I THOUGHT I learned something about gullets this weekend.

[DucTruckin379]

I got a few extra loops of the square Oregon chain in this last week, so that I could keep practicing filing, and try some new things as well. On one loop I knew I needed this weekend, I just cleaned out the gullets, and didn't touch the cutters (figured it might get buggered up doing what I needed to do).
I gave them a real deep angle, much deeper than I had done in the past. Heck, it looks good right?!

When the whole bar was buried, it drug down the saw a whole lot more than I expected, so I started to pay a little attention. It was obvious it wasn't clearing chips very well at all. I swapped it with a loop that I hadn't done anything to, and the non-gulleted loop smoked it... (hadn't touched the cutters on either, and hadn't had a chance to bugger the gulleted one up yet, so basically brand new chain only difference was the gullets)

I think the severe angle on the gullets that I tried are what the problem was. When I've cleaned them out in the past it's not been at a full 90deg to the chain, but it's been a lot more blunt than these. I think the angle lets the gullet ride right past the chips instead of sweeping them out.

I'm probably preaching to the choir, and it seems kinda obvious now that I think about it, but heck, I thought they looked good at the time! I read about the safety chain with the second rakers filed flat to sweep chips being really fast, and this is kinda the opposite...

Anyway, thought it was interesting. Picture of the gullet below:

 

[huskihl]

Did it slow down the engine or did it slow down the cutting speed?

 

[DucTruckin379]

@huskihl Both. It would start off good, but quickly bog once the kerf got full of chips. It was actually pretty interesting how bad it was at pulling chips out. The first inch or so of cut seemed normal, but by the time the top of the bar was in the wood it seemed to load up pretty bad. The pile of chips under the log after the cut was at least as big as the pile by my feet, which was odd to me, and even running it was hard to pull the bar back out of the top of the cut because it was clogged up.
It definitely didn't feel like it was cutting faster but the saw couldn't pull it if that's what you mean.
I honestly thought something else was going on with the saw until I swapped to the loop I hadn't messed with, and then swapped back to confirm. That's when I really noticed the chip part.
The chips out of this chain were also way more chewed up/small, kinda like they had been run over a bunch before they made it out of the cut, where the chips out of the stock chain were normal.
I guess there's still a possibility that this loop was bad somehow, but the cutters looked and felt the same as the other loop.

 

[huskihl]

@huskihl Both. It would start off good, but quickly bog once the kerf got full of chips. It was actually pretty interesting how bad it was at pulling chips out. The first inch or so of cut seemed normal, but by the time the top of the bar was in the wood it seemed to load up pretty bad. The pile of chips under the log after the cut was at least as big as the pile by my feet, which was odd to me, and even running it was hard to pull the bar back out of the top of the cut because it was clogged up.
It definitely didn't feel like it was cutting faster but the saw couldn't pull it if that's what you mean.
I honestly thought something else was going on with the saw until I swapped to the loop I hadn't messed with, and then swapped back to confirm. That's when I really noticed the chip part.
The chips out of this chain were also way more chewed up/small, kinda like they had been run over a bunch before they made it out of the cut, where the chips out of the stock chain were normal.
I guess there's still a possibility that this loop was bad somehow, but the cutters looked and felt the same as the other loop.

I was curious if it was pulling the motor down because it was digging and cutting faster. Sometimes the saw sounds like it’s cutting faster because it’s turning more rpm’s, but it’s actuality cutting slower due to being loaded up with chips, dull chain, high rakers, things like that. Not doubting your findings, just making sure I understood what you meant. I believe Oregon had a chain race awhile back and the fastest was a square chain with the shelf still there and not filed out

 

[DucTruckin379]

So now the more I think about this the more I'm confused... What drives the "cleaning the gullet out" wisdom? I can see it needing to be clean right below the cutting faces, but I can also see wanting to have the chip from the cutter before it pushed out of the way so it doesn't make it rock out of the cut. Almost seeing the logic in those crazy looking folded over rakers on some chains...
All of this I was doing was with the bar buried past the tip (should've run a longer bar), so chip clearance was doubly hard.
I didn't take it as doubt, I just wanted to make sure I was explaining it right!

 

[davidwyby]

I remember seeing this quite a while back. Stock chain 26 sec, dulled in gravel, resharpened with the oregon guide, 22 sec. Gullet removed, 18 sec.

Then recently Buckin has been playing with baby c (1/8” file). He says the gullet is actually at the bottom of the c. Below that doesn’t matter much. I think maybe “getting the gullet” is to put a hook in the top….? He left the shelf in and it was a smidge faster…and he says smoother. I think it stabilizes the cutter and maybe keeps the top plate from pushing the side cutter into the wood more and making more drag. I could see it helping with a smoother cut milling. Maybe that’s why square is fast and smooth. Less top plate angle and often the gullet is left in.

I wonder if one could test that theory by running a 30° top plate round against square or milling chain and measuring the kerf width.

