- #1
Guineafowl
- 810
- 388
I’ve been given a food mixer to repair - more sentimental value than monetary. It’s barely been used, if at all - the brushes still have their bedding-in ribs. It would only run if I gave it a spin, but this was just bad contact between brushes and commutator. Solved with switch cleaner. When running, it arcs badly and gets hot.
The motor is a series-wound, brushed universal type, and is very badly built. There is no epoxy to stabilise the windings as they leave the commutator, and one of the segments has been left unconnected. The windings have been looped under the tab for each commutator segment, and the tab has been pressed down over it.
The ‘good’ segments have a resistance of about 1.8 ohm between each pair, but many are much higher, and the reading changes if I press down the tab.
When such a motor is made, how is good contact normally made between the winding wire and the commutator tab? Is pressure sufficient to displace the varnish, or are they normally heat-staked or spot welded? Solder?
The motor is a series-wound, brushed universal type, and is very badly built. There is no epoxy to stabilise the windings as they leave the commutator, and one of the segments has been left unconnected. The windings have been looped under the tab for each commutator segment, and the tab has been pressed down over it.
The ‘good’ segments have a resistance of about 1.8 ohm between each pair, but many are much higher, and the reading changes if I press down the tab.
When such a motor is made, how is good contact normally made between the winding wire and the commutator tab? Is pressure sufficient to displace the varnish, or are they normally heat-staked or spot welded? Solder?