Chain not sliding inside the gauge but riding on the top of nose sprocket teeth.

[NAKATA]

Good evening Gents!

I need your expert opinion on the following matter:

Is this gap between the bar`s gauge and the chain on the nose normal or the chain has to be touching and sliding on the gauge?

My opinion is that the chain has to slide on the gauge and not riding on the sprocket teeth as it create too much stress on the sprocket teeth bearing.

See photos bellow!

 

[Franny K]

The drive links fold around the teeth at the nose and if you see sparks it is because it is rubbing. If the first picture has sort of rounded tips after the chain is removed for viewing it is the correct one for 3/8lp but if the tips are kind of pointy that tip is for full sized 3/8.

 

[J D]

The whole point of the sprocket nose is to stop the chain riding on the bar rails. If the chain rides on the bar rails around the tip it has to be a hard nose bar with considerably harder metal... in this situation there is more friction, drag & wear (but no sprocket to get clogged up or fail). In most situations the increase in cutting power that goes along with a sprocket tip is well worth their use, & in the situation that a quality bar would likely outlast the sprocket they are generally replaceable

 

[Matt81]

The sprocket nose is designed to fully support the chain. There should be a gap to prevent extra friction and wear and a slowing down of the chain speed. Over time as the sprocket nose teeth wear down the chain will eventually touch the bar nose. Often you will start to see sparks when this gets bad enough. Time for a new sprocket nose if your bar supports this or a new bar if it does not.

Never had a sprocket nose bearing fail yet from a correctly tightened chain in around 30 years of cutting. It is what they are designed to do after all.

Also the gauge of a bar is the width of the groove where your chain drivers run in. The drivers of the chain must have the same gauge to work properly. Sounds like you are using the word gauge to refer to the gap between the bar nose and the chain.

 

[NAKATA]

Thank you all for your answers!
That's much appreciated!
Apparently I have been wrong, there should be a gap between the chain and the bar on the nose.

Can you give me advice on something else I'm having problem with....
How tight the chain has to be on a 42" milling bar.
If its too tight the chainsaw won't run its like the brake is on, but if I leave it little bit loose it jumps off the bar when I hit the throttle and makes sparks.
I get away with loose chain on 24" bar with 60cc chainsaw but on 42" with 92cc 7hp Husqvarna 592xp it has so much more power that makes a wipping wave on the upper side of the bar with sparks.
Some say the chain has to be 1cm of the bar when pulled with 2 fingers.
Regards!

 

[J D]

Do the drive links slide freely around the bar groove? Does the sprocket spin freely without any play? Is the sprocket worn or damaged? (This can happen very quickly from clamping a mill frame too close to the sprocket). Do the pitch & guage match on bar, chain, & drive rim? Are the rails clear of debris & receiving adequate lubrication?
After you confirm all that, your 1cm when pulled with 2 fingers is about right. Make sure bar tip is raised as you tighten or tension may change when cutting. For most cutting conditions, minimum chain tension should have no visible chain sag of the bottom of the bar. You also don't want the chain so tight you can't lift a couple of drive links clear of the bar rails at the center of the bar (without straining, using just your thumb & forefinger).
Tension can be pretty subjective & is guaged differently for shorter or longer bars.
There's no good reason a 592XP should struggle to pull the chain around a 42" bar so I suspect there is some physical/mechanical issue you need to address