Felling/gunning sights

[davidwyby]

Howdy. Thinned a bunch of dead trees out last weekend, some tight shots between other trees. I was using my Jonsered 2166 (red 372 with a 90 degree handle across the top). I noticed a discrepancy between where the sights on the clutch cover vs. the starter cover aimed, and also between where I gunned and where the trees landed. When I got home, I put the saw (bar) in a vise, leveled the bar, and put the level on the handle and the gunning sights. They all vary, and some are better or worse depending on whether I pulled the saw up or down with the bar nuts loose. Thoughts/ solutions? I guess practice with one saw and mental and maybe physical notes on the saw...kind of a bummer when trying to be precise.

@Burnham after discovering this, I used a 50' logging tape from a stake in the desired lay to measure out where the hinge should be one each side of the tree as described in FGTW by @gf beranek and it worked.... of course :-)

 

[davidwyby]

Part of me wants to drag a big T square out and shove it in the face....maybe at least for testing purposes. Not practical for work.

 

[lxskllr]

Maybe I misread, but the bar should be all the way up before you tighten. I'd keep the bars all the way up, then check the sights with a square. Make some correction marks on the plastic if need be.

 

[Burnham]

@davidwyby I'm not sure I'm getting what you mean by "leveled the bar and put the level on the handle and the gunning sights". Isn't the issue whether the bar and the gunning sights are 90 degrees to each other, to get accurate guns using the sight? Level doesn't really play into it, that I can see.

So I'm likely not understanding something.

 

[Marc-Antoine]

He leveled the bar in the wise to get an horizontal reference, then verified if the sights were more or less vertical, so 90°from each other or something else. It isn't related with an actual cutting position. Easier to do with a level than directly with a square due to the fatness of the saw's body.

 

[Burnham]

Ahhh...thank you M-A, now I see it.

 

[cory]

Part of me wants to drag a big T square out and shove it in the face....maybe at least for testing purposes. Not practical for work.

Put a laser pointer in center of face and use a small framer's square to align the laser perpendicular to the hinge, laser points exactly where the face is aimed

 

[davidwyby]

Put a laser pointer in center of face and use a small framer's square to align the laser perpendicular to the hinge, laser points exactly where the face is aimed

Brilliant! I Might even make a little holder fixture for a laser pointer

 

[stig]

Part of me wants to drag a big T square out and shove it in the face....maybe at least for testing purposes. Not practical for work.

Stick a folding ruler in your pocket.
Fold it out and use it as a shooting stick.
I teach my apprentices that, when they start out felling.

Most saw pants have, for some obscure reason, a side pocket for a folding ruler (and for collecting lots of saw chips)

 

[Tree09]

I carry one all day everyday as a fitter, never even thought of using it for that, thanks!!!!

 

[Nutball]

Maybe I misread, but the bar should be all the way up before you tighten. I'd keep the bars all the way up, then check the sights with a square. Make some correction marks on the plastic if need be.

Keeping it all the way down should decrease the chance of the chain derailing.

 

[gf beranek]

Don't forget... just because the hinge is set in the right direction doesn't always mean that's where the tree will go. There's generally a few other details in the equation that must be met as well.

 

[Burnham]

Understatement and a half, Gerry. You are so right, yet again!

 

[davidwyby]

Ok, so lean, limb weight, rot, wind…? What other knowledge are you learned ones holding?

 

[Burnham]

Cariolis effect.

 

[sotc]

If you dress to the left or right can skew things too😆

 

[BlackSmith]

My dress always gets hung up in the briars.

 

[gf beranek]

The list of reasons why a tree might not follow the undercut could fill volumes of text. One reason that stands out the least of all, but is no less important for a sawyer to understand, is 'parallax error'.

 

[stig]

With the low stumps, we are required to set, non-vertical fiber is the biggest issue.

 

[stikine]

Side lean in relation to the lay. Most don't understand how to adjust the gun to compensate for side lean to actually hit the lay.

 

[SeanKroll]

Side lean in relation to the lay. Most don't understand how to adjust the gun to compensate for side lean to actually hit the lay.

What do you do? What errors are people displaying?

 

[davidwyby]

Side lean in relation to the lay. Most don't understand how to adjust the gun to compensate for side lean to actually hit the lay.

I usually “steer from the back cut” by leaving a fatter hinge on the tension side. I don’t have enough experience for a feel as to how much is needed on the face and back cuts to compensate for xxx lean though.

I think this was a combo of parallax, sight off, punky wood, and I did not leave enough hinge on the tension side. Where it ended up was perfect, but the intended lay was the base of that rotten fallen tree in the distance.



@gf beranek i will refer back to FGTW

 

[stikine]

What do you do? What errors are people displaying?

What we teach new sawyers is to stand in the desired lay a tree length away and plumb the tree to determine how much side lean it has. You also need to consider the center mass of the limb weight in that determination. The sawyer then adjusts the gun (aim) of the hinge either right or left an equal amount opposite direction of the side lean.

Heavy side leaners may require a 1.5 compensation factor and a support wedge just behind the hinge on the compression side.

 

[davidwyby]

What we teach new sawyers is to stand in the desired lay a tree length away and plumb the tree to determine how much side lean it has. You also need to consider the center mass of the limb weight in that determination. The sawyer then adjusts the gun (aim) of the hinge either right or left an equal amount opposite direction of the side lean.

Heavy side leaners may require a 1.5 compensation factor and a support wedge just behind the hinge on the compression side.

So simple I now feel kinda dumb, haha.

So 4’ lean at the top, adjust gun/lay on the ground 4’.

 

[stikine]

I usually “steer from the back cut” by leaving a fatter hinge on the tension side. I don’t have enough experience for a feel as to how much is needed on the face and back cuts to compensate for xxx lean though.

This is where boring the backcut to set your hinge really shines. Leave a trigger of uncut wood in the back and cut (release) when you are ready to fall it