I have craftex CT089 lathe, 13 x 24 I believe, anyway last night I was working away and I stopped to take a measurement and then when I went to start again it would not start. I could hear it laboring but it would not turn, it would however start in reverse. So I took the belt off to unload the motor it runs fine in reverse but it will not run forward, if I start it by spinning the pulley on the motor it will turn slow but it will not come up to speed. Any ideas?

I have no experience with that particular machine. But in general, those are symptoms that the starting capacitor has failed (unlikely since it still runs in reverse), or the centrifugal switch contacts have stuck and it is on the run windings instead of the start windings. I'm not sure why it will run in reverse, but my shoptask growls like this every now and then, and it will also run in reverse, which clears the problem, so I am assuming stuck contacts. On my motors, the contacts are under the removable end bell of the motor. If you can get to yours, see if they are stuck together, just gently pry them apart and clean them a bit with a very fine file.

Dennis

Yeah I was thinking the starting cap as well, mine hase too caps on it so would one be reverse and the other on forward? I'll switch them and try and I'll aslo check the contacts, thanks for you input.

Kevin

Kevin,
With two caps, it sounds like it also has a run cap. The two are probably different values so DON'T interchange them. The start cap is used for both directions. The forward reverse is handled in the switch by changing the ends of the start winding.

As Bubba has posted, one cap is the starting cap and the other is the run cap, and they are different. If you suspect them, they can be checked if you know anyone with a capacitor checker. Grainger sells replacements that are rated for more starts per hour than the original cheap caps that come on most import motors.

Another thought, since it runs in reverse, is that the switch has a problem. I would check the contacts. Like I posted earlier, mine will occasionally growl and run slow in forward, but if I start it in reverse it has cleared the problem everytime so far. I can't explain why it would start in one direction and not the other.

Dennis

i had a similar issue with my 11x26 lathe. In the end I replaced my start and run capacitor as well as my switch. Although I beleive it was the run capacitor that was my original problem. I just figured while i was at all of this I would just upgrade everything in there.

Hi All, one thing a lot of people don't know is that single phase motors, (as are fitted to the majority of the cheaper home type lathes) are not designed to be stopped and started more than a few times per hour.

This is not a problem with 3 phase maotors.

The fact that the manufacturers fit single phase motors with on/off switches for stopping and starting is because it's too expensive to fit a clutch in the drive mechanism which allows the motor to keep running.

Every time you hit the start switch the start windings are engaged, and as they are only designed to start the motor and bring it to synchronous speed and then drop out without burning out, it doesn't take much imagination to realise that after a few starts the windings get hot.
Most, but not all, single phase motors are designed to run continuously, but this doesn't mean they can be stopped and started frequently.

I overcame this problem by fitting the electric clutch from a cars airconditioner pump to my Colchester Bantam lathe, and this allows me to keep the motor running continuously and stop and start as many times as I want for measuring purposes.

The clutch is powered by a 12 volt transformer with rectifier for DC, and only requires about 2 amps to power it.
I've also fitted an electric clutch to my 1-1/4" capstan lathe and this usually runs for 6 or 7 hours at a time.
The motor on this lathe is a 3HP 3000 rpm single phase induction motor.

The electric clutch will handle quite a few horsepower and at high speeds as well without a problem.

Most car wrecking yards throw the aircon pumps away as scrap because they're too expensive to repair when they fail, but the electric clutch on the pumpshaft end is usually still good, and the whole assembly can be had for a few dollars, just don't say why you want it or the price goes up.
Ian.

Hi Ian

This is my first post: I was Googling "electric clutches" because I had an idea that I could fit one to my Bantam and I found you had already done it!! My concerns were price (of course) and whether a cheap (aircon) clutch would handle the torque. I think your post answers both questions. Would you be willing to share details (and maybe a picture)?

Regards

Tony (in Cumbria, UK)

Hi Tony, no problem.
I've got a few photos I took but need to be resized for the forum, but the fitting is straight forward and all it needs is to get the clutch as mentioned previously, discard the airconditioner part, or make it into a compressor, and go from there as the mounting could differ a bit from model to model.

I don't know what model Bantam you have but mine is the flat belt type dating from the 1930's and as it used power from a line shaft, it came as just a bare lathe, so I had to build a countershaft to carry the second step pulley and input reduction drive with motor mount etc.

Once you've had one fitted you'll never do without it.
I hope you are up on your engineering skills as there is a bit of fitting and turning to be done.
Ian.

Ian

Thanks for the quick response. Mine's a 1960s MkII Bantam - ex-school & appears to have been mothballed for some time before removal. I've only just installed it. My previous experience was with a Super 7 (with clutch of course) so I know I'll miss having one. Although the machines are so different & photos are unlikely to be of help in installing a clutch on mine it would be nice to see photos what you've done - if it isn't too much trouble.

I don't mind machining & fitting :)

Thanks again

Tony

Hi Tony, heres a couple of photos I already have. I'll take a few more so that you can see the mounting.
The mounting will differ from make to make but the principle is the same I think.

The pulley size is about 160mm in diam with a B section Vee belt.
Some of the air-con compressors have twin vee belt drives.

I think your lathe has the drive directly into the top of the headstock casting with the motor down near the floor.
Ian.

