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  1. #1
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    Default Alaskan chainsaw mill, what angle for chain is best?

    Normally when using a chainsaw you sharpen the teeth to approx 30 degrees.
    However when using an alaskan mill I have heard and used teeth sharpened to closer to say 10 degrees as you are basically cutting end grain.
    Is this the normal practice?
    I have been milling up a few celery top logs with a rather underpowered saw with a brand new ripping (10 degree sharpened chain) and the sawdust that comes off is as fine as talcum powder.
    Today I bought what looks like a reasonable condition 395 XP husky saw that I intend to buy a 25-30 inch bar for and chain to do the job.
    Just wondering what those who know think about the angle one should use on the chain?

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  3. #2
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    Quote Originally Posted by artful bodger View Post
    Normally when using a chainsaw you sharpen the teeth to approx 30 degrees.
    However when using an alaskan mill I have heard and used teeth sharpened to closer to say 10 degrees as you are basically cutting end grain.
    Is this the normal practice?

    Yes it is normal.
    Theory says the 10º angle should reduce the kerf size but despite repeated measuring I have not detected and difference
    Theory says you should get a better finish and that is probably correct for chisel chain. However I reckon operator skill is more important than this in determining finish
    No sideways seesawing down the cut, No fanging the saw in and out of the cut, just constant steady pressure.
    I have been milling up a few celery top logs with a rather underpowered saw with a brand new ripping (10 degree sharpened chain) and the sawdust that comes off is as fine as talcum powder.
    Today I bought what looks like a reasonable condition 395 XP husky saw that I intend to buy a 25-30 inch bar for and chain to do the job.
    Just wondering what those who know think about the angle one should use on the chain?
    The same but that angle is one of the least important chain parameters for milling because you can mill with almost any angle between 30 and 5º
    Talcum powder sawdust is almost certainly incorrect raker depth setting - most folks leave their rakers WAAAAAY too high. Post a picture of an couple of cutters and I will diagnose if it is a chain problems.
    Make sure the cutters are side one as level as possible in the picture and as magnified as possible - like this if you can.
    BBs-chain.jpg

  4. #3
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    Thanks Bob.
    The chain I used was a brand spanking new one I got the local shop to grind to the 10 degrees.
    Knowing that the grind would reduce the length of the teeth somewhat I did ask them if they ground down the "rakers" or depth gauges to suit?
    They said, "no"
    After the first cut which was ordinary, I filed the depth gauges down for a very slight noticeable improvement.
    Here is a picture of the chain after cutting 6 slabs and dusting out the neighborhood.
    The fine dust has stuck to the chain like you would not believe, picture was taken after soaking the chain in petrol and scrubbing with a stiff bristly brush. Almost like the dust has vulcanised on to the chain.
    DSCF5972.jpg
    Guess I will just try the new second hand 395xp Husky with the new chisel tooth chain that is on it to see how that goes.
    Was really just after clarification on the best angle for the teeth. So if you reckon 5 deg to 30 deg then I am in the ballpark.

  5. #4
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    Will analyse your cutters in a bit.
    That's not dust - that is gum. The more incorrectly the cutters are set up the more heat is made and the more gum is extracted and sticks to the chain.
    That will jus compound you problem.

    To get it off fill a spare bottle with a bit of diesel and spray it on a few times and leave it overnight.
    The cut some dry wood and it will just come off.

    Are you using an Auxiliary oiler?
    This make a big difference with gum.
    Tuart is one of the worse and I find I have to double oil flow over normal use to keep the gum under control.

  6. #5
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    Normally I do a photo analysis with measurements on the cutters but I don't even have to do that with yours to see what's wrong.

    There are two main problems and they are both very common ones.
    Start by reading this link and then come back y the rest of this post
    CS Milling 101, Hints tips and tricks | Page 6 | Arboristsite.com
    As usual you will have to register to see the pics

    The first problem is the cutters don't have anywhere near enough "hook" .
    The correct term for this is "top plate cutting angle"

    Look at the cutters in the pics below
    The top one is the late Will Malloff's (chainsaw milling guru) and the bottom one is mine.
    This allows the cutter to bite and make chips rather than dust
    BUT the rakers must also be set correctly for this to occur.

    MalloffBobLchain.jpg
    Now look above at how low the rakers are compared to yours.
    A rough guide is the rakers should be 1/10th the width of the gullet.
    So if the gullet is 0.25" the raker depth should be 0.025" below the cutter
    So if the gullet is 0.35" the raker depth should be 0.035" below the cutter
    So if the gullet is 0.45" the raker depth should be 0.045" below the cutter
    You can measure your own gullets and do the maths.

    But rather than using thou of inches in depth its better to think of a raker angle - see post referred to above for details
    This is raker angle
    rakercorrect.jpg

    Even chain out of the box is not really set up right for milling.

    The following is an extract of what I wrote about new chain in another forum

    New chain (even ripping chain) is rarely set up right for milling on big saws.

