# Variable speed control for a small lathe



## Shopgeezer

So my King 10X22 lathe is a traditional belt drive 110v single phase machine. Prying the belts off to change speeds gets old real fast. I know, they won WWII with belt drive lathes. I should just respect the heritage. But Ebay has all these cheap speed controllers........

The motor shops all tell me that there is no way to install speed control on a 110v motor. Has to be 3 phase they all say. I could easily swap out the 110v motor for 220v if that would help. Motor shops say no, but Ebay......etc. 

So I am thinking maybe a mechanical variable speed arrangement on the belts themselves?  Sort of like a split pulley?  Anybody have any ideas/experience with this?


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## Bully

G'day Shopgeezer,  If you really want to do the adjustable pulley thing, I would have a look at Google and search for Continuously Variable Transmissions (CVTs). There several different belt and pulley types.  
However, for lathes,  the best solution I think is a device called a Variable Frequency Drive.  An electronic motor controller that creates a variable AC power frequency allowing the user to control the motor speed.    Versions for Single Phase or Three Phase supply are available.  If you have a lathe with a Three Phase Motor but no 3P supply then you can use a device called an Inverter to create the 3P to run the motor.  There are two types; electronic only (no moving parts) and rotary converters (1P motor drives 3P generator) which are used for higher horsepower industrial type lathes.  VFDs are used on most modern small lathes.  I have an Optimum TU2506V, (V: read VFD) which has this setup and find it excellent.  I can adjust the spindle speed from 120 to 1200 rpm without touching gears or pulleys.  PS The supply voltage (110Vac) should not be an issue if the motor size not over 1hp.  I am currently restoring a BV-20 lathe and thinking of putting a VFD on it.
Hope this helps,
Bully


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## BaronJ

Hi Guys,

There is no fundamental way to control the speed of a single phase induction motor without being able to change the frequency of the supplied voltage.  That in itself creates a number of problems.

A three phase motor can be driven from a single phase voltage source by means of an inverter that generates a fixed or variable frequency three phase output voltage !  Variable speeds can be obtained from a single or three phase supply by varying the frequency of the output voltage.  These inverters are normally referred to as VFD's.

Otherwise a single or three phase induction motor driven from a 50 or 60 Hz supply is effectively speed locked to the supply frequency.

NOTE that the voltage does not vary to control the motor speed. A 110 volt motor still requires 110 volts.


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## awake

Another possible option is to re-purpose a treadmill motor and controller. You will want to keep the step pulleys so that you can gain additional torque for slow-speed operation.


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## Shopgeezer

Well Ebay features these:

https://www.ebay.ca/itm/CNC-VARIABL...ispr=1&hash=item258aaefb6b:g:oxkAAOxy-WxTFZcT

If this forum strips out URLs just type VFD  110v in the Ebay search window. 

Sounds like it would do the job. Question is how to integrate it with all the switches and safety relays on the lathe.


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## dnalot

I used a treadmill motor on my old lathe an it has worked out very well. It has been in use now for over two years and I use this lathe a lot, I would do it again in a heart beat. I have also installed treadmill motors on my drill press and my wood cutting band saw. 

Here is a link showing my conversion and some comments and observations from other members. https://www.homemodelenginemachinist.com/threads/variable-speed-for-my-atlas-10-lathe.24610/


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## dkwflight

A VFD is a good way to go.
Any three phase motor can work. If the motor is rated for electronic controls it will work much better.  If not the motor can be noisy.
Do the research and pick the pulley sizes for the range you really need. better a little on the slower top speed. Remember the chucks have a top speed rating too.
It would be better if the VFD devise is a little over size.
Dennis


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## lemelman

When I converted my lathe from 1ph single speed to 3ph + VFD, I was dismayed when I opened the control box to find a mass of relays and a network of wires. It seemed horribly complicated until I realised that one relay was for implementing the NVR switch, and the other relays were just for setting the 1ph motor direction (forward or reverse). I simply made the NVR outputs to control the VFD, and used the VFD to control the direction of the 3ph motor. So what looked horribly complicated turned out to be quite simple. The relay used is the one for NVR,   all the other relays and wiring were just left untouched and do nothing at all.


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## Rickus

The only thing I know about electrical is quite "shocking."    But what about a router speed controller like the one Harbor Freight sells?


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## tornitore45

There are only two options:
DC motor + Controller   Controller can be electronic or a simple Variac followed by a bridge rectifier

VFD + 3 ph motor, is a little more expensive.  I have it done for a total of $200 and never regretted. Works great and requires practically no adaptations

The mechanical approach may work but is just a pile of aggravation, bulky, slipping low torque, needs protection from swarf, and still needs a motor


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## awake

Rickus said:


> The only thing I know about electrical is quite "shocking."    But what about a router speed controller like the one Harbor Freight sells?


That type of controller works on the "universal" type of motor (brushed, very high speed), but not on an induction type of motor. I'm not aware of any lathe that use the former; most use the latter, except for the smaller import lathes (e.g., Grizzly 7x14) that use DC motors.


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## Rickus

I can manipulate metal to pretty much do what I want, but electrical gets to me.  Like nature abhors a vacuum, I abhor electrical stuff.


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## SpringHollow

If you replace the motor with a 3 phase motor, the KBAC VFD's are an extremely simple unit to install and operate.  Turn a dial to vary the speed, flip a switch to change the direction.  I have one on my mill for variable speed capability even though I had it initially hooked up to my rotary phase converter.

https://acim.nidec.com/drives/kbelectronics/products/ac-drives/ac-drives-nema-4


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## cds4byu

I converted my single-phase 13x40 lathe to a 3-phase motor with a VFD and made it so the existing controls all work.
https://13x40.blogspot.com/2018/11/adding-vfd-to-my-enco-13x40-lathe.html
I'd be happy to give you personal advice if you'd like.

I added a VFD to my Bridgeport mill clone to replace a static phase converter.  I elected to replace the existing control switch, and just use the VFD panel on that one.  One could use the same approach on a lathe.

I'm happy with my lathe modification, and also happy with my mill modification.

Carl


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## Wizard69

There are lots of options if you want to consider them.  

One mechanical solution is to go with a Reeves Drive.  

a second option is a DC drive / motor combination.  

a third option is to consider a 3 phase motor with a VFD drive.  

Considering the 3 phase motor and VFD, this is one of the better options but getting the best results requires a bit of thought.  First upgrade the VFD to one affording vector control.   Second you need some understanding as to what the ideal speed range will be for this lathe ideally you will work with a 4 pole motor when figuring this all out.  You then need to figure out the best belt ratio for the motors ideal operating range.  The larger the ratio (speed reduction) The better the low end performance.  However you need to consider if you will have suitable spindle speed when the motor is topped out.  Topped out depends upon the max recommended motor rotor speed and the VFD’s capability.    Also it doesn’t hurt to up rate the motor horsepower maybe as much as 3X the current motor to help with that low end torque.  

without too much effort you can get good results however if you have a back ear option don’t give up on it.   Running a back gear or additional speed reduction can really help at the low end especially if your setup isn’t ideal.   A low end VFD/ 3 phase motor installation can benefit from keeping the rotor speed up.   You get more power but maybe more important you get better motor cooling.


