Kick back

[jnahnet]

I have 10 tons on live oak left to process, I upgraded to a 20" bar (Husqvarna 450 Rancher) from my 16" Sthil 250's.
I'm cutting much larger rounds than I'm used to; every time I almost finish a cut the chainsaw violently kicks up and
out of the cut, not only is this terrifying but, I'm 71 years old and this killing my rotary cuff and shoulder.
What am I doing wrong? Working on a hill if that makes a difference.

 

[Philbert]

Kickback is typically a reactionary force. One of several possible with chainsaw chains moving near 60 mph.

Some chain movement will pull the saw into the wood. Some will kick it out of the wood.

Touching the upper part of the guide bar nose to the wood, with the chain running, as you withdraw it from the log, could be a cause.

Also, the saw kerf pinching closed as the cut is completed (a wedge to hold the kerf open may help).

Good info at this link:

https://www.ccohs.ca/oshanswers/safety_haz/chainsaws/kickback.html#

Philbert

 

[Del_]

A chainsaw's three reactionary forces:

1, Kickback-caused when the chain at the tip of the chainsaw bar contacts something.
2. Push out- caused when the chain on the top of the bar gets pinched.
3. Pull in- caused when the chain on the bottom of the bar gets pinched.

 

[jnahnet]

Kickback is typically a reactionary force. One of several possible with chainsaw chains moving near 60 mph.

Some chain movement will pull the saw into the wood. Some will kick it out of the wood.

Touching the upper part of the guide bar nose to the wood, with the chain running, as you withdraw it from the log, could be a cause.

Also, the saw kerf pinching closed as the cut is completed (a wedge to hold the kerf open may help).

Good info at this link:

https://www.ccohs.ca/oshanswers/safety_haz/chainsaws/kickback.html#

Philbert

Thank you for your time and info, I will definitely start using wedges.

 

[jnahnet]

A chainsaw's three reactionary forces:

1, Kickback-caused when the chain at the tip of the chainsaw bar contacts something.
2. Push out- caused when the chain on the top of the bar gets pinched.
3. Pull in- caused when the chain on the bottom of the bar gets pinched.

 

[jnahnet]

Thank you, excellent specifics of these forces. It's Push out, so hopefully the advice to use wedges will help.

 

[Del_]

Thank you, excellent specifics of these forces. It's Push out, so hopefully the advice to use wedges will help.

I use plastic wedges but be careful.......it's hard to tell when the round breaks loose and it's easy to hit what ever is under the log.

Sometimes as the piece seperates the wedge falls onto the top of the chainsaw bar. Metal wedges can be bad.

 

[snobdds]

The first lesson in chainsaw cutting is knowing where the tip of your bar is, at all times.

You put the tip in the kickback zone, you will get kickback.

 

[Seachaser]

Watch the tip. Sounds like your tip is hitting something. Some good advice already.

 

[Del_]

Thank you, excellent specifics of these forces. It's Push out, so hopefully the advice to use wedges will help.

You're welcome.

Push out can be quite violent.

 

[jnahnet]

I use plastic wedges but be careful.......it's hard to tell when the round breaks loose and it's easy to hit what ever is under the log.

Sometimes as the piece seperates the wedge falls onto the top of the chainsaw bar. Metal wedges can be bad.

Thank you, I appreciate the advice, with the 250's I didn't cut anything big enough to warrant wedges, but with 12 mature oaks toppled from snow load, I'm learning, again thank you.

 

[Philbert]

Wedges are a great tool. You may wonder how you worked without them. They will get hit: that’s why we use plastic.

Another approach can be in the way you plan your cuts (I haven’t seen you work, so maybe you already do this!).

Often, you can make relief cuts, on the top or bottom of the log, so that your bar does not get pinched when you finish the cut.

Sometimes, you may ‘guess’ wrong, but over time, you will get better at predicting possible binds.

This can be used, together with the plastic wedges.

Philbert

 

[muddy42]

Or lift the trees up off the ground with a tractor. Or cut halfway and rotate the log to finish the cut.

 

[lone wolf]

Keep your self off to the side of the saw when cutting so when it does kickback you are not in that arc!

 

[telecasterfool]

All of these replies are correct. This is happening at the end of the cut because the space between the two pieces is changing - you've removed the wood "spacer". All of this is good practice, already mentioned, cut half or 2/3, then roll and finish, use a tractor to hold the piece, cut half, wedge (plastic) then finish. An important concept to learn is compression and tension. A log sitting on the ground probably already has some in different areas. Compression exists in an area that - when you cut it - the two pieces will move closer together, or the "kerf" closes. If you cut and the pieces move away from each other, there was tension. Often, in a single cut, one side of the log will be under tension, while the other side is under compression. Picture a log sitting on both ends with space under the middle. Because the middle of the log wants to go down, the top of the log is pushing together (compression) and the bottom is pulling apart (tension). The compression is what you are having a problem with - it's pinching your bar. you can cut the compression first (letting the tension wood hold the space), you can prop something under the log so it can't fall down and then compress, you can wedge, etc. Start looking for compression and avoid it. Hope this helps.

 

[jnahnet]

Or lift the trees up off the ground with a tractor. Or cut halfway and rotate the log to finish the cut.

The 1949 Allis-Chalmers tractor my Dad left, died right after my husband. The problem with rotating (which I generally do) is these are root ball trees, it's getting the trunks off the butt that I suck at.

 

[jnahnet]

All of these replies are correct. This is happening at the end of the cut because the space between the two pieces is changing - you've removed the wood "spacer". All of this is good practice, already mentioned, cut half or 2/3, then roll and finish, use a tractor to hold the piece, cut half, wedge (plastic) then finish. An important concept to learn is compression and tension. A log sitting on the ground probably already has some in different areas. Compression exists in an area that - when you cut it - the two pieces will move closer together, or the "kerf" closes. If you cut and the pieces move away from each other, there was tension. Often, in a single cut, one side of the log will be under tension, while the other side is under compression. Picture a log sitting on both ends with space under the middle. Because the middle of the log wants to go down, the top of the log is pushing together (compression) and the bottom is pulling apart (tension). The compression is what you are having a problem with - it's pinching your bar. you can cut the compression first (letting the tension wood hold the space), you can prop something under the log so it can't fall down and then compress, you can wedge, etc. Start looking for compression and avoid it. Hope this helps.

As a retired collage professor, I must say I'm impressed with your teaching style. That's exactly what happen, one of the main trunks was on the ground with a slight bow to it leaving a section that I thought would be easy to cut without getting my chain in the dirt. I'm going to have practice my under cuts. Thank you for your help.

 

[telecasterfool]

As a retired collage professor, I must say I'm impressed with your teaching style. That's exactly what happen, one of the main trunks was on the ground with a slight bow to it leaving a section that I thought would be easy to cut without getting my chain in the dirt. I'm going to have practice my under cuts. Thank you for your help.

It sounds like the plastic felling wedge will be the best solution for you. It's not unusual to use two or three on a big cut like you are describing. A small sledge hammer or boys axe, or big hatchet is handy for setting them and getting them out. Something not mentioned so far is cutting a wedge of any size on the compression side of the wood, similar to a felling cut when dropping a tree. This creates space for the kerf to close without pinching the bar. Good luck to you.