Dave Grey
10-07-2007, 5:16 AM
This is my first post so I will make it count!
I am the recent, proud owner of a 3520 - an anxiously awaited (and major!) upgrade from a mini lathe which got me hooked on turning. The first thing I noticed when I turned it on for the first time was a high-pitched electronic kind of chirping sound coming from the motor when running in either direction at the lower speeds. It is not super loud, but kind of squeaky or chirpy in nature - reminds me of an ultrasonic device we had to repel rodents growing up or those insects like cicadas or katydids that chirp rapidly at night, but a bit more electronic in nature. The frequency of this sound is indexed to the speed of the lathe, although the pitch is fairly constant across the speed range. Above 700-800 rpm, it's hard to hear it because the combination of the high frequency of the sound itself (runs together) and the additional fan noise from the motor. I removed the motor cover and unhooked the drive belt and made sure that it wasn't the fan hitting or a belt or something else obvious. I checked my voltage at the outlet and current draw and there are no issues there.
I rigged up a system to manually spin the motor (via the handwheel) and there is no sound whatsoever, even spinning at similar speeds, so that rules out bearing sounds and the like, I think. It really sounds to me that the sound originates from within the motor. I called Powermatic and they sent out a guy to replace the motor. New motor, exact same sound. At this point, I was told by the Powermatic repair guy that this is normal. I had a distinct impression that he had no evidence to back that statement up. The sound is pretty annoying to me due to it's high pitch and piercing nature. I have asked others to listen to it and they agree that it is noticable and annoying. I have been very happy with the lathe in all other respects, but as my main reason for going to such a large lathe was to extend my skills and get into 12"+ stuff, I am often turning at the lower end of the speed range.
I wanted to put it to other 3520 owners to see if this really is a feature of this Powermatic motor, or if something odd is going on with my unit - perhaps related to the phase converter which I know nothing about. In other words, do any of you have such a sound at lower speeds, or are your motors "whisper-quiet" at low speeds?
For interest, my "shop" (basement) necessitates some mobility for the lathe. I have seen other posts about mobility with this lathe. I installed 4 levelling casters from Great Lakes Caters (ca $12 each) and they work well. Prior to installing the casters, I carefully mounted an 8" deep X 14" oak blank (green) straight from the bandsaw where I had cut the cylinder "to the line". I then increased the speed until the lathe began to rock back and forth a little (ca. 650 rpm which is scary to me for a rough blank of that size). I then mounted the casters (I had tapped the feet to the necessary M12 prior to assembling the lathe) and repeated the experiment). This time, the rocking began at around 500 rpm. Interestingly, at higher speeds (800+), the rocking kind of stabilized. I also tried spinnning a mostly dry shallow 8" blank that was trued and it was very stable up to 1200 rpm (with casters mounted). My conclusion is that there may be a slight sacrifice in overall stability with the casters mounted (perhaps due to some play in the caster mechanism or the caster rubber), but I cannot see it influencing my turning. The mobility is excellent and the levelling is efficient. As an added bonus, I am about 6'2" and the added 3 inches of height are welcome.
Thanks in advance for your replies
Dave
I am the recent, proud owner of a 3520 - an anxiously awaited (and major!) upgrade from a mini lathe which got me hooked on turning. The first thing I noticed when I turned it on for the first time was a high-pitched electronic kind of chirping sound coming from the motor when running in either direction at the lower speeds. It is not super loud, but kind of squeaky or chirpy in nature - reminds me of an ultrasonic device we had to repel rodents growing up or those insects like cicadas or katydids that chirp rapidly at night, but a bit more electronic in nature. The frequency of this sound is indexed to the speed of the lathe, although the pitch is fairly constant across the speed range. Above 700-800 rpm, it's hard to hear it because the combination of the high frequency of the sound itself (runs together) and the additional fan noise from the motor. I removed the motor cover and unhooked the drive belt and made sure that it wasn't the fan hitting or a belt or something else obvious. I checked my voltage at the outlet and current draw and there are no issues there.
I rigged up a system to manually spin the motor (via the handwheel) and there is no sound whatsoever, even spinning at similar speeds, so that rules out bearing sounds and the like, I think. It really sounds to me that the sound originates from within the motor. I called Powermatic and they sent out a guy to replace the motor. New motor, exact same sound. At this point, I was told by the Powermatic repair guy that this is normal. I had a distinct impression that he had no evidence to back that statement up. The sound is pretty annoying to me due to it's high pitch and piercing nature. I have asked others to listen to it and they agree that it is noticable and annoying. I have been very happy with the lathe in all other respects, but as my main reason for going to such a large lathe was to extend my skills and get into 12"+ stuff, I am often turning at the lower end of the speed range.
I wanted to put it to other 3520 owners to see if this really is a feature of this Powermatic motor, or if something odd is going on with my unit - perhaps related to the phase converter which I know nothing about. In other words, do any of you have such a sound at lower speeds, or are your motors "whisper-quiet" at low speeds?
For interest, my "shop" (basement) necessitates some mobility for the lathe. I have seen other posts about mobility with this lathe. I installed 4 levelling casters from Great Lakes Caters (ca $12 each) and they work well. Prior to installing the casters, I carefully mounted an 8" deep X 14" oak blank (green) straight from the bandsaw where I had cut the cylinder "to the line". I then increased the speed until the lathe began to rock back and forth a little (ca. 650 rpm which is scary to me for a rough blank of that size). I then mounted the casters (I had tapped the feet to the necessary M12 prior to assembling the lathe) and repeated the experiment). This time, the rocking began at around 500 rpm. Interestingly, at higher speeds (800+), the rocking kind of stabilized. I also tried spinnning a mostly dry shallow 8" blank that was trued and it was very stable up to 1200 rpm (with casters mounted). My conclusion is that there may be a slight sacrifice in overall stability with the casters mounted (perhaps due to some play in the caster mechanism or the caster rubber), but I cannot see it influencing my turning. The mobility is excellent and the levelling is efficient. As an added bonus, I am about 6'2" and the added 3 inches of height are welcome.
Thanks in advance for your replies
Dave