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## Ken I

You can normally get a single phase rewound to three phase by a competent rewinder. I've done it several times - as long as the number of stator slots can be divided by three it can be done (they normally are as the laminations are invariably used for both single and three phase).
While you are at it, you can easily double your horsepower by running the motor at double the rpm - see my article on getting more power.

https://www.homemodelenginemachinis...re-power-from-your-squirrel-cage-motor.25236/

You can send me a PM for the full article.

People are forever telling me you can't do this - I do it all the time - I'm in robotics and I invariably need more power to weight than a squirrel cage can provide at 50/60Hz - if you use 200Hz - with an appropriately rewound motor - 4 times faster - same torque = 4 times more power - you do have to gear it down of course.

Small motors are a doddle - I have pushed 15kW out of a 3kW motor - the biggest was a 5kW 4 pole pushed to 30kW at 300Hz - nearly 9000 rpm - it did require lubricated ceramic ball bearings and fine balancing (it was a replacement for an extremely expensive German import HF fan drive).

Yesterday I took an out of the box 1.5kW unit to my rewinder - who always rolls his eyes at having to rewind a motor that is not burned out - rewound for 150Hz & 4.5kW - The third such unit for this particular customer - his oldest has been running production for 8 years.

Do it right - no problem.

Regards,
                Ken


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## tornitore45

Rewinding a 50Hz motor for 200Hz will give you 4 times the power.
Sure but only long enough to melt.
The Iron losses will raise 8X  (exponent 1.5)
And that is not counting the effect of the carrier frequency when the drive come from a VFD


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## Ken I

I am talking from practical experience - Iron losses are 20-25% of all losses and yes they increase but so does the fan speed - which generally more than offsets this.
There is a lot more to this than my simplified explanation - if you start with a low duty cycle (or cheap Chinese) motor - then yes you can turn it into smoke PDQ.
But doubling the power is within the realms of reason for almost any motor.
Torque remains the same, I^2R (copper losses) remain the same - magnetic saturation remains the same - eddy current losses go down, hysterysis losses go up, mechanical losses go up. Cooling increases.
I ran a 3kW Siemens rewound for 250Hz delivering 15kW - for a robot mounted saw in a continuous production environment - it burned out after 10 years - nothing particularly unusual there. The conversation with Siemens at the time was fun - they told me rewinding the motor would void the warranty - NSS.
Check out most of your power tools - brush motors - doing 20000 to 30000 rpm - not one squirrel cage in the lot.
The power comes from more revs - this is an electric motor not your V8.
I can't argue with the maxim that "if you need more power - buy a bigger motor" - I am simply offering another option if you are stymied by space and weight constraints.

P.S. Commercial aircraft use 400Hz in order to gain more efficiency from motors etc.

Regards, Ken


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## awake

With regard to rewinding a single-phase to 3-phase, or rewinding for higher frequency, or so on - I've no doubt it can be done, and I'm sure in some circumstances it makes sense due to space constraints or such. Question is, in the situation described by the OP, would it make sense economically to go this route, when there are such low-cost alternatives?


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## Ken I

Awake - point taken.
However just by chance I am in the same boat - I am about to upgrade my lathe to VFD.
Rewinding the single phase motor is cheaper than a new motor - regardless of the frequency its being set up for - the rewind costs the same (less turns of heavier wire is all).
All other costs the same.
My lathe is so underpowered it has trouble starting on high speed range.
So while I'm at it, I'm going to double its power by doubling its output rpm and changing the primary belt ratio 2:1 - that's the only additional cost.
The VFD has to be sized to suit - which you might consider an on-cost - but you have to pay for more power - you might be able to get 2kW from a 0.75kW motor but you can't get 2kW from a 0.75kW VFD.

P.S. I use H.F. motors all the time and they are not that different from your run of the mill squirrel cage - except for fine balancing and close spec. bearings needed for 24000 rpm operation.
Sometimes they use copper squirrel cage bars in the rotor (as opposed to the more commonly used Aluminium) to reduce "copper losses" in the rotor.

Regards,  Ken


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## ignator

Shopgeezer said:


> So my King 10X22 lathe is a traditional belt drive 110v single phase machine. Prying the belts off to change speeds gets old real fast. I know, they won WWII with belt drive lathes. I should just respect the heritage. But Ebay has all these cheap speed controllers........
> 
> The motor shops all tell me that there is no way to install speed control on a 110v motor. Has to be 3 phase they all say. I could easily swap out the 110v motor for 220v if that would help. Motor shops say no, but Ebay......etc.
> 
> So I am thinking maybe a mechanical variable speed arrangement on the belts themselves?  Sort of like a split pulley?  Anybody have any ideas/experience with this?



As others have indicated, a VFD is the best solution. And yes you will need a new motor. I've gotten them off ebay for a very affordable cost.

I can only speak from my experience on a 10X24 bench lathe, I've owned since new in 1976. It had a single phase motor, and it was not the most difficult to change the speed of the final 3 step V-belt drive line. But from the motor to the jackshaft, it had an addition 2 V-belt selection. That did require messing with the motor mount bolts that tensioned this initial drive belt.
So about 25 years ago, when VFD controllers were well into being commodity items, and affordable by the home shop, I purchased a 1HP 3 phase motor and a VFD from a US company. It was a package special (dealerselectric.com). This VFD was not of the 'vector' type, and so low speed use had a cogging effect. But it worked great outside of trying to use it below 20Hz operation.
Since then, I've replaced every single phase motor in the shop with a 3 phase and VFD of the vector type. And as the motors are 4 pole, the phase speed for 60Hz input is ~1720RPM. I program the drive to allow 120Hz max operation, this allows the motor to run at ~3600RPM, giving a very wide speed range. I typically set my V-belt reduction to the mid range of the machine.
When you know this reduction ratio, you can program that into the VFD so the LED display will show spindle RPM, which is very handy on the mill and drill press for setting the correct SF/M (surface feet per minute, or metric equivalent in your country) for the cutter diameter in the machine.
My milling machines (Wells-Index 645, and a 1930's Rockford Mill, horizontal) came with 3 phase, and I initially used a home built phase converter to power (I would never go back to a RPC, no speed control, another noise and power burn in the shop).
I also have a lathe with a 7.5HP 3 phase motor, that is powered with a VFD of 10HP capacity. Typically once you get over 3HP, VFDs want 3 phase input. And the derating is typically 2:1, assuming you will want to use the machine at its full capacity, when feeding them single phase input, as it is the input rectifiers of the VFD that can be damaged. So my example is not the 2:1, but I've never had a shut down overload of the drive, and I've done some pretty good depth of cuts. VFDs can be oversized, and you program the parameters of your motor, and it will prevent overload damage. At very low speeds, motors may overheat, but I'm not doing production, or running the machines hard in my shop, so I've never seen a hot motor from low speed lack of cooling.
The best solution is not to mess with a 120V input VFD, and just accept you need a 240V power jack at the machine. The 120V input VFDs have a voltage doubler, as they are intended to drive a 240V 3 phase motor. It works at low HP levels. And I see if this is the path you want, here is a link to an affordable solution (currently out of stock) https://dealerselectric.com/1-HP-1800-RPM-115-Volts-Input-Package-4.asp this includes the  motor and VFD of a quality manufacture.
Installing a VFD will require rewiring the machine, I could not find a wiring diagram for your lathe on line. The owner manual and parts list did not have this, so I don't know how difficult integrating a new motor to your existing power will be. You do need to look at your current motor nameplate, and find the frame number, as well measure the shaft diameter, as this will make putting a new motor in its place easier, as having it bolt in place of the old motor, and reuse the V-belt sheave is the desired path. You want to measure the mounting holes and locations relative to the shaft, and then look up an equivalent in a NEMA chart, to ensure a new motor fits without excess effort. At worst you may have to make an adapter plate, and purchase a new sheave.
That's my input to this post.


