I measured the current to the 8.6a motor on my table saw while ripping some
6/4 oak with a combination blade. I figure that is about the heaviest I
ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.

"Toller" wrote in message
...
I measured the current to the 8.6a motor on my table saw while ripping some
6/4 oak with a combination blade. I figure that is about the heaviest I
ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.
small typo, the motor is rated at 8.4a, not 8.6a. 240v.

"Toller" wrote in message
...
I measured the current to the 8.6a motor on my table saw while ripping some
6/4 oak with a combination blade. I figure that is about the heaviest I
ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.

Perfectly normal. When motors wear the bearings are one of the first
things to go and a quick way to find out is to measure the load. It will be
higher than the rating. Left to go too long that way the motor will burn
out. Same with blower motors when the bearings on that start to bind the
motor overworks. Pumps, same deal.

You did not harm running that way for a few minutes, but after a few hours,
you'd potentially have a problem.

According to Toller :

"Toller" wrote in message
...
I measured the current to the 8.6a motor on my table saw while ripping some
6/4 oak with a combination blade. I figure that is about the heaviest I
ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.
small typo, the motor is rated at 8.4a, not 8.6a. 240v.

Well, there's always the question of how accurate the meter is - expecting
high precision in amperage and voltage measurements on AC circuits is a bit
of a mistake, particularly with normal "consumer grade" voltmeters.

That said, the plate rating is more-or-less the maximum amperage expected
when running the motor at the rated duty cycle/loading that you could
continue indefinately without overheating.

Chances are that you were loading the motor a bit beyond its ratings,
and the amperage reflects that.

It's of no great import for short periods, however, if you kept at it long
enough, there's a darn good chance that the motor will begin to overheat
and have the thermal protector cut-in.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

"Edwin Pawlowski" wrote in message
...
"Toller" wrote in message
...
I measured the current to the 8.6a motor on my table saw while ripping
some 6/4 oak with a combination blade. I figure that is about the
heaviest I ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.

Perfectly normal. When motors wear the bearings are one of the first
things to go and a quick way to find out is to measure the load. It will
be higher than the rating. Left to go too long that way the motor will
burn out. Same with blower motors when the bearings on that start to bind
the motor overworks. Pumps, same deal.

You did not harm running that way for a few minutes, but after a few
hours, you'd potentially have a problem.
I would never use it like that for more than a minute at a time. So, am I
okay, or are you warning me my bearings are going?

"Toller" wrote in message
I would never use it like that for more than a minute at a time. So, am I
okay, or are you warning me my bearings are going?

No, just a heavy load. No harm for short periods. Knowing what it takes
under no load, you can always check it years from now if you suspect a
problem.

"Toller" wrote in message
...
I measured the current to the 8.6a motor on my table saw while ripping
some
6/4 oak with a combination blade. I figure that is about the heaviest I
ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.


Peak meter or RMS meter?
Where did you measure?
When was the meter last calibrated?

How big of a cord are you using and how far are you from the source? (total
distance)

I have a 10 inch dewalt that I hammer occasionally. I just let the motor run
for awhile after I am done pushing it so it can cool off.

"Edwin Pawlowski" wrote in message
...
"Toller" wrote in message
I would never use it like that for more than a minute at a time. So, am
I okay, or are you warning me my bearings are going?

No, just a heavy load. No harm for short periods. Knowing what it takes
under no load, you can always check it years from now if you suspect a
problem.
It was like 3.8a no load.
Reason I was looking at it so I could compare it to my "new" shaper.
The shaper has a 14.4a motor (120v) and draws 11.5a no load, and 12.1a while
shaving an eighth inch off the same 6/4 oak. The no load is rather high,
but it hardly goes up while doing serious work. I am not sure what to make
of that.

Peak meter or RMS meter?
Where did you measure?
When was the meter last calibrated?

Just a $60 HD special. I don't know how accurate it is, but it is extremely
consistent.

How big of a cord are you using and how far are you from the source?
(total
distance)

12 gauge, maybe 60'. Wouldn't be significant voltage drop.

I have a 10 inch dewalt that I hammer occasionally. I just let the motor
run
for awhile after I am done pushing it so it can cool off.

If I am not going to cut with it again immediately, is it best to let it run
afterwards anyhow?

My habit it to hit the "off" with my knee when the cut is done; but could
let it run if that is important. (saw came with a 10"x12" off switch; seems
like a waste of $100 to me, but it sure is easy to use.)

Toller wrote:
I measured the current to the 8.6a motor on my table saw while ripping some
6/4 oak with a combination blade. I figure that is about the heaviest I
ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.



Hmm. Ever see the amperage given and stated as
maximum. Electric motors draw more power the
harder they are worked. Of course if you work it
hard enough it draws a law of power (liked at
locked rotor) and will burn up rather quickly.
Most however are are protected.

So what does it read when the motor is just
spinning and not sawing? 9.1a is not
significantly higher than 8.6a, depending on the
accuracy of your meter.

"George E. Cawthon" wrote in message
...
Toller wrote:
I measured the current to the 8.6a motor on my table saw while ripping
some 6/4 oak with a combination blade. I figure that is about the
heaviest I ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.

Hmm. Ever see the amperage given and stated as maximum. Electric motors
draw more power the harder they are worked. Of course if you work it hard
enough it draws a law of power (liked at locked rotor) and will burn up
rather quickly. Most however are are protected.

So what does it read when the motor is just spinning and not sawing? 9.1a
is not significantly higher than 8.6a, depending on the accuracy of your
meter.

It was 3.8a no load.
I guess I will just forget about it then, except to avoid cutting too much
6/4 oak at a shot. Thanks

"Toller" wrote in message
...
I measured the current to the 8.6a motor on my table saw while ripping some
6/4 oak with a combination blade. I figure that is about the heaviest I
ever stress it.
It measured 9.1a.
What should I make of that? Is it normal to go over the rating on heavy
loads? I haven't had any problems; I was just curious what the current
would be.


Completely normal. I know of a couple motors running exhaust fans that
operate 24/7. The motors were slightly undersized for the job. When we left
the job the motors were pulling 1 amp over the name plate rating. That was
four years ago and the motors are still running fine! Your few second
venture into a slight motor overload will not hurt them at all.
Greg

According to Toller :

If I am not going to cut with it again immediately, is it best to let it run
afterwards anyhow?

After hard slogging, even a few seconds of freerun will make a huge difference in
"bake time" - having given the blower chance to move cold air without the coils
producing any heat. Whether that decreases safety otherwise, is something
only you can answer.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

I have a 10 inch dewalt that I hammer occasionally. I just let the motor
run
for awhile after I am done pushing it so it can cool off.


If I am not going to cut with it again immediately, is it best to let it run
afterwards anyhow?

My habit it to hit the "off" with my knee when the cut is done; but could
let it run if that is important. (saw came with a 10"x12" off switch; seems
like a waste of $100 to me, but it sure is easy to use.)


One way to tell if the motor should be run to cool is how hot it gets,
including a little after it is turned off. Motors can run pretty hot in
normal use. I don't see any problem with what you are doing either.

A lot of motors also have a Service Factor, or SF, rating. Typical would
be a SF of 1.15 which means you can run the motor at 1.15 times the
rated current full time at a slight reduction in life.