# Motor recommendation for Hercus 9" AR lathe



## Gr1m3eaper (Apr 6, 2017)

Hey guys after searching for a while ive settled on buying a 9" Hercus lathe i found on gumtree. Ive had a look at it in person and its in amazing condition, all the bits are included the slides and ways move very smoothly. The only issue is it has a 3 phase motor with it, i want to replace it with a single phase so i dont have to buy an inverter. Ive been having a look at motors and i think this one should be suitable, what do you guys think? Ill attach some pics of the lathe and motor


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## Bob Korves (Apr 7, 2017)

It is cheaper to buy a VFD than it is to buy that motor.  Besides that, the lathe will run smoother with the three phase motor, and you will be able to control the spindle speed with the VFD.


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## Rustrp (Apr 7, 2017)

What's the condition of the existing motor, and the HP? My experience with three phase is I've always had it available. I know there's pro's and con's to VFD's but the pro's weight heaviest and the acquaintances who have had to use them only complained about the extra cost along with wiring them.


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## Gr1m3eaper (Apr 7, 2017)

Ive had a look online and the cheapest VFDs or inverters are at least $150 and thats for the cheapy models so its looking a lot more cost effective to go single phase. As for having three phase power im living with my parents and siblings so only got a small workspace, ive enquires about getting three phase power wired but its not worth it at the moment, better to invest in it when i have my own place


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## Bob Korves (Apr 7, 2017)

Gr1m3eaper said:


> Ive had a look online and the cheapest VFDs or inverters are at least $150 and thats for the cheapy models so its looking a lot more cost effective to go single phase. As for having three phase power im living with my parents and siblings so only got a small workspace, ive enquires about getting three phase power wired but its not worth it at the moment, better to invest in it when i have my own place


I recently bought a 3HP VFD on eBay for $109 including freight.  A 2HP VFD was $104 at the same time, about 6 months ago.  Prices are going down, not up.  There will be wiring involved with installing the VFD, but there will not be the additional work of adapting and installing a new motor to the lathe.
http://www.ebay.com/itm/DELTA-VFD01...844968?hash=item3d377b7d68:g:DlYAAOSwTM5Y5BZX  (used)
http://www.ebay.com/itm/DELTA-VFD01...844968?hash=item3d377b7d68:g:DlYAAOSwTM5Y5BZX  (used, guaranteed)
http://www.ebay.com/itm/2HP-1-5KW-V...526278?hash=item28205aff06:g:CZcAAOSw2xRYeX9r  (new, $99.87 including freight)


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## just old al (Apr 7, 2017)

Bob, I would agree in a heartbeat but this gentleman is in Australia if I read my flags correctly...so he may be on the money (pun intended) with the prices.


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## Rustrp (Apr 7, 2017)

Here's an added piece of technical information on VFD's specific to motors. I think grounding is something that's overlooked in many cases and for the most part emphasis is placed on electrical shock or electrocution.
http://ecmweb.com/motors/diagnosing-understanding-motor-bearing-currents

I know we are discussing the home shop hobbyist but the same electrical theories apply, yet the question may be; Will I ever encounter this issue based on the time I spend using this piece of equipment? To that extent I would look at this based on the age of the motor and it's condition. 

I also take this back to assisting in the set up of large refrigeration compressors and motors. I'm still two years old when I'm assisting or instructed to do something. i.e. Why? We used multiple bonding jumpers on the frame (skid), to the motors and compressors which are all connected to the ground wiring. This was three phase across the board but leakage still occurs from the winding to the frame and these were big motors/compressors (25, 50, 100 HP) as they age and the owners wanted then to last a long time.
http://www.designworldonline.com/how-to-protect-bearings-in-inverter-duty-motors/


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## just old al (Apr 8, 2017)

OK, back to the original question, though!

Looking at that motor, it's about 1 horsepower (yes, silly Imperial standards) and 1140 RPM. That's right in the range you want to be in for a Hercus or the South Bend it's modeled on (I have one myself). It's reversible, and sealed/fan cooled as well - all pluses.

