VFD

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Rat Bastid

Rat Bastid

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I need VFD for my lathe. I’m looking at a 3 HP 10A model. Is that going to be enough for a 2 HP lathe as far as the amps go?

I know less than nothing about these infernal VFD’s but I have to have one.

I don’t want to buy two of them so I need to get the right one the first time.

TIA
 
You can't go wrong with a VFD spec'd over what the size of the motor is.
I assume this is a 3-phase motor....you just need to set all your parameters according to the motor requirements.
 
Should be fine... I've been running a 3HP VFD on my 2HP mill for about three years now... It's been flawless... However some guys like to use the VFD as a speed control which it is able to do... But if you really plan to do that you need a VFD rated motor or the motor will probably overheat & fail...

FWIW this is the one I bought.. Cheap... Works fine..
Amazon product ASIN B07D76365G
My small lathe is 2HP single phase which is nice...

I run a rotary phase convertor for my big lathe because VFD's generally don't do well much above 3HP & my big lathe is 7.5HP
 
1WildRT said:
Should be fine... I've been running a 3HP VFD on my 2HP mill for about three years now... It's been flawless... However some guys like to use the VFD as a speed control which it is able to do... But if you really plan to do that you need a VFD rated motor or the motor will probably overheat & fail...

My small lathe is 2HP single phase which is nice...

I run a rotary phase convertor for my big lathe because VFD's generally don't do well much above 3HP & my big lathe is 7.5HP
Click to expand...

I was hoping to use the VFD as a speed controller. Maybe not but I’d like to.
 
Is it more cost effective to use a VFD instead of just getting a single phase motor? Be gentle, I know nothing here. LOL
 
1WildRT said:
Should be fine... I've been running a 3HP VFD on my 2HP mill for about three years now... It's been flawless... However some guys like to use the VFD as a speed control which it is able to do... But if you really plan to do that you need a VFD rated motor or the motor will probably overheat & fail...

FWIW this is the one I bought.. Cheap... Works fine..
Amazon product ASIN B07D76365G
My small lathe is 2HP single phase which is nice...

I run a rotary phase convertor for my big lathe because VFD's generally don't do well much above 3HP & my big lathe is 7.5HP
Click to expand...
That is really cheap....as in a great price. :thumbsup:
 
RustyRatRod said:
Is it more cost effective to use a VFD instead of just getting a single phase motor? Be gentle, I know nothing here. LOL
Click to expand...
I don't know about USA....but 3-phase motors are cheaper and more efficient than single phase equivalents.

Besides, a traditional single phase motor requires a 'start switch' or second winding to initiate rotation and get up to run speed.
 
kiwigtx said:
That is really cheap....as in a great price. :thumbsup:
Click to expand...
Yeah, when I bought it I didn't have high expectations but the reviews were good & being Amazon I knew I could return it.... But It's been great... But again, I don't use it for speed control just three phase power...
 
Stay away from Chinese garbage VFDs. They are junk. Yes, you might get lucky and get one that doesn’t fail, but you’re rolling the dice. Go with US brands like Parker or Automation Direct.
 
Yeah, the big lathe I jumped into before I figured out the power... I'd had such good luck with a small VFD... I thought I could do the same for the big lathe.... First VFD wouldn't even start the motor... Then I tried a DPC it started the motor but the motor didn't sound happy.... The RPC works great but it cost more than I paid for the lathe....
 
I typically use Danfoss and Allen-Bradley........my clients expect to pay big money.....and they are never disappointed. :lol:
 
Righty Tighty said:
Stay away from Chinese garbage VFDs. They are junk. Yes, you might get lucky and get one that doesn’t fail, but you’re rolling the dice. Go with US brands like Parker or Automation Direct.
Click to expand...
I know three other people who've bought the same cheap VFD as me since I bought mine.. They've all been good.... A Parker the same size as my $90 Chinese VFD is $1100.... I'm sure the Parker is a better unit, but for a hobby lathe I think I would roll the dice...
 
As far as the VFD rated motor, just use a small external cooling fan blowing through the existing motor. Have it run whenever the motor runs. That will solve your problem. Running at a lower speed the motors own fan just doesn't move enough air to keep it cool.

Cley
 
89on35s said:
As far as the VFD rated motor, just use a small external cooling fan blowing through the existing motor. Have it run whenever the motor runs. That will solve your problem. Running at a lower speed the motors own fan just doesn't move enough air to keep it cool.

Cley
Click to expand...
When a motor is running well below rated speed, and accessory fan on the back is the best option. I have done that a few times.

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I'd used VFDs for the better part of 20yrs. From a single 4HP unit to a 60hp unit running an entire production line of 10 3HP motors. [All Danfoss & Allen Bradley] We used the VFDs as speed controls.
The most important thing is when you're programming the drive, input all the specs from the motor you can.
 
IfItsGotWheels said:
I'd used VFDs for the better part of 20yrs. From a single 4HP unit to a 60hp unit running an entire production line of 10 3HP motors. [All Danfoss & Allen Bradley] We used the VFDs as speed controls.
The most important thing is when you're programming the drive, input all the specs from the motor you can.
Click to expand...
I previously stated VFDs generally don't do well above 3HP... I should have specified VFDs don't do well generating the third leg of three phase power above 3HP... They are great for speed control.... I've worked with AB stuff in plants, definitely better equipment but it comes with a much higher price....
 
I can tell you that in larger installations when a is being VFD being used to convert to three phase service in continuous usage that the recommendation is to double the hp rating of the VFD to the HP of the motor. It’s a safe rule of thumb to go by, but those were also in 20 hp and larger installations.
 
1WildRT said:
I know three other people who've bought the same cheap VFD as me since I bought mine.. They've all been good.... A Parker the same size as my $90 Chinese VFD is $1100.... I'm sure the Parker is a better unit, but for a hobby lathe I think I would roll the dice...
Click to expand...
That’s great, I personally haven’t had great luck with the Chinese units. And yes, Parker is expensive, but a 3HP VFD from Automation Direct is $250.
 
Righty Tighty said:
That’s great, I personally haven’t had great luck with the Chinese units. And yes, Parker is expensive, but a 3HP VFD from Automation Direct is $250.
Click to expand...

In your experience do the Chinese units fail relatively early on or do they go for say, a year or so before they crap the bed?
 
Dfr360cuda said:
A VFD IS a speed controller. Variable Frequency Drive. Only way to control speed on an AC motor. We’ve got many where I work. As big as 1500 horsepower.
Click to expand...
Just curious what voltage those are running on. The biggest I've been around have been 250hp on 480 and that pair with power filters took up a 12 feet of wall space.
 
Rat Bastid said:
In your experience do the Chinese units fail relatively early on or do they go for say, a year or so before they crap the bed?
Click to expand...
The two that I have had fail, failed almost immediately. And my friends who’ve had failures usually experienced them within a year. That was enough consistency to sway me away from them.

I should specify that these were just cheap no-name Chinese VFDs from eBay. Not the model mentioned earlier sold on Amazon.
 
We have a VFD on a 200 HP pump at work(petroleum plant). It replaced a huge worthington diesel engine and was designed to be variable speed. It can run anywhere from wide open to just barely turning.
Old engine looked very similar to this one but was on a concrete pad. Last time we had it rebuilt there was only a couple guys in the country who specialized in them. The dude looked to be about 80 but damn if he didnt get it done.
 
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