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## WOB

Shopgeezer, your problem is actually simple to solve.  Find a standard 1800 RPM ( 4-pole), 1 HP, 50 or 60 Hz, 230V  motor( TEFC enclosure preferred) and fit it in place of your existing motor.   Small 3-phase motors are often cheap on ebay.  It will likely be the same frame size so should fit easily.  Find a 1 HP VFD rated for single-phase 120V input.  Standard V/Hz type is acceptable and cheap.  Sensorless vector is better ( more low speed torque) but more expensive.     I would be wary of the super cheap Chinese VFD's sold on ebay)  .   I like VFDs sold by automationdirect.com. Wide selection, good prices and excellent customer support.    For a control panel, you might be able to dismount the panel on the VFD and mount it locally within reach in some sort of small box.   For a more physically durable control, you might be able to rewire  the original motor control switches to control the VFD directly.   You might  need to find some local electrical person to help to make the correct decisions, purchase the needed parts (if any) and program the VFD ( actually very simple in most cases).  None of the existing motor control relays ( if present ) are needed.

You should be able to run the new motor from 5 Hz up to 120Hz safely which will give you a very wide speed range without moving any belts.  Usually a belt position that gives you a commonly used spindle RPM at 60 Hz is preferable.  Once selected, you will probably never need to move the belts again.  Back gear is still usable and might be needed on rare occasions.

WOB


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## awake

Ken I said:


> Rewinding the single phase motor is cheaper than a new motor - regardless of the frequency its being set up for - the rewind costs the same (less turns of heavier wire is all).
> All other costs the same.



Ken, I must confess ignorance - I've never had a motor rewound. What's the ballpark cost for rewinding a motor?


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## stragenmitsuko

If you can find one , use a 6 or even an 8 pole motor in combination with a decent ( vector ) vfd .
It's better  to increase the relatively low rpm from a 6 pole to a higher value using the vfd  then
to decrease an 1800 or a 3000 to a lower value . Both cooling and torque will benefit .

Round here , I'm in Belgium , a small 2nd hand 3 phase motor will cost 40$ give or take .
Rewinding will start at 200$ at least .
I'de say get a suitable  used motor , add a couple of new bearings and combine it with a good vfd .

Oh and btw , 3 phase motors will accept two voltages . 
So a 3phase motor can be used as 110V in delta or 220V in star . 
Or , wich is common round here , 220in delta and 380Volt in star . 

Pat


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## tornitore45

> When you know this reduction ratio, you can program that into the VFD so the LED display will show spindle RPM,


What brand/model of FVD can do that?  Would be handy but I have not seen that capability on mine.


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## tornitore45

I bought a surplus 3 Phase 1HP motor for $50,  looks on ebay and on surplus dealers


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## dazz

Hi
The thing that often gets left off the glossy brochures is that the best frequency to run a motor on a  VFD is rated mains frequency.  Above this freq the motor is power limited. Below this freq the motor is current limited. 

I have a 3.7kW industrial Yaskawa VFD on my large lathe. I use the 6 speed gearbox to keep the rpm close to name plate rating.
Dazz


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## WOB

tornitore45 said:


> What brand/model of FVD can do that?  Would be handy but I have not seen that capability on mine.


My Hitachi and AutomationDirect GS Series units do that by programable scale factor on the digital freq. display.   

WOB


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## ignator

tornitore45 said:


> What brand/model of FVD can do that?  Would be handy but I have not seen that capability on mine.


Every name brand model, except the Huan Yang import on eBay. At least I don't recall seeing the programing parameter. I purchased one about 8 years ago, and it immediately had a capacitor blow up with a big bang. They replaced it, but I had to send the useless one back. So I have a "spare" on the shelf. I know others have had good luck with theirs. 
Tornitore, the following is not so much directed at you, but to capture info for other folks that are new to VFD's.
A general comment about purchasing VFDs, make sure they are the 200V class, as the 400V class will not work on home power. At least I'm not aware of them being able to work at a lower voltage, as they will trip out on a monitor for low voltage input. I've had good luck with used ones off eBay. But some sellers don't say what the input voltage is, so you must check the part number and download the manual. The one brand I've never found a manual for (on old discontinued VFDs) is Allen Bradley (Rockwell Automation), seems they purge this from their web site.
Another note, never switch the output between the VFD and motor, this can cause big inductive kick spikes that blow out the transistors in the drive.


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## cds4byu

I've used inexpensive Chinese import VFD's on my lathe and mill.  So far, everything is working well.

Unfortunately, in my part of the US, small (.75 - 2.25 kW) 3-phase motors are not cheap, but expensive, even in surplus.

I purchased a new 3-phase motor for my lathe, and made the mistake of purchasing a 2-pole (3450 RPM) , rather than 4-pole (1750 RPM) motor.  This means that 30 Hz is rated speed for my lathe, as the motor I took out was a 4-pole motor. Fortunately, I'm seldom using all the power available from the motor, so it doesn't give me any trouble.

I have thought about reprogramming the display, but decided against it, as I want to change the gear or belt setting if I need a very fast or slow speed.


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## nurd77777

Hi I am in the UK and the washing machines we have contain very good 1 hp motors. I have these motors on both of my machines and a closed loop controller from calenterprises which gives a full torque speed range of 500-12000 rpm. This is translated to lower speed by using the big pulley off the scrap washing machine. This may not be a help for USA as I know your w machines are different.


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## tornitore45

> I have thought about reprogramming the display, but decided against it, as I want to change the gear or belt setting if I need a very fast or slow speed.



I change the belt occasionally but most of the turning I do is in the "middle" sheave where RPM would be more Useful than Hz.  If I change the belt is, obviously, to go either solver of faster and in those rare cases I go by feel and hear and knowing the RPM is not so important.   One threads as fast as comfortable on a low speed setting and changing belt for high RPM is for small diameter where is hard to reach the right speed anyway so if one can keep the chuck from exploding all is good.


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## retailer

I have a 3ph motor and VFD on the lathe and use just the one pulley combination along with the VFD speed control for 99% of my turning operations. I believe most VFD's have a pair of terminals marked 'Output Terminals of Digital Frequency 0-10V' one of these days I'm going to experiment with a volt meter to see if the relationship is linear, if it is, then it should be possible to scale a volt meter to show spindle speed, an analog meter would be ok as it doesn't require power and it would be easy to draw extra scales on the meter face for each drive pulley combination.

If you wanted to get really fancy an Ardunio, Picaxe or similar could be used along with a keypad and multiline LCD display to show preferred and actual surface speed once the work diameter and material type is entered into the keypad - so many projects so little time.