    The rakers on new 3/8 and 404 chain are usually set at 25"' which translates to a raker angle of 5.7º.
    This is done by the manufacturers to ensure small saws don't bog down and to minimise kickback.
    However it is far from optimised for big saws especially in softwoods.

    All my comments below are for stock 90+ CC saws.
    Nothing is hard and fast - the figures provided are rubbery and are just a guide.
    Only you can determine what is right for your setup and woods being cut.

    For milling in <24" or thereabouts softwoods, you could use up to 8.5º. On new chain where the gullet is 0.25" this translates to a 0.037"' raker depth, thats right WAAAY more than you ever thought advisable
    This setup will VIBE (a lot), there will be more B&C wear and tear, and it will harder to produce a good finish but it will make big chips and cut fast.
    Be aware if you use this setup for cross cutting it may kick back much more easily that a stock chain.
    For less vibe try 8º, for better finish try 7º, for Lopro chain try 9.5º!
    For skip - sorry I don't have the time to describe the requirements

    For logs wider than 24" or hardwoods, or smaller saws you will need to reduce the raker angle.

    For really hardwoods, like the sort I tackle with the 076 and 880 and 42-60" bars, I use 6.5º raker angles.
    With my 441 with Lopro chain on a 25" bar even in hardwood I use 7.5º
    BTW very few so called chainsaw professional know about this level of detail for setting up chains.
    It is known by chainsaw racers but you won't see it in chainsaw manuals although the old Carlton chain manual did refer to it.
    I won't claim being the first but I was probably amongst the first to quantify (put numbers) to the method (its called "progressive raker setting") for chainsaw milling.
    In Nov 2009 I started a thread on the Arborisite Forums about this and it has been running ever since
    Are FOP really progressive depth raker generators? | Arboristsite.com
    Some of the epiphanies from chainsaw operators in this thread makes for interesting reading - well it swells my head reading it anyway. )
    Post #95 in that thread has some vids of how I set the rakers and file the cutters.

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    Thanks Bob for such an informative response.
    Looks like I have a bit of fine tuning ahead of me.

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    Bob, as a matter of interest you wouldn't happen to know how those numbers compare with the angles of one of the old Carlton file-o-plates or similar? Y'know the one, flat plate with slots in it for hard and soft: I've been setting my rakers with one for years. I just looked in the Carlton catalogue and see they dont even make them for .404 anymore... I'm becoming a dinosaw (pun intended) apparently... ouch.

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    So Bob, if my side plate cutting angle is not enough do you suggest using a 13/64 file in a 3/16 file guide to increase it? Seems to be the opposite of what one would expect.
    Never knew the raker angle was so important!. I always just use the raker filing guide that came with the saw to file them down and do it regularly(maybe every 4- 5 sharpens). The raker filing guide does seem to give a very flat angle though compared to the picture you posted. How do you get a consistent angle on it? Do you just do it by eye?

  10. #9
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    Not all raker filing plates are created equal.
    The stihl style runs off the top of the tooth and gives a flat top. As your tooth gets filed back it gets more aggressive because even though the relationship of tooth height to raker height stays constant, tooth geometry means it increases the bite it'll take. the other thing with the flat topped rakers is the flat top increases the risk of kickback.

    The carlton style runs off the relationship between the top of the tooth and the chain in front of the raker so gives an angled top, so the geometry doesnt change much as you file everything away. It also reduces kickback that way.

    Nicely rounded rakers are lowest kickback risk but it also means its filed by hand.

    Raker height is tres important. You can take a new chain and file every right hand side tooth back to the worn out stage and leave the left side alone and if your rakers are set to the correct height for each tooth the chain will still cut straight: its why they're correctly called depth guages not rakers. If the depth of cut is consistent on every tooth regardless of the length of any individual tooth it cuts a straight line. Conversly you can have even height teeth and if the rakers are out the saw will still pull sideways.

  11. #10
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    Kickback is largely irrelevant in an alaskan chainsaw mill because the area around the nose does not contact the wood - this is why much deeper rakers can be used on an alaskan that on a free standing chainsaw. However, operators using the same saw/chain with lowered rakers, as used in their mill, to then cross cut need to be extra careful avoiding kick back. If I have to fell and break up a tree I do not use the same chain as the chain I use for milling.

    Quote Originally Posted by John.G View Post
    Not all raker filing plates are created equal.
    The stihl style runs off the top of the tooth and gives a flat top. As your tooth gets filed back it gets more aggressive because even though the relationship of tooth height to raker height stays constant, tooth geometry means it increases the bite it'll take. the other thing with the flat topped rakers is the flat top increases the risk of kickback. .
    I agree a flat top raker increases the chance of kickback and feels more aggressive, but it is actually less aggressive because for the same raker depth the raker angle is lower with a flat than a rounded top.
    The chains saws that are brought to me to look at because they are making dust and not chips invariably have flat tops.

