Steve Harder
03-17-2010, 3:30 PM
Nova 1624 – adding variable speed – followup.
My original article had over 1500+ views between all the forums – so thought I’d do a quick followup.
So far, all pro and no con.
The motor/VFD combo performs well, and in many ways goes beyond my initial expectations.
The three lowest belt positions give me lathe headstock speed ranges of
(42)107 to 321, (72)180 to 540 and (136)342 to 1026 rpm.
The numbers in parenthesis are at the bottom end of the safe operating range for this motor. So on low belt setting, to get 42 rpm lathe shaft you are running motor at 12hz – this is fine for sanding all day, or for a short session of roughing a very out of balance blank. The 107 thru 321 rpm can be run all day, as the motor fan is turning fast enough to adequately cool motor.
As a test I mounted a 45# oblong, very out of round blank. Normally I would have done some chainsaw and bandsaw work to clean up the blank, but I wanted to test my new setup. Initially I could only turn at 60 rpm, above that the lathe with 550# of added ballast was starting to shimmy. So I hogged into the blank, working it as hard as I dared. The pounding was a good reminder as to why I usually start with a nicely trimmed up blank. Took 10 minutes or so at pretty slow rpms before I could work up thru the low speed range, and move belt to 2nd postion. After 20 minutes or so I had a blank that I could turn at 500 rpm. The motor was barely luke warm.
Earlier this week I sanded out a couple of bowls and ran at 50 rpm on the 2nd belt setting, so I was well under 12hz going to motor. I wasn’t putting much load on the lathe and after 30 minutes or so, motor was barely luke warm.
So, this motor is running cooler than I remember my OEM Nova motor running.
Motor has enough torque, even at low rpms, that I’m always going to keep a slightly slack belt, in case of a major catch.
I really like the scaling factor on the VFD that lets me see the headstock rpm for each of the belt positions. I’m setting my speed based on how the blank looks on the lathe, but it’s nice to be able to verify where I am by glancing at the rpm.
The remote box is a definite plus. Not having to reach across to get a run/stop and change speed is really nice. I’ve marked my speed dial with “hz” – so when I’m between 30 and 90 I know I’m in a safe all-day motor speed range.
If I were doing it over again, I would mount the VFD chassis in a large metal box underneath the lathe and buy the $45 extension cord so the keypad could be up by the motor. It’s a dust issue. While a lot of other VFDs are mounted up on the headstock, out in the open, I will have to remember to blow out dust once in a while.
All in all, I’m a very happy camper.
---
Links to my original article on Nova 1624 variable speed.
http://www.sawmillcreek.org/showthread.php?t=134952
http://www.woodturnersresource.com/c...num=1268097435 (http://www.woodturnersresource.com/cgi-bin/yabb2/YaBB.pl?num=1268097435)
And a link to article on Remote Box
http://www.sawmillcreek.org/showthread.php?t=135179
My original article had over 1500+ views between all the forums – so thought I’d do a quick followup.
So far, all pro and no con.
The motor/VFD combo performs well, and in many ways goes beyond my initial expectations.
The three lowest belt positions give me lathe headstock speed ranges of
(42)107 to 321, (72)180 to 540 and (136)342 to 1026 rpm.
The numbers in parenthesis are at the bottom end of the safe operating range for this motor. So on low belt setting, to get 42 rpm lathe shaft you are running motor at 12hz – this is fine for sanding all day, or for a short session of roughing a very out of balance blank. The 107 thru 321 rpm can be run all day, as the motor fan is turning fast enough to adequately cool motor.
As a test I mounted a 45# oblong, very out of round blank. Normally I would have done some chainsaw and bandsaw work to clean up the blank, but I wanted to test my new setup. Initially I could only turn at 60 rpm, above that the lathe with 550# of added ballast was starting to shimmy. So I hogged into the blank, working it as hard as I dared. The pounding was a good reminder as to why I usually start with a nicely trimmed up blank. Took 10 minutes or so at pretty slow rpms before I could work up thru the low speed range, and move belt to 2nd postion. After 20 minutes or so I had a blank that I could turn at 500 rpm. The motor was barely luke warm.
Earlier this week I sanded out a couple of bowls and ran at 50 rpm on the 2nd belt setting, so I was well under 12hz going to motor. I wasn’t putting much load on the lathe and after 30 minutes or so, motor was barely luke warm.
So, this motor is running cooler than I remember my OEM Nova motor running.
Motor has enough torque, even at low rpms, that I’m always going to keep a slightly slack belt, in case of a major catch.
I really like the scaling factor on the VFD that lets me see the headstock rpm for each of the belt positions. I’m setting my speed based on how the blank looks on the lathe, but it’s nice to be able to verify where I am by glancing at the rpm.
The remote box is a definite plus. Not having to reach across to get a run/stop and change speed is really nice. I’ve marked my speed dial with “hz” – so when I’m between 30 and 90 I know I’m in a safe all-day motor speed range.
If I were doing it over again, I would mount the VFD chassis in a large metal box underneath the lathe and buy the $45 extension cord so the keypad could be up by the motor. It’s a dust issue. While a lot of other VFDs are mounted up on the headstock, out in the open, I will have to remember to blow out dust once in a while.
All in all, I’m a very happy camper.
---
Links to my original article on Nova 1624 variable speed.
http://www.sawmillcreek.org/showthread.php?t=134952
http://www.woodturnersresource.com/c...num=1268097435 (http://www.woodturnersresource.com/cgi-bin/yabb2/YaBB.pl?num=1268097435)
And a link to article on Remote Box
http://www.sawmillcreek.org/showthread.php?t=135179