Just bought Skill Saw 5150 with no blade and bought a 7 1/2'' blade and the saw has a wrench but can't find anyway to lock to undo the nut so I can replace the blade. I pulled on trigger and held it but nothing seems to lock blade. Anyone have idea or where I can find a manual to read on this thing?

UNPLUG THE SAW first!! Look for the blade lock on the top or front of the motor body, Hold the lock button down while turning the blade nut with a wrench. After a bit you'll feel the lock button engage and hold the blade firm. Rotate the the wrench counter clockwise and remove the nut, Slide the blade out from under the guard and replace with a new one. Reinstall the nut following the above procedure.

Most times when I need to change a blade on my 7 1/4" saw I simply grab the blade on the front side, below the saw's support table, with a pair of channel lock pliers and then use the box end wrench on the blade nut, pushing down from the back side of the saw blade. That should loosen the nut so you can take it out with your fingers. The reverse of this procedure should tighten the nut on a new blade.
I'm not real familiar with the Fury saw, but if it requires saw blades with the diamond shaped cut-out in the center, most of the older blades had a knockout that will fit the diamond shape it would need.

If the saw doesn't have a locking mechanism for changing the blade then you will have to jam a piece of wood in the teeth of the blade so that it cannot turn. Remember safety first. Ensure the saw is unplugged and wear leather gloves when changing the blade. Use a socket or wrench to loosen the nut that holds the blade on and remove the blade. Use the reverse procedure to tighten the blade.

Should be a locking mechanism on back of saw push or pull the hold blade still...then use adjustable wrench to loosen nut on saw blade..pull off blade..slap a new one on..and away you go!!

There is not a lock on this saw. If the blade is to tight to hold by hand you need to use an impact wrench. It will loosen the nut before the blade has time to start spinning.

With the saw UNPLUGGED, check around the base of the motor shaft, there should be some kind of button that you can depress to lock the blade from turning. Then with the appropriate sized wrench, turn the blade locking bolt clockwise (it is a backward thread) to loosen it. Then simply remove the washers, etc carefully and replace them the same way they came off. If there is no locking button, you can use a scrap piece of wood on the saw table and push down on the blade to lock it in place.

First, there is no blade lock button on the Skil model 5150. I called the Skil customer service and they emailed me the exact manual for this circular saw. The method I used to loosen a VERY TIGHT blade stud was: spray with WD-40, imbed the blade in scrap wood, set Skil wrench (usually found in back of foot under handle) on so it could be struck going in counter-clockwise direction. Use hammer to strike handle of wrench a couple of times. To replace blade, finger-tighten blade stud, then use wrench to tighten 1/8 turn or (45°).

should be a blade lock button, if not i clip vise grips on mine let the table keep the blade from turning put wrench on nut and tap wrench with hammer see if ya can loosen nut good luck billy

I can't seem to access the parts view for your model, because of its age.
But I'm thinking skil probably hasn't changed things all that much.
Take a look at the 5450 and see if this doesn't help any...click here ...and scroll to page 7.

take a pair of good vise grips and hook onto blade tightly, slide uo against back braket. that will hold the blade from spinning while you remove the nut, try bumping your ratchet/ wrench w/ a rubber mallet or hammer. hope this helps