Magic Cut?

[lxskllr]

When/why/how is a good time to use a magic cut? I suggested Mike try it today on a no consequence chunking down of a willow stem. I gave him instructions that were cobbled together from fragmentary data I've collected, and may or may not have been correct. This is what I said....

Make a standard, but deep facecut, and dutchman the horizontal portion
Make your backcut about 0.5" below the horizontal part of the facecut

Any corrections? That worked, and the chunk went over, but I'm uncertain why that's better than other alternatives that could be used.

 

[Burnham]

Magic Cut for vertical spars, etc

Originally brought to my attention by Gord's TB post, years ago. Deep horizontal Sloping cut, conventional or Humboldt--- forms the full bypass at traditional hinge area Low back cut/ snap cut All three cuts ( I was sloppy... Not a clean, 2 plane intersection). Normally, green wood...

www.masterblasterhome.com

Pics not loading, for some reason. Description is there.

 

[Burnham]

And here.

euc removal with wrench

The Tree Doctor - Eucalyptus Dunnii Removal - Bri…: http://youtu.be/-2lciI23WgE

www.masterblasterhome.com

 

[SeanKroll]

That's the gist of it.

To my recollection, Gord from BC was the feller who introduced it on TB, in the relatively early days.

I've never heard it discussed outside the forums, but I don't know many people in the industry.




Cut the first side of snapcut, add a snipe (square or at an obtuse angle).
Cut second side of snapcut, as per usual, lower than the first side.


The snipe should be deep. It doesn't need to be particularly wide, unless you are trying to add 'English', in one direction/ rotation or more.

I generally make the snipe so my horizontal full-dutchman bypasses the intersections of planes by 1-2".

When chunking heavier, I'll come down 2"ish or more on the second side.

Generally, it's no-frills.


Works well when cutting well more than a bar length. I had to chunk down, without overhead TIP, a 5-6' dbh cottonwood with a single stem to about 80' (leave logs lay in the forest, thankfully). I was running an ms660 with a 36" bar. Making a hinge would have been hard. Luckily, it was a cold, wet winter that year, adding to the challenge. Needed the dollars at the time.

Helps if your chainsaw becomes a metal detector (I was in a tv antennae tree, topped doug-fir) or if you get sent up a crooked cutting saw, as you don't need much precision.

Clearly, a sharp chain is right. But sometimes you get two more chunks down and you're on the ground, so make it work.


I haven’t figured a length limit. 12' are easy for me to be judging a relatively plumb trunk's COG by sight. If you see the kerf close AT ALL, Stop on your first horizontal!

Consider crocheting density.



On a side note...
Some people will use a long wedge or stick in the kerf, inserted ay a slight angle from horizontal, lightly placed, to form a "tattle-tale". The Stick or wedge is commonly in the backcut of a standard felling cut. The faller can see small movements magnified by the length of the line/ stick/ wedge. The felling wedges being pounded are straight in the kerf, giving the feller a reference.


Start small, even practice on the ground with small spars in totally no-consequence situations.

 

[lxskllr]

What value do you see in it over a conventional felling cut?

 

[SeanKroll]

Bigleaf maple is barber chair-prone.
I consider that factor whenever cutting maple, hearing and feeling the spar and chunk pop as is cut.
I'll wrap the first horizontal kerf around both both sides, snipe it, then bring in the second horizontal.

This is like a "box-cut" used to prevent slabbing of a log being bucked. All the sapwood and some heartwood cut. There is a square/ rectangle of heartwood under strain. The buck is finished from tension to compression, commonly. If not, anti-binding measures (plastic or log-end wooden wedge in the kerf or reaming the cut).

 

[cory]

What value do you see in it over a conventional felling cut?

I always thought a big plus was that there is less cutting involved compared to a conventional cut- the snipe vs a full, open face

 

[SeanKroll]

What value do you see in it over a conventional felling cut?

Faster, easier, less precision required for the same result, cutting big wood is where the precision is harder (bar length and a half+). Double-cutting with a very slightly j-cutting chain in bigger wood sucks to match up! The evidence and problems of a chain with some damage shows most when the bar is buried.


No ropes, wedges/ax or deep precision cuts.

It's just a simple technique for some basic situations, nothing fancy like hinge- mastery when it counts.

 

[lxskllr]

I think some of my confusion was the snipe. I explained it as being a conventional cut, but that's closer to a rip in speed(slow), whereas it sounds like you're talking about a shallow cut(narrow face) that's much closer to a crosscut(faster).

 

[SeanKroll]

I always thought a big plus was that there is less cutting involved compared to a conventional cut- the snipe vs a full, open face

If you use a rear of COG hinge, you need to cut deeper and a steeper snipe as the hinge eats energy when bending.


