Erattic behaviour from da air sander

  1. julianf

    julianf Member

    Messages:
    3,720
    Location:
    devon, uk
    I have a mirka air sander.

    It's behaviour is erratic. Sometimes it works fine for ages. But other times it works, then slows right down, speeds up again. Sometimes I push the trigger and it won't even spin.

    This seems entire independent of air supply. And, yes, I put some oil down the air inlet before every use.

    It requires a special tool (that I don't have) to open it up.

    Does the behaviour sound familiar to anyone?

    Thank you
     
  2. 123hotchef Member

    Messages:
    6,294
    Location:
    Kent
    my die grinder did that too i put it down to cheap carp
     
  3. RWD3M Member

    Messages:
    242
    Location:
    Wiltshire, UK
    Hmm.. this is a bit of a long shot but I had similar symptoms on my Craftsman D/A and eventually discovered that it had it's own air control valve that had worked a little loose and was restricting, quite randomly, the airflow. Tightened up and adjusted, now works perfectly.

    Good luck.
     
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  4. 123hotchef Member

    Messages:
    6,294
    Location:
    Kent
    someone told me to put a shot of derv through the air intake to clean it out that worked on my ratchet for a while
     
  5. postie jon Member

    Messages:
    728
    Location:
    Aberdeenshire, Scotland
    probably dust and oil combined into a paste inside , good strip down and wash with degreaser ,will prob cure it , our old sanders were allways clogged up.
     
  6. Craig-SM

    Craig-SM Member

    Messages:
    100
    Location:
    Leeds
    ^ this
     
  7. 8ob

    8ob Member

    Messages:
    3,345
    Location:
    moscow on thames
    Dont know about the da but nut guns can freeze , give them a few minutes and they are away again. Probably down to a tad of moisture in the system but we do get this.

    Bob
     
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  8. julianf

    julianf Member

    Messages:
    3,720
    Location:
    devon, uk
    This is kind of what I suspect. But as I say I can't even get I to it at present.

    I'll have another look and see if I can't make the required tool, as I suspect it costs about as much new as I paid for the sander : /

    I purchased a 1/2 gun from the boot sale once. Stripped that, freed the vanes, and it's been fine ever since. But that one just did not work at all. This one works spot on one day and is an arse another.
     
  9. slim_boy_fat

    slim_boy_fat Forum Supporter

    Would a run through an ultrasonic cleaner do the job without dismantling - or perhaps it wouldn't like total immersion? :dontknow:
     
  10. fizzy Member

    Messages:
    3,837
    uk
    Perhaps total immersion in Kero? Leave it soak for a while. Could cause O rings to swell though.
     
  11. brightspark

    brightspark Member

    Messages:
    25,391
    Location:
    yarm
    just shot a load of wd40 through it and run it on high pressure the vanes might be gummed up or the bearings it has worked on a couple I got cheap :laughing:
     
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  12. Daz2012 Member

    Messages:
    155
    Staffs,UK
    I just stripped one down.....not a Mirka...
    because of similar symptoms to yours.
    Cleaned it out and oiled it,put it back together,nothing, wouldn't work at all.
    Took it apart again,cleaned it out,WD40'd it and now it works great.
    So on that basis I'd suggest WD40 rather than oil
     
  13. Hitch

    Hitch Moderator Staff Member

    Messages:
    11,752
    Somerset
    I tend to flush air tools through with a good dose of SAS spray when they start playing up. (similar to wd40). Run it few seconds, repeat a few times. Then a bit of slightly thicker air tool oil to run it on.
     
    brightspark likes this.
  14. julianf

    julianf Member

    Messages:
    3,720
    Location:
    devon, uk
    Ive pretty much filled this one with penetrating oil.

    This one is a different colour to mine, but im sure its the same -



    Its irritating, as, first i need that thin bicycle spanner thing - which i dont have. Then the custom tool to unscrew it - which i dont have. Then a puller - which i can probably bodge, but even still...


    I think my 1/2" ratchet needs an allen key.
     
  15. Daz2012 Member

    Messages:
    155
    Staffs,UK
    All the DAs I've ever owned have used a single circlip to hold the bearing in.
    That looks complicated for complications sake
     
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