[Katoh]

G'Day Friends
For those that are interested at moment I am actually replacing my 1hp VFD driven spindle with a 2Kw (3hp) servo motor. This drives the spindle with a toothed belt directly from motor with a slight ratio of 1/0.8.
Rpm range from 0 to 2000 no changing belts or gears. The other advantage I can swap axis and use the spindle as a Rotary "DEG" as "C".
The toothed pulley to the spindle is only plastic keyway held in case of an "oopsy" moment as the point to give first. Just working on the mounting bracket now and once mounted I will be upgrading the control side to Ethernet driven Smooth stepper, then to Mach4.

[rwskinner]

You all can have all the fun you want, but the 10x22 will not handle the full 1 hp even when it's bolted down and level.
The lathe is not rigid enough so going with 2,3,4 hp motors is kind of senseless. My opinion only.

[Azalin]

You all can have all the fun you want, but the 10x22 will not handle the full 1 hp even when it's bolted down and level.
The lathe is not rigid enough so going with 2,3,4 hp motors is kind of senseless. My opinion only.

I also have an Optimum D210x400 (8x15) lathe. The stock motor was 700w. I've pulled it and replaced it with a 1.3kw DC motor. The lathe feels more comfortable now. It's been a year since and it works very well.

I understand you tho, my 3kw instead 750w was unrealistic but I believe Sieg C6 (same as your G0602) lathe can handle a 1.5w without any problem. The only problem will be the fixture.

[rowbare]

You all can have all the fun you want, but the 10x22 will not handle the full 1 hp even when it's bolted down and level.
The lathe is not rigid enough so going with 2,3,4 hp motors is kind of senseless. My opinion only.

I agree about the lack of rigidity however when using a VFD it actually makes sense to use what would appear to be a grossly oversized motor since it will improve metal removal rates at lower speeds.

Induction motors are essentially constant torque devices. Since HP is a function of torque and speed when you slow down a motor, you reduce its HP.

When you gear down a constant speed motor by a factor of 4, you reduce the rotational speed at the chuck by the same factor but more importantly, you increase the torque by a factor of 4 maintaining your HP. However when you slow down a variable speed motor by a factor of 4, you reduce the HP by a factor of 4 and your metal removal rate goes down accordingly. Remember HP removes metal and torque twists the bed.

So providing the machine can handle the additional torque at 1/4 speed with the original constant speed motor it should be able to handle it just as well with a much larger motor throttled down with a VFD. In our example above with a 3 hp motor at 1/4 speed you still are only putting 3/4 HP into the cut. However at higher speeds, you have to be mindful not to get carried away.

With a VFD, it is nice to have 2 fairly widely overlapping speed ranges. That way you can do most of your work in either range but you can deal with the extreme requirements too.

bob

[Katoh]

You all can have all the fun you want, but the 10x22 will not handle the full 1 hp even when it's bolted down and level.
The lathe is not rigid enough so going with 2,3,4 hp motors is kind of senseless. My opinion only.

I do agree, I think it wouldn’t be practicable to mount a large induction motor on this size of lathe, you wouldn’t really have any benefit at all, you would still only be able to take the same max cuts at what you could with the smaller rated motor. The fitting of the much larger frame would be a pain as well.
Now in my case you can't compare apples with apples, Yes the servo is nearly 3hp and has 7.7Nm of torque where the original 1hp motor has only 4.5Nm at 1400rpm, but when geared to 700rpm and lower has 9Nm at spindle more than the 3hp servo. The servo also has a smaller footprint than the original 1hp induction motor making it easy to install.
Either way I think anything up to 1.1kw in Induction with gearing to 2.2kw Servo direct drive will work well on these machines.

[skyguynca]

Great Thread