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## stragenmitsuko

@nurd7777  Out of curiosity , what kind of motors are those ? 
Souns like brushed or DC motors ? 
Round here a washmachine will be  brushless or the older ones single phase capacitor start .


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## nel2lar

Anyone wanting or needing to replace a motor should checkout 3 phase. Worked out well for me.
What I want to do is put a reciprocal on the 3 phase side and run a motor on my lathe 2 hp @ 3450 rpm and the motor on my mill is a 2 hp 3 phase @ 1750 rpm. I am a one man shop so if I am running my equipment it is one at a time so I can use the power wherever I require it. So far running the mill I have been very satisfied with the VFD. Not needing a capacitor to start just thrills me after replacing them from time to time, an expense that I can use elsewhere.


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## el gringo

Years ago I installed a motor and DC drive from a treadmill I found in used goods store ~ 25$USD. It is still running strong on my Southbend 9" model A. 
I think I reported it at the time on this site...don't remember any comments.
Ray M


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## nurd77777

nurd77777 said:


> Hi I am in the UK and the washing machines we have contain very good 1 hp motors. I have these motors on both of my machines and a closed loop controller from calenterprises which gives a full torque speed range of 500-12000 rpm. This is translated to lower speed by using the big pulley off the scrap washing machine. This may not be a help for USA as I know your w machines are different.


I think VFD,s have various difficulties they require expensive 3 phase motors. These motors must be designed for VFD this is because the inductance of the windings is important. As frequency and revs go up current reduces so torque reduces. You can off course have low inductance windings but then at low frequecies and low revs too much current is drawn and things are liable to overheat. The 25 to 1 top  speed ratio of the triac controlled washing machine motor takes a lot of beating. Which is of course why manufacturers  use them.


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## Shopgeezer

el gringo said:


> Years ago I installed a motor and DC drive from a treadmill I found in used goods store ~ 25$USD. It is still running strong on my Southbend 9" model A.
> I think I reported it at the time on this site...don't remember any comments.
> Ray M



I have an early treadmill motor and controller from a surplus store (1/4 hp) that was supposed to go on a home made cnc milling machine. Not enough torque for that use. It was cheap but Ebay treadmill motors have become expensive. And the controllers are another separate item for more money.  Probably why they have disappeared from our local surplus outlets.


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## awake

Wait - you can _buy_ a treadmill motor and controller - ?? I just thought they came from the thrown-out discards that I scavenge from time to time!


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## Shopgeezer

Lots of them for sale on Ebay. Never seen a treadmill in the dump yet but can always hope. I am sure there are a lot in basements that haven’t been used for years.


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## nurd77777

stragenmitsuko said:


> @nurd7777  Out of curiosity , what kind of motors are those ?
> Souns like brushed or DC motors ?
> Round here a washmachine will be  brushless or the older ones single phase capacitor start .


Hi there
            The motors I mentioned are universal brushed they are used on front loading washers. I can get loads I know a guy that scraps washers. They have a flat belt pulley and are designed to turn a big pulley which turns the drum. For machines its best to use the drum gear and cast another pulley where the internal drum was. On my lathe the total reduction is around 40 to 1 and this divides the 500-12000 rev range. With tacho feedback the speed is constant with load .


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## almarghi

nurd77777 said:


> Hi there
> The motors I mentioned are universal brushed they are used on front loading washers. I can get loads I know a guy that scraps washers. They have a flat belt pulley and are designed to turn a big pulley which turns the drum. For machines its best to use the drum gear and cast another pulley where the internal drum was. On my lathe the total reduction is around 40 to 1 and this divides the 500-12000 rev range. With tacho feedback the speed is constant with load .


I have successfully used one of those on a BF20L for about 2 years, but upgraded to a 3-phase motor + VFD, due to noise


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## nurd77777

Hi Almarghi I only have small machines which are lashed together with bits I have accumulated. I would not have a lathe or a Gingery imitation mill if it was not for the versitility of motors. The type of controller I have/make feeds back speed info so the speed is constant at setting unless its overloaded in which case it limits at 20 amp. It does sound like a vacuum cleaner so I suppose it is noisy.


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## velocette

Hi Shop Geezer " Prying the belts off to change speeds gets old real fast" Have you considered using an Eccentric or over centre belt tensioner on the motor to loosen the belts and just lift them between  grooves.  Loads of ideas posted that all require a considerable expense and modifications. Treadmill  DC motors  are fine but run at 4000 to 6000 RPM so require a sizable reduction ratio. A couple of Photos of the tensioner - clutch on my wood lathe may explain better.


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## Shopgeezer

On my lathe the motor is firmly bolted to the frame. The belts are tightened by eccentric pulleys that are also bolted to the frame. They can slide in slots when loosened, so changing the belts requires digging out two different sized wrenches and loosening everything, prying off the belts and rearranging them (or swap them for longer or shorter ones) and using a bar to retension the pulleys while bolting them back down. Clever engineering insures that over centre levers would require some major re-design of the belt system. Just turning a knob on a VFD sounds sooo much better.  But it would require bypassing all the safety relays that prevent the spindle from turning if the cover is up and I am guilty of leaving the key in the chuck and trying to turn the lathe on. So I leave it set at 520 rpm for everything. Too slow for aluminum and way too fast for reaming and tapping.


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## TonyM

No need to worry about incorporating old safety features Shopgeezer. I changed my Warco 240 to three phase motor and VFD, kept all the original safety switches and even added another emergency stop near the VDF . bottom left of VDF in pic 2


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## nurd77777

Hi The problems of providing a wide speed ratio with VFD have all ready been out lined earlier in this thread. I am sticking with my triac controlled washing machine motor 500 to 12000 RPM since I also get a free drum pulley off the donor washing machine for 10 to 1 reduction. 
Regards Keith


----------



## TonyM

nurd77777 said:


> Hi The problems of providing a wide speed ratio with VFD have all ready been out lined earlier in this thread. I am sticking with my triac controlled washing machine motor 500 to 12000 RPM since I also get a free drum pulley off the donor washing machine for 10 to 1 reduction.
> Regards Keith



My point was that all safety features are easily retained or even improved which was what shopgeezer was concerned about. 

I can't compare my set up to a washing machine motor or treadmill motor so I have no idea if they are better or worse so I do not decry the use of scrap yard bits and pieces. . 

I do know my lathe does a lot of work. It has better power and control than the original setup without the need for belt changing. It runs with more power than I need from 40 rpm to 1800 rpm. It rarely takes 8 amps even when starting and the cooling fan on the VFD rarely runs. I have retained all of the safety features plus one more. Work involved was minimal. However the cost was substantially more than a second hand washing machine motor and control from a scrappy.

We all do what we can with the resources we have.


----------



## velocette

"Just turning a knob on a VFD sounds sooo much better". Variable spindle speed with independent variable speed power feed lets you find the "Sweet Spot" for machining all materials. The development of VFD drives has come a long way since I first experienced them used in industry in the early 1990's.
Eric


----------



## Shopgeezer

The power feed is another question. My lathe has the two selector knobs at the bottom of the front panel that gives different speeds. Even on the slowest setting speed is still relatively fast. Since the gear train driving the lead screw is driven by the motor, slowing down the motor will also slow down the lead screw. Good unless you want high spindle speeds and slow speed rates as I would for aluminum.  I have seen You Tube videos for electronic lead screw drives. That is really next generation but would be great to have.


