For most folks, the Skil 574 Circular Saw, like most hand tools, is not worth repairing. In the case of this saw, it made a god-awful shrieking noise when operating, which seemed beyond the decibel level and audio frequency of what a Skil Saw should sound like.
I wanted to fix this saw because (1) it is a "Made in USA" tool, (2) I'm cheap, (3) I like taking stuff apart.
This Instructable covers the disassembly and reassembly of the Skil 574 Circular Saw.
You will need
(1) Torx T-25 Tip
(2) Phillips Screwdriver #1 or #2
You might need
(1) Bearing Grease
(2) Electrical Tape
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Step 1: Freeing the Blade Guard and Base Plate
The Blade Guard
The blade guard of this saw is attached with a spring. Detach the spring at both ends and set it aside.
Using a Torx 25 wrench, detach the rubber stop. The blade guard should now be free to rotate.
The Base Plate
The base plate is attached with a long bolt and a wing nut. Remove the wing nut and the bolt, and the base plate can move freely.
Swing the base plate free of the saw. The base plate contains a stop that keeps the blade guard from rotating completely. Once the base plate is freed, the blade guard is also freed.
Step 2: Free and Wrap the Motor Brushes
Wrapping the Motor Brushes
The motor brushes should be freed before you remove the motor shaft. To keep the carbon brushes from springing loose, they can be wrapped in tape so they don't get tangled.
Turn the motor over, and remove the screw that holds on the grate that covers the motor. Put the screw aside.
Remove the acrylic pieces that hold the brushes in place, and free the brushes.
Step 3: Removing the Front of the Saw
There are 4 screws holding the front half of the saw (the part with the blade) to the back part of the saw (the part with the motor).
Three of these screws are easy to see, the fourth is near the center.
Removing all 7 or so screws in the front of the saw is fine -- just follow the pictures.
Step 4: Removing and Cleaning the Motor Shaft
When the front part of the saw is removed, the motor shaft may come out with it.
Step 5: Freeing the Drive Gears
Remove the 3 remaining screws on the front plate.
Step 6: Cleaning the Gears (Optional)
If you (1) know what you're doing, or (2) feel adventurous, you might want to clean the gears.
I chose to do so because I have some general-purpose bearing grease left over from some automotive work. I don't know whether it'll be okay for the saw to use this grease.
Step 7: Removing the Motor Coils
Step 8: Removing the Switch, Power Cord, Motor Coils
Step 9: Cleaning the Motor Cavity
Step 10: Reinstall the Power Switch
Step 11: Lubricating the Motor (Optional)
I figured it wouldn't hurt to lubricate the motor while I had it disassembled.
The saw was previously shrieking like a 10 amp banshee, so I figured a bit of general purpose grease would help. I used automotive grease.
Step 12: Reinstalling the Motor Coils and Motor Shaft
Insert the motor coils back in the motor cavity, and adjust the tape-wrapped motor brushes until the motor coil assembly sits comfortably in the cavity.
Using the two bolts, bolt in the motor coils. Be careful to not crush (1) the motor brushes at the back of the motor, and (2) the wires that come very close to the retaining bolts.
Take the motor drive shaft, and replace the washers at each end.
Insert the motor drive shaft, being careful not to lose the washer, nor crush the tape-wrapped motor brushes.
Go back to step 4, and you can see that I screwed up the order of the washers on the geared end -- the metal washer should be on the bottom!
Step 13: Install the Gear and Blade Guard
Step 14: Reinstalling the Motor Brushes
Using a small screwdriver, you can keep the brushes inside the casing, so they don't spring out when you reposition the brush housing.
When reinstalling the acrylic pieces, do not over-tighten.
Step 15: Reinstall the Base Plate
Reposition the base plate, and secure it with the long bolt. The bolt fits through the base plate as shown in the assembly pictures.
Note the position of the base plate and the blade guard. There is a right and wrong orientation of these parts when you screw in the rubber stop.
Reattach the rubber stop and the spring.
Step 16: Conclusion
Hopefully you have no parts left over.
If everything's accounted for, the saw should be ready for test.
I found that the saw was still quite loud when I finished, but it worked.