Re: LOSS OF APPEARANT POWER AND SPEED IN A 3/4 HP 1725 MOTOR UNDER NORMAL LOADS!


Nfwood
 

Steve,  Why not haul the motor to a local electrical shop and get their technicians to analyze the bearings/bushings and the electrical circuitry.  They can do this in a fews minutes and you will get good information.  And probably a fix that will keep it running for years into the future.  If the 35 year old motor is beyond hope you need to know that NOW so you can find a replacement and get back to making chips.

Good luck.

Nelson Wood


-----Original Message-----
From: steven_karvelis@... [SOUTHBENDLATHE]
To: SOUTHBENDLATHE
Sent: Sat, Aug 2, 2014 12:39 am
Subject: [SOUTHBENDLATHE] LOSS OF APPEARANT POWER AND SPEED IN A 3/4 HP 1725 MOTOR UNDER NORMAL LOADS!



HELLO EVERYONE.

I'M HOPING SOMEBODY CAN GIVE ME SOME INSIGHT OR SHARE THEIR KNOWLEDGE REGARDING THIS TOPIC. I HAVE OWNED MY SB 9 INCH LATHE FOR ABOUT 35 YEARS NOW. RECENTLY AN ODD SITUATION HAS BECOME MORE PREVALENT IN THE PAST FEW WEEKS. THE MOTOR (3/4 HP 1725 RPM) SLOWS CONSIDERABLY UNDER LOAD, AND I AM NOT TALKING ABOUT A HEAVY LOAD EITHER. THE MOTOR STARTS NORMALLY, SEEMINGLY OPERATES AS EXPECTED EXCEPT THAT IT "SLOWS" WHEN TAKING A NORMAL CUT EVEN IN ALUMINUM. EARLIER THIS EVENING I WAS TURNING SOME 1" 6061 T6 STOCK TAKING A 0.040 CUT AT A FEED RATE OF 0.0015 PER REVOLUTION AT ABOUT 300 RPM. i AM USING "TAP MAGIC" CUTTING OIL AND EVERYTHING STARTS FINE. IN ABOUT 15 -20 SECONDS INTO THE CUT THE SPINDLE RPM STARTS DROPPING DRAMATICALLY AND MAY HAVE STOPPED, I DISENGAGED THE FEED AND THE SPEED PICKS UP AGAIN. NEITHER OF THE DRIVE BELTS SLIPPED DURING THIS TIME. ANYBODY KNOW WHAT IS GOING ON WITH THE MOTOR? IS THIS A SERVICEABLE SITUATION OR AM I GOING TO HAVE TO LAY THE OLD WORKHORSE TO REST AND GET A NEW PONY? SOMETHING ELSE  ALONG THE SAME LINE, I'M RUNNING MY MACHINE WITH THE BELT ON THE MIDDLE OF THE CONE PULLEY TURNING (X RPM), CHANGE THE BELT TO THE SMALLEST PULLEY ON THE SPINDLE AND INSTEAD OF THE SPEED INCREASING APPROXIMATELY (1.5 X) THE SPINDLE RPM  ACTUALLY SLOWED????? WHAT IS GOING ON? ANYBODY

SINCERELY,

STEVEN KARVELIS



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