Clarke CL250M wiring

[Ian MellorsParticipant @ianmellors72388]

I have just bought a second hand CL251MH milling attachment for my lathe, connected it up and thrown the switch to direct power to the mill motor and nothing.

 

Before I start sending it back is there any way I can v

Check my lathe is outputting correctly to the mill power socket at the back?

 

I’ve looked online for a wiring diagram but can’t find one.

 

The motor is 150w 220v dc brushed. The same as the lathe, which works fine.

[Michael GilliganParticipant @michaelgilligan61133]

This may [or may not] help:

https://www.clarkeservice.co.uk/manuals/metal_lathes/CL251MH_Mill_Drill_Attachment.pdf

It appears, from p6, that it simply plugs into the socket on the lathe.

MichaelG.

.

Edit: a wiring diagram for the lathe is on p22 of this:

https://www.clarkeservice.co.uk/manuals/metal_lathes/CL250M.pdf

[not done it yetParticipant @notdoneityet]

Do you have a multimeter to test out voltages and circuits?

[HollowpointParticipant @hollowpoint]

First thing to do is check the fuses. One in the plug socket and one on the mill head.

[Michael GilliganParticipant @michaelgilligan61133]

Shame about the low resolution on that wiring diagram 🙁

MichaelG.

.

[Hollowpoint]

On Hollowpoint Said:

First thing to do is check the fuses. One in the plug socket and one on the mill head.

<p style=”text-align: center;”>I don’t think the mill head has a fuse 🙁</p>

[HollowpointParticipant @hollowpoint]

Sorry, yes. The fuse will be on the lathe somewhere.

[Michael Gilligan]

On Michael Gilligan Said:

Shame about the low resolution on that wiring diagram 🙁

MichaelG.

.

Thanks

 

Think I’m going to get a plug for the rear socket and connect a 60W (or 100W) light bulb to it to make sure the lathe is outputting correctly.

 

I did fit a replacement motor control PCB a few years ago that I got from Arceurotrade. It is possible that I messed things up somewhere.

[HollowpointParticipant @hollowpoint]

Do you have a lab type power supply? You could try putting say 30vdc directly to the mill head to see if it spins. At least you would then know if the motor is kaput.

[Hollowpoint]

On Hollowpoint Said:

Do you have a lab type power supply? You could try putting say 30vdc directly to the mill head to see if it spins. At least you would then know if the motor is kaput.

Sadly not. I do have one of these though, would this work?

https://uk.hornby.com/products/hm7020-psu-solution-harness-digital-15v-4-amp-transformer-r7337?gad_source=1&gad_campaignid=16260431725&gbraid=0AAAAADlZjdCnbIa77Lq1yt9ia1ultRZX_&gclid=Cj0KCQiAvtzLBhCPARIsALwhxdrFgX5LgSrdto4uyqFylUr8uYdhSE5oloDEj2_TGVPBA8LFFz9_EJoaAhfDEALw_wcB

[HollowpointParticipant @hollowpoint]

Not sure tbh. You probably need to be a bit closer to the motor specs. You may risk burning it out.

Does the motor have a plate or sticker on it showing the specs?

I know there is a sticker on the mill head but that is deceptive, because it shows the voltage and amps to the lathe, not the mill head motor. (I had this exact lathe/mill setup and also had problems).

A lab power supply is safer because most of them have multiple protection features.

 

[Hollowpoint]

On Hollowpoint Said:

 

I know there is a sticker on the mill head but that is deceptive, because it shows the voltage and amps to the lathe, not the mill head motor.

 

Yeah it’s mad isn’t it that it states 220v AC  when we all know it’s a DC motor

[SillyOldDufferModerator @sillyoldduffer]

The circuit doesn’t show how power gets to the motors so I’ve added them, red + and blue – :

 

• Power comes out of terminals 1 and 2 on the AP Board
• DC + and – pass via reversing switch (P1 P4) to SA1
• SA1, has 3 switches, of which two (10, 11) are used to power either the lathe or the mill.  The circuit is very simple – mot much to go wrong.
• There are no fuses or safety cutouts between the power supply and motors.

Testing requires a multimeter.  Buy one, cheap will do, anything with a 200V-ish DC range.

Power On, if the lathe turns, the power supply is good and the fault lies elsewhere.

• The fuses must be OK, and, power must be reaching connectors 10 and 11 on switch SA1, and from there to the lathe motor. Otherwise the lathe wouldn’t turn.  Set speed to low, but ensure the motor spins.
• With the mill unplugged, set switch SA1 to the mill position (lathe should stop), and carefully probe the pins on the socket with the multimeter set to 200VDC or more.
  • If needle moves then power is reaching the socket.   Therefore SA2 and the wiring to the socket is good.
  • No needle movement means SA1 is faulty, or a connection broken, or the socket is fault.  Check for power on the socket terminals with the multimeter.  Look for loose connections etc.
• If power is available at the socket pins, gets more difficult.  Plug the mill in:
  • Probe the motor to see if power is reaching it. If it is, the motor is the problem. Check brushes.
  • If not, something wrong between socket and motor
    • the plug and socket may be a poor fit.   Depends on the design and how well made they are.  Might be as simple as splaying a split pin with a screwdriver so it makes contact.  Or cleaning corrosion.   Otherwise, replace both.
    • As the mill head is plugged in and out, the cable may have broken inside the plug, or less likely, fractured inside somewhere along the cable.   Replace plug and cable.

