Plunge saw query..

Discussion in 'Carpenters' Talk' started by John Bunyan, Jan 5, 2022.

  1. John Bunyan

    John Bunyan Active Member

    Ripped a load of joists down today with not the ideal blade, 40 tooth. I could have forced the cut a few times. On the last cut it seemed to be labouring and poss slowed down. Just checked the bushes and they seem ok with plenty of length. Looked at motor vents earlier on and there were a few blue flashes nothing major. Could it just be overheating or could it need a new motor or is it armature? Will try it again tomorrow.
     
  2. Wayners

    Wayners Screwfix Select

    Armature burnout causes noisy rough running in vacuum motors I know.
    How dose it run after cooling?
     
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  3. John Bunyan

    John Bunyan Active Member

    I'll run it again today and update tonight
     
  4. John Bunyan

    John Bunyan Active Member

    I ran it yesterday but didn't get round to using it. It seemed ok apart from the intermittent blue flashes when you look through the vent at motor. So I'll see how it cuts next week. Got a 16 tooth blade now. So is an armature a motor? Not knowledgeable with motors.
     
  5. Wayners

    Wayners Screwfix Select

    Blue flashes are normal with brushed motors.
    Only brushless motors don't flash.
     
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  6. DIYDave.

    DIYDave. Screwfix Select

    It’s worth giving the commutator a clean up and service which is easy to do

    This is the copper segmented ring that the brushes make contact with

    In normal use, the carbon brushes wear down and leave dusty deposits inside the machine casing - which you see with a machine that’s been well used and has had some brush wear and/or changes

    Carbon deposits can also form on the commutator, leading to poor conductivity between brushes and motor, which equals a dip in power and performance and may also cause sparking, as your seeing

    Just look up ‘commutator cleaning’ (or such) on YouTube and give it a go - basically wire wool and/or super fine wet and dry paper is all that’s needed

    Good luck - worth a try
     
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  7. Astramax

    Astramax Super Member

    As @Wayners...best to replace the brushes................sourced DeWalt brushes from ebay 3 years ago no problem.
     
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  8. John Bunyan

    John Bunyan Active Member

    I can't see anywhere where Wayners mentioned replacing bushes
     
  9. John Bunyan

    John Bunyan Active Member

  10. Wayners

    Wayners Screwfix Select

    I was in screwfix and this gas fitter was kicking off regarding sparks from dewalt drill and how dangerous it was being he was a gas fitter.
    Hum.
    They took it for repair but that's normal and I thought all sorts while this guy played up. He should of known better about tools plus not blowing himself up.
    I can smell gas. Right I'll start drilling.
     
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  11. Astramax

    Astramax Super Member

    I wrote...As @Wayners.....(re flashes and brushed motors).....then I wrote the next thing for you to investigate and do!
     
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  12. John Bunyan

    John Bunyan Active Member

    I can see what you mean. No one should be making sparks indoors when there is a gas leak or gas in the air to the extent that it smells. Apart from that how can a spark from a drill ignite gas if it's not there.
     
  13. Astramax

    Astramax Super Member

    ....tis your brushes.
     
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  14. John Bunyan

    John Bunyan Active Member

    So is there ever a situation where brushless motors flash?
     
  15. Astramax

    Astramax Super Member

    What make and model is the plunge saw?
     
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  16. DIYDave.

    DIYDave. Screwfix Select

    But not necessarily ,,,,,,,

    OP mentioned he’s got ‘plenty of length’ (brushes I assume) ? :)

    He also mentioned been putting the saw under strain as likely cutting timbers with the wrong blade so this causes some heat to build up within the motor

    Could be a combination of worn brushes and a dirty/burnt commutator or just one or the other. Both easy to fix and inexpensive (unless the commutator is totally destroyed)

    A quick inspection will confirm the above and/or post pictures

    Important to not mix and match the brushes in their holders when removing and replacing with the same brushes - ie, remove and return to same holder as each one will have a unique wear pattern

    This is for individually mounted brushes where the brush holders remain as part of the tool. Some replacement brushes come complete with holders and mounted complete on a ‘card’ where you replace the lot
     
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  17. John Bunyan

    John Bunyan Active Member

    I do appreciate your help by the way
     
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  18. John Bunyan

    John Bunyan Active Member

    Astramax, it's the standard Makita 6000 240v
     
  19. John Bunyan

    John Bunyan Active Member

    @DIYDave. Thanks. I'm glad to hear it may not be expensive to fix. Bare in mind it may be ok if it can temporarily overheat and slow down. I pretty much just finished cutting when it happened and haven't had chance to cut with it again since. I did start it up yesterday and it seemed ok but I couldn't tell if it was noisier or sounded rougher. I may cut with it tomorrow but certainly Monday. I hear what your saying and will look on YouTube for how to do what you said. Is that what part of a service would be?
     
  20. Astramax

    Astramax Super Member

    I had another similar problem 20 + years ago with an ELU MOF router....the problem was the on/off switch full of sticky dust, once replaced it was fine.
     

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