By Julian
Youtuber, shed dweller, solar charge controller aficionado
Good morning all…
Youtuber, shed dweller, solar charge controller aficionado
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When I plug my battery in, my saw starts up even though I haven’t pressed the trigger
Had the exact same problem saw starting intermittently. It turned out to be the micro switch in the handle at the trigger. The trigger was always exactly pushing the switch in far enough. Slight adjustment and working perfectly now.
You are using a 2.0Ah battery. These saws work best with 4Ah or bigger batteries.
Pretty bad repair attempt lol. Just clean the commutator with 1000grit sandpaper and it will come up new.
Oh darn, You just killed the motor…
Julian, You are a fine and clever chap… But this was so painful to watch I had to stop at the five fifty-three mark. I already knew where this was heading. No oil on brushes, EVER. To clean away carbon use 2000 grit sand paper, glass pen, melamine foam, or a pencil eraser. The stick was not damaging but would be minimally effective for the incredible amount of effort to scrap away everything. Also get yourself a can of contact cleaner, if you can still get hold of chemicals, what with pandemic lock-down and all. I like the one CRC makes, but other options are available.
If you need to bed in a brush slip the sand paper between it and the commutator with the grit facing the brush, then spin the shaft by hand in the direction it would normally operate. Blow away any carbon dust left behind. Be very careful when slipping the paper out to not chip or round over the brush; in fact lift the brush away from the holder side if possible. Then run things with the new contour for 3 ~ 8 minutes. Sparking should decrease and motor operation should become smooth as you would expect. If not, try contouring again. Brushes should be contoured/bedded sequentially, in pairs. When one has run-out like that, it will often glaze the surface of the other.
You are to be commended for giving it a go rather than chucking the whole thing in the bin, which is unfortunately what many people do these days. I'm very impressed to learn that saw has inrush protection, may add one to my general workshop kit. Always liked my 18v one plus tools, milwaukee in sheep's clothing. Though I don't bother with the mains only corded tools, they are made to a lower standard. Cheers!
What we used to do with dynamos many years ago is bed in the brushes using high grit sandpaper (>800) by cutting a strip the same width as the commutator and feeding it round the commutator withe the rough side facing the brushes then just spin up the armature. The sandpaper then forms the face of the brush to the curve of the commutator. Check the brush isn't just stuck in it's slide first though 🙂
Commutator needs a scrape. Negative brush needs replacing. Oil no NO NO!
Why not putting in new brushes?
I made a mistake in my comment. They are called commutators, the armatures are the windings.
Sorry about that.
Scotchbrite pads work very well on armatures. Being black in one side like that is a bit questionable. They should be the same width as the brushes are. Oil on the brushes makes them soft, and ware out faster. They are graphite, and like already mentioned, they are self lubricating. I have seen them build up black, and that is OK, because it is the graphite. Some times it catches metal particles, and builds up in the spaces of the armature, and that needs to be cleaned off to prevent them from shorting. The spring need to be a bit tighter. It shouldn't spark like that being as it is very new. That much sparking usually means the brushes are waring out, and if you watch another motor , they all have an even sparking surface all across the brushes. That is partly the metal in the graphite, and the collapsing field spark from the coils in the motor. I think that is why they put the capacitors on.
Never oil brushes. They are mostly graphite which is a lubricant.. Lift the spring, remove the brush, check the brush holder for trash or dents during assembly. Check the wiring for a short or stiff wire that prevents the brush from moving freely. Use some alcohol and clean the oil off the brush and the brush holder.
i take a hard file to the contacts if the contacts are abrasive and uneven on a worn out motor with good brushes and basically use it like a lathe till it starts running smoothly. those motors with replaceable brushes are meant to be replaced and if they do not have a clean flat surface will wear unusually quickly. (internationally certified electronics technician) "if its fucked and you cant make it work it will have to be replaced. the two parts or the whole thing."