Thread: Show Us the Things You Find in Logs...

I prefer to hit metal with my slabber than my blade, it seems to make an awful mess of the blade more often than not, but the slabber, a touch up seems to get it back to 'new'

Originally Posted by Sigidi

I prefer to hit metal with my slabber than my blade, it seems to make an awful mess of the blade more often than not, but the slabber, a touch up seems to get it back to 'new'

I find that if I'm doing a deep blade cut and hit a nail it does a lot less damage than doing a shallow cut quickly and snapping teeth. Is this the same for bigger mills? Mine is a 6"

Mines a 6" too, sometimes, I've found it hardly does anything to a blade, but more often than not, hitting metal seems to shatter teeth, not sure if the broken bits then tumble in the cut and bugger up more teeth... but like you said Glen, (I tend to cut faster in a shallow cut, than a deep cut) it does seem to do more damage than just going steady, but I don't really have much other than a feeling as proof of this happening.

I take it the blade has TC teeth, which are renowned for their brittleness - they just shatter, but (most) chainsaw blades obviously don't which probably explains what you have seen Sigidi. Glenn, do you know a supplier of those ground penetrating radars? I know some places where, if it can identify buried gold at 2-5 metres, it would pay for itself in no time!

Couple of references for tree radar http://www.treeradar.com/TRUSystem.htm http://www.treeradar.co.uk/
They also find sewer and water pipes so gold is a possibility, I have no idea.

Weaver I think is close to the mark with the very edge of the cutter (melting) or at least becoming hot enuff to destroy the edge without affecting the temper of the whole tooth, an analogy might be something like when we grind a piece of metal on a grinding wheel...the metal being removed is heated up enuff to become red hot (sparks) allbeit tiny little particles but red hot ones without necessarily affecting the temper of the parent metal, in the case of a chisel that is being ground to an edge we have to take care not to turn it blue thus losing the temper and if we want to destroy the edge alltogether just leave it on the wheel toooooo long .
Might be something like what is happening right there at the cutting edge on the chain tooth...yes ....no???
Peter

Just wondering how the heck would someone ever know? by the nature of cutting, there isn't any room for something else in there to have a look or take readings???

One of those sort of things that we r probly never gonna be able to get to or see in any way, but we can all look at the evidence and make some sort of calculated guess based on experience and if we don't know ...ask questions of someone who we think might know

I'm sure things like this have been tested in a lab by people before. There are numerous ways of testing and examining materials to find out what has happened to them or how they have changed. This is the sort of thing they do to figure out what sort of materials and designs to use for saw blades in the first place.

Originally Posted by weaver

Not saying that you guys are wrong but the chain can get that hot or rather the edge gets that hot. Research into how blades go blunt has discovered that when a blade makes contact with the material it is cutting the edge becomes molten. This molten edge is one of the major sources of heat as the energy is conducted away from the cutting edge into the tooth, chain, bar etc. The theory is that as the edge "melts" the molten metal is stripped away and the new edge "melts" and is then stripped away blunting the blade.

I'm not saying that this heat could temper the cutting edge because it is very localized, just a few molecules (hundreds? thousands?) along the cutting edge at a time, but the temperatures are pretty extreme.

Ordinary use wear of a sharpened blade is not a "melting", it's just "abrasion". Edge wear starts with any small crystals of metal along the outer edge just breaking away. Then the material being cut just acts like sand paper and wears away the edge. Even on a proper grinder with all those sparks flying around it's not melting, its just friction and bond breaking. This has been demonstrated by research, the wear cause by normal use and grinding can be looked at under an electron microscope and the few layers of atoms inside the groove of individual microscratches left from the abrasion can be examined. If they were melted even on a local scale their metallic crystalline structure would be different, but they are not.

