Thank you. Had this new saw on the shelf for a long time now it's working with a little bit of knowledge comes power

Yes, when brushes get worn down and very short, there's not as much spring pressure pushing them down tightly against the commutator. The com bars are never perfectly flat and even. So, as the armature spins, the brushes get lifted up and fall downward as each bar goes under them. If the spring isn't pushing firmly against the brush, it lags going back down and is able to "jump" up higher. It vibrates in place and those gaps as it vibrates up and down lead to the arcing. The arcing blasts away carbon and copper each time the ionizing arc forms which accelerates the wear a lot. The arc also causes power loss so the magnetic field is weaker and the motor is low on torque. Resurfacing the brushes and commutator after they have been all chewed up from arcing can fix the issue temporarily, but it'll happen again soon. Also FYI, brushes are different hardnesses which is something that varies motor to motor. The hardness determines how quickly they will reshape their tips by themselves to match the curve of the commutator. When you install new brushes, always shape them exactly to the commutator curve. When you sand down the brush tips to renew them, always re-shape them. Whenever you sand down and smooth the com bars, always re-shape the brush tips. And, whenever you improve the brush tip face or the com bars faces, you should improve the other as well. If you do one, just do both so the old one will not screw the new one up quickly. To shape the brush tip to the commutator curvature, just cut a strip of sandpaper slightly wider than the width of the brush. Wrap the strip tightly around the commutator with the grit side facing out and tape it in place. Then insert the brush and install the cap or tighten down the holder so the full spring pressure is applied, and then rotate the armature back and forth so that the sandpaper cuts away the brush tip until it fully matches the curvature of the commutator edge to edge and the entire brush width is being used to transfer current to the com bars. Soft brushes will wear themselves in eventually, but it's not ideal. Harder brushes could take a long time to do it and it's hard on both the brushes and the com bars because there's more current flowing through a smaller surface area. With a nice smooth and even commutator surface and brand new long brushes which are shaped to the commutator curvature, you will be good to go for a long time unless the armature has coil problems on one or more coils that will continue to cause arcing issues (which will rapidly chew up the nice surfaces you just made).

This fixed my problem. Thanks!

Did you ever think of putting small washer or hex nut in between the spring and the cap holder to increase the spring tension? I tried that after buffing the end of the brush to a mirror polish and it worked great!

Nice guide .Thank you

Great video. Very simple instructions and well narrated. One comment: probably best to NOT use emory style paper. Some of the metal fragments from the paper will get embedded in the brush. I would recommend garnet.

I got a Makita chop saw and it seems the brushes are totally stuck in place. Tried tapping them a bit with a skinny screwdriver, but the spring just isn't pushing them onto the commutator. Is there a good way to unstick them, or do I just need to drill them out and replace?

In terms of motor maintenance and repair, orange sparks are good. They are easy to fix and it is just a simple problem of new brushes, reseating brushes, or polishing the commutator. Blue sparks are kind of bad, it means there is some fault with the armature winding or the commutator and armature communication (short). 00:28 green sparks like that are extremely bad. they indicate critical motor failure which will result in a flashover explosion of the motor wiring.

nice bro

I hope this will fix my problems. ill let you know

Helwig Carbon is a brush manufacturer here in the States.

I am from the UK. And have a saw like this. And all the shops and places I have been don't stock bushes \brushes one man said when I showed him the broken one said what's that for.?. I asked him how old are you he said 43 years I said well... WTF you should know then he said no never seen any thing like this befor. I asked have you never fixed a drill or a saw motor befor. his answer was no bin and get new. We are a long way from the make do and mend of yesteryear. Do know a part no. For your brushes as I don't think I will be able to even get some off eBay?

add some thick aluminium foil behind the screw cap?

I need some brushes for some hedge clippers that cost me £35 12 years ago, can only find one set on Ebay for £12, obviously over priced to discourage repairs.. I used to fix av equipment but found this problem with expensive spares just killed the business in the end.

My chop saw is also giving me the same problem...bosch gco(14-24)...the thing is its new and I’m using it to cut roots using a multimaterial blade...the point is i have only chopped off 300kg of roots and my armature is emitting this kind of blue sparks...how often should i rest my chopsaw...i usually use it for 20mins and change to my other chopsaw till this one cools off...i have a huge contract to finish...help me sort this situation...how long should i use my chop saw

Gotta try this on my Porter cable 890 series that’s discontinued!! I’ll be back in a hour to let you know if it worked🤣🤣🤣🤣

I am from the UK. And have a saw like this. And all the shops and places I have been don't stock bushes \brushes one man said when I showed him the broken one said what's that for.?. I asked him how old are you he said 43 years I said well... WTF you should know then he said no never seen any thing like this befor. I asked have you never fixed a drill or a saw

Why do manufactures use carbon brushes instead of the metal ones? Because the metal ones can cause more sparking because of too much friction, and metal brushes can melt, that's why they use the carbon ones, so the carbon ones need to be very slippery to let the motor turn freely and frictionlessly.

can worn down brushes cause a saw to not start up??

Can’t you use a longer spring and use the rest of the carbon?

Hello world the worth brushed cause over heating of the motor

Make sure to unplug the saw before working on it.