Confused on snap cuts

[Mark Chisholm]

What do you call that Kevin?

 

[Gord]

In that illustration i called that a bypass bored backcut...i don't know of a common name for it.

 

[Norm_Hall]

We call it a bore cut with a strap. Before cutting the strap, give a warning to all crew members.

 

[Kevin]

That would be a bore or plunge cut.

 

[Lumberjack]

Its important to not trust the strap to hold the tree. Giving the warning sounds good, when the back cut starts, its a "Do not approach" zone IMO, the warning is redundant, but that can be a good thing eh?

 

[Mark Chisholm]

[ QUOTE ]
That would be a bore or plunge cut.

[/ QUOTE ]

Well, I agree with that. I would call the front cut a "face cut" or "notch", the second step would be to set up the hinge with a "bore cut" and then the third step is cut the strap, BUT making it a "bypass" or "snap" cut. What I was suggesting is that Dwayne talks about combining these procedures for the "snap" cut release. That's all.

 

[Gord]

[ QUOTE ]
That would be a bore or plunge cut.

[/ QUOTE ]

Although a bore or plunge back cut can also be a one step procedure for heaver leaners; just bore in and cut back until the tree tears away from the stump, often leaving a spike.

 

[Kevin]

Copy that. /forum/images/graemlins/icon14.gif

 

[Mark Chisholm]

[ QUOTE ]
Copy that. /forum/images/graemlins/icon14.gif

[/ QUOTE ]
Right on! /forum/images/graemlins/fruit.gif

 

[Kevin]

Gord, I would agree that will work but it increases the risk to the saw and sawyer.
I think it's better to cut from the outside of the tree to trip it.

 

[120770]

[ QUOTE ]
In that illustration i called that a bypass bored backcut...i don't know of a common name for it.

[/ QUOTE ]

Ive sometimes heard it called a envelope cut.

 

[TheTreeSpyder]

[ QUOTE ]
Ahh, but if you are have a lateral limb, and want to cut short pieces (say max 4 feet),then break it free, and drop it, just make your mismatch cuts vertically. Works like a charm.

[/ QUOTE ]



Great trick Rog. i think this works in several stages. i think ya kerf under the horizontal limb, then come down from above. The initial failure/fold is the same strength as any other kind of face etc.; because the load pulling on it is the same. The kerf shows early close strategy.

This close gives a push up/out on the branch; as the still connected tissue/'hinge' is now tensioned. This can hold sometimes until seperation, then let go like it was suddenly dropped; not kicking back towards tree, or perhaps sometimes not kicking back as hard is enough.

Mostly this early close doesn't let the Center of Gravity of the limb rotate too far below the close of the kerf at close/ release i think. If the CG does come too far below the pivot/ close of kerf; then the limb is more likely to 'kick'/swing back towards the tree. If a limb is too long for this, i think it is becasue the CG can settle too low in the few degrees of movement the limb makes to clsoe the kerf; can make it kick back towards the tree at close. Then this responding push by the close, and the CG as ForcePoints have an angled branch between them so are more likely to 'spin'/tourque branch back towards tree; especially if the angled force down the limb can also flex it back to move CG even more unfavorabley lower than clsoed kerf before release. They are working in opposite directions and not inline anymore, so there is rotation. But if the CG is higher(like in an upswept but horizontally attatched limb), i can usually drop a longer length for the CG won't settle below the limb when the kerf closes; because it starts higher/ more likely to get a 'snap' at release.

i think a deeper kerf gives an earlier close; to let the limb's CG settle downwards less, for more straight drop release. But also, this gives the support at kerf close/prep for re-lease more leverage. Now the distance from the closed kerf to the kerf's 'hinge' is a longer distance for higher multiplier. i think this gives less fibers to cut, for a more instantaneous release. Quick, sudden release being another factor of a straight drop. i also think this is more friendly to the tree, in that the fibers aren't pulled as tight, so the stretched fibers don't go back that far beyond the cut.

Many times, i can work this slow, purposefully close the kerf then detatch. If set right, and you know CG won't come below limb, can go faster and slam it close to get a 'pop' out/off. But if CG can come below branch back towards tree at close, the speed only accentuates that bad positioning of CG to pivot at hold, right before release; throwing back harder(which is sometimes useful).

Lots of times if there is a heavy side, i'll undercut/kerf that side deeper, and purposefully close it early, for more pushup support on that side. The harder the lean/CG pulls to the side, the better that works.

In larger stuff, i might close the heavy side early with a close for this push effect, with the opposite side of the face still open/pulling at the same time. This gives both the push and pull working to center at once. Also, the pushes and pulls work in opposite dirctions for more of a tourqued, than linear pattern of force (stronger force like opposing out of line forces whne CG drops below kerf close before tearoff/release) i think.



Or something like that...
/forum/images/graemlins/propeller.gif

 

[mikeyott]

use a bore cut when topping safer,better communicatoin, more controled, never blow through your hinge
cheers!

 

[tomthetreeman]

Old thread alert!

 

[mikeyott]

haha guess i should have read on first haha

 

[chris_girard]

Old threads are sometimes the best threads.

Lots of good info here.

 

[jomoco]

I understand the pic of the snap cut with an opposite face.

I use it on fat vertical spars that have a bomb window that I can align my facecut to.

This allows me to pull back once on the piece to unsnap it, then push forward towards the window/face for a nice easy launch in the exact direction I want the piece to go. This is far easier than waddling the piece to its fulcrum point with both hands.

And it is captioned as a "faced" snap cut.

I've always referred to what you guys call a snap cut, as a holding cut, as in holding the piece until your chainsaw is secured.

jomoco

 

[Gord]

There's also variation on this cut that I use to fall short logs off a spar. I came up with it myself, I'm sure others have too but I haven't seen any mention of it so I thought I'd post it. I call it a 'Magic Cut' because of the work it saves in getting large wood off of a vertical spar. You can see one used in this vid at about 3:00:

http://www.youtube.com/watch?v=5aM-_OK0raw

 

[cory]

Nice takedown, Gord. And real nice work with a relatively short bar, especially while aloft.

The magic cut is a good one. I learned it from Gerry's book, he calls it cutting lean into a tree.

 

[mikeyott]

alllllright now that ive read through the whole thread personaly i do the same a bore with a strap but also for every large tree i attatch a 5:1 and i put 1 or 2 wedges on a straight tree and 2 to 3 wedges on a leaning tree this way here you can make your by pass/back cut half way shut your saw off walk away put tension on the 5:1 she might go if not walk back hit sum wedges she might go if not cut a bit more then repeat tension wedge i always use wedges with the bore cut because its less saw well sometimes less saw, more communication a bit more time but its your life no point not using a 5:1 and wedges even if you are sure of the tree when felling because after practice each take an extra 10 minutes out of your time and in the tree i use 1 wedge when topping just to be sure and if its small enough i make my bypass/backcut with my handsaw abit more energy but you have perfect communication which is key.
cheers!