Variable speed control for a small lathe

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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.
 
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
 
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?
 
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
 
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
 
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
 
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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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.
 
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 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.
 
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.
 
@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 .
 
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.
 
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
 
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.
 
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.
 
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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