One for the motor experts

[Skeety]

Hi all,

I have just rebuilt a faulty Triton TPT 125 Planer. It's symptoms were sparking from the armature at the commutator end, this was present when not under load. I replaced the brushes to no avail so then did a complete strip down.

From what information I can find many have failed with the exact same symptoms, many under warranty, many not.

On the replacement armature the bearings didn't have to be driven on, they were a light interference fit. I replaced the originals as they had play in them.

The armature that was removed had damage to the commutator, at least 3 segments shorted and damage to the dialectric from heat but was cracked. At this point i didn't investigate further.

Now, the replacement armature sourced from Triton seems to have to me a significant difference in that the fan that is pressed onto the armature shaft seems to have balancing marks on it, the original had no marks whatsoever!

Just interested to see what you think? This is purely out of interest but wondering if the original unbalanced fan could have caused the bearings to wear and then cause damage to the armature...

Pics below:

 

[Spectric]

Perhaps they have tried to address a known issue with the motor, if they have had a lot of warranty returns then they may have done improvements to the motor in that they now realise a balanced assembly runs more smoothly or it could just be the motor is now sourced from a different company. The fact it is metal is unusual as most motor fans are now plastic and therefore lighter.

 

[Inspector]

Old fan may have been in tolerance so there was nothing to correct whereas the new one may have needed some work to bring into tolerance.

Pete

 

[Sideways]

I'm not sure why they would use a metal fan over a plastic one. I don't imagine the tool drags significantly dirty air through the motor to need the durability of metal. The added mass means that simple pressed metal would need balancing for smooth running.
To be fair, balancing the metal fan ought to be done after assembly as the whole thing is pressed together. Perhaps those balancing cuts are balancing the armature as well as the fan ?
More normally, an armature is balanced by making V shaped cuts into the armature laminations to remove metal. If it is well balanced, the cuts are made at both ends of the armature to balance each end somewhat independently. Cheaper manufacture doesn't bother.

 

[Spectric]

I think you can just see the balancing cuts on the armature laminations

 

[Fergie 307]

I had an issue with a Samsung washing machine where several of the commutator segments popped and stood proud, causing very rapid wear of the brushes. Apparently due to them switching to a more eco friendly glue in the construction, which turned out not to last very long! Got a free replacement after some to and fro. Reminded me of when BMW introduced water based paint. If a bird left you a present you had to wipe it off almost immediately or it would eat right through to the metal. Cost them a fortune in warranty claims before they got it sorted out.

 

[Skeety]

Thanks all

Pretty much what I thought. My planer is now working with the new armature and brushes. I bought it faulty so have fully stripped it, cleaned, lubricated as part of the repair.

A Triton TPT 125 almost like new, including the purchase of the planer and all part for £156