Need Help With Decision on New Lathe and VFD

BB 777

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Hi all, I’ve been a member for a while, but I think this is my first post. I’m looking at a new Taiwan-made 1440E lathe from Eisen. I want to go with the 3 phase 3hp motor, but there are 2 options. The less expensive option is a 2-speed motor 4p,6p. Oddly, the more expensive option is a 3hp single speed motor. I’m no electrician, but from what I’ve read on this site it can be difficult getting a VFD to work with both speeds. So, I have a few questions:
1. Would it make sense to go with the less expensive 2-speed motor, try to get both speeds working and if that doesn’t pan out, just connect to the high-speed portion? At that point would the result be the same as if it was just a single speed motor?
2. These lathes also have little 3ph coolant pumps. Does that complicate things?
3. Is there a resident expert on these boards who helps people out with their VFD installation and re-wiring?

I’ve already looked through most of the threads on VFD use on 2-speed motors....and I saw a lot of differing opinions, sometimes conflicting opinions. At this point, the most important question to me is #1. Clarity on that will help me make my purchase decision.

Thanks in advance for your assistance.

btw I live in Canada and I’ll need to convert from single to 3-phase as the lathe will be in my house. I won’t receive the lathe until April, but I’ll be making my purchase decision in the next few days to a week.
 
I would get the two speed motor OR the 3ph motor and put a VFD on it.
18 speeds 50 to 2000 is a good situation on a lathe like this.
I would want an inverter duty motor which the 3ph motor supplied with it is probably not.
The extra expense of the VFD and how to mount the controls, etc is a complication that you might not wish.
The single speed motor is probably beefier having a slightly better set of windings and more iron.
That is usually the basis for a change in the motor price.
3 Hp should be more than enough to run this lathe for a hobbyist.
I am getting lathe envy now.
 
I would go with the single speed motor, there is no reason to use a 2 speed motor and try to set it up to use both speeds of the motor. I have done quite a few VFD systems/installs and for the most part I have had problems with dual speed motors and VFD's with the exception of constant Hp motors, which I run on a single speed. Constant Hp motors, I use the highest pole setting, and not the high speed winding. The motor is already rated for the high speed RPM, you typically get more torque with the higher pole setting, you overspeed the motor to its high speed rated RPM. I would check with Eisen as to the poles and if the motor is constant Hp or Hp at each speed, and then give some thought to it vs. the price difference. They do not list a dual speed for the US version of the 1440E, and typically dual speed is more expensive. The VFD pretty much does all the speed adjustment so you only need to use a single motor speed, most likely you will use just a few headstock speeds. On VFDs, I would recommend either the WJ200-022SF or the Yaskawa CIMR-VUBA0010FAA, you will need a braking resistor (47-50 ohms, ~500W).

I previously outlined some guidance on a simple basic VFD install for the PM-1440GT which is the same base model as the Eisen 1440E, but with a larger 2" spindle bore and a few other features. I can't say the wiring is identical, as even within the same model there are different wiring specifications, in particular with Canadian models. Previous export machines to Canada required additional safety features. I do update my files periodically, so when you get your lathe send me a PM and I can send you the most recent version. The information is provided is for informational purposes only as a guidance, you assume all responsibility for adaptation to your lathe and use.
https://www.hobby-machinist.com/thr...he-contactors-to-switch-the-vfd-inputs.64965/
You can compare the specs. of both lathes
https://eisenm.com/products/eisen-1440e-14-x-40-precision-engine-lathe-made-in-taiwan-220v-3ph
https://www.precisionmatthews.com/shop/pm-1440gt/

On the coolant pump, I would either just skip it (I have yet to see anybody use flood coolant on these smaller manual lathes), or just switch out the coolant pump for a single phase model if you want to use it. The pumps are easily replaced and run around $100 with US shipping, just match up the pump dimension specs. I recommend an air system with low volume drip/mist coolant, you can use an air solenoid to trigger the coolant.
https://www.ebay.com/itm/MC-8180-Co...inder-Mill-1-Phase-180mm-115-230/171369845473
 
Wow. Thanks so much for your quick and thorough replies. I’m going to get back in touch with Eisen and see if I get some answers to the questions posed.

Update: I just talked to Jason at Eisen.

The two speed 3 phase motor is as follows:
The high speed is 3hp with 4 poles
The low speed is 1.5hp with 6 poles

The single speed 3 phase motor is 3hp

The coolant pump is 3 phase in each case, but they can replace it with a single phase motor for me. If so, I just want to make sure I can run the pump using the switch on the control panel. Not sure what they have to do with the wiring/electronics in that case.
 
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I would go with the single speed motor if the price difference is close, as mentioned the I have had problems with VFDs and 2 speed motors. The alternative is replacing the stock motor, but not really practical. If using the 2 speed motor, you would use the 4 pole setting.

On the coolant pump it is a simple rewire of the coolant contactor overload relay so you would use 2 of the 3 phases coming in, but as mentioned, flood coolant on a manual lathe is very messy. So give it some thought as to the practicality of it. I use it on my horizontal metal bandsaw, but would not consider it in a lathe unless I was machining exotic metals.
 
Thanks again MKJS. Just the kind of advice I needed. As soon as I get a copy of the wiring diagram and a picture of inside the electrical box I'll post them.
 
I don't know much about Eisen but looking at the web page some variations seem to emphasize that they are "Made in Taiwan" while others don't say that. Specifically it doesn't say that for the 2 speed motor versions but does for the single speed 3ph and the single speed 1ph. It might just be an omission or it might be the reason the 2 speed is less expensive.

https://eisenm.com/collections/engine-lathes
 
I don't know much about Eisen but looking at the web page some variations seem to emphasize that they are "Made in Taiwan" while others don't say that. Specifically it doesn't say that for the 2 speed motor versions but does for the single speed 3ph and the single speed 1ph. It might just be an omission or it might be the reason the 2 speed is less expensive.

https://eisenm.com/collections/engine-lathes
Thanks for the tip. I’m going to buy the 3hp 3phase single speed. I was told the 2 speed is less expensive because it is less popular with hobby machinists. Probably because you need real 3 phase power (as in commercial wiring) or a rotary phase converter in order to have it work properly.
 
I would go with the single speed motor if the price difference is close, as mentioned the I have had problems with VFDs and 2 speed motors. The alternative is replacing the stock motor, but not really practical. If using the 2 speed motor, you would use the 4 pole setting.

On the coolant pump it is a simple rewire of the coolant contactor overload relay so you would use 2 of the 3 phases coming in, but as mentioned, flood coolant on a manual lathe is very messy. So give it some thought as to the practicality of it. I use it on my horizontal metal bandsaw, but would not consider it in a lathe unless I was machining exotic metals.
MKSJ, Here are some pictures Jason at Eisen sent me. Are they useful in determining the conversion to VFD?IMG_20190122_110608.jpgIMG_20190122_110437.jpgIMG_20190122_121554.jpgIMG_20190122_121603.jpg
 
Another update. Eisen is going to install/rewire for a single phase coolant pump in my machine, solving that problem. Per recommendations, I’m going to go with the single speed, 3phase motor option...it’s not much more expensive.
 
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