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Which Vfd For A Heavy 10


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I bought a nice old Heavy 10 with a 1 hp 3 phase Baldor motor. It looks to be an old motor, but ran well when I tested it. I will need to get a VFD and I wanted to run it by the more experienced guys here to make sure I get the right VFD. I know Hitachi makes one that works well for most and I believe Teco makes one that some have used. This is my first lathe and I have two things I am not sure about.

1) Since the Heavy 10 is a belt drive, is it worth getting a capacitor for VFD braking. I am guessing not, but to be honest am not sure. When I was looking at a gear head lathe it made sense. I am not so sure now. My thought is that a belt will slip if there is way too much torque put on the spindle for some reason and likewise if the motor would try to stop the spindle and it has a large mass moving, wouldn't it just slip as well. That's my feeble thinking, but not sure of the reality.

2) I thought I saw a Teco model with a potentiometer built in and that seemed to make some sense. I have the 12 speeds, but thought it could be nice to be able to dial in a speed if needed since I need to get a VFD anyway. Assuming cost is comparible, it seems like it would be nice to not have one more thing to have to interface/install. I would probably install something like a Machtach if I did that. To be honest, I am not sure I even need to worry about varying the speed, but if it doesn't cost much more, I also think why not.

Any help is appreciated. The lathe should be headed this way in a few days so I want to get my VFD ordered.



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So there are a number of VFDs that will work well, and a few things to consider. With a 1 Hp motor, you can use either a 120V or 240V single phase input VFD, you will bay a bit more for the former. You do not need a fancy VFD, but there are some features which may be desirable. Specific to you lathe and the use of an older motor, I probably would not push it as hard as a newer motor, so something like a frequency of something like 30-75 Hz and probably a carrier frequency of around 6Khz. Feature wise, I am not sure if you want it to operate with a drum switch, momentary buttons or keypad. The ones I have done have used momentary switches which select forward stop reverse and jog, plus a speed pot. A drum switch converted to handle low voltage VFD signals is also possible. So one setup would use 3 wire control, the other 2 wire. I always try to incorporate a do not start feature if you loose power or accidentally hit the drum switch. The features vary by VFD.

So which one. I have used mostly the Hitachi WJ200 and Teco, but also a host of others. A lot of people also use the Automation Direct VFDs, they have better manuals and very good tech support. The Teco VFDs come in many flavors, the older FM50 are lacking in many features, but work ok. The new replacement Teco VFD is the 510 series, and I have heard a few comparability issues with some motors. I think the N3 is much better,and maybe $50 more. The higher priced ones are more configurable and are sensorless vector control, so tighter motor control.

External braking resistors can only be added to certain models, if I recall the FM50 1 Hp does not have this provision. I think there is some benefit to an external braking resister, and on some you can set two braking rates. You would need to experiment to see the reasonably braking times.

If you decide on the controls, input voltage and price range, I can provide more specific recommendations. Having variable speed on a lathe is a big plus, you can always hit the desirable speed on the fly.



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Thanks Mark. I think the last VFD I was quoted was the Hitachi WJ200-015sf for $280. If there is one with better functionality for a $100 more, that is ok too. I figure it is best to get something now that I could use later should I decide to get a different lathe. I will run this on 240v single phase.

Right now the person had a wiring box fitted with breakers in it (you can see it sticking up below). I was thinking I would replace all of that with a VFD (not sure if that is the right thing to do or not) and I was also thinking of putting an emergency stop somewhere as it doesn't really have one right now.

So I would say my goal would be to:

1) Have something that supports the 3 phase motor (obviously)
2) Have something that supports an emergency shutoff switch
3) Have variable speed
4) Supports braking

I have a friend that is an EE and he can help me get it setup connection wise, but I want to make sure I get a VFD that works best for my purposes.

Here is the lathe. You can see the factory on/off - forward/reverse switch on the front of the cabinet. It is ok as is for me, I don't necessarily need the VFD to control that part of it unless there is a better reason to have it do it.


Thanks again.


Active Resistor
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Personally I would wait to order a VFD until you get a look at the tag on the motor. You want to order a VFD that is rated for the motors current (amps) or larger. Most probably a 1 hp VFD will work but some are borderline. I'm mostly familiar with the TECO products. The TECO N3 and similar 7300CV series are both nice drives and should be available online for about $250 + shipping for a 2hp version, a bit less for 1hp. These are all 220V input VFDs.


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As long as it won't hurt the existing motor, I would just as soon buy one that will handle a 2-3 hp motor in case I decide to move to a larger lathe later. I know that it isn't always good to buy too big, so don't know if that is an option or not.


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That helps, so if you are looking at a 2Hp VFD, that will give you options to use it on something else at a later date. so I would suggest the following:
1. Keep the current breaker box (I assume that it is the one on the wall behind the machine), the fusing for a VFD uses either fast acting (not dual element) fuse that are sized to the VFD rating, not the motor rating. So usually 30A for a 2Hp VFD. Alternatively one can use a 30A dual pole breaker (C curve), breakers protect the wiring not the device. But either should be fine, if a VFD fails, it is usually toast. The VFD input power is directly wired to the breaker/fuse. A higher rated VFD can always work with a smaller motor, the specific motor properties and overload parameters are programmed into the VFD.

2. The motor is directly wired to the VFD motor outputs, there is no switch gear used between the VFD and the motor. So you would disconnect all the high voltage wiring going to the forward reverse switch. If the spindle direction is a maintained switch (does not return to off position), then the forward position would make a contact from the VFD common or P24 to input 1 (forward), the reverse position would make a contact to input 2 (reverse). On the WJ200 I also use two diodes from input 1 and 2 going to input 7 (USP) which prevent the VFD from starting on power up if you have the spindle selector in the forward or reverse position. Any diode can work, but you need to get the direction correct, if you need two I can drop them in the mail. I can send you more detailed information and programming parameters if you go forward.

