G0602 And A Vfd

way back nearly a year ago when i had finally decided the grizzly 10x22 was almost exactly the perfect size lathe to suit my needs i found myself in another quandary , grizzly offered the lathe in two models .

the g0602 with a somewhat limited speed range do to using a step pulley arrangement .
and a variable speed model the g0752 that i was unsure of due to not knowing the quality of the components used in the variable speed drive .

i ended up going with the g0602 simply because i could afford it . i was also somewhat sure i could convert it to 3 phase and a vfd for roughly the same money as the difference in price .

$1250.00 for the g0602 and $1695.00 for the g0752 .

fast forward 10 months or so and i now have most of the conversion finished . and have learned i made the right choice . not because its going to be cheaper by a few bucks for me .
but because i now have something you do not get with the g0752 ... step pulley's .... that is right step pulley's .

i think most people who do this conversion do it with the mind to have the wonderful variable speed option
and no longer have to deal with changing the belt .

i think that is the wrong attitude , having the step pulley's with the vfd is a huge advantage i failed to see until
last night when i flipped the switch and turned it on .
the first thing i did was to put the belt on the speed i used the most ... 750 rpm and played with the speed control .

i giggled a little when i found i could go from about 5 rpm clear up to who knows what speed with just a turn of the dial .. woo hoo i thought this is great .
then i thought ... gee it cant be to good to run the motor at 5 hertz or at 100 hertz to get that nothing to everything speed range , and i wonder how much power it loses when turning that slow .

then it dawned on me ... hmm if i leave the belt on that pulley it will cover 99% of the work i do without slowing the motor down so far i have to worry about over heating it ,.. or over speeding it so much i need to worry about the bearings or frying the motor .

but because i have the step pulley's i can use them to keep the motor running fast enough to keep cool when i want super slow , and not have to worry about over speeding it to run at my lathes intended 2400 rpm top speed
over all its a win win giving me a much more versatile speed range

once i get things finished up i'll post some pics , i still need to dig up a box for the controller , and buy a braking resistor and a remote potentiometer along with hook up the forward reverse switch and an on button , at the moment i just have it wired in roughly to test .. err play with it is more truthful

a tach is also on my list once funds permit

I went with the 602 for similar reasons. I also don't mind changing belts. All of the old heavy iron used step pulleys and back gears. The only thing I miss is the really slow speeds for low SFM materials and large diameters. I will probably convert to a metric motor and VFD next fall. Do I really need a braking resistor? There's no brake on the single phase motor..

Larry

my thoughts on the braking resistor , i have lived this long with no brake and have not needed one yet .

the key word here is yet , but i think having the ability to come to screeching halt with my e stop button could be a very good thing .
i think the extra $20-30 it is going to cost is cheap insurance against a possible crash or god forbid an injury .

some braking is available without a resistor as well

one function i found today that could come in handy is the jog function ... i can see this being used for a loosening a tight chuck

Braking: Maybe not needed on a lathe in this size range. But I am appreciating the braking features of my new VFD install as it does take a bit for a 60+ lb. chuck to stop spinning from 2000 rpm. Do I 'need' it? Maybe not, but I am enjoying it.

And as bosephus said, there is some braking available in the VFDs without the resistor.

i spent a full day using my lathe today and there really is no comparison to how the lathe preforms now and before the vfd and three phase motor .
everything operation is easier , and smoother .
i will be quite honest , if i had known then what i know now , i would have done this before buying a quick change tool post .

surface finish has improved dramatically not that i wasnt able to get a good finish before , its just that now its effortless .
drilling is much much easier , threading is much much easier , i can now thread at exactly the speed i want .
parting ... well i had thought parting was so much easier when i did the compound clamp improvement and added a qctp .
throw a smoother motor and the ability to fine tune the speeds and i can now part like a true champ ,.... 300% improvement .

a few hours into my day i started to wonder how much of the improvement was due to now having variable speed and how much of it was from having a three phase motor
so i set the vfd to 60 hertz and used the lathe as i was before and changed belts for the speed ,... there are a few who might doubt my next statement but....

i do believe at least 60% of the improvement i see has come from just the three phase motor it runs smoother and has twice the power

The VFD is the source of your extra power.

I'm new at this, and must be missing something. But it looks like the G0752 does have step pulleys. I know it has a VFD and variable speed. It has a 3 phase motor with a Delta brand VFD.
I just received mine the other day, and I must admit I'm curious about the difference between what the 752 has, and the mods made to the 602.

Looking at the two machines' pictures on the Grizzly web site, they both seem to have step pulleys. I'm genuinely curious about this.

6mmBR

What you are missing is the g0752 does not have the other half of the step pulley arrangement .
The two step pulleys on it would be the high speed side on the g0602 for 720 1200 and 2400 rpm

The g0602 has a third step pulley that gives you the low side speeds .. 150 300 and 560 rpm

If you look at the pic I included you will see the third step pulley

Understood. I wasn't sure if that was how it worked. I did see the different pictures, but I am new to all of this.

Thanks for the explanation.

bosephus said:

i do believe at least 60% of the improvement i see has come from just the three phase motor it runs smoother...

Click to expand...

Common statement from those who have added a 3 phase motor to their lathe. The 3 phase motor does run smoother, and eliminates some vibration that shows up as unwelcome patterns on the workpiece.