Dogging in vs self feeding - Tooth length too! The truth of it.

[davidwyby]

My std bar with stihl NK helps keep me from getting pinched. Bars slide out easier than chains.

 

[Philbert]

My std bar with stihl NK helps keep me from getting pinched. Bars slide out easier than chains.

That’s one of my ‘standard’ methods for removing a pinched saw:

- pull the powerhead (STIHL type saws with outboard sprocket);

- silde out the guide bar (chain may prop open the kerf);

- work out the chain (maybe), OR drive in a wedge where the guide bar was; OR cut out the chain with your spare bar and chain

Worst case: you lose the chain, the least expensive part.

Just one method. Good to have options!

Philbert

 

[davidwyby]

My skinny chain and fat bar give a little
More time to react or forgiveness for cutting in a way that will pinch. I can usually snatch it from the tree’s jaws sliding on the bar before I’m actually stuck. 3/8” chain has such a wider kerf yer stuck.

 

[Squish9]

Back to sharpening to suit the wood. This is a Stihl 36RS cutter, sharpened using the older style of sharpening recommend by Stihl decades ago.

Stihl 3/8 file guide, 3/16 file as recommended because it's file more than half way back. File guide at 30 degrees across, 10 degrees of tilt.

Side plate angle is 80 degrees
Top plate cutting angle is 60.

Look at the witness mark. They might tell you to have it 30/60/60 but they mark the f'ing thing with a 80 degree side plate angle.

 

[Squareground3691]

Yes that is correct the kerf gets narrower as the cutters are sharpened and length is reduced.
We have all run a saw and a few sharpens in as the kerf is reduced and the chain hits that sweet spot the perfect load to power ratio.
I don't believe the kerf gets that narrow at the end of the chains life the rivets and bar start binding well at least I've never experienced it personally.
If the cutter in front has done it's job and has the same set as the one behind it the side of the rakers shouldn't be rubbing against the kerf? I see no benefit in trying to make a cutter cut further sideways the cutter would have to tilt to achieve this would wear out the bar groove in no time I'd imagine? But I could be wrong never messed with filing the sides of rakers myself.

She cuts eh ,

 

[el33t]

Back to sharpening to suit the wood. This is a Stihl 36RS cutter, sharpened using the older style of sharpening recommend by Stihl decades ago.

Stihl 3/8 file guide, 3/16 file as recommended because it's file more than half way back. File guide at 30 degrees across, 10 degrees of tilt.

Side plate angle is 80 degrees
Top plate cutting angle is 60.

Look at the witness mark. They might tell you to have it 30/60/60 but they mark the f'ing thing with a 80 degree side plate angle.

View attachment 437340

In fact, if the USG chart is to be believed, the standard top plate cutting angle for Rapid Super is 50°, and the side plate angle is 60° (vise offset of 15 mm).

I also looked at the 3/8 RS factory grind and to me it looks like the the side plate angle is about 50°. I don't even want to guess how much the top plate cutting angle is. 50°? 45° (cuts fast!!!)?

It is indeed interesting that on the side plate they left the witness mark corresponding to 80°, which is that oldest value for their full chisel chains (Rapid Super), although they changed it to 60° about 30 years ago.

 

[el33t]

Yes that is correct the kerf gets narrower as the cutters are sharpened and length is reduced.
We have all run a saw and a few sharpens in as the kerf is reduced and the chain hits that sweet spot the perfect load to power ratio.
I don't believe the kerf gets that narrow at the end of the chains life the rivets and bar start binding well at least I've never experienced it personally.

Race chain makers have all kinds of ‘secret sauce’ type things they do make their chains special.

But for us mortals, I believe that a chain loop with its cutters worn back behind the witness mark will still carve a kerf wide enough for the chain and bar to pass through.

Unlike Oregon, Stihl has not introduced special bars for their .325 Pro chains. I've seen in a few places complains from users that after half the tooth wear their chains won't cut, so maybe there's something to it.

A similar problem probably applies to Hexa (3/8) as well. @Squish9 has a video showing it hanging up on the bark trunk. On the same bar with Carlton A3LM there is no such problem.

In the old manuals, there was sometimes a recommendation to gradually increase or at some point to switch to an increased top plate filing angle, that is, to decrease the side plate cutting angle, resulting in a slightly wider kerf.

 

[el33t]

Janka:

PNW

Doug fir 660 (fibrous, lot of drag on the back chain robs hp, square ground helps)
Madrone 1460
Alder 590
Big leaf maple 850


Central/east US

Rock maple 1450
Black locust 1700
Osage orange 2620
Pignut hickory 2140
Red oak 1220
White oak 1350
Bur oak 1360
Pin oak 1500
Swamp white oak 1600
Ash 1350
Wall nut 1010

Turkey oak 1200


Southwest US


Monterey pine 710 not hard of fibrous but very stringy. Very hard springy tough once sap desert dried.
Live oak 2680 tough when green, chain skating hard when desert dried.
Alligator juniper 1160 “softwood”
Desert ironwood 3260 (74lb/cu ft, doesn’t float)
Olive 2700
Mesquite 2340 tough when green, hard when dry
Borrowed from Oz : not so hard when green
River red gum euc 2160
Iron bark Euc 2600-3600
Blue gum 2680



Oz:
Buloke 5060 !!!
Yellow box 2930
Gray box 3310

These guys have compiled a database of properties of various woods, including some that may be more decisive of the forces needed for cutting than just hardness or density.