----------



## velocette

I had a similar setup and changing gears from roughing cuts to a fine finish cuts a pain. So fitted a 24 Volt DC gear head motor with a Poly Vee belt to drive the lead screw.
The motor speed is controlled with a PWM unit with a reverse switch. Ten years of use and so much easier to use the lathe would recommend it to anyone.
Eric


----------



## chrsbrbnk

for a kinda cheapo variable voltage supply for dc motors I'v used light dimmers  and a bridge rectifier      they make some pretty good wattage ones for fairly cheap at the home supply stores


----------



## velocette

chrsbrbnk said:


> for a kinda cheapo variable voltage supply for dc motors I'v used light dimmers  and a bridge rectifier      they make some pretty good wattage ones for fairly cheap at the home supply stores


 A problem with this setup you get very little torque at low speed with a large diameter work piece in a lathe chuck.


----------



## TonyM

velocette said:


> I had a similar setup and changing gears from roughing cuts to a fine finish cuts a pain.
> Eric


You are right about that. I tend to leave mine set on the slowest feed and rough by hand feed.  What power motor and controller did you use. It seems like a good idea to me.


----------



## EJay

cds4byu said:


> I converted my single-phase 13x40 lathe to a 3-phase motor with a VFD and made it so the existing controls all work.
> Adding a VFD to my Enco 13x40 lathe
> I'd be happy to give you personal advice if you'd like.
> 
> I added a VFD to my Bridgeport mill clone to replace a static phase converter.  I elected to replace the existing control switch, and just use the VFD panel on that one.  One could use the same approach on a lathe.
> 
> I'm happy with my lathe modification, and also happy with my mill modification.
> 
> Carl



I recently bought a 13X 40 Enco lathe with a 3-phase motor. I'm trying to hook up a Teco L510 VFD. I read thru your blog. But appears my factory lathe wiring is a little different than yours. I'm not an electrician. So I'm having a hard time following along.  Do you have an e-mail address I can contact you with ?


----------



## cds4byu

EJay said:


> I recently bought a 13X 40 Enco lathe with a 3-phase motor. I'm trying to hook up a Teco L510 VFD. I read thru your blog. But appears my factory lathe wiring is a little different than yours. I'm not an electrician. So I'm having a hard time following along.  Do you have an e-mail address I can contact you with ?


I've sent you a reply on my blog.  It gets a little less traffic than HMEM.


----------



## TorchHypnosis

Good morning all, I just wanted to chime in to this convo and bring up a few talking points.

I'm actually in the same boat as the OP.  I have a small parts lathe, which I use daily for my business.  The controller dies religiously once every 12 months.  At the moment, I'm looking at 12 days down time while waiting for a replacement controller to arrive, which is unacceptable.  I have orders that need to go out yesterday.

I have a 480 3 phase motor and inverter that would be perfect for my application, a SEW Eurodrive...$4000 of motor for a $1000 lathe, but I cant use it until I get 480 3 phase into the shop.  Would be great as the inverter is an explosion proof sealed unit that can provide excellent torque at 1RPM, but I cannot satisfy the power requirements at this time.

That being said, I am looking for alternatives to replacing my motor controller every year.  Someone said use a treadmill motor/gearbox/controller.  That seems like a very realistic alternative as you can still receive a decent amount of torque at low RPM's while not risking burning out the motor.  I noticed a lot of folks here are recommending VFD's.  I cant help but notice that not much attention has been drawn to the fact that you drop the RPM's too low(reduce the Hertz) you will burn out the windings in your motor.  While the VFD solution may be fine and dandy for folks who keep their RPMs up, I typically run at 80 RPMs.  Super slow.  If I were to try and use a VFD to operate a motor that wants to run at, oh, I dunno, say 1000 RPMs, and dropped it down to what I need(80), I would burn out the windings in my motor.  Not only that, but lose torque.  So, anyone correct me if I am wrong, but a VFD is not going to be a permanent solution for me.  I'm thinking something like a treadmill motor with a reducing gearbox would be best to maintain the motor torque and still provide the motor RPMs I need.

But the single phase motor that I have and am currently running at low RPMs does not seem to be experiencing any issues.  This motor is 120VAC, controlled by a small PCB with a potentiometer.  The motor isn't the part that is burning out...it seems to be the controller.  There are 2 black wires and 2 white wires going to the motor, then 3 ground wires going from the motor controller to the lathe chassis.  I have to wait 5 more days before my new controller gets here, but the symptoms I am experiencing are the exact same as those I experienced last time I had to replace my controller.  I will update when I install the new board, but it seems to me that the motor is still fine and the controller is burning out.  Always seems to go out in the winter time, and the lathe is in an un-heated shop so the electronic components of the PCB might be failing due to freezing temps.  I would definitely be interested in hearing anything anyone else has to say on the topic.

Regardless, I just wanted to throw in my 2 cents, and would welcome any knowledge any of you might like to share.  Still trying to find a cost effective solution that will not require me to replace parts every year.  I have two conveyor belt motors with controllers but I am not sure what their power requirements are.  I can do 230 3 phase, just not 480.  I also have extra 120 single phase to 230 3 phase VFDs.  It's just going to take me too much time to make the mounting, program the control, and wire up all the parts when I can just spend another $160 to get another controller and work for another year.

Thanks for reading!


----------



## dnalot

TorchHypnosis said:


> I can just spend another $160 to get another controller and work for another year.



I would just replace the controller and go back to work. And order an extra controller to have on hand. If you use it so much $160 a year is not so bad. The treadmill motor should cost next to nothing. Just ask around, someone has a treadmill they would like to just get rid of. 


Mark T


----------



## cds4byu

What gearing do you have between the motor and the spindle?  Is it direct drive?

If you have gearing that could get you to, say, 300 RPM at the spindle for a full speed motor, a VFD would reasonably get you to 80 RPM.

I would expect that your present motor is not an AC motor, but rather a Universal brushed motor.

I'm delighted with my VFD on my 13x40 lathe.  It gives me plenty of "oomph" and works well at the speeds I need to run.  But I don't use the VFD to control all the way from 30 RPM to 1500 RPM.  I shift my gears, and use the VFD to give me a finer adjust.  I actually only use about three of the gear ranges, and use the VFD to cover the rest.

But as Mark says, if you are using the lathe a lot, $3 a week to replace the controller annually is small change.  Order a spare board so you can change it out in 30 minutes when it fails, and you avoid the 12 day down time.

Carl


----------



## TorchHypnosis

Mark, good point.  The first time it went out I thought it may have been a fluke so I just bought another.  In retrospect I should have bought another one with the replacement to keep on hand, but hindsight is always 20/20.

Carl, it is not direct drive.  The motor drives a belt which turns adjustable gears.   I don't even know where to start to look for a motor and VFD...I have an extra 120V 1 phase to 230 3 phase VFD I am not using ATM...that kind of power seems a bit overkill...I will look to see what I can find as far as a low RPM 230 3 phase motor.  Any suggestions would very much be entertained!  But you both are right....just replace the da*# controllers as I need to.  Still, there's always the desire to make your machine better...


----------



## cds4byu

Seems like your VFD is exactly perfect for driving the lathe -- 120V 1 phase is limited to about 1.5 HP, so it ought to work.

