New brushes are sparking real bad - Skil Circular Saw 7 14" HD77 Worm Drive

Sparks and smoking from an air compressor after installing new brushes could indicate a problem with the brush fit or alignment, or with the armature.
Here are some possible causes and solutions to try:

1. Brush fit: The brushes may be too long or not fit properly, causing them to stick and spark. Try removing the brushes and inspecting them for proper length and fit. If necessary, trim them down or replace them with the correct size.
2. Brush alignment: The brushes may not be making proper contact with the armature, causing them to spark. Try adjusting the brush holder or armature to ensure proper alignment.
3. Armature issues: If the brushes and holder are properly aligned, the problem may be with the armature itself. It could be worn or damaged, causing it to spark and smoke. In this case, the armature may need to be repaired or replaced.
4. Spring pressure: If the brush springs are too strong, they could be putting too much pressure on the brushes, causing them to spark. Try replacing the springs with lighter ones to see if this resolves the issue.

Note: It's important to use the correct type and size of brushes for your specific air compressor model. Using generic or incorrect brushes could cause damage or safety hazards.

Clean the spaces between the copper segments on the armature of the motor where the brushes touch. Put new brushes in it too.

Forgive me as I'm not too educated on the configuration of this saw but when I heard you mention armature replacement it made me think....are there armature brushes that are worn out. I know a lot of my angle grinders spark, get real hot, and smells like burnt plastic when brushes are worn out. Are there brushes on this saw? Just a thought.

You probably have no brushes left running on the armature hence the big sparks and noise. The armature will be beyond repair Take to an appliance repair shop but I fear that it will be cheaper to junk it and get a new one.. My experience with Makita is that the brand is selective in the quality.

The bad sparking can be several different things. The bad sparking at contact points or burned contracts on the switch can be caused by a faulty phase control or wrong wiring. Open the mixer, check wiring, if that is correct remove an replace the phase control board.
If the bad sparking is at the motor brushes this can be caused by worn motor brushes, rough commutator, faulty armature or shorted motor field. First remove the brushes and check that they are not worn to less that 5/16'. Replace with new brushes if excessively worn. If Brushes are fine remove and check armature. you will most likely have to replace the motor/armature assembly.
Thank you,
Colleen
MendingShed.com
800-339-9297

Squealing is usually associated with bad bearings. Sparks from the brushes is being caused by the motor pulling harder than usual because of the bad bearing. Sparks come from the carbon being burned off the brushes. I'd replace both, brushes are inexpensive and will make the tool work better and longer.

if brush and spring are in good shape you have a major problem;
spark on 1 brush : stator are bad
spark on 2 brush: check both rotor and stator for damage

Either your new brushes don't meet up with the armature properly or the commutator is damaged. Brushes usually 'wear in' within the first couple minutes of running. If it's getting excessivly hot you most likely have bad armature contacts and need to at least resurface the commutator or replace the armature.

not good! if one holder is melting you most likley had a sticking or worn out brush. if both are sparking heavily id have to say the armature and or fields are bad. if only one is sparking im sure you can get a new brush holder assembly. try ereplacement.com they have a decent sight . hope this helps.

Check for a weak/collapsed spring on the sparking brush. Also check the brush holder for any interior debris which might impede proper brush movement. Do both brushes spark? There should be a fine line of spark at the brush contact to the commutator normally. Make sure the motor tuns easily, as a bad bearing can cause sparking due to overload conditions. Hope this helps!