Chester DB7 Lathe Motor issues

[trexcareyParticipant @trexcarey]

Guys and Gails, I have an issue with the drive on my small DB7 lathe. When I haven’t used it for a while, the motor on startup is very slow and then builds up to the speed it is set at on the VFD. Plus, it doesn’t seem to have the power it used to and stalls on some of the lightest cuts. Does anyone have a suggestion as to whether this is likely to be the motor or the VFD drive electronics?

Thanks

Andy

[bernard towersParticipant @bernardtowers37738]

Before you dig in to the electronics check all the mechanicals for free running. And run the motor with the belt/drive off.

[trexcareyParticipant @trexcarey]

Yes the whole system all runs free

 

 

[Brian WoodParticipant @brianwood45127]

Hello Andy,

I don’t know the lathe model but it sounds to me to be the result of dry bearings that are loading the motor, added to which you say its performance once running is now feeble. It is clearly struggling.

Try an extended run with belt off to see of the motor gets hot or noisy and act accordingly.

Brian

[bernard towersParticipant @bernardtowers37738]

If its a brush motor try the brushes

[Les Jones 1Participant @lesjones1]

Can you confirm that  the version of DB7 does use a 3 phase motor and a VFD ? The only versions with variable speed I have seen have used a DC motor and speed controller.

Les.

[trexcareyParticipant @trexcarey]

Sorry yes VFD was the wrong terminology it is a DC motor by the looks of it. I think I will drag the motor out and see if there are any serviceable bits and check the bearings as the bearings on the lathe seem fine.

[Les Jones 1Participant @lesjones1]

The only servicable parts on the motor will be the bearings and the brushes.  If you connect a mains voltage 100 watt filament lamp in place of the motor it’s  brightness should increase as the speed control is increased. If this happens the speed controller board is probably OK.

Les.

[trexcareyParticipant @trexcarey]

Hi Les,

Thanks for that. I have been away all weekend and will try this next week.

Andy

[Hugh Stewart-Smith 1Participant @hughstewart-smith1]

hello Andy,

If you are still having the same problem then you’re welcome to contact us at Amadeal as we can send you a test chart which may be of help to diagnose the problem.

Hugh                                                                                                                Amadeal Ltd

[mark costello 1Participant @markcostello1]

WOW, excellent  service.

[Author]

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