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.
 

tcarrington

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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.
 

mksj

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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/threads/pm-1440gt-basic-wiring-changes-for-using-the-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-Coolant-Pump-for-Lathe-Grinder-Mill-1-Phase-180mm-115-230/171369845473
 

BB 777

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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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mksj

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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.
 

BB 777

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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.
 

CluelessNewB

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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
 

BB 777

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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.
 

BB 777

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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.
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
 

BB 777

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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.
 

mksj

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It is pretty much the same as the PM-1440GT (it is the same manufacturer, the specs are vendor specific). I would go with the basic VHD 1440GT wiring directions posted previously. The directions are based on using the WJ200-022SF VFD, it can be purchased from Eisen or https://www.driveswarehouse.com/ . You will need a braking resistor, this and VFD enclosure suggestions are in the attached document, availability my be different in Canada. This is a general guidance as well as the suggestions for the basic VHD1440GT wiring directions. If you are unsure on any of the electrical's, get an electrician to check your work. Also in Canada, there are different code requirements, if I recall they require a power disconnect at the machine/VFD enclosure along with proper fusing.

I am constantly tweaking the VFD parameter files, when you get ready to program the VFD, send me a PM and I will send the current iteration for the WJ200.

Be aware that when rewiring the lathe with a VFD, the motor must be directly connected to the VFD, contactors are not used. The VFD motor output will sense overload/short conditions. The VFD input power should be fused along with a power disconnect. You need to provide 240VAC power to the lathe control box for the transformer power and for the coolant pump, but you could reduce the size of the control box fuses since they are no longer supplying power to the motor via the contactors. Single phase power to the lathe control board for the transformer per your schematic would be connected to terminals R and S which go on to connect power to the transformer. On the coolant pump power would be supplied through the contactor, you would need to see which terminals the overload relay is connected to and which coolant motor wires are connected (should be R and S).

You need a dual pole brake switch to replace the stock one, so when depressed it breaks power to the contactors and the other pole issues a free run command to the VFD. Otherwise the VFD will fight the foot brake when applied.

This all assumes you have some basic familiarity with electrical wiring and know what you are doing.

This is the PM-1440GT control board, you can see it is the same, the earlier models had a cartridge fuse holder.
system.jpg
 

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BB 777

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Mark, I really appreciate your thorough replies. Thank you very much for taking the time and effort to be so helpful. The lathe won’t be shipped until April because it’s bloody cold here. In the meantime I’ll be doing all the research and preparation to be ready...including finding local electrical expertise. Anyway, I can’t thank you enough for sharing your knowledge and advice.
 

BB 777

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Just wanted to update anyone interested in my new lathe. I’m back from holiday and just wired the funds to Eisen yesterday. The person I always talk to, Jason, has been fantastic to deal with. He takes the time to answer all my questions and is just a nice person to deal with. My next job is to get busy and order all the stuff that Mark has recommended. I won’t take delivery for another month or so..it still looks like the middle of winter here. I’ll try to post as much as I can so people can follow along my journey. Cheers.
 

BB 777

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Yes it is. Almost the identical Taiwan machine as the PM 1440GT...just minus 3 gears (which I won’t need with a VFD) and the GT’s larger spindle, which would be nice. I probably would have been very tempted to get a heavier Eisen machine if my shop was at ground level, but no such luck. In any case, I think it’s going to be a great machine.

There is still quite a bit of snow where I’m at. I won’t pick it up from Montana shipping outlet until the snow is gone. Then I have to get it into the basement (ugh)....and think it will take a while to get it rewired. I’d love to give you an update much sooner, but it’s a big project for me. I’m building a spreadsheet with everything I’m going to need, vendors, costs, notes etc. to do the rewiring/added components. I’ll share that once I’ve had it validated. So far my experience with Jason at Eisen has been great. Very nice/helpful so far.
 

Lucky Liverider

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Yes it is. Almost the identical Taiwan machine as the PM 1440GT...just minus 3 gears (which I won’t need with a VFD) and the GT’s larger spindle, which would be nice. I probably would have been very tempted to get a heavier Eisen machine if my shop was at ground level, but no such luck. In any case, I think it’s going to be a great machine.

There is still quite a bit of snow where I’m at. I won’t pick it up from Montana shipping outlet until the snow is gone. Then I have to get it into the basement (ugh)....and think it will take a while to get it rewired. I’d love to give you an update much sooner, but it’s a big project for me. I’m building a spreadsheet with everything I’m going to need, vendors, costs, notes etc. to do the rewiring/added components. I’ll share that once I’ve had it validated. So far my experience with Jason at Eisen has been great. Very nice/helpful so far.
BB, I too just purchased the Eisen 1440E 3ph single speed, I've been following your convo with Mark and the wealth of information he has shared with you...Post some pictures when she arrives, Im waitng for another 2 weeks for mine.
 

BB 777

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Lucky Liverider, you made a wise purchase decision. . I’ll definitely be posting pictures as I go through the process.
Mark is very popular on these boards and it’s obvious why. He’s been very, very helpful to say the least. I also picked up some great ideas from jbolt’s thread on his 1440GT build. I’m really looking forward to getting this machine...Im sure it’s going to be really nice. Lots to do before It makes chips though. Good luck with yours. I’ll be watching your posts.
 