World's Strongest Woods | The Wood Database

www.wood-database.com

 

[davidwyby]

These guys have compiled a database of properties of various woods, including some that may be more decisive of the forces needed for cutting than just hardness or density.

World's Strongest Woods | The Wood Database

www.wood-database.com

That site is where I got all my numbers from.

 

[Stihl036]

I was just watching this video from Vallorbe Swiss files and noticed a little bit of 'side nip' on the depth gauge. I was told of this technique in the early 1990's by a Stihl Tech out of Virginia Beach named Brian. Brian had come out to help me set up my USG Square Grinding attachment and we spent a few hours running saws, Stihl of course. Brian's theory was the side of the depth gauge prevented the tooth from leaning over into the work just a little bit. It seems changing the filing angle as suggested above by el33t must let the tooth move out just a little, too. If it didn't I don't see how a wider kerf would result.

Here's a still shot from the Vallorbe Swiss video.









Here's the whole video.

What's it all mean? LOL.

 

[rogue60]

I'll see if I can find the vid of one them guys in the jungle free hand ripping out boards with an 070. He takes a pair of pliers and snapped off all the rakers! He's cut's and kerf were dead straight and smooth.
I'm unconvinced rakers have anything to do with controlling kerf width? If everything is in order a cutter should stand up straight in use. Any tilting sideways or the like would promote fast excessive wear of chain and bar I'd imagine?

 

[Squish9]

I was just watching this video from Vallorbe Swiss files and noticed a little bit of 'side nip' on the depth gauge. I was told of this technique in the early 1990's by a Stihl Tech out of Virginia Beach named Brian. Brian had come out to help me set up my USG Square Grinding attachment and we spent a few hours running saws, Stihl of course. Brian's theory was the side of the depth gauge prevented the tooth from leaning over into the work just a little bit. It seems changing the filing angle as suggested above by el33t must let the tooth move out just a little, too. If it didn't I don't see how a wider kerf would result.

Here's a still shot from the Vallorbe Swiss video.

View attachment 437534







Here's the whole video.

What's it all mean? LOL.

I have tried so many times to contact Vallorbe but have had no luck. Maybe it's the language barrier but I always wanted to know why they leave the side beak. I have filed just like that and it works, I just don't understand why.

I have tied filing some of the side of the depth gauge but didn't notice a difference

I'll see if I can find the vid of one them guys in the jungle free hand ripping out boards with an 070. He takes a pair of pliers and snapped off all the rakers! He's cut's and kerf were dead straight and smooth.
I'm unconvinced rakers have anything to do with controlling kerf width? If everything is in order a cutter should stand up straight in use. Any tilting sideways or the like would promote fast excessive wear of chain and bar I'd imagine?

The way they file is just insane to me. Dig in with a 4.8mm file and then come back with a small rectangle file to add even more of a beak in 46RM chain. It obviously works for them.

I think the filing angle causes them to wonder side to side more and that's why dropping them to 0 or 10 degrees for milling cleans up the cut surface. If you try 35 or 45 it cuts big lines in the side of the kerf as the cutters try to pull sideways more

 

[el33t]

I think the filing angle causes them to wonder side to side more and that's why dropping them to 0 or 10 degrees for milling cleans up the cut surface. If you try 35 or 45 it cuts big lines in the side of the kerf as the cutters try to pull sideways more

This seems to be the logical explanation, and that's how it was explained in that oldest version of the guidebook on bars and chains. For some reason they removed this part in later versions.




If anyone is interested, the 45° top plate filing angle was not unusual at first. That's how J.B. Cox imagined it in the chipper patent. Later, probably in practice, it turned out not to be a very good idea, even for chipper.



I wrote that Stihl somehow doesn't specifically mark (Pro or NK) the .325/.050 bars with which they equip their saws at the moment. I know that they previously had some .325/.050 bars on offer, which were not found here at all. It would be nice if someone measured what the widths of the various bars are, because maybe, after all, the people complaining about problems with these new Pro chains somehow got bars that are wider than the latest ones designed for all new .325/.050 Pro Stihl chains, which generally replaced all kinds of old .325/.050 ones.

I haven't seen it, but maybe there is such a database somewhere.

All this probably doesn't change the problem with Hexa.

 

[Stihl036]

I'll see if I can find the vid of one them guys in the jungle free hand ripping out boards with an 070. He takes a pair of pliers and snapped off all the rakers! He's cut's and kerf were dead straight and smooth.
I'm unconvinced rakers have anything to do with controlling kerf width? If everything is in order a cutter should stand up straight in use. Any tilting sideways or the like would promote fast excessive wear of chain and bar I'd imagine?

I've seen that video too.

The fellow is barefooted!

If I remember correctly he was cutting with the lower quadrant of the bar tip.

This isn't the video I'm thinking of but this guy is very similar.