Thread: Conflicting info on ripping chain

Both types of chains will rip.

The lower top plate cutting angle chain will generate a slightly narrower kerf because it is not being pulled sideways into the log. When cross cutting, the kerf has torn wood fiber ends dangling inside the cut so cross cutting needs the higher top plate cutting angle but ripping can use a narrower angle. A narrower kerf places a slightly reduced load on the saw so it is worth doing for that alone

Some say the finish is better with a lower angle on ripping but poor finish depends on a lot more than top plate cutting angle, eg jerky milling action, fanging the trigger without reason and a sloppy mill will put gouges and marks all over a cut, even with 5º top plate cutting angle.

I buy full comp semi-chisel regular top plate cutting angle chain and over successive sharpenings I file the top plate cutting angle to 10º

It's the small things that make the difference eh.

Cheers Mr B. Most helpful as always

Originally Posted by RedShirtGuy

It's the small things that make the difference eh.

Cheers Mr B. Most helpful as always

No worries RSG

and what about the depth gauges? I've been told by two seperate millers that you can take them right down though haven't been game to do it myself.

Bring up the Oregan Chin site. All the details are given there.
Rowley.

Everyone has their own theories on rakers.

The chain manufacturers (like Oregon) that are nervous about people fiddling about with rakers will recommend a constant (0.025" or 0.030") raker depth.

Those with a few more intestinal fortitude will tell it like it is. The best document by far on the web that describes how chain really works is here
http://www.sawchain.com/images/complete%20book.pdf

The way chain cuts means it needs progressively deeper rakers depending how worn the cutter is. A basic rule of thumb is the 10:1 rule, ie divide the gullet width by 10 and that will tell you what rakers to use. This gives a cutting angle (raker-cutter- wood angle) of 6º.

This is what I mean.


The cutting angle (or raker depth) you can use depends on how hard the wood is, width of the cut, power available etc.
I use 6.5 - 7º with the 880. It's a bit grabby at the start of a cut but settles down after a half metre or so of cut.

This is a thread that discusses this angle

i have some youtube videos of how I set the rakers with a digital angle finder (DAF)
[ame=http://www.youtube.com/watch?v=FSr9j2EDoqk]YouTube - rakersetting.m4v[/ame]

Of course I don't do it every time - In the field I swipe the rakers a couple of times after every 2-3 touchups. I only use the DAF when I want to reset everything.

Is there a difference in angle used between a dedicated slabber in a Lucas mill and a hand held or smaller CS mill?
Also is there any need to change that angle between hardwood milling and milling a decent sized burl?
What angles are fellow Lucas mill owners using?
Cheers all.

Originally Posted by comgreserv

Is there a difference in angle used between a dedicated slabber in a Lucas mill and a hand held or smaller CS mill?
Also is there any need to change that angle between hardwood milling and milling a decent sized burl?
What angles are fellow Lucas mill owners using?
Cheers all.

Yep there is a ideal optimum angle for different woods, different chains, the width of the wood being cut and the power available. This of course only applies in situation where there is limited power, like on a CS. On a Lucas slabber you could almost remove the rakers and just go for it.

In practice I use the same angle for all my chains unless I'm cutting wide logs when I drop the angle a touch to maybe 5º to take the load off the power head.

Few CS operators don't know about this cutting angle I'm referring to. Even on the Chainsaw and milling forums of the Arboriste site in the US it is still a relatively unknown idea. Everyone that uses this method is surprised how old chains previously filed with a traditional constant depth raker tool that just made a heap of dust, cut like new again.

Constant raker depths are designed for chain companies. It reduces the chance of kickback (largely irrelevant in CS milling) and means that operators buy more chains than they should.

The basic idea has been around for a long time and is reflected in the use of a few CS raker tools. One of these is the Carlton File-O-Plate (FOP) although I find the cutting angle FOPs generate to be too shallow (~4.5º). Husky also have a similar device. Stihl and Oregon still recommend constant raker depths in all their manuals etc. In some CS stores you can see that they sell individual raker depths setting tools that go well beyond the classic 0.025" settings.

The other raker depth setting tool I have seen is this one - I think it's a Pioneer CS tool.
Attachment 153315

Note how it has a range of raker settings. These are easy to use since all you do is measure the gullet and then divide that by 10 and then use the nearest raker setting. A small issue with this tool is the maximum depth is 1 mm but many chains can have gullets of 15 mm and still cut chips provided the rakers are set to 1.5 mm.

Bring out your set of hand planes. The ripping direction plane knife is different then a crosscut plane knife.

