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Boxford electrical problem

Boxford lathe kept cutting out.

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Graham Halstead19/02/2021 21:44:09
15 forum posts
9 photos

Hi

im new to the forum. I have inherited an old boxford CUD III lathe from a great old friend who died recently.

the lathe works of 240v. It seems to work fine when I moved it into my garage, albeit I switched it in for 5 mins to try everything.

now when I switch the power on it runs for about 10 seconds and stops. The motor Doesn’t sound as quiet as I remember first time I ran it so maybe that’s a sign.

If I leave it and switch the mains power off and on again it will run again for 10 seconds or so.

can anyone help and suggest what the issue may be or has come across this problem. I have no circuit diagram for the lathe. I have a volt meter and can do some basic electrics. Is there some sort of overload trip. I am running via an extension reel, which seems ok when I first tested the lathe. I wondered if this could be the issue. I tried another shorter reel and different wall socket and same issue.
any help would be appreciated .

many thanks

Tony Ray20/02/2021 08:24:46
178 forum posts
43 photos

Hi,

I’m sorry to her about the loss of your friend. I’m sure your problem with the lathe can be resolved , I have had some great help from the forum in the past. Boxfords are a good machines and I’m sure yours will serve you well.

Firstly can I check that your motor is single phase? Then can I ask that you take some pictures of the motor the starter and the wiring We [ as I alone may not be able to solve this) need to see if we can establish what type of motor it is and to see whether a motor starter or simple switch is used and to assess the condition of the wiring. May I also ask if you have done anything to the lathes electrics? Eg changed the flex or anything else, just trying to establish if a fault has been created by something you did or by deterioration of a component.

I suspect the issue is with the motor itself, we may need to ask you to remove it from the lathe as having owned an AUD I know access is quite tight but removal isn’t difficult just fiddly, but I’m jumping ahead. Do please unplug the lathe before you take the pictures to ensure nothing untoward happens while you do.

Look forward to seeing the images and helping you to fix the issue.

Tony

Clive Foster20/02/2021 08:46:37
2890 forum posts
104 photos

Graham

If the machine has a proper contactor / No Volt Release switching system with an overload current detection system I'd start by investigating the overload.

10 seconds sounds about right for the device to trigger if its set a bit close to the motor current demand. Sometimes they just need a tweak. Especially if its pretty much never operated before.

You say the motor doesn't sound as quiet as it did suggesting that its seeing more load on start up which needs more current which may trigger the overload. Worth releasing belt tension and seeing if its OK off load. If it spins up OK off load time to see if any of the rotating parts need lubrication.

Clive

David George 120/02/2021 08:48:23
avatar
1677 forum posts
497 photos

Can you check that the back gear lever on top of the headstock has not been moved as some have a microswitch to protect the gears which cuts the power if moved whilst under power. Just a thought.

David

Dave Halford20/02/2021 14:39:28
1820 forum posts
19 photos

Is it slow spinning up to speed? It might be starting OK on the start coil then when the centrifugal switch kicks out the run coils don't take over because the run cap is dead.

noel shelley20/02/2021 15:29:41
873 forum posts
19 photos

Where in the country are you ? We need much more info, If it has a proper contactor then that may need adjusting. On the data plate there should be a figure for Full load amps of just amps, the contactor must be set to this figure. Is something running tight ? With the belt off the motor should rotate freely by hand. It IS single phase ? Centrifugal switch sticking or capacitors failed.

Never mind about changing lightbulbs, it may Take several of us to sort it - but we will ! Noel

Steve Pavey20/02/2021 21:34:41
354 forum posts
40 photos

My Boxford, (when I had it) did much the same. It was fitted with a ½ hp single phase motor and was mothballed for a while. When I finally got round to setting it up it was sluggish to start and ran slowly. It turned out to be old thick grease in the headstock bearings. After stripping it all out and cleaning it ran a lot better, though 1/2hp is really on the border line of inadequate for a Boxford, and it was much better when I fitted a 1hp motor.

Graham Halstead21/02/2021 17:18:53
15 forum posts
9 photos

8c9fa453-5cfc-4c49-a220-e0c1604fa457.jpeg99cf67d7-11f1-4abd-b84f-22ca3713a4ee.jpegHi everyone thanks for you kind words and help. I removed the drive belt and it ran fine no problems. As soon as I attach tthe belt the machine cuts out after 10 seconds. So maybe a clue. When it runs with the belt on it sounds like a whirring oscillating sound rather than a constant one. Sounds constant with belt off. I don’t remember it whirring like this before when I first got it, I did give the lathe a good clean. Did not remove any gears tho, maybe I’ve knocked something ?. Cant see any label on the motor so can see it’s HP. I don’t think it’s very powerfull. It running of mains so I’m guessing it’s a single phase motor. Sorry photos don’t show much very little access to see the motor .

Many thanks.

Dave Halford21/02/2021 17:22:58
1820 forum posts
19 photos

Now take the belt off the 5 cone pulley and try it.

Graham Halstead21/02/2021 17:46:52
15 forum posts
9 photos

Was the left hand 5 belt pulley end that I disconnected so the shaft and bearings seem ok. Albeit fair bit of play in the bearings due to age,

thanks

Oldiron21/02/2021 17:55:55
865 forum posts
23 photos

How does it run with the tumbler gear in neutral?. If ok have you checked that the carriage lock is loose and the half nuts disengaged?

regards

Edited By Oldiron on 21/02/2021 17:57:06

Dave Halford21/02/2021 18:05:39
1820 forum posts
19 photos
Posted by Oldiron on 21/02/2021 17:55:55:

How does it run with the tumbler gear in neutral?. If ok have you checked that the carriage lock is loose and the half nuts disengaged?

regards

Edited By Oldiron on 21/02/2021 17:57:06

That or part operated back gear lever.