A 4 pole (1725 RPM) 3-phase motor would be ideal.  Here's one (new) from eBay for $170 shipped: General Purpose Electric Motor 1 HP 3 Phase 56C Frame 1725 RPM TEFC 230/460 Volt  | eBay

And here's one for $160: ebay link

I *love* my VFD on my lathe.  I think it's a great upgrade.

Carl


----------



## retailer

For those contemplating a repair on their small lath/mill motor speed controller I found a comprehensive repair document on an electronics forum and uploaded it in the downloads section, it may be helpful.


----------



## TorchHypnosis

I am inclined to agree with you Carl, having a VFD that can be controlled by a computer is best, especially when dealing with harmonics.  Being able to set the RPMs on the lathe has enabled me to eliminate chatter and get really nice looking mill marks.  Integrating PLC control on a VFD will most certainly give me the control I need to attain the finish I am looking for.  I will look at those motors, and will post the results once I get the hardware integrated.  It might take me a minute(I already shut down production for about 4 months while we performed some major mechanical upgrades) but as soon as I install a new motor I will be sure to post my findings.  We work daily, but as soon as I get the new controller in I will be using it for manufacturing, so upgrading the motor will go onto the back burner.  But I will have to deal with our issue during the next 10 months.  I will let you know the results of what I come up with as I test solutions out.  Thanks for the recommendations, and thanks for the input!


----------



## Richard Hed

TorchHypnosis said:


> Mark, good point.  The first time it went out I thought it may have been a fluke so I just bought another.  In retrospect I should have bought another one with the replacement to keep on hand, but hindsight is always 20/20.
> 
> Carl, it is not direct drive.  The motor drives a belt which turns adjustable gears.   I don't even know where to start to look for a motor and VFD...I have an extra 120V 1 phase to 230 3 phase VFD I am not using ATM...that kind of power seems a bit overkill...I will look to see what I can find as far as a low RPM 230 3 phase motor.  Any suggestions would very much be entertained!  But you both are right....just replace the da*# controllers as I need to.  Still, there's always the desire to make your machine better...


Keep an eye on recycle junk places -- that's where I got a treadmill motor.  There were thrown away treadmills all the time.  Sold to me by weight at steel scrap prices.


----------



## ignator

TorchHypnosis said:


> I am inclined to agree with you Carl, having a VFD that can be controlled by a computer is best, especially when dealing with harmonics.  Being able to set the RPMs on the lathe has enabled me to eliminate chatter and get really nice looking mill marks.  Integrating PLC control on a VFD will most certainly give me the control I need to attain the finish I am looking for.  I will look at those motors, and will post the results once I get the hardware integrated.  It might take me a minute(I already shut down production for about 4 months while we performed some major mechanical upgrades) but as soon as I install a new motor I will be sure to post my findings.  We work daily, but as soon as I get the new controller in I will be using it for manufacturing, so upgrading the motor will go onto the back burner.  But I will have to deal with our issue during the next 10 months.  I will let you know the results of what I come up with as I test solutions out.  Thanks for the recommendations, and thanks for the input!


As for resonance, i.e. harmonics, every VFD I have in my shop has the ability to skip over these by simple front panel programming. I'm looking at my Hitachi VFD manual, and 3 areas can be programmed with jump through those frequencies.
As odd as it seems, I've removed single phase motors and replaced them with 3 phase and a dedicated VFD. The feature I like, I can program a Hz to spindle ratio, and have the LED display on the front panel indicate spindle RPM. As the RPM range is so great, I leave the belt setting in the mid range reduction, and have all the torque needed both at low and high spindle RPMs. I can thread using taps and dies, without back gear on my 10x24 lathe. Having that stop button where I can hit it, is my only issue.
Just make sure the VFD is of the sensorless vector type, as this gives high torque at low Hz operation. The motors are all 4 pole, so I program the max Hz to 120, as this will give 3600RPM operation, which the rotor is capable of.


----------



## Steamchick

TorchHypnosis said:


> Good morning all, I just wanted to chime in to this convo and bring up a few talking points.
> 
> I'm actually in the same boat as the OP.  I have a small parts lathe, which I use daily for my business.  The controller dies religiously once every 12 months.  At the moment, I'm looking at 12 days down time while waiting for a replacement controller to arrive, which is unacceptable.  I have orders that need to go out yesterday.
> 
> I have a 480 3 phase motor and inverter that would be perfect for my application, a SEW Eurodrive...$4000 of motor for a $1000 lathe, but I cant use it until I get 480 3 phase into the shop.  Would be great as the inverter is an explosion proof sealed unit that can provide excellent torque at 1RPM, but I cannot satisfy the power requirements at this time.
> 
> That being said, I am looking for alternatives to replacing my motor controller every year.  Someone said use a treadmill motor/gearbox/controller.  That seems like a very realistic alternative as you can still receive a decent amount of torque at low RPM's while not risking burning out the motor.  I noticed a lot of folks here are recommending VFD's.  I cant help but notice that not much attention has been drawn to the fact that you drop the RPM's too low(reduce the Hertz) you will burn out the windings in your motor.  While the VFD solution may be fine and dandy for folks who keep their RPMs up, I typically run at 80 RPMs.  Super slow.  If I were to try and use a VFD to operate a motor that wants to run at, oh, I dunno, say 1000 RPMs, and dropped it down to what I need(80), I would burn out the windings in my motor.  Not only that, but lose torque.  So, anyone correct me if I am wrong, but a VFD is not going to be a permanent solution for me.  I'm thinking something like a treadmill motor with a reducing gearbox would be best to maintain the motor torque and still provide the motor RPMs I need.
> 
> But the single phase motor that I have and am currently running at low RPMs does not seem to be experiencing any issues.  This motor is 120VAC, controlled by a small PCB with a potentiometer.  The motor isn't the part that is burning out...it seems to be the controller.  There are 2 black wires and 2 white wires going to the motor, then 3 ground wires going from the motor controller to the lathe chassis.  I have to wait 5 more days before my new controller gets here, but the symptoms I am experiencing are the exact same as those I experienced last time I had to replace my controller.  I will update when I install the new board, but it seems to me that the motor is still fine and the controller is burning out.  Always seems to go out in the winter time, and the lathe is in an un-heated shop so the electronic components of the PCB might be failing due to freezing temps.  I would definitely be interested in hearing anything anyone else has to say on the topic.
> 
> Regardless, I just wanted to throw in my 2 cents, and would welcome any knowledge any of you might like to share.  Still trying to find a cost effective solution that will not require me to replace parts every year.  I have two conveyor belt motors with controllers but I am not sure what their power requirements are.  I can do 230 3 phase, just not 480.  I also have extra 120 single phase to 230 3 phase VFDs.  It's just going to take me too much time to make the mounting, program the control, and wire up all the parts when I can just spend another $160 to get another controller and work for another year.
> 
> Thanks for reading!