Depending on the footprint (base holes dimension) you may well, other than controls be able to bolt up and go. Pulley on the motor shaft may require swapping out for a similar size with the proper shaft diameter - not expensive, and trivial really.

Now comes the fun bit. Depending on what the 3-phase motor has for controls you may be able to adapt its drum switch or whatever to reverse and turn the single phase motor on and off. However, there is a chance it may not be adaptable.

At that point you have two courses, potentially. The first is to get a drum switch for a single phase motor and wire it up with the proper multiconductor cables - not impossible but not a dollar fifty in parts. The second (and quickest way to get making swarf) is to fit it with a simple on/off switch and forego reversing for the moment, then add the switching when you regrow your wallet contents.

Either will work. Personally I rarely use reverse other than screw cutting, so if you make smaller parts or are willing to wind it back by hand when screw cutting you can do without it.

Up to you - and hope this helped.

                                     Al


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## Silverbullet (Apr 8, 2017)

First welcome to the site, have thought about just using a three phase buzz box. Those are under fifty dollars. . I've never had a vfd but I'm thinking about one for an enco mill I own. My only reason is the belt changing for me will be a pita. I'm in a wheelchair and high reaching is out, besides some rotocup pain I'm experiencing. I'm going to build my own RPC soon I hope, if I can get out of pain. My second round of epidural shots may be helping ill know in a few days. Going out asap with a nice weather day ill find out cause I've got tons of moving to do just to get in the shop , it's piled now from not being able to do it right. I truly am very sympathetic with anyone suffering in pain. I've been in pain that's gotten unbearable . So if this epidural don't work I'm getting spinal surgery.  If you can the vfd may be your best bet. No belt changes is a plus.
I just had another thought how about a sewing machine motor set up ? Should be strong enough, it's variable and reversible.


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## Laytonnz (Apr 8, 2017)

I think you are overlooking what these guys are saying the 3 phase motor is far better in every way instant reverse more power more robust, and bigger selection you only have to buy the VFD once... if you choose to go single phase you have to factor in switchs wireing plus the motor may be just a piece of junk that eats one piece of swarf and dies...

Ebay, aliexpress ect wil get you a  cheap VFD 

But at the end of the day you will choose what you want, and it sounds as if you want a single phase motor, and I understand it is probably an easy option being at home then possibly going flatting (plug and play)


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## Gr1m3eaper (Apr 9, 2017)

Bob Korves said:


> I recently bought a 3HP VFD on eBay for $109 including freight.  A 2HP VFD was $104 at the same time, about 6 months ago.  Prices are going down, not up.  There will be wiring involved with installing the VFD, but there will not be the additional work of adapting and installing a new motor to the lathe.
> http://www.ebay.com/itm/DELTA-VFD01...844968?hash=item3d377b7d68:g:DlYAAOSwTM5Y5BZX  (used)
> http://www.ebay.com/itm/DELTA-VFD01...844968?hash=item3d377b7d68:g:DlYAAOSwTM5Y5BZX  (used, guaranteed)
> http://www.ebay.com/itm/2HP-1-5KW-V...526278?hash=item28205aff06:g:CZcAAOSw2xRYeX9r  (new, $99.87 including freight)



im in australia so VFDs are not that cheap, ive been looking around and ive found a few for the $150 to $160 mark being the cheapest, im not sure of the condition of the three phase motor that comes with it ill have to check it out when i bring the lathe home. as for single phase motors id really prefer to go that route 1 because ive already ordered the switches for the motor and lathe and 2 i work at an industrial aircon factory and we use motors big and small, i talked to my boss this week and he says if i can give him the specs i need for the motor hell order me one in and only charge me what he pays so it could work to be a LOT cheaper.



just old al said:


> OK, back to the original question, though!
> 
> Looking at that motor, it's about 1 horsepower (yes, silly Imperial standards) and 1140 RPM. That's right in the range you want to be in for a Hercus or the South Bend it's modeled on (I have one myself). It's reversible, and sealed/fan cooled as well - all pluses.
> 
> ...



