I am trying to get the saw blade off. Is it reverse threads? Thanks, Jerome

I am no expert on your saw but on my table saw what I do is block the blade from rotating with a scrap of wood by hooking a tooth on it. Next use a wrench to loosen the blade nut (which is reverse threaded) and simply swap blades.

The arbot bolt on your saw has reverse threads or righty-loosey, lefty tighty. You should be turning it clockwise as you are looking at it or in the same direction the blade turns when cutting. The arbor bolt on these saws are reverse thread so that they are self tightening while the saw is in use.

Unplug the saw, first and foremost.
Then see if your saw arbor has facets for a wrench behind the blade, and if so, try to find a slim wrench that fits there to hold the arbor while you attempt to loosen the arbor nut that holds the blad on. If that doesn't work, take a stick of wood, like a piece about 3/4" x 1 1/4" x 12-16" long, remove the throat plate from around the blade, wedge the stick between the blade teeth and the edge of the throat slot to hold the blade in place firmly, exerting levered force toward the center of the blade to hold it in place, and using the wrench, loosen the arbor nut. Make sure you are attempting to loosen in the correct direction. Depending which side of the blade the nut is on, some nuts are reverse threaded.
Good luck.

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To change the blade turn it to the right hand to loosen and turning it to the left will tighten. It is a reverse thread. I hope this helps, :)

the threads arent reversed,so left or downward will loosen the blade,i have the same saw,dont over tighten when installing the new 1

some saws have a button to hold down that will lock the blade in place. if yours doesnt have the button, try putting a screwdriver in one of the cutouts or on the blade tip itslef and lock it in position. your problem may be that the screw on the saw is actually reverse threaded. they usually are reverse threaded.

Check at home depot or a lumber supply outlet that retails your brand. good luck

sounds like its striped. may be a clockwise thread or reverse thread. try to pry the bolt up while turning

Their web site seems to be down at the moment but most circular saw you just need to lock the blade somehow. Sometimes putting the blade up against a piece of wood so it can't turn will get the job done. Unplug the saw so it can't run. Some saws come with a custom wrench to turn a custom bolt, others a regular combination wrench would work. There should be a bolt that goes into the center of the blade. To keep the bolt from coming out while cutting, they are reverse threaded so you loosen it by turning the bolt the reverse direction you on a normal bolt. take the bolt out and be careful you don't loose the washers on each side of the blade. Put in new blade and reverse the process of taking it apart.

Exploded diagram for your SM100M miter saw is here.
User manual is here.

Page 20 covers blade change operation.

Make sure you unplug your saw! You need to remove a screw from the cover and rotate the cover to the rear. Use a hex wrench in the motor shaft to keep the saw blade from turning, and loosen the arbor nut with a 1/2" wrench. The arbor is reverse threaded, so you'll turn it clockwise to loosen, then counterclockwise to tighten it up after you have swapped the blade.
Rotate the cover back after that's done, and replace the screw.

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