I am not an Electrical Engineer, but my experience with small brush motors says you can get all the torque you want with gearing, but direct drive of any electric motor will either run too low for torque at low spedds, or cook, due to high electric current with near no cooling. (SLOW fans). So the compromise is some gearing and some VSC. I have 2 speeds (belt pulleys) and Variable speed DC PM motor. Very poor min speed torque, and overheats if on continuous use below half speed of the motor. So I need more pulleys! A 6 speed gearbox (very traditional, pre-electronic VFD, etc.) Was always good enough for speed and torque. Just costs more initially! And people buy cheap, so why make "good"?
K2


----------



## Iampappabear

When converting my lathe and mill to inverter driven 3 phase motors I gave serious consideration to mounting one inverter on the wall then with a set of cheap relays sending the output to each machine along with a light duty wire for for/rev (would double as start stop) and potentiometer. 

When it comes to motors, there is nothing cheaper or more reliable than a 3 phase motor and partnered with the Powerflex you have an amazing drive system.  I particularly like the "ramped up" start & stop, so nice to get away from that harsh stop start most small AC motors have.

The only drawback from this system is having the same max current for all machines which for me means the 2hp motor on my mill has to have the same max current as my Emvcomat lathe 1/2hp motor as I am not a big fan of thermal overloads.

Colin


----------



## Steamchick

Just spotted Richard's post #64: What a good idea! I didn't know treadmills used these motors.
Some of these 1HP~3HP motors are essentially the same design as my Lathe motor - 1HP 4500rpm 180V DC - with a variable speed (DC voltage variation) control. I don't think I need a replacement motor (yet) but have had issues with it  - the carbon dust from the brushes shorts the brush holder and flashes over with some frightening loud bangs at random times. (Makes me jump - which isn't a good idea when doing a careful cut by hand feed!). The brush holder has sharp corners and gaps to earth as small as 1mm (0.040") - which show signs of flash-over as well. The Original brush-holder resin/fibre board had burnt away with repeated flashes: Having replaced that, it still flashes from the sharp corners - I guess when a bit of carbon dust get in the gap? I have tried removing sharp corners to double the gap and give a rounded edge, and filling gaps with silicon sealer, but all to no avail. It _Still _pops occasionally! The control board is a common type - but is limited to the 1HP motor (current) - even so I have burnt-out the switching thyristors and had them replaced (professionally). And even had some of these short (flash) to earth at the mounting bolts. All-in-all I am not impressed with reliability from these Chinese designs. But that is all that will fit in the motor space on my lathe.
As to usage, with a 4:1 reduction gear to the lathe main-shaft, at lathe 50rpm, I can stall the motor with a 1/4" Whitworth taper tap in mild steel. As that is at the full 5A that the VSC can deliver, the torque is NOT impressive, compared to my mate's 1HP AC motor and GEARS.  He gets 30:1 increase of motor-torque at his lowest speed, but I am not sure how the motor-torque compares to mine.... - maybe 3/4? - as he is at 240V and so "3/4" of the current than my lathe for the same HP rating... (But rotor diameter, field strength in the motor based on current and number of windings, all go to define the torque).
My lathe is good for small model stuff, as I generally only make 0.010~0.020" cuts in most materials. Having started taps/dies larger than 1/4", I have to do the job by hand. It also gets awkward when trying to de-scale cast iron or steel at over 2" diameter, as the slow speed needed and lack of torque sets a limit to what I can machine. - My next plan is to make new pulleys for the belt drive to get maybe 10:1 ratio - which would give me 2.5 x torque compared to now at up to ~500rpm. So while the treadmill motors are cheap - as are the second-hand controllers, you really need to consider the limitations of 1HP motors and I suggest gearing is the way to get the torque and power needed for mild steel above 2" and up to 6" diameter.
How about the lads with 3-phase and VFD? Can these do better with a 1HP motor? - So far I have priced a package at over £200 - but the motor is too large to fit inside my lathe!
Hope this helps?
K2


----------



## dnalot

Steamchick said:


> I didn't know treadmills used these motors.



I repowered my old Atlas 10" lathe about 6 years ago with a treadmill motor and it is still running great. My only expense was a $10 pot to control the variable speed. and a few more dollars for an E-Stop switch. 

Here is a link to my conversion thread                treadmill repower

Mark T


----------



## SmithDoor

I agree  
Simple controls and low cost too.

Dave 



dnalot said:


> I repowered my old Atlas 10" lathe about 6 years ago with a treadmill motor and it is still running great. My only expense was a $10 pot to control the variable speed. and a few more dollars for an E-Stop switch.
> 
> Here is a link to my conversion thread                treadmill repower
> 
> Mark T


----------



## Richard Hed

Steamchick said:


> Just spotted Richard's post #64: What a good idea! I didn't know treadmills used these motors.
> Some of these 1HP~3HP motors are essentially the same design as my Lathe motor - 1HP 4500rpm 180V DC - with a variable speed (DC voltage variation) control. I don't think I need a replacement motor (yet) but have had issues with it  - the carbon dust from the brushes shorts the brush holder and flashes over with some frightening loud bangs at random times. (Makes me jump - which isn't a good idea when doing a careful cut by hand feed!). The brush holder has sharp corners and gaps to earth as small as 1mm (0.040") - which show signs of flash-over as well. The Original brush-holder resin/fibre board had burnt away with repeated flashes: Having replaced that, it still flashes from the sharp corners - I guess when a bit of carbon dust get in the gap? I have tried removing sharp corners to double the gap and give a rounded edge, and filling gaps with silicon sealer, but all to no avail. It _Still _pops occasionally! The control board is a common type - but is limited to the 1HP motor (current) - even so I have burnt-out the switching thyristors and had them replaced (professionally). And even had some of these short (flash) to earth at the mounting bolts. All-in-all I am not impressed with reliability from these Chinese designs. But that is all that will fit in the motor space on my lathe.
> As to usage, with a 4:1 reduction gear to the lathe main-shaft, at lathe 50rpm, I can stall the motor with a 1/4" Whitworth taper tap in mild steel. As that is at the full 5A that the VSC can deliver, the torque is NOT impressive, compared to my mate's 1HP AC motor and GEARS.  He gets 30:1 increase of motor-torque at his lowest speed, but I am not sure how the motor-torque compares to mine.... - maybe 3/4? - as he is at 240V and so "3/4" of the current than my lathe for the same HP rating... (But rotor diameter, field strength in the motor based on current and number of windings, all go to define the torque).
> My lathe is good for small model stuff, as I generally only make 0.010~0.020" cuts in most materials. Having started taps/dies larger than 1/4", I have to do the job by hand. It also gets awkward when trying to de-scale cast iron or steel at over 2" diameter, as the slow speed needed and lack of torque sets a limit to what I can machine. - My next plan is to make new pulleys for the belt drive to get maybe 10:1 ratio - which would give me 2.5 x torque compared to now at up to ~500rpm. So while the treadmill motors are cheap - as are the second-hand controllers, you really need to consider the limitations of 1HP motors and I suggest gearing is the way to get the torque and power needed for mild steel above 2" and up to 6" diameter.
> How about the lads with 3-phase and VFD? Can these do better with a 1HP motor? - So far I have priced a package at over £200 - but the motor is too large to fit inside my lathe!
> Hope this helps?
> K2


Remind me what kind of lathe you have?  Can you send a photo and a photo of the motor area?  Could you mount the motor on the outside of the lathe?


----------



## Steamchick

Hi Richard,
It is a Chester DB8VS Lathe. 700W motor. Chester machine tools version of many lathes based on a Chinese supplied lathe.
As I have a tiny space for my workshop, there is no space behind, above, or beneath my lathe for an external motor. The internal space is only 6in. max height, for the current 4in diameter motor.