I agree with PJT about the cutter temp changing if a chain continually strikes something hard the temper can be changed.

ok this is my thinking, there is a hell of a lot of heat generated when hitting even a nail. chains or blades will always be hot to touch but try touching the nail, it hasn't done any work and i bet its hot. as for it changing the characteristics of the cutter, well for this to happen it would need to get at least hot enough to change the color of the cutter, a good example of this is the first time i used my 240V chain sharpener .any other damage would be from the cutter being chipped on the object or by small bits of the cutter still in the wood.

as for things that i have hit in logs, well i am new at this and so far only done scrap wood for firewood but pieces of quarts would rate high in damage done but nothing so far that i have seen or read about tops this. an old chainsaw chain in a very seasoned old Bloodwood that was on the ground for 30+ yrs. stuffed a whole 86 drive link chain before i could take my finger off the throttle

Originally Posted by Metal Guy

ok this is my thinking, there is a hell of a lot of heat generated when hitting even a nail. chains or blades will always be hot to touch

The temp reached by a chain depends very much on the wood size, type and dryness.
A really well sharpened, well oiled chain in small green softwood can be easily be touched without getting burned. The same goes in small green hardwoods. Even in bigger green hardwood, if the bar is long enough (ie bar not buried fully in timber) and there is plenty of oil, the chain is still only in the 50 - 60ºC range. In dry hardwood it can be reach 100ºC, much hotter than this and the chain is not set up right.

but try touching the nail, it hasn't done any work and i bet its hot.

This depends on how hard the nail is, how hard it is hit and for how long the operator leaves the saw in contact with the nail. If I hit a small (eg 2") soft iron nail full on my chains cuts straight thru these with just a minor hiccup not unlike hitting a knot or the mill rolling over a bump on the side of the log. Sometimes I notice a second or two after the hit, "humm . . . the edges seems to have gone of the chain a little while back there". When I lift the slabs off there was is no bluing on the cut edges of the nail so I reckoned the nail didn't get that hot and could easily have been picked up without burning. When I hit something really hard like a rock or a hardened tek screw the saw/mill bucks and rattles and I stop as quick as I can. Depending on how quick I can stop, things like tek screws are cut only about half way and sometimes have a faintly blue edge so I reckoned these do get pretty hot. This is why I don't like winches on CS mill - by the time the operator senses there is a problem the chain can be toast!

as for it changing the characteristics of the cutter, well for this to happen it would need to get at least hot enough to change the color of the cutter, a good example of this is the first time i used my 240V chain sharpener .any other damage would be from the cutter being chipped on the object or by small bits of the cutter still in the wood.

If the chain is already little (or a lot) blunt and the operator is really hoiking on the saw then they might hit something hard and keep pushing away for 5 - 10 seconds before they realize there is a problem. Keeping a really sharp chain help identify these problems and allow the operator to stop sooner rather than later in the cut. For a CS operator the most dangerous time is at the end of a long hard slab. Even if they start out with a freshly sharpened chain by the time they get near the end the chain can be blunt and hitting something at that point is potential the most damaging.

as for things that i have hit in logs, well i am new at this and so far only done scrap wood for firewood but pieces of quarts would rate high in damage done but nothing so far that i have seen or read about tops this. an old chainsaw chain in a very seasoned old Bloodwood that was on the ground for 30+ yrs. stuffed a whole 86 drive link chain before i could take my finger off the throttle

Glass, quartz, concrete, metamorphic type rocks are all pretty similar and all mess up chains good and proper.

thanks for the insight into the milling side of things.
so far i have just cut firewood but am sick of cutting some very beautiful pieces of wood just to split for the fire.
i intend to make myself a small CS mill in the next little while and had planned to put a winch on it but you make a very valid point of the operator not feeling what is happening in the wood.
i have a nice red mahogany hidden away about 800mm through and 5 mtrs long with heaps of branches, hoping i get my mill built soon so i can cut some slabs and see what its like inside.
is there any wood thats no good for slabbing, boards or wood turning?

Originally Posted by Metal Guy

is there any wood thats no good for slabbing, boards or wood turning?

Left hand twisted logs - I've never tried milling one but apparently they fall apart like a loose jigsaw puzzle!