Mike Forsyth

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Just a quick question - Do you have 3 phase available? Residential areas and many farms only have single phase. Industrial areas have 3 phase in Alberta.
 

bretthl

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"Inverter Duty" or "Inverter Rated" is a marketing term. Ignore it. You will spend hundreds of dollars for this term. All modern three phase motors will handle power supplied by a VFD with no problem. Especially on a small hobby lathe.
 

mksj

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There is inverter duty or rated, and what is known as inverter/vector motors. There are some differences depending on the application. Typically inverter rated motors have a higher voltage/temperature rating for the internal motor wiring, so less susceptible to insulation breakdown which can occur with the voltage spikes generated by the VFD's. This is also exacerbated with very long motor cables. The issue why this is not really a factor for most non-inverter rated motors is that most are dual rated for 230/460V and wiring insulation is already rated at something like 1000V. If you a running the motor at 230V with short motor cables, it pretty much is not a problem. This may only be an issue with older motors say 20+ years old or working under extreme duty/temperature where the insulation is deteriorating. Lowering the carrier frequency in older motors diminishes the spikes, one can also use an inductor/reactor which also decreases the spikes and smooths the voltage. Most newer 3 phase motors are designed with high voltage/temperature insulation magnet wire, I believe it is something in the 1000-1500V range. Many newer 3 phase motors are inverter rated at no additional cost, i.e. they are using better insulated magnet wire.

On a separate note, there is a difference in how motors will perform (torque and Hp) over a designed speed range and also a maximum RPM that motors are rated to. You will often see a CT (Constant toque) rating on motors and this is the speed range that the motor will maintain constant torque below a base speed (60 Hz). Older 3 phase motors this may be 2:1 so the constant torque would be 30-60 Hz, an inverter rated motor it is typically 10:1 so 6-60 Hz, and inverter/vector motor it is 1000:1 or higher so full torque down to 0 Hz. So if you are operating the motor down to say 15Hz, you would be better off with an inverter rated or vector motor. On the Hp end, inverter rated 4P motors are typically good to run up to 120 Hz (2X) their base speed, but Hp will often diminish above 90 Hz. A true inverter/vector motor maintain full Hp typically to their maximum speed which is around 3X their base speed.

Last but not least their is motor cooling issues, TEFC motors have a fan attached to a back shaft. The fan air flow is speed dependent and efficiency of cooling becomes an issue outside of an operating range of ~15-90 Hz. Dedicated inverter/vector motors are typically TENV (no fan) or TEBC (separate electric fan) so cooling is not an issue over the full speed range.

Performance wise if you are using the motor over a narrow speed range of around 20-80Hz, you won't see much difference, operating over a wider speed range, the difference is much more significant. On mills and lathes with factory VFD systems, the motors are often operated over a 10 fold speed range, so my mill motor operated from 20-200 Hz. This would be a problem for a standard motor. Also speed stability of an inverter/vector motor I have found to be better than a non-inverter motor, but a non-issue in most applications.
 

BB 777

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Lucky Liverider, you made a wise purchase decision. . I’ll definitely be posting pictures as I go through the process.
Mark is very popular on these boards and it’s obvious why. He’s been very, very helpful to say the least.
Just a quick question - Do you have 3 phase available? Residential areas and many farms only have single phase. Industrial areas have 3 phase in Alberta.
I just have single phase available as far as I know....I’m assuming single phase
 

bretthl

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If you are running at 20 Hz you should be be in gear box low in the first place so torque should not be an issue. If you are tapping or making threads you surely don't need maximum torque. I can't prove it but I would think it best not to exceed the maximum spindle rpm intended for the lathe? So if the pulley diameters in the VFD setup are close to the original then no reason to run over ~60 Hz?

If you are buying a 3 phase motor for your lathe, why would anyone go with a TEFC "explosion proof" motor unless you were working the machine shop in a gas plant? I have heard some talk about rigidity due to the cast iron frame. Why? That is simply not needed. A rolled metal frame is beyond sufficient. I think open frame drip proof will get the job done and operate sufficiently cool.

What I want to know (and this is off topic of course) is it better to go with a lower or higher resistance on the break resistor (given the same power rating)?
 

mksj

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If you look at factory installed VFDs, they generally reduce the gearing/pulley ratio to 2 or 3 speeds, the rest of the speed range is handled by the motor. The motor is generally oversized by 1.5-2X so that the performance (Hp/Torque) is similar to the non-VFD multi-speed version. The goal is not to have a faster spindle speed, but to adjust the ratios for optimal performance over the desired spindle speed range, so you have a mechanical advantage when over speeding the motor and changing the drive ratios to give the same spindle speed as a 60 Hz. motor. So if you have a 2 Hp motor 60Hz with a 1:1 final drive ratio vs. a 2 Hp motor at 120 Hz with a 2:1 final drive ratio, you have a mechanical advantage of 2X with the latter with the same Hp. You need to change the drive ratio when using a VFD. When you go below the motors base speed the torque is flat and Hp drops in a linear fashion, but you loose the mechanical advantage if you are running the VFD at say 20 Hz instead of 60 Hz. In practice most VFDs can provide up to around 180% torque for up to 1 minute, beyond that you will get an over current fault if you exceed 100% of the output amperage.

