I don't know how long it sat before it arrived
here. It's had about 10 hours of run time since arrival.

Put the belts back on and cranked up the grinder to 60 Hz - no standing
waves. A test grind with some 12L14 and a blue 5sG46-IVS Norton wheel
produced passable results.

It sounds good to me.

Tried to call KO Lee today but got put on automated hold and gave up
before
a live voice responded. I'll try them tomorrow and see what they say
about
motors. I also need to find out what sort of tension the belts are
supposed
to have.

FWIW -- the manual for my Sanford grinder, which uses a flat
rubber belt says the following:

"Belt tension should be such that the belt between pulleys may
be compressed to within one inch of touching. This is rather
loose, and should be so."

I don't know how this may apply to your machine, as it is a
different size and a different manufacturer.

KO Lee tells me that this motor (GE K163) is the one that they installed on
surface grinders (although they now specify 2 HP instead of the 1 HP on
mine), that they do not specify any special sort of balancing and that the
(2) belts should be adjusted so that there is about 1/8" "give" when pressed
from the side. The tension was a lot less in my tests the other night so
I'll play with the tension a bit to see how that affects things.

The tech support guy seemed pressed for time and was not interested in any
kind of detailed answers, so I'm not feeling any better informed than
before.

Mike

In article ,
Mike Henry wrote:

[ ... ]

I've no clue on what changed unless maybe the grease in the motor bearings
suddenly re-arranged itself for more complete lubrication. The grinder was
bought used from a dealer and I don't know how long it sat before it arrived
here. It's had about 10 hours of run time since arrival.

Or perhaps some swarf was cushioning the support, and that was
displaced when you adjusted it.

[ ... ]

"Belt tension should be such that the belt between pulleys may
be compressed to within one inch of touching. This is rather
loose, and should be so."

I don't know how this may apply to your machine, as it is a
different size and a different manufacturer.

KO Lee tells me that this motor (GE K163) is the one that they installed on
surface grinders (although they now specify 2 HP instead of the 1 HP on
mine), that they do not specify any special sort of balancing and that the
(2) belts should be adjusted so that there is about 1/8" "give" when pressed
from the side. The tension was a lot less in my tests the other night so
I'll play with the tension a bit to see how that affects things.

The tech support guy seemed pressed for time and was not interested in any
kind of detailed answers, so I'm not feeling any better informed than
before.

Well ... at least you now know what the tension should be for
your machine. Are those flat belts, V-belts, or something else, like
perhaps poly-V belts? It sounds like V-belts just offhand.

Good Luck
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 15 Dec 2004 18:36:17 -0500, (DoN. Nichols)
wrote:


"Belt tension should be such that the belt between pulleys may
be compressed to within one inch of touching. This is rather
loose, and should be so."

After going over lots of machine tool manuals over the years..the
1 1/8 - 1 1/4" gap seems to be pretty common.

Gunner

"Gunner, you are the same ridiculous liberal f--k you ever where."
Scipio

Actually, VFD's do provide true 3-phase. While the phase voltage waveform
has high harmonic distortion, the phase current waveform is sinusoidal, with
a little ripple(not enough to matter); the current waveform is what counts.

Didn't mean to imply that the output from a VFD is not true three phase in the
sense that the output from a static converter is not, but just that the
distortion or ripples cause - in the opinion of some experts - problems with
some motors. No more, no less.

John Martin

"DoN. Nichols" wrote in message
...
In article ,
Mike Henry wrote:

snip

KO Lee tells me that this motor (GE K163) is the one that they installed
on
surface grinders (although they now specify 2 HP instead of the 1 HP on
mine), that they do not specify any special sort of balancing and that the
(2) belts should be adjusted so that there is about 1/8" "give" when
pressed
from the side. The tension was a lot less in my tests the other night so
I'll play with the tension a bit to see how that affects things.

snip
Well ... at least you now know what the tension should be for
your machine. Are those flat belts, V-belts, or something else, like
perhaps poly-V belts? It sounds like V-belts just offhand.


I'm not sure what to call them - they look like a truncated V in cross
section and the periphery is serrated. There are two individual belts so I
guess that they are V-belts. A brief Google search indicates that Poly-V
belts are like two or more V-belts joined along there edges into a single
belt. Is that right?

While checking the belts I noticed that there is some light rust on both the
motor and spindle pulley grooves. That's probably not good for a grinder.
I wonder if cleaning them up with some fine steel wool or a 3M abrasive pad
would help or hurt?

Mike

In article ,
Mike Henry wrote:

"DoN. Nichols" wrote in message
...

[ ... ]

Well ... at least you now know what the tension should be for
your machine. Are those flat belts, V-belts, or something else, like
perhaps poly-V belts? It sounds like V-belts just offhand.


I'm not sure what to call them - they look like a truncated V in cross
section and the periphery is serrated. There are two individual belts so I
guess that they are V-belts.

Yep! Some are notched and some are not. The notched ones do a
better job bending around very small pulleys -- but might contribute
more vibration in your application. Check how flexible they are. It
might be that they have taken a permanent set from aging unused. In
that case, new belts might be a good idea.

A brief Google search indicates that Poly-V
belts are like two or more V-belts joined along there edges into a single
belt. Is that right?

Correct -- and the grooves are a lot smaller. These are common
as fan belts in modern vehicles, while the V-belts are found on older
ones.

Flat sides (not sloped) along with the serrations are timing
belts, and engage pulleys like gears.

While checking the belts I noticed that there is some light rust on both the
motor and spindle pulley grooves. That's probably not good for a grinder.
I wonder if cleaning them up with some fine steel wool or a 3M abrasive pad
would help or hurt?

As long as you don't remove more than the rust, it will probably
not do much one way or the other. Running for a short while will remove
the rust where it matters.

Good luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---