3. An alternative is to get a small control box and use a momentary switch for the start/stop and a sustained for direction, you can add a speed pot. This would use what is know as 3 wire control. You could also use the current forward reverse switch, and just add a momentary ON button and momentary OFF button. The speed pot can be located just about anywhere, it would be a 1K or 2K linear poteniometer.

4. Any of these VFD will work with an E-Stop or STOP button, this just interrupts the signaling to the VFD inputs, it is not a good idea to use it to interrupt power to the VFD.

control box.jpg

5. As far as VFDs, the WJ200 works well, the manual stinks, but they have a lot of features and I can provide some details on the programming and wiring. Teco makes good VFDs, the FM series is pretty minimal and has some limitations, I would go with the N3 or 7300 series, or the Automation Direct GS3 drive. They all do pretty much the same thing, I would just stay away from the generic Chinese eBay specials unless you are on a very tight budget and need no technical support.

6. What ever you decide, I can provide a simple schematic, programming and suggestion on parts if you go forward.


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Thanks Mark.

So looking at the Teco N3, it looks like I could potentially just use it for everything but the emergency stop? The electrical box you see is actually mounted off the back of the lathe, not on the wall. That is a photo from where I bought it, not my shop. I can move it or do whatever I want as I need to still run a drop to where I put the lathe, but I was thinking that if I can use the VFD itself in the same location (or mount next to it), it really would be easy to just use the start/stop, forward/reverse, and pot on the VFD itself. And then just wire in an emergency stop somewhere.

One thing I don't understand on the other VFD's for sure is do the arrows control the frequency or would I have to add a pot? I don't care how I have to change the pot settings so long as I can do it easily. If I can do it all on the device as mentioned above, then I am back to wanting the best quality and ease of use. The prices are all close enough that price won't be deciding factor.

I don't mind building a control box like the one you linked, but also don't see an issue just using what is on the VFD if it makes sense. Is that reasonable or is that a bad idea? Again, it's not a cost issue if it is better to have separate control box. I am just thinking less parts makes for an easier install. The ultimate goal of course it to make the the easiest to use in context of using the lathe.

I will probably get a 3hp rated VFD no matter so I have room to grow.

Sorry for all of the questions, I just want to make the most informed decision.


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Well either the Teco N3 or the WJ200-22SF, way oversized but should not be an issue as long as you set the motor parameters correctly. I prefer the WJ200, just because I have used a lot of them and never had an issue with them, but the N3 is one of Teco's better quality units. They all have extensive abilities, you will be using maybe 1% of the programming parameters. Sometimes it is easier to buy a less expensive VFD (1 Hp) and sell it with the lathe, and then upgrade to a bigger one with a net machine. On mounting, doesn't really matter where the VFD goes as long as it is away from the chips and has some cooling. I mounted mine in the machine cabinet, but you could also mount it behind the machine on the wall either in the disconnect box or a separate enclosure. A small box would need some screened vents, should be fine with passive ventilation. But the N3 may be a bit easier to control from the front panel, but it is not going to be convenient.
A bit of a discussion on the WJ200 build vs the older Teco JNEV and the N3. It seems everyone has a slightly different opinion.

The WJ200 is a PTA to use from the front panel and does not have a rotary speed pot (they do have a remote panel with one), I would go with remote switches and speed control. I often change the speed as I am machining a diameter, since the SFM changes with the diameter. You do not want to be reaching over the machine to push contact switches. Just too dangerous and awkward. I think you could build a little pod like the link to the mill shown above and be much better off for very little additional cost. The pod can be mounted in the front of the machine or to the side vertically, or anywhere which is comfortable. I have used Drives Warehouse in the past for VFDs, seem to have very good pricing and they are mainstream. https://www.driveswarehouse.com/wj200-022sf-2527

No problem with the questions, we all go through this process. After you have done your first install, it becomes much easier the next time.


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Thanks. Thinking about it, I think the idea of just selling the VFD with the lathe if I ever did sell it would be fine.

I will order the Hitachi WJ200-015SF.

I will find a control box and switches for the other items and install them on the front or side of the machine as you mention. I will go ahead and get a capacitor for braking as well.

I am sure I will have other questions, but I certainly appreciate your help.
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Ok, so continuing my quest to setup the electrical for my lathe, I have looked at various setups and I think I have in mind what I would like to do with the layout of switches, etc. I have outlined it below. I have been looking at switches on Automation Direct, but I am not sure if I need NO or NC switches and which ones in which locations if I need both. I want to make sure my parts list is correct and complete before I make my order.

I diagrammed these as I am a visual person, so if anyone has a better idea, please let me know. Some of the main things I wanted was an overall Power On/Off Switch for the entire lathe (with lighted indicator) as well as an emergency stop separate from the main start/stop buttons.

I plan to put a power on/off (with visual indicator) and E-Stop in a box next to the box holding my VFD on the wall. I suppose it there was a box to hold the VFD and these switches all in one, that would be ok too.

Then I will go with a box connected to the lathe which has separate buttons for start and stop. A switch for Fwd/Rev, a Pot and an RPM readout.

Here is a simple diagram of what I am thinking. Does this seem reasonable? And what types (NO or NC) do I need?



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Look in the downloads for SB under "how to". There is a complete set up there for an automation VFD that I got for myself.