Ah sweet man i was hoping that these motors would be ok, theres so many of them available online and really easy to get where i live. I havent had a look at the dimensions of where its to be mounted, im waiting till i get the lathe next weekend. ive got at least 2 weeks before the switches i ordered (forward/reverse, emergency stop, tachometer with LCD diaplay) come in so ill use that time to get the motor in and make sure the pulleys and belts fit alright, everything ines up etc. My uncle is an electrician so when ive got the right motor, pulleys, switches in ill get him to help me wire it up safely. i know the lathe comes with the 3 phase motor, dont think it comes with the switches though so ill use the ones ive ordered off ebay if it doesnt. 



Silverbullet said:


> First welcome to the site, have thought about just using a three phase buzz box. Those are under fifty dollars. . I've never had a vfd but I'm thinking about one for an enco mill I own. My only reason is the belt changing for me will be a pita. I'm in a wheelchair and high reaching is out, besides some rotocup pain I'm experiencing. I'm going to build my own RPC soon I hope, if I can get out of pain. My second round of epidural shots may be helping ill know in a few days. Going out asap with a nice weather day ill find out cause I've got tons of moving to do just to get in the shop , it's piled now from not being able to do it right. I truly am very sympathetic with anyone suffering in pain. I've been in pain that's gotten unbearable . So if this epidural don't work I'm getting spinal surgery.  If you can the vfd may be your best bet. No belt changes is a plus.
> I just had another thought how about a sewing machine motor set up ? Should be strong enough, it's variable and reversible.



na ive never even heard of it, ill look into it


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## 12bolts (Apr 9, 2017)

I have a 1/2 hp motor on my hercus and I can stall it without too much difficulty.


Silverbullet said:


> I just had another thought how about a sewing machine motor set up ? Should be strong enough, it's variable and reversible.


Industrial sewing machines run around the 1/2hp mark. Domestic, 1/4-1/3 hp.. And sometimes DC operation for the speed control ability and direction

Cheers Phil


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## Silverbullet (Apr 9, 2017)

I don't think you'll stall the new ones there 3/4 hp and there gear reduction .


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## Gr1m3eaper (Apr 9, 2017)

Ok sweet thats given me some confidence, the motor im looking at is a 1HP 1440RPM model so fingers crossed thats got enough grunt and i can get them brand spanking new for around the $150 mark. Im trying to organise a trailer this week so i can pick it up on the weekend, been debating about whether i should take pics of the adventure and make another post.  It will be my first time using a trailer let alone towing something with it, ill have to completely move everything out of my tiny shed to get it in there etc


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## Bob Korves (Apr 9, 2017)

Can't you buy from someone like Ali Express in Oz?  They show a 1.5 KW VFD for US $80.00 and free shipping.  
https://www.aliexpress.com/item/VFD...lgo_pvid=6c54f8cf-15b1-4762-aeb8-801969710a33
I would jump on that in a minute over buying and installing a different motor.  Your choice, of course...


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## Gr1m3eaper (Apr 11, 2017)

Alright mate youve got a good point. Im picking up the lathe this weekend, if the motors in good condition, pulleys belts etc ill get a VFD. How hard are they to wire up?


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## Bob Korves (Apr 11, 2017)

Gr1m3eaper said:


> Alright mate youve got a good point. Im picking up the lathe this weekend, if the motors in good condition, pulleys belts etc ill get a VFD. How hard are they to wire up?


The manual will be in Chinglish, and can be confusing at times.  The wiring on the lathe will need to be changed.  The VFD must turn the motor on and off and reverse, not a switch between VFD and motor.  The existing lathe switch can be used to control the VFD.  The wiring will all be low voltage and low amperage except for the three single phase wires (incl. ground) from the wall to the VFD and then four wire (incl. ground) three phase direct from the VFD to the motor.  Some programming is involved, many of the parameters can be ignored or dealt with later for fine tuning.  If I can do it, anybody can, and there is help on this site.


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