How long you cut between sharpening ripping chain

[Czech_Made]

I moved from the Eastern Red Cedar to white oak logs I need to rip now. While the ERC was easy - smaller too - and I could cut 100" long, 12" diameter log into 1" slabs using one chain, with the oak (100" long, 14-16" diameter) I feel 2 cuts a chain is about right.

Yeah, I understand, this is a dumb question, but how long do you usually go between swapping ripping chain for sharpenned one? As of now I have two (24", 3/8") and I use them both, clean up and sharpen for the next day operations. Seems like for the oak I should have three chains to keep it at log/afternoon.

 

[BobL]

100" =~8 ft, 15" = 1.25ft so your total cut is 10 sq ft x 2 = 20 sq ft
Now you have to factor in the bar length - I believe yours is 2ft
So your spec is" 10 sq ft of cut per ft of bar"
More specific than ft of bar is number cutters as this takes into account skip chain.

I generally sharpen about every 32 sq ft but I have a 3ft 6" bar.
So mine comes out to 9.1 sq ft of cut per ft of bar - its actually pretty similar to yours and given how much harder the wood is that I cut I find that surprising.

 

[Czech_Made]

Thank you, sir! Now I know what to look for and I will actually do some measurements. Thats great that there is a single number to represent the performance; I will be back with more accurate data.

 

[BobL]

Thank you, sir! Now I know what to look for and I will actually do some measurements. Thats greats that there is a single number to represent the performance; I will be back with more accurate data.

Well it's not really that simple and its more of a guide.

I already said wood hardness is significant.

Then there is the side plate filing angle (TPFA) or hook on the cutter, and in conjunction to that the raker angle.
A low TPFA is desirable because in conjunction with raker it will grab a bigger wood chip and produce a more self feeding saw but to also produces a pointier cutter edge which breaks of more easily and will need sharpening more often
A higher TPFA will not go as blunt as quickly. This is what I prefer and lower the raker a bit so it does the work.

And practicalities also come into it.
If our saws have enough grunt we could run really low TPFA and low rakers but wouldn't it be a nuisance if we had to pull the saw out of half completed cut to sharpen it.
A simpler guide is to touch up when you fuel up - that way you are already stopped.
However I wouldn't want to swap chains that often - I touch up the chain direct on the mill.

 

[Czech_Made]

I was doing the fuel stop + touch up when I milled with a chainsaw.

Anyway, thanks for the info, I am not looking for peak performance, just the right combination of time, effort and cost.

Now the next logical question: Do you have chains dedicated to wood type?

Thank you.

 

[Quietfly]

I'm always amazed at how much knowledge @BobL has to share off the top of his head, as well as the science he backs it up with.
Personally I sharpen as i feel the saw start cutting differently. I know very subjective, but so far it's worked "ok" .
JMO YMMV

 

[BobL]

Now the next logical question: Do you have chains dedicated to wood type? .

If I did more CSM'ing I'd probably set up some chains this way.
However, because 95% of the logs I cut are hard my longer (42 and 60") chains are all set up for hardwood (raker angle ~6.5º).
I don't even use different raker settings for the longer or shorter chains although I have though about doing this.
Instead for extra hard/wider wood I usually use a 7 pin sprocket instead of the 8pin.
I do have some 9 and 10 pin sprockets but have never used them.
For the times when I do occasionally have a softwood log I usually just swipe the rakers 3-4 times more than usual which increases the raker angle.

I have a 24" cross cut, full chisel, full comp, 3/8 chain for the 441 with ~9º raker angles for trimming branches off trunks. That's quite aggressive and prone to kick back - not something I let a newbie use. When milling with the 441 I use a 25" bar low pro chain set with rakers set to~ 7.5º.

Personally I sharpen as i feel the saw start cutting differently. I know very subjective, but so far it's worked "ok" .

Feel is important but by the time the saw feels like it needs an extra load to keep cutting the chain should probably have been sharpened although if you near the end of a cut practicalities indicate you just finish the cut.

On the BIL mill I can compare the temperature gauge reading with the feel or speed of cut and infer a degree of bluntness - its not rocket science - it is pretty obvious what is going on.
It's not that easy to see this effect because the temperature always increases as any cut proceeds but is more noticeable in wider/longer cuts).
Initially the temperature always increases rapidly as the powerhead warms up under full load and after about 3-4 ft of cut the temperature starts to increase more slowly.
At some point (hopefully in the second half of the cut!) the temperature starts to increase faster again and sort of steps up to a new level (still increasing) over a distance of about 1-2 ft of cut.
This is clearly the chain going blunt because after this point the mill also needs greater pressure to keep cutting at the same rate and more powder and fewer chips are generated.
At this point I open up the aux oiler a bit more and it sort of helps.
The point in the cut where this happens varies quite a bit probably due to how sharp the chain was to start with, wood hardness, dirt, dryness.
In something like Iron Bark (very hard wood) I have seen this happen around 25 sq ft.
In silica infused Tuart (this tree is notorious for sucking up silica when water deprived) it can be less. On one Tuart log I had to back the mill out of the cut and touch up the chain for the 2 wider middle slabs of the trunk. The other problem with Tuart is it's pointless pushing the saw too much past this point as the chain heat starts to extract a black resin out of the wood and it gums the chain up something horrible making things even worse. This is where extra aux oil really helps.

 

[IyaMan]

When milling with the 441 I use a 25" bar low pro chain set with rakers set to~ 7.5º.

Are you using a low-pro bar with that chain, or just a standard bar?

 

[BobL]

Are you using a low-pro bar with that chain, or just a standard bar?