Originally Posted by sgschwend

Bring out your set of hand planes. The ripping direction plane knife is different then a crosscut plane knife.

Except perhaps when it is ripping along the grain (noodling) a chainsaw cutter cannot really be compared to hand plane blade.

Ripping lengthwise down the log (Milling) with a chainsaw is still primarilly a cross grain cutting action with the top plate of the cutters always cutting across grain. This is why cross cutting chain still works when milling, it just makes a slightly bigger kerf than is necessary.

Chainsaws gnaw or chip at the wood with cutters porpoising in and out of the cut (see here). The cutter rocks or wriggles its way into the wood until the gullet is filled or the tension on the chain pulls it back down onto the bar.

Bob, forgive my ignorance, but do you need to purchase "ripping" blades to rip small (600mm) sections of logs in half to turn into turning blanks? Or can one blade do the ripping in half then crosscut section in half to end up with 4 approx 300*300 blanks?

I have a little dinky Stihl MS180 with a 16" bar.

Originally Posted by Pat

Bob, forgive my ignorance, but do you need to purchase "ripping" blades to rip small (600mm) sections of logs in half to turn into turning blanks? Or can one blade do the ripping in half then crosscut section in half to end up with 4 approx 300*300 blanks?

I have a little dinky Stihl MS180 with a 16" bar.

No worries - ask any questions you like
By blades I presume you mean chains?
Yes, you can use a cross cutting chain to do the lot.

Thanks for the link, I down loaded a copy. I see what you are writing about. I haven't found the part about the tooth angle but I will keep reading.

I still think that if you want to cut wood and not tear it then the hand planers are still applicable designs. The ripper chains are nearly straight, just like the joiner plane and the rabbiting plan has a steeper angle just like the crosscut chain.

Originally Posted by sgschwend

Thanks for the link, I down loaded a copy. I see what you are writing about. I haven't found the part about the tooth angle but I will keep reading.

You won't find it in any books or documents, nobody except a few chainsaw geeks refer to it.

I still think that if you want to cut wood and not tear it then the hand planers are still applicable designs. The ripper chains are nearly straight, just like the joiner plane and the rabbiting plan has a steeper angle just like the crosscut chain.

Using your argument the chainsaw manufacturers have got it the wrong way around. When cross cutting the side plate of the cutter has to cut through fiber and the top plate of the cutter chips wood out. When milling, the top plate is the one cutting straight through the fiber and chipping out the wood (the side plate does very little). This suggests the top plate should be angled on the milling chain and straight on the cross cutting chain - but it isn't. While it is easier to slice through fibre on an angle this will have another effect which I explain later on.

No matter what top plate filing angle (the one you refer to as straight or steeper) is used chain doesn't work like a plane. A plane uses a solid blade firmly attached to the body of the plane. The chain on a chainsaw is flexible and not firmly attached to the bar. When a cutter grabs wood it comes up off the bar. What prevents the cutter diving deep into the wood is the raker which causes the cutter to rock, the cutter tries to bite more and pulls the raker goes into the wood a little (few people realise this) this allows the cutter to go slightly further into the wood and come further away from the bar. This rocking and rolling of the cutter and raker continues until either the gullet is full or the chain tension is so high that the cutter is snapped back onto the bar. Few people realize the chain on a chain saw is right up off the bar when it cuts, it is not sliding along like a series of little planes, only every 3rd or 4th cutter is chipping a substantial amount of wood and the other cutters are just going along for the ride and maybe nibbling a little something along the way. This "cutting chipping" action is exactly how chainsaws are designed and is quite a different cutting action to a plane. Chainsaws "hook and tear" as much as the "cut"- this is why chain saw injuries are so awful, while they slice they're also doing a lot of tearing.

The reason for higher top plate filing angle on cross cuts is because the higher angle causes the cutters to sightly dive sideways (when it lifts off the bar) into the wood creating a slightly wider kerf. A wider kerf is needed because when cross cutting because many severed or rather chopped fiber ends are dangling into the side of the kerf and block sawdust escape which can jam the bar. When milling (ripping down the log) there are fewer fibre ends hanging in the side of the cut and so a narrower kerf can be used. The more fibrous the wood the greater the reason to so this.

Cross cut chain can be used when milling but it is not advisable to do it the other way around. Although on dry hard brittle wood, ripping or straight chain will cross cut this wood just fine.

Some folk believe the lower angles give a better finish but there are many other factors involved besides top plate filing that affect finish.

This is one example - same; saw, wood, chain. Only difference is width of cut.
C0ntrast.jpg