I suspect if you left your gullet in or filed it 90° to the chain it would sweep chips better. I bet that angle is letting the chips fall down into the chassis and/or wedging them against the side of the cut.
I have a thread somewhere around here about baby c. Haven’t tested it much yet.

 

[huskihl]

So now the more I think about this the more I'm confused... What drives the "cleaning the gullet out" wisdom? I can see it needing to be clean right below the cutting faces, but I can also see wanting to have the chip from the cutter before it pushed out of the way so it doesn't make it rock out of the cut. Almost seeing the logic in those crazy looking folded over rakers on some chains...
All of this I was doing was with the bar buried past the tip (should've run a longer bar), so chip clearance was doubly hard.
I didn't take it as doubt, I just wanted to make sure I was explaining it right!

More room for chips I believe is the reason for removing as much metal as possible. Whether it works or not is another story.

 

[Maintenance Chief]

It looks like you've created 2 cutting profiles for one tooth.
If you think about the gullet as one continued angle from the top plates cutting edge it works to cut the curl of fibers from the chip. The cutting angles you have on that tooth would be either working on cutting 2 chips or slamming the upper tooth into a block of unserved wood while the bottom of the tooth is under cutting it.

 

[ManiacalMark]

I think it’s more of a “depth” of how far you took the gullet out and the angle of it. The chain is making the saw work 2x harder. The depth when the chips start to build up is where is see a problem because I would bet money it can push chips back in front of the tooth. Chips in the kerf also won’t clear in a long cut because it’s essentially a pocket under the cutter.

 

[Redfin]

Both right and left side cutters are spreading away from each other in the kerf. Leaving material below and ahead of the side plate keeps the cutter from widening the kerf.

 

[davidwyby]

Both right and left side cutters are spreading away from each other in the kerf. Leaving material below and ahead of the side plate keeps the cutter from widening the kerf.

“Great minds….”

“kerf bumper, cutter guide, side depth gauge”

Different brands of cutters have different profiles viewed from front or rear and may have more or less metal to the outside down at the bottom there.

 

[jakethesnake]

I was curious if it was pulling the motor down because it was digging and cutting faster. Sometimes the saw sounds like it’s cutting faster because it’s turning more rpm’s, but it’s actuality cutting slower due to being loaded up with chips, dull chain, high rakers, things like that. Not doubting your findings, just making sure I understood what you meant. I believe Oregon had a chain race awhile back and the fastest was a square chain with the shelf still there and not filed out

I’m not certain my source. However I believe it was walkers saw shop. Was said the shelf should be left. Obviously at some point it becomes too long but a little shelf was better. I believe it.

 

[jakethesnake]

That said I run round cutters.

 

[huskihl]

I’m not certain my source. However I believe it was walkers saw shop. Was said the shelf should be left. Obviously at some point it becomes too long but a little shelf was better. I believe it.

I would imagine it’s like anything else in that it depends on the size of the wood versus how soft it is. 36 inch white pine probably is faster with a different chain than 16 inch diameter sugar maple

 

[Duane(Pa)]

Maddsen's had a Square Ground chain race a few years ago. The top chains had the shelf/fang intact. Until they are around 1/8" they don't seem to do any harm. When mine get to that point, I remove the whole thing with a file or round grinder. I didn't notice what the OPP is experiencing.

Gullet Getting as BBR preaches is for round filed/ground chains

 

[DucTruckin379]

Gonna have to change the thread title to "I THOUGHT I learned something about gullets"

This is great stuff guys. I can totally see the lack of side control now that I'm thinking about it, and if it's fluttering sideways that can't be good at all.

Come to think of it, I even saw some chips that looked too wide. Gonna have to go see if I can find some of them.

Now I feel like I am learning something.

 

[ManiacalMark]

What @Duane(Pa) said is spot on too. Big deep gullet like that works on round ground chain good just usually more grabby. A grabby round chain in hardwood works best with the heels clipped a little.

 

[davidwyby]

I suspect taking the gullet out with the file close to 90° to the bar n chain might be the ticket.

 

[Wilhelm]

What @Duane(Pa) said is spot on too. Big deep gullet like that works on round ground chain good just usually more grabby. A grabby round chain in hardwood works best with the heels clipped a little.

I need to try clipping the heels on one of my work chains!
I buck a lot of turkey oak.

 

[DucTruckin379]

What @Duane(Pa) said is spot on too. Big deep gullet like that works on round ground chain good just usually more grabby. A grabby round chain in hardwood works best with the heels clipped a little.

This is where I went astray... Before I started playing with square filed, I devoted a pretty decent amount of time to learning to round file, both in manual technique and in what I found to be good cutter geometry for what I run into the most. The big gullets had never really done anything negative, other than maybe making it a little more grabby as you say.

It seems that is not the case for square, and I mistakenly/inadvertently applied some of what worked there here...

I haven't had time to ponder it much, but I'm guessing the side cutter angles on round filed are less prone to pulling the cutter off track than the more aggressive side cutter angles of square. So I'm guessing this is why it may not be as much of an issue to have less side control on the round filed stuff (maybe the raker can take care of all of it on round?).