If the plug and socket are hard to find, there’s nothing special about them.  Any plug and socket that takes 200vdc will do.

Comment:  these mill-heads often fail, implying a design fault.  The motor, cable and plug are simple – nothing complicated in the head, so it should “just work”.  My guess is the plug and socket don’t stand-up to being plugged in and out or dislike vibration.  Not quite fit for purpose.

As usual, grateful if others review what I’ve suggested:  I may have missed something or misunderstood the circuit.

Good luck.

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Well done, Dave

… I knew we could rely on you !

MichaelG.

[Ian MellorsParticipant @ianmellors72388]

Thanks Dave, just seen this post.

 

I have a fluke 77 DVM

 

I have removed the brushes and continuity checked between the pins on the mill plug and the brass parts where the brushes connect to and it’s open circuit on both wires. surely there should be a connection?

 

There is around 100v at the socket on the Lathe on the milling position.

Plugs and sockets are standard IEC 3 pin

[Ian MellorsParticipant @ianmellors72388]

I can’t see how to get into the motor to check the wiring connections, there must be a way as the IEC plug on the other end is moulded on. The wire passes through a grommet at the base of the mill, up through the support tube and out the top before going into the motor. Unless there is a join somewhere the wire must be connected into the motor after threading through.

[Ian MellorsParticipant @ianmellors72388]

LOL

 

That’s one hell of an insulation gap!

 

Think I have found the problem 😉

[Ian Mellors]

On Ian Mellors Said:

… 

I have removed the brushes and continuity checked between the pins on the mill plug and the brass parts where the brushes connect to and it’s open circuit on both wires. surely there should be a connection?

That’s very suspicious!  Both wires suggests violence such as pulling the plug out by hauling on the cable.

If certain the brass connectors link electrically to the cable and aren’t just insulated seats in the plastic:

• Can the plug be opened up?  Possibly the wires have pulled off the terminals.   Or have snapped inside the cable.   Possibly the conductors are brittle Copper plated steel or soft Aluminium.
• With the meter set to measure resistance, connect from plug pin to brass brush thingy and see if flexing the cable gets a response.  Hit and miss, but flexing can temporarily bring the ends into contact and show roughly where the break is.   Might be possible to cut out and repair a mid-section breakage.
• My bet is the problem is in or near the plug.  If opening up is impossible, I’d chop the cable off several centimetres back and test the bare ends for continuity back to the motor.  Fingers crossed, back to the motor will be good, whilst the plug and it’s cable test bad, proving it’s a plug/cable problem.
• Also, another delicate point such as where the cable enters the mill-head, presumably via a grommet.

The head was probably meant to be installed once and then left well alone.  Dismantling for sale or to get the head out of the way to do ordinary lathe work may have been too much for the connector.  The plug might not have any strain relief…

Just a guess.  Something odd going on – the arrangement is simple and should be reliable, yet I’ve seen several reports the mill motor has failed.

I wouldn’t bother testing the motor because the evidence points at the cable and plug. However, the motor should turn when connected to a car battery, or visibly try.   For the reasons given by Hollowpoint I wouldn’t power the motor with the Hornby because the Hornby  might be damaged, and we don’t need any more woe.    A car battery charger might do.

Dave

[Ian Mellors]

On Ian Mellors Said:

LOL

 

That’s one hell of an insulation gap!

 

Think I have found the problem 😉

Ian posted whilst I was typing, whoo hoo – that’s conclusive!  Well done.

🙂

Dave

[Ian MellorsParticipant @ianmellors72388]

one choccy block later (will make a more permanent solder/heatshrink join soon) and it all works as it should 🙂

My guess it that someone tried to rotate the mill head out of the way by loosening the clamp bolts at the base and promptly guillotined the wire where it passes through quite a jagged hole in the tube.

I will remember to loosen the top clamps and rotate just the head out of the way if I ever need to.

[SillyOldDuffer]

On SillyOldDuffer Said

• Also, another delicate point such as where the cable enters the mill-head, presumably via a grommet.

 

Spot on, well at the base 😉

[John HaineParticipant @johnhaine32865]

Yeah it’s mad isn’t it that it states 220v AC  when we all know it’s a DC motor

It has to be an AC supply as the controller uses a triac to control the power. Triacs are 3 terminal devices which can be turned on by a pulse on their gate but not turned off  they rely on the current reversing to turn them off for the next cycle.  The triac controls for how long in each AC cycle power is applied.  The actual supply to the motor will go through a rectifier as it’s a DC motor.

[Ian MellorsParticipant @ianmellors72388]

Only thing left to do now apart from a good clean and oiling is to machine the end of an M6 cap head screw down to 4mm to make a new pin that retains the main gear shaft. If only I had a lathe….. 😉

[DiogenesParticipant @diogenes]

Try searching ‘M6 Dog Point Grub Screw’ and see if that’s the thing..

[Ian MellorsParticipant @ianmellors72388]

One thing I have noticed is that the mill seems to run the wrong way round. With the lathe switched in Forward, drills will be running the wrong way.

Has anyone else with one found this too? it’s no biggie to throw the revering switch, but it just grates with me. Before anyone asks, yes, I did connect the wires up blue to blue, brown to brown 😉

[Author]

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