iDRY Vacuum Kilns

Sponsors:

chain grinding with out hardening

Started by postville, April 06, 2011, 08:21:12 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

postville

I have problems hand filing a chain after I have ground it. I try to grind very light and "touch, touch, touch" as someone showed me. Using a MoMab red wheel on Chinese Oregon type grinder.  Still cannot get as sharp and long lasting as when I hand file. Any tips?
LT40 25hp Kohler, Gehl 6635, Valby grapple, Ford 4600, Farmi winch, Stihl