Most people, I would guess, have had a chunk tip, hinge bend, face- close, stallout. Then, you have to release the whole hinge cleanly, to avoid the chunk pulling to one side.


I'll draw a picture. Let me DM @Tree09 for tips.

Brb

 

[SeanKroll]

Your saw, so far as I can tell, can stay put in kerf 3.

In contrast, If you cut through your hinge, accidently, you can get your saw pulled or bar bent.

 

[SeanKroll]

The chunk should probably be at least as tall as it is wide, double the width would be a solid minimum.



There is only trigger pulling, no manual anything.

 

[lxskllr]

Kyle would proud :^P

The pics are very clear though, and that's what matters most :^)

 

[SeanKroll]

When?
When you are on one spar reaching for other spars, taking down all the spars on one trip downward... If the bar can reach it, gravity will pull it over.

 

[davidwyby]

I’m practicing my Humboldts today on spars. It occurred to me that cutting them (deep) and then adding the bypass would decrease my effort. I did regular back cut though because I wanted to do some wedging. Palm fibers hold pretty well, this one anyway…so yeah I got my wedging in, haha. I like that fat green wedge, I think it’s forester. It’s wider than the poll of the axe, so can be chased indefinitely. I drove it in the center, then the others on the sides for more lift, hinge rip since it stalled on the Dutchman. Then pulled Green out and gutted the hinge. Blue wedges cut clear thru the hinge, palm isn’t real hard…it’s grass after all.

 

[Burnham]

I'm missing some things, David. What are you calling a "bypass"? And why the dutchman, I presume intentional? That is not normal procedure for a Humbolt, any more than for a conventional face.

 

[cory]

Jed would be eating up this convo. RIP

 

[davidwyby]

I'm missing some things, David. What are you calling a "bypass"? And why the dutchman, I presume intentional? That is not normal procedure for a Humbolt, any more than for a conventional face.

I’m chunking down short sections of spars, using a spin on the magic cut that is the subject of this thread. Yes, Dutchman/bypass intentional. Doesn’t work very well as a magic cut though without the opposing “bypass” cut like a snap cut

 

[pete mctree]

Humboldt or traditional face, it does not matter. Keep the first cut deep (60% minimum) and the bypass cut close - the centre of gravity will work for you.

@davidwyby the whole point of the cut is to remove the need for a hinge or a wedge. The Dutchman requires a lot of force to get a piece moving as you have no space to rotate and flex fibres

 

[davidwyby]

It did work well in this case (cut properly). Chunk tipped itself off

 

[Marc-Antoine]

The magic cut with fibers left untouched at the hinge's emplacement isn't magic at all, more a pain in the ass. It will fight you all it cans and even is dangerous because the actual lay becomes imprecise at best.

 

[Tree09]

It's more of a snap cut with undermining and a snipe, you want it to break cleanly and not veer to a side from uncut wood, basically letting the saw do all the grunt work. There's no hinging, it snaps and then goes on its own. It's a confusing cut at first, took me awhile to wrap my head around it, but it's truly the easiest way to do so without a tag line or booming up to push it over. I still often prefer those options because it's even easier quicker, and has even more control imo. You don't need to undermine it as much, you just need enough that the cog can be easily be tipped to the lay and the snipe takes care of the rest. Since there's no hinge wood a directed push/pull has the ability to steer the piece, so I'll often cut it up and then boom up so i shove it right where i want it to go, the precise control over the fall worth the extra minute to reposition when you're in a lift.

There's another similar trick that's handy sometimes, you do the same cut but with a large enough gap that it'll need to be triggered by an external force, usually a tag line. On a leaning limb you can even do a tensioned tip tie to hold it up perpendicular to the hinge (aiming to the side), this removes the side force that would cause the limb to drop down and go "sideways" in respect to the hinge. This allows you to perform the cut then move out of the way to a safe spot, and then the cut is triggered by the pull. I'll even do this on the back cut on certain pull trees, when you have enough tension to break the snap cut it'll have enough force on the pull line to make the tree commit quickly and fully to the hinge, and you can do so solo or to get to safety when it's in a terrible spot. Everything is cut normal, you just bore your back cut and leave a strip of wood in the far back, then do a lower snap cut to sever the rest of the back cut fibers. Lots of residential trees have no good way to get away from the tree because of fences and landscaping blocking your exit paths, so the snap cut to trigger it buys you enough time to escape before movement is triggered by the pull line. Wedges can ensure it won't tip back, just don't beat them in so hard that it tips it for you.