AC VFD vs. DC Variable Speed

[Chazz]

Greetings, both my Lathe and Mill came with .75 HP motors and I am thinking of beefing them up to 1HP variable speed. My search skills don't seem to be working right to find any threads regarding the above, because I'm sure this must have been discussed already, if not a lot?

From what I've read so far, both can provide good torque at low RPM's. So is it really a matter of cost? Either way, I'd be looking at a turnkey solution as I have nil electrical skills.

Thanks for any pointers to threads or ideas.

Chazz

 

[Stan]

A question that is rehashed many times on all the boards. There are strong arguments on both sides. For many people, cost is the primary concern so what is available at the right price frequently determines what is used. If good used three phase motors are available for low cost in your area then a three phase converter is inexpensive but requires some knowledge to set it up.
Likewise for DC motor and controller availability but easier to set up.

Motors are heavy and expensive to ship so you want to buy locally if possible.

DC motors are constant torque at all speeds which is not the case with the variable speed three phase motors.

Like all products, there many levels of quality and getting the best quality at the lowest price requires some advance knowledge.

 

[John Rudd]

AC vfd gets my money...I have one on my Chester 9*20...Never looked back.

A dc motor has wearable parts like the comm and if you overheat the motor there's a risk of the magnest losing their magnetism...

3ph motor....just bearings I guess...

 

[Noitoen]

Ac motors, and VFD's, correctly programmed are also constant torque as with dc. The only problem is that, for continued low speed operation, far from the motor's nominal speed, the motor's fan does not cool the motor enough so, some forced cooling should be added (if necessary).