My wife runs a 40 volt Ryobi saw and she loves it, perfect tool for her. The chain comes off frequently, more than any saw I’ve used in the last 45 years. I can put it back on, tension it and within a few minutes it will come off. It is mostly used for limbing so the nose of the bar gets most of the action. I believe it has the original Ryobi bar and chain. Anyone got any ideas?

Too thin gauge chain for the bar?

Dopp creek,

A couple of things to check. One: is the adjusting tang in the bar slot?

Two; get the adjuster lock nut tight.
If it's an hand adjuster (no tools) get it tight. Most people are not strong enough to do it by hand only, use a pair of pliers.

Never seen a worn bar causing your issue,

Guido.

I knew my neighbor had a Ryobi (corded) pole saw. I had a branch on a wire and asked to use it. The chain was off, so, as normal, I fixed it. The chain adjuster was pretty flimsy. I put it together and used it gently. No issue. Look it over to see if you can't "improve" the adjuster. Under cutting limbs a bit befor cutting through from top helps avoid bend pinching ! Jim

too little oil will cause them to heat,stretch and jump out of the groove.

I have had a chain get a twist in it from being pinched and it would not stay on.

"It is mostly used for limbing so the nose of the bar gets most of the action." Natural off balance of the limb twists the limb as the cut is near completed and pops the chain off the bar??

Has it always been a problem or is this something new?

If it's always done it, could be something assembled wrong or mfg defect.

Take the bar and chain off, look things over carefully, look for a worn or bent bar, something caught up in the bar, the sprocket for wear, the sprocket alignment with the bar.

Does the chain stay tight? If it backs off, could be a problem with the tensioner or the nuts not tightening down correctly on the bar. Be sure the bar sits flat against the case, nothing caught up under it or a screw backed out keeping it from sitting flat and tightening down.

Hold the chain stretched out between your hands, bow it side to side, it should bow the same both ways. If it has been run on a bent or misaligned bar it may be worn in such a way it favors one side and will continue to jump off even if the root cause is corrected.

Check the sprocket shaft for front to rear, and in and out play. If the bearing is bad the sprocket will be misaligned.

I see this often with the little dinky saws. You have a tiny chain on a plastic saw. Anything gets under the chain and it will flip the relatively flexible chain right out of the relatively shallow groove it rides in. My Stihl 011 is horrible about that.

Quoting Removed, click Modern View to see

Or the bolts that hold the bar in place?

Quoting Removed, click Modern View to seeIs there any chance the threads on the tensioner are worn or undersize causing the chain to go slack when she puts a load on it?

Sounds like the bar is worn . Take it off and trace its shape onto a piece of paper , flip it over and then see if the shape is symmetrical. If not rotated often the under side will wear and create a gap that lets the chain fly off .