Mini lathe blown fuses and Motor overheating

[Martin KyteParticipant @martinkyte99762]

Posted by Martin W on 27/08/2020 19:25:58:

Martin

That is just the first fuse in the supply chain in the property which is then normally broken down into lower current circuits but it is the final safeguard. Yes I totally agree that it is sealed, is the responsibility of the energy provider and is there to protect the incoming supply.

As I had stated that I was looking at Fast Blow fuses I purposely did not include the Consumer Unit or any other fuse in the circuit and was giving just a general description as to the rationale re the fusing system and their purpose.

Cheers

Martin

It's actually the last fuse in the energy suppliers cabling and ensures that whatever the householder does they cannot overload the incoming cables.

So we can agree then that any downstream fuses are not there to protect the energy suppliers cables.

best regards Martin

[David Joyce 6Participant @davidjoyce6]

Posted by Dave Halford on 27/08/2020 17:55:22:

Posted by David Joyce 6 on 27/08/2020 16:47:42:

No I am using dcmt070204 inserts for steel.

That's half your trouble, you need dcgt as suggested by Jason they are a lot sharper and therefore need less power. They work fine on steel at mini lathe feeds and speeds. Just don't use then on brass.

oh ok thanks for the tip. I will have a look for some of those

[Martin WParticipant @martinw]

Yes it is the last fuse that the energy supplier is responsible for but it is, as I said, the 1st fuse 'in the supply chain in the property' .

Cheers

Martin

[Werner SchleidtParticipant @wernerschleidt45161]

The small fuse hopefully saves the motion control.Otherwise the Triac is burned. But you see this with the bulb test.

Werner

[An OtherParticipant @another21905]

This seems to have wandered away from Davids Lathe Problem –

Just to re-iterate for Davids sake: The control board is a Pulse Width Modulation controller and DC power supply, providing something like 200VDC. The DC supply powers the motor, and is switched by the controller – varying pulse width controls the motor speed.

As mentioned by other members, the motor can be tested by connecting across a 12V car battery – it should turn fairly slowly – if it does, chances are it is OK.

Also as mentioned, the controller board can be tested with a 100 Watt incandescent filament bulb – connect it in place of the motor, and it should be possible to vary its brilliance using the motor speed potentiometer. If its on Full, and uncontrollable, chances are the output devices (there are various types) on the controller board are short – circuit – this is a common fault, but can be repaired relatively inexpensively with the appropriate skills. The alternative is a replacement board at about 120 Pounds. Arc Euro Trade is a good source (no connection) for spare boards and motors – look at their web-site.

Hope this helps a bit, David

[Stuart Smith 5Participant @stuartsmith5]

If you need a motor or control board, Amadeal sell these and most other parts for their CJ18A mini lathe. ( I think this will be the same as your 618 lathe. There are photos of the motor and control board on their website.

Stuart

[David Joyce 6Participant @davidjoyce6]

I found the parts I need its for my exact model the only down side is waiting 2 weeks to a month for delivery but I guess thats the price you pay. I had to order a bulb on ebay especially for this test as all my bulbs are smart bulbs so I just have to wait for that before I do the test. I will keep you updated.

Edited By Neil Wyatt on 29/08/2020 21:51:49

[David Joyce 6Participant @davidjoyce6]

***UPDATE*** So the motor definitely has a short. I will do the bulb test later today when I get back and I will find out if I need to buy a new circuit too 😒

[David Joyce 6Participant @davidjoyce6]

Sorry guys for the late Update but I have confirmed the short in the motor. Did the 180 degree test on the commutator and got an average of 30 ohms on most of the contacts then it dropped to 20 ohms then went right down to 9 ohms on one or two of them so I have ordered a rotor for my motor.

The circuit was then tested with the bulb method and I confirmed that the circuit is operating correctly, no issues. The bulb got brighter as I turned up the pot and duller as I turned it down . It turns off when the pot clicks to zero.

So thats good news for me it spares me the extra £50 cost for a new circuit so its just the motor. Have to wait a couple weeks for delivery but I don't mind that.

Edited By Neil Wyatt on 05/09/2020 16:02:29

[Howard LewisParticipant @howardlewis46836]

Good!

Looks like you are on the way to sorting it! So shouldn't be too long b efore you are up and running again.

Howard

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