Ian - thanks again.

Mounting it shouldn't be too difficult on mine: the pulley on the headsock gearbox is under the changewheels cover & the shaft it drives protrudes around 3.5". The pulley itself is installed 'boss outwards' & hides the bearing cover. The bearing cover contains an oilseal & is a flange fit with 4 bolts so either a new bearing cover with mounts for the clutch stator/coil or an adaptor to fit the stator to the existing bearing cover will be easy options. The shaft protrusion will, I hope, be long enough to accept the driven & driving elements.

Whilst Googling electric clutches I've found them used on tractor PTO's and on the cutter drives of lawn tractors - all of similar size to the aircon pump clutch.

Yours looks to be a nice, handy, setup.

Regards

Tony

Hi Tony, if you look at the right hand photo you'll see the diam of the countershaft which is about 15mm at that end, and the clutch pulley fits on the other end which is turned DOWN to about 12mm diam.

I think from memory, when I last worked on that type of lathe you've got, in bristol in 1975/80, the input shaft was about 30mm diam, so you'll have to either turn the end down for about 25mm to 12mm diam, or bore the shaft end for an insert.

The stator coil body, on my air-con compressor, was bolted to the compressor body, and seated on a spigot
This ensures that the pulley is concentric with the drive shaft, very important, as the bearing housing cover on your lathe would have to be faced flat and also have a spigot to make it concentric.

I just made a new bearing housing end cover with an interface to accept the stator body recess and it went together like clockwork.
Ian.

Ian

An alternative that would avoid serious lathe modification (like turning down the input shaft) would be to fit it to the motor. There'd be some advantage in doing that: move it to where the torque is lower. It isn't the extra work in fitting it to the (as you rightly say) large diameter input shaft that worries me - it's the rather permanent modification of the lathe. I'd quite like to keep it original or, rather, retain the ability to return it to original.

Regards

Tony

Hi Tony, I am not a great believer in originality for originality's sake.

When the damm thing don't work, modify it till it does etc etc.

Of course there's the other mob that modify anything just because it seemed like a good idea at the time.

I draw the line at improvement where needed.

I've seen a few Myfords that only resemble one by the nameplate, but that's a long story.

I think in your situation I'd add a countershaft between the motor and lathe input shaft, at the back of the lathe, so that the lathe itself can remain untouched, apart from maybe a few attachment tapped holes.

As I remember it there is quite a long vee belt between the motor and input.

I wouldn't go adding the clutch to the motor due to the mounting method which would need the motor output bearing cover being modified to accept the clutch body mount, (bit tricky), and also the diam of the pulley might make the speed too high if it's bigger than the existing motor pulley.

I could never abide the clunk on switch on the Colchester, especially when you've got a bit of a tight tolerence job and the jerk on start up moves the crosslide a bit.

The real advantage of the electric clutch is the ability to stop and start smoothly, without a jerk, at the touch of a simple low voltage switch.

I power the clutch with a 12 volt 4 amp ex lighting transformer, that I got off of some machine or other, but any trannie will do as long as you add a bridge rectifier to get DC, and I don't think you even need DC as the clutch magnet isn't polarised when it works.

I think a battery charger would do the trick as it's already 12 volt DC and the current rating should be able to supply at least 4 amps, as the clutch, when it's on, draws about 2 amps.

I've got another clutch fitted to my 1-1/4" Taylor capstan lathe, and that drives 3 HP to the main spindle.

Even after running for six or seven hours constantly, with stopping and starting for gauging and material movement etc, it doesn't even get warm.

The original drive motor on the capstan was a 3 speed motor, and I kid thee not, it was the size of a dustbin, so that was the first thing that disappeared, (as well as the cast iron suds tray that also weighed a ton or more), to be replaced by a countershaft framework, attached to the back of the headstock, and a 3HP 3000 rpm single phase motor.

Even doing 1000 rpm at the spindle, the clutch connects smoothly as it's designed to connect in the car at the engine speed when it's doing about 4000 rpm.

All the best, hope you get it to work OK.
Ian

Hi Tony again, another solution to the problem, which is the path I'd go down, would be to get another input shaft as a spare part and modify the old one to accept the clutch, very simply and cheaply done.

Where I worked in Bristol in the 70's we had a Bantam, same model as yours, and they used to use it between jobs when it was idle, for tumbling small parts.

One day it seized up, that is the input shaft ran in bronze bearings and they ran dry, overheated and needed a press to get the shaft and bearings out.

We had a new shaft and bearings fitted.

The Colchester agent knew about the problem and said they were not designed to run continuously as in a tumbler situation etc.
Ian.

Ian

Me neither. I've already removed the lever / link / reversing switch (much too difficult to use & a very 'clunky' system). Stop / Start / Forward/Reverse is now on buttons just above the change levers on top of the headstock. The starter & reverse contactors are in a box on the wall behind the lathe). Modifying the input shaft though is a step too far for me - once done the machine can't then be returned to it's original state. You're probably right that a countershaft is a better option although the motor & input shaft centres are actually very close together (around 12" without going out to check).

You've totally convinced me that the electric clutch is the way to go & that it'll handle the power/torque - I'm running 1hp @ 1450rpm (standard power & speed) so it'll have no problem.

Thanks for all the help

Tony