Brian Morehen22/02/2021 08:14:04
avatar
177 forum posts
11 photos

Big question is the motor 3phase or single phase . My guess is single phase if so a very common problem the centrifugal switch has stuck . does happen if the motor has been used for some time . does the motor run on its own if everything else has been disconnected IE the drive belts . More info may provide the right answer from someone.

Regards Bee,M

Hopper22/02/2021 09:53:50
avatar
5505 forum posts
137 photos

Does the chuck spin around for that 10 seconds?

Is the chuck and headstock spindle free to rotate by hand when not under power?

If the problem goes away when you remove the upper belt, then the problem has got to be something binding on the spindle or associated back gears or change gears.

Try putting the feed lever in the neutral position and the screw cutting lever if it has one. And make sure the carriage feed nuts and half nuts are disengaged.

Then if it runs ok, work through the drivetrain and engage one thing at a time then start the motor again until you find what is binding and stalling/tripping the motor.

Edited By Hopper on 22/02/2021 09:55:36

not done it yet22/02/2021 10:57:17
6445 forum posts
20 photos

Checking with the belt off the jack shaft does not necessarily mean the shaft bearings are good - it is pulling up on one side and down on the other. Unlikely, but possible....

First question is will it run with the belt on the smallest pulley on that shaft? Move up, checking the drive system from there.

SillyOldDuffer22/02/2021 12:39:21
Moderator
7714 forum posts
1705 photos

Just wondering about the symptoms: motor starts, runs for 10 seconds then stops. Maybe noisy. Lathe moved recently.

Hard to tell but I think it's a single phase motor, exact type unknown - is a picture from the back possible (with a mirror)? It might show the motor plate (what does it say), start and run capacitors (which conk out), or a detached wire.

May not be a coincidence the lathe has failed after being moved. A terminal loosened by years of vibration, followed by the power cable flopping about enough during transit to detach one or more wires.

Single-phase motors fail for various reasons. As there are at least 5 different configurations, it helps enormously to identify the exact type. They all have a start and run winding, some way of shifting their relative phase (typically a capacitor or two), and maybe a mechanism (usually a centrifugal switch) for disconnecting the run winding once the motor has started. Some motors also contain a thermal cut-out.

Noting the power feed dangles inside the pulley cabinet I'd look first for a cable damage due to rubbing and then check both ends at the terminals for solid connections and continuity (multi-meter test).

I can't think of a fault that would cause the motor to start and then cut out. AsI don't have lots of practical experience with single-phase motors, perhaps an expert knows? It suggests power gets to both windings correctly, then something fails. Maybe the centrifugal switch or the thermal cut-out is tripping prematurely. If it's type with both start and run capacitors, then maybe the Run capacitor is faulty. Works well enough to start the motor, but can't supply enough current when the run winding is disconnected by the switch.

Dunno!

Dave

  • Start Winding
Clive Foster22/02/2021 13:12:13
2890 forum posts
104 photos
Posted by SillyOldDuffer on 22/02/2021 12:39:21:

I can't think of a fault that would cause the motor to start and then cut out. AsI don't have lots of practical experience with single-phase motors, perhaps an expert knows? It suggests power gets to both windings correctly, then something fails. Maybe the centrifugal switch or the thermal cut-out is tripping prematurely. If it's type with both start and run capacitors, then maybe the Run capacitor is faulty. Works well enough to start the motor, but can't supply enough current when the run winding is disconnected by the switch.

Dunno!

Dave

I'm inclined to go with Brians stuck centrifugal switch diagnosis.

If the switch doesn't open when the motor comes up to speed rough running is common and it will draw more current.

Grahams picture shows an industrial standard installation with a proper starter control which will have an overload sensor to release the contactor if too much current is drawn for too long. Typically, when a single phase motor is fitted, the overload current sensor will be set so as to have a delay of around 5 to 10 seconds before it trips the contactor off to allow for the initial high starting current.

Sticky switches are not uncommon on motors more than a few years old if they haven't been used for a while. Crud'n dust build up and dried oil usually. The one on my "used every second blue moon" import bandsaw responds nicely to a swift thump! (Its on the fixit list).

Clive

Graham Halstead22/02/2021 21:49:24
15 forum posts
9 photos

Hi many thanks for all the great advice.

im new to owning a lathe, so the terminology is foxing me a bit so please bare with me . I will try all your suggestions. Where would I find the contractor switch. Is there something I should do like. Good strip and clean of the gears etc to help reduce friction etc. I’m guessing there much be a fair bit of of gunk causing high load on start or a tired old motor? Happy to strip some bits and clean if your think it would help in certain areas. I’m not too bad with a pair of spanner’s but electrics are not my strong point. If I knew where the contractor is situated I could take a look at it. Apologies again for any stupid questions I have. I doubt the machine has had a good strip and clean and regrease for along time. I’ve pumped the grease ports when I did the clean of it. The grease on the back gears looks very sticky old and dirty.

I would probably feel ok about spending the money on a new motor or upgrade if one exists that would fit in without too much trouble.
many thanks again.

Nicholas Farr22/02/2021 22:19:37
avatar
3059 forum posts
1389 photos

Hi Graham, the contactor will be behind the panel that your start / stop buttons are on. Make sure that your lathe is totally disconnected from the mains before you look inside.

Have you tried running it on the slowest speed?

Regards Nick.

Edited By Nicholas Farr on 22/02/2021 22:23:35

Nicholas Farr22/02/2021 22:29:07
avatar
3059 forum posts
1389 photos

Hi, these lathe's usually had a 3/4 hp three phase motor fitted, when using a single phase motor, the advice is to use a 1 hp motor to get the higher speeds.

Regards Nick.

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