Clarke CMD10 Milling Machine

[Richard Parker 1Participant @richardparker1]

[Richard Parker 1Participant @richardparker1]

Hello,

My Clarke CMD10 has packed up. Sometimes it will start, sometimes not, and it stops with the slightest load applied.

I understand it is either down to the motor or PCB (or both)… can anyone advise how to work out which is it so I know what to order? The cost of both parts is not much less than a new machine…!

Thanks

Richard

[Pat BraveryParticipant @patbravery]

Hi, The plastic cogs have probably stripped, they are sacrificial. Remove the motor and top plate and the damage if there will be obvious. They are cheap to buy and easy to fit. All the best Pat

[Richard Parker 1Participant @richardparker1]

Hi Pat, sadly it's not that, I've just taken the motor off and the gears look OK. When I try and run the motor with it removed, it still makes sort of "stuttering" noises…

[john carruthersParticipant @johncarruthers46255]

Sticky or worn brushes?

[Richard Parker 1Participant @richardparker1]

They look OK…

[nigel jones 5Participant @nigeljones5]

then its the famed pcb…I had two go so i put a zenor diode in to halve the motor speed and left it at that. Crude but very cheap!

[John RuddParticipant @johnrudd16576]

Disconnect the motor wiring completely and replace it with a 100 watt light bulb. With the speed pot at zero, the bulb should be out….advance the pot, does the bulb start to glow and progressively get brighter? If so then chances are the board is ok and the motor needs looking at….could be shorted windngs or open circuit…

[Richard Parker 1Participant @richardparker1]

OK the PCB rather than the motor… fizzy, please could you explain the zenor diode fix, I presume you remove the PCB completely, but where does the diode go in it's place…?

[Richard Parker 1Participant @richardparker1]

John, just seen your post – will try that and report back too.

[Richard Parker 1Participant @richardparker1]

Just tried John's test – bulb varies in intensity when turning the switch, so maybe it's the motor rather than the PCB…? Is that something which can be repaired or just needs a replacement? Thanks for all the advice so far.

[John RuddParticipant @johnrudd16576]

Before condemming the motor, I'd be inclined to clean up the commutator….

Look closely at the copper segments, the slots between each one should be clear. You can check this by running a junior hacksaw blade up and down the slots( a worn one is best, remove the pin from the end….)

If this doesnt improve things, then chances are the motor is u/s….( try and limit the time taken when running the motor with the board…damage limitation…)

The zener diode trick isnt something I'd advocate…..these motors run on dc and need a hefty diode to run direct from the mains, not just some BZX 85 series zener…

[Richard Parker 1Participant @richardparker1]

Thanks, John. I will try that – but just how do I open the motor housing to do that!?!

NB – the resistance of motor is around 25 Ohms and varies as I turn the spindle.

[John RuddParticipant @johnrudd16576]

Can you remove the motor end caps?….screws?

As you have a meter, you could check the continuity between the windings, if you measure between adjacent segments, the readings should be the same. This test will also reveal any winding that is open circuit…as the machine isnt blowing fuses, an open winding is the likely cause of the motor running poorly

[Richard Parker 1Participant @richardparker1]

The only way in as far as I can tell, is via two nuts on the underneath. However, they are recessed in a hole, and the hole is too small to get a socket on them… most helpful.

However, having proved the PCB was OK, and since I couldn't easily open the motor housing, I connected the motor back to the PCB to see what would happen, and it seemed OK, so I put the motor back on the top and all evening the machine has been running fine. So I really don't know what the problem was, but fingers crossed all will be well.

Many thanks for all the help!

Richard

[John RuddParticipant @johnrudd16576]

Loose connection somewhere?

[Neil WyattModerator @neilwyatt]

Have you checked the brushes for wear?

If not sounds like blown windings to me. Probably 2, as the motors usually run with one blown winding.

Neil

[Neil WyattModerator @neilwyatt]

Have you checked the brushes for wear?

If not sounds like blown windings to me. Probably 2, as the motors usually run with one blown winding.

Neil

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