TEFC, TENV and TEBC are pretty much the industry standard for motors on lathes and mills in the 2-5 Hp range, and larger. TENV and TEBC are primarily used in VFD driven motors. The cooling will be better at speed extremes due to the mass/design, and there is no risk of chips/swarf entering the motor with a totally enclosed case.

Regarding a brake resistor, there is usually a range of resistance specified by the manufacture based on the size and voltage of the VFD, and it is also dependent on the type of machinery being operated (momentum and frequency of braking) and if the braking is static or dynamic. I have attached the recommendations for the Hitachi WJ200. Bigger/lower resistance is not necessarily better, the lower the resistance the more voltage/current can be dissipated over a shorter period of time. This is at the expense of a decreased duty cycle, or frequency of stops over a given time period. Since in mills and lathes, there are not a lot of stop start cycles and there is no static brake hold, usually being at the lower end of the recommend resistance is preferable. So something like the 2 Hp 200V WJ200 I usually recommend something in the 50-75 Ohm range for a braking resistor. Since common resistor sizes are 47 Ohm and 68 Ohms, I recommend using the 68 Ohm. On the 3 Hp 200V WJ200 either 35 or 47 Ohm resistors are commonly available sizes. With high braking duty cycles the resistors can get very hot, and there is usually a thermal oveload contact built into the braking module provided by the VFD manufactures, in mills and lathes this is not needed because of the low duty cycle time.

290819
 

BB 777

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I’ve reviewed Mark’s (mksj) documents re: VFD conversion components and wiring and I have done up a diagram showing as much detail as I could fit in. My goal was to make sure that I understood the components and and how they are wired together. Details such as how the contactors are wired to each other and exactly how wires are connected to switches have been left out. Otherwise everything is in the attached PDF file. There were a few places where I wasn’t sure, so I just took my best guess. As they say, a picture is worth a thousand words, so I’m hoping that I can get some feedback re: where I might have misunderstood Mark’s information.
 

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bretthl

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I’ve reviewed Mark’s (mksj) documents re: VFD conversion components and wiring and I have done up a diagram showing as much detail as I could fit in. My goal was to make sure that I understood the components and and how they are wired together. Details such as how the contactors are wired to each other and exactly how wires are connected to switches have been left out. Otherwise everything is in the attached PDF file. There were a few places where I wasn’t sure, so I just took my best guess. As they say, a picture is worth a thousand words, so I’m hoping that I can get some feedback re: where I might have misunderstood Mark’s information.
I think you can eliminate a lot of complexity by taking advantage of the USP and ESD features built into the WJ200. This is how I rigged up my VFD. Not shown is a breaking resistor I recently added. I do not use a coolant pump.

290984
 
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BB 777

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Thanks Bretthl. You are so far ahead of me, it’s going to take time for me to catch up. I’m committed to learning this stuff though. Installing a Roush supercharger in my 2013 Mustang was difficult, but it was more mechanical focused than electrical...more up my alley.
 

mksj

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One issue with the USP is that if the lathe is powered up with the E-Stop or cover switch open, if the spindle switch is in a run position the lathe will restart when either of those are reset. A latching relay always needs to go through the spindle stop position to reset. I use USP, but only in conjunction with another interlock system. Redundancy of systems, I have also had spindle switches break and switches can fail either NO or NC.
 

bretthl

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One issue with the USP is that if the lathe is powered up with the E-Stop or cover switch open, if the spindle switch is in a run position the lathe will restart when either of those are reset. A latching relay always needs to go through the spindle stop position to reset. I use USP, but only in conjunction with another interlock system. Redundancy of systems, I have also had spindle switches break and switches can fail either NO or NC.
If power is applied to the VFD with the motor control switch in the FWD/REV position, the USP function will prevent the lathe from starting until the motor control switch is returned to neutral.

If the lathe is shut down using the ESD (E-Stop) the lathe will not start until the ESD and the VFD are reset. If the motor control switch is in FWD/REV at that point then lathe will start. You can't engineer out all of the idiots.

I have not tested the scenario where the ESD is tripped before power is applied to the VFD with the motor control switch in FWD/REV. I suspect that if the operator resets the ESD (with the motor control switch in FWD/REV) the lathe would not start until the motor control switch is cycled back to neutral. I will test that in a few weeks when I return home.

I like your new lathe. Awesome. How did you get QMT to order that machine for you?
 

Lucky Liverider

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Lucky Liverider, you made a wise purchase decision. . I’ll definitely be posting pictures as I go through the process.
Mark is very popular on these boards and it’s obvious why. He’s been very, very helpful to say the least.

I just have single phase available as far as I know....I’m assuming single phase
I only have 1ph; going with a Teco E510 VFD
 

Dabbler

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late to the thread... sorry. I've converted my mill and surface grinder using the Teco 510 VFD. Happy to help if you need additional info. Not too far away, either.
 
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