Cheers!
K2


----------



## Vietti

K2

Don't give up hope.  One of my treadmill motors is less than 6" in dia.  I suspect it came from an inexpensive treadmill.  I wonder if other exercise equipment might have smaller motors?

John


----------



## dnalot

Vietti said:


> One of my treadmill motors is less than 6" in dia



I have two treadmill motors in my shop. Rated at 2.25 HP. They are 9" long overall including stub shaft and a little under 3.5" in diameter. 300 RPM to 4600 RPM

Mark T


----------



## Steamchick

I think I can fit a 2 1/4 hp. motor that is on E&@y.... which should give me double torque, but I would need the controller as well as my controller cannot deliver the current. (I am sure the smoke would leak out if I tried it! Or the current limiter would stop me gaining the torque the more powerful motor will be capable of supplying!). The cost would be the same as 3-phase VFD, But I haven't seen comparitive torque figures, nor found a 3 ph motor small enough. Yet! The only advantage I can see between 3 PH AC with VFD and DC PM with VSC is that the 3 PH motor has no brushes! It does seem that the 3ph motors have a slower "sync" speed but larger armature diameter. I don't know about field strength comparison between the electromagnets in a 3 PH motor compared to field in the DC PM motor...? But it all combines to define the torque from the motor.
I think the pulley change can give me double torque, at low cost and complexity. So that's my first step, I think?
K2


----------



## Randoo

Iampappabear said:


> When converting my lathe and mill to inverter driven 3 phase motors I gave serious consideration to mounting one inverter on the wall then with a set of cheap relays sending the output to each machine along with a light duty wire for for/rev (would double as start stop) and potentiometer.
> 
> When it comes to motors, there is nothing cheaper or more reliable than a 3 phase motor and partnered with the Powerflex you have an amazing drive system.  I particularly like the "ramped up" start & stop, so nice to get away from that harsh stop start most small AC motors have.
> 
> The only drawback from this system is having the same max current for all machines which for me means the 2hp motor on my mill has to have the same max current as my Emvcomat lathe 1/2hp motor as I am not a big fan of thermal overloads.
> 
> Colin


You can set the drive for the highest max current then add individual overload blocks between the relays and the smaller motors.


----------



## Steamchick

Aha! - A 3Hp DC treadmill motor for £60 - Not bad.
But £150 for the treadmill controller and stuff to make it go? And I doubt my knowledge of eletrickery is adequate to re-wire the whole thing for the existing rev. meter /speed-feedback etc. - so I'll research this a bit more. Makes a pair of pulleys sound tempting?
K2


----------



## Bentwings

TorchHypnosis said:


> Good morning all, I just wanted to chime in to this convo and bring up a few talking points.
> 
> I'm actually in the same boat as the OP.  I have a small parts lathe, which I use daily for my business.  The controller dies religiously once every 12 months.  At the moment, I'm looking at 12 days down time while waiting for a replacement controller to arrive, which is unacceptable.  I have orders that need to go out yesterday.
> 
> I have a 480 3 phase motor and inverter that would be perfect for my application, a SEW Eurodrive...$4000 of motor for a $1000 lathe, but I cant use it until I get 480 3 phase into the shop.  Would be great as the inverter is an explosion proof sealed unit that can provide excellent torque at 1RPM, but I cannot satisfy the power requirements at this time.
> 
> That being said, I am looking for alternatives to replacing my motor controller every year.  Someone said use a treadmill motor/gearbox/controller.  That seems like a very realistic alternative as you can still receive a decent amount of torque at low RPM's while not risking burning out the motor.  I noticed a lot of folks here are recommending VFD's.  I cant help but notice that not much attention has been drawn to the fact that you drop the RPM's too low(reduce the Hertz) you will burn out the windings in your motor.  While the VFD solution may be fine and dandy for folks who keep their RPMs up, I typically run at 80 RPMs.  Super slow.  If I were to try and use a VFD to operate a motor that wants to run at, oh, I dunno, say 1000 RPMs, and dropped it down to what I need(80), I would burn out the windings in my motor.  Not only that, but lose torque.  So, anyone correct me if I am wrong, but a VFD is not going to be a permanent solution for me.  I'm thinking something like a treadmill motor with a reducing gearbox would be best to maintain the motor torque and still provide the motor RPMs I need.
> 
> But the single phase motor that I have and am currently running at low RPMs does not seem to be experiencing any issues.  This motor is 120VAC, controlled by a small PCB with a potentiometer.  The motor isn't the part that is burning out...it seems to be the controller.  There are 2 black wires and 2 white wires going to the motor, then 3 ground wires going from the motor controller to the lathe chassis.  I have to wait 5 more days before my new controller gets here, but the symptoms I am experiencing are the exact same as those I experienced last time I had to replace my controller.  I will update when I install the new board, but it seems to me that the motor is still fine and the controller is burning out.  Always seems to go out in the winter time, and the lathe is in an un-heated shop so the electronic components of the PCB might be failing due to freezing temps.  I would definitely be interested in hearing anything anyone else has to say on the topic.
> 
> Regardless, I just wanted to throw in my 2 cents, and would welcome any knowledge any of you might like to share.  Still trying to find a cost effective solution that will not require me to replace parts every year.  I have two conveyor belt motors with controllers but I am not sure what their power requirements are.  I can do 230 3 phase, just not 480.  I also have extra 120 single phase to 230 3 phase VFDs.  It's just going to take me too much time to make the mounting, program the control, and wire up all the parts when I can just spend another $160 to get another controller and work for another year.
> 
> Thanks for reading!


We have a stock grizzly BFF motor on our small lathe it has great pier for a small piece so far no problems. There is a reduction belt rive before the main gear train so it runs a bit faster motor rpm than some I think. There is electronic tach that give chuck speed I think . Generally 1000 rpm or more the little other cuts through 4130 and 4150 like butter it’s hard to stall it electrically it does not he hot at all. 480 vac is way beyond my level actually if I can’t just plug I in nd use it I’d call the electrician LOL I DONT LIK MESSING WITH LINE OWER ANY MORE THAN NECESSARY 

BYON


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## animal12

Treadmills can be picked up for free  quit often . After they sit doing nothing folks just want them gone . You can use the controller that in in the treadmill  to run the motor , & there's several Youtubes on how to make your own controller for @ $30.00 .
animal


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## SmithDoor

I agree  

They get motor and most buy treadmill and use it one or two times and then the belt goes bad from lack of use.

Dave 



animal12 said:


> Treadmills can be picked up for free  quit often . After they sit doing nothing folks just want them gone . You can use the controller that in in the treadmill  to run the motor , & there's several Youtubes on how to make your own controller for @ $30.00 .
> animal


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## Steamchick

I think it may be a bit different in the UK, we are tight with money, so buy the cheapest (Low powered) stuff, then sell on e&@y when we decide it's not what we want. That's why a powerful motor is £50 or more, and controllers are upwards of £125! And wiring harnesses then cost more (for plugs, etc.), and transformers, or whatever!
If I can find give-away stuff I will, but a lump of aluminium and machining time is much more enjoyable, then I only need a new belt!
QED? - I hope.
K2


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