    In the following diagram I have exaggerated the overall raker depth to demonstrate this effect.
    Let's assume the rakers are filed flat to the red line - this produces the yellow raker angle (angle between wood - cutter tip - raker)
    If they are filed to the same depth but now curved to the blue line this results in the green raker angle.
    The green line is clearly at a greater angle than the yellow line so a cutter with this raker will take a deeper bite.

    Rakergeometry.jpg

    The reason flat top rakers feel aggressive is the front of a flat top raker that makes contact with the wood is squarer and so they rattle hard and bounce against the wood. This also contributes to increasing the chance of kickback. A rounded raker tends to slide over the wood and producers less vibe.

    Safety chains specifically designed to reduce kickback have either long wide sloped rakers liked this old school Vangard chain
    Screen Shot 2017-04-09 at 8.28.14 AM.png

    The other type of low kickback chain uses a drive link with its own raker, immediately in front of each cutter. This has the effect of adding a sloped front to each cutter's raker so even if the operator files the raker on the cutter flat this takes the edge of the square shoulder generated by a flat topped raker.

    Screen Shot 2017-04-09 at 8.28.57 AM.png

    There's an extra factor as to why rounded rakers are more aggressive than flat topped rakers. Most folks think that chainsaw cutters cut like a hand plane and shave the wood our of a cut, and this does happen to a great extent when cutting with the grain (noodling) but when cross cutting and milling chains behaves quite differently.

    The process starts with a cutter tip penetrating the wood up until the raker prevents it going any further.

    The cutter then rocks on the raker point of contact (POC) lifting the chains of the bar and rotates a little so it can bite a bit more. This puts a enormous force on the raker and it penetrates the wood slightly, which allows the cutter to lift and rock a touch more.

    This process repeats at high speed until the cutter cannot penetrate any further and the chain tension tears a chip out of the wood.

    During each pass of the chain only about one in 3 sequential cutters tear a significant chip out of the wood as the chain porpoises along the bar.

    If the rakers are flat topped they cannot penetrate as far as a rounded raker is so they are less aggressive.

    The degree of penetration of a cutter tip into the wood from the chains point of view thus depends on
    - the top plate cutting angle of hook
    - the raker depth which determines the raker angle
    - the shape of the raker top.

    The serious chainsaw racing people really have this under control but CS racing is like a short term sprint whereas milling is like a marathon, nevertheless we can learn from these guys.

    The other factors are saw power and chain gauge (thickness).

    All factors can be combined and with a little care allow small chainsaw to mill timber for long periods. In the past we have tended to get the biggest gruntiest saw we can find and not worry about the other things too much. However, even on a big saw optimising all factors can take a considerable load off a saw and increase its longevity.

  12. #11
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    BobL- you are such a guru with chainsaw work - yet you continue with the fabrication of "rakers". They are depth gauges - they affect the depth the cutting teeth attack the wood. Sorry - I accept that you have made 000's more posts than myself - but they are "depth gauges". Review your comments,.

    Brosh

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    Brosh, I have read many of Bobs posts on milling both here and arboristsite and I think he has resigned himself to the fact that most of the other posters use the word "raker" he has used the correct term depth gauge and others haven't had a clue what he is talking about. He has even corrected others about the term "rakers"
    Cheers Cal


    Sent from my iPhone using Tapatalk

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    Surprised a bit that this thread is still going.
    Going back a bit (first post) it was obvious I was pushing pooh uphill in my first attempts.
    Seem to have things going better now.
    First improvement was to buy a bigger saw for the mill , a second hand 94cc Husqvarna, This thing has got grunt. Plus an adjustable oil feed that I turned up to full. So, no more baked up matter on the chain.
    Bought a new chisel tooth chain for the 24 inch bar and left it at the factory grind of 30 degrees. Worked fine, now don't really know why I ever bothered grinding them to 10 degrees in the first place...was just told that is "the go".
    Gotta say that the sawdust is still very fine but reckon you would have to expect that? Not like you are cutting along the grain when you get heaps of long bits of kerf.
    As for the term "raker". When I got my tree feller license the instructor of the course seemed to have a "pet hate" about the word raker. He would only accept depth gauge. But who cares? We all know what it is referring to.
    That is why I rake the lawn with my chainsaw

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    Quote Originally Posted by Brosh View Post
    ... but they are "depth gauges". ...
    I have always known them to measure depth, and I know some call them depth gouges, some others call them Rakers and also Riders. I have always known them to be Rakers and ALL my friends and who are millers & tree loppers, even my local Stihl shop and my references, call them Rakers. Perhaps it depends on where you are from
    Neil
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    Every day presents an opportunity to learn something new

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    I do use depth gauges sometimes.
    The way I look at it is, any term with the word "gauge" to me implies a measurement and they don't measure anything so why call them a gauge.
    The depth gauge to me is that tool sometimes used to set the depth of the raker.

    I see Baileys calls rakers "Depth gauge rakers"
    Depth Gauge Raker Files | Files & Filing Accessories | Husqvarna Chainsaws, Outdoor Power Equipment and Tree Care Supplies from Bailey's

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