I started by using the standard bar and 3/8 drive sprocket even though I knew there would be difficulties with this and indeed the chain jumped off the bar several times.
I then did what Mtngun did and used a 404 sprocket that has been turned down to the radius to suit the Lopro chain and have had no problems since them
The nose sprocket teeth are not a perfect fit but they has sort of worn their way into shape.

 

[IyaMan]

BobL, your ingenuity and resourcefulness is impressive. I was wondering how people went about using low-pro chain on a longer bar. I've only been able to find low-pro bars for up to 20" (even though Stihl sells 24" low-pro ripping chain loops). And most low-pro bars are not for large-mount.

 

[BobL]

BobL, your ingenuity and resourcefulness is impressive.

Not my idea Iyaman - I just coped what someone else has done.

I was wondering how people went about using low-pro chain on a longer bar. I've only been able to find low-pro bars for up to 20" (even though Stihl sells 24" low-pro ripping chain loops). And most low-pro bars are not for large-mount.

The 25" was a GB bar. I've though about using it on even longer bars but I found the 441 stretches the Lopro enough to stop me doing this for example on the 880. If and when I get my 660 restored maybe I'll think about something for that one.

 

[Czech_Made]

Thank you again, Bob.

 

[scheffa]

@BobL what size file and guide do you use for 404 chain to get the desired tpfa, I currently just use the standard Stihl file guide and their 404 files and it cuts pretty good, just curious for your input for cutting our hardwoods

 

[BobL]

@BobL what size file and guide do you use for 404 chain to get the desired tpfa, I currently just use the standard Stihl file guide and their 404 files and it cuts pretty good, just curious for your input for cutting our hardwoods

Blimey its so long since I used 404 I can't remember what sharpening gear I used.
All except a couple of my mill loops are is 3/8.
I think I last used 404 in 2007 and it wasn't for milling.
I know it was an Oregon file guide and I think it was a 7/32" file

 

[Mad Professor]

066 and stihl PMX usually hardwoods and just enough bar for the logs. Important to have clean logs, I wash them or use a stiff brush. Be careful with a pressure washer as you can drive the crud into the bark.

I sharpen as soon as the cut slows down, if not you heat up the bar and chain. Sometimes I get many cuts, but others I wonder what junk I missed?

 

[BigOakAdot]

This may sound stupid but when talking about raker angles, what is this angle you're recommending? Is it a slight angle down away from the corresponding tooth? Not sure how to explain this correctly but I always thought the rakers depth was the important part.

 

[scheffa]

Is there a reason you no longer use 404? I use 3/8 up to 42" then jump up to 404 for longer bars

 

[Quietfly]

This may sound stupid but when talking about raker angles, what is this angle you're recommending? Is it a slight angle down away from the corresponding tooth? Not sure how to explain this correctly but I always thought the rakers depth was the important part.

FOP's are semi-progressive but ay least they work (sort of) for longer through a chain life than regular gauges do. FOPs are also not very aggressive and they do not allow the operator to optimise their cutting speed. BUT if you can't be bothered with full progressive raker setting then FOPs are a worth getting


That is one way of doing it and the raker depth can be measure using feeler gauges. I would not suggest starting on 1/9 or 1/8. Start at 1/10 and see how this goes.

Here's a link to a vid showing how I do it.


A couple of explanatory notes about the video.
Instead of measuring gaps and distances I'm using a Digital Angle Finder (DAF).
The DAF is far quicker for raker depth setting and is are also useful for other aspects of milling, like measuring and eliminating twist in log rails
The gullet width to raker depth ratio of 1:10 corresponds to what I call a raker angle of 5.7º (lets call it 6º)
Lower raker angle is equivalent to higher ratios and VV
A ratio of 1:6 = 9.5º (this will rattle your teeth)
Well worn chain set with a standard raker gauge will have a ratio of 1:20 or about 3º
One of my friends once brought me his CS so I could investigate why it was not cutting. The rakers were down to less than 1º - 15 swipes on each raker and he was back in business.
The video shows the initial setting up of a chain that has rakers that are all over the place.
Some of those raker angles were less than 3º (powder makers) and you will see how much filing was involved to get them down to 6ª
It's takes some time to set a chain up but the results are well worth doing.

I don't use the DAF this in the field. I swipe the rakers 2/3 times every 3/4 touch ups and this is usually enough to keep the chain cutting well.
I check the rakers with the DAF back in my shop after every 2/3 days of milling. Usually I am within 1º of the desired angle.

Using this method means it is not necessary to make all the cutters the same length - PROVIDED there is a random scattering of cutter lengths on the chain. Sometimes the cutters on one side (LHS or RHS) do end up differing in length compared to the other side - this is not good and needs to be corrected.

here's a post of @BobL explaining it

 

[BigOakAdot]

Thanks!

 

[BobL]

Is there a reason you no longer use 404? I use 3/8 up to 42" then jump up to 404 for longer bars

When I bought my 076 it came with a 30" bar and a loop of 404. I used this combo it on my small mill for a while and it seemed to work fine but when I bought my first 42" bar I bought a roll of 3/8 and Ive never used anything else since.

The 3/8 does stretch a fair bit when new and there is not a lot of kerf advantaged of 3/8 over 404 so I am interested in giving 404 a go with the longer bar especially in harder wood. The 60" Stihl sprocket bar I got with the 880 came with a loop of 404 for milling. It has never been used because I already had a 60" bar that is in good condition. I have since modified the at bar to run a roller nose and in doing so it is now 3" longer.

I could return this bar to the 404 sprocket nose and try the 404 chain out instead I'prefer to lengthen the chain by 6 drive links so I could use it on the roller nose bar.
If anyone in Oz has 6 spare 404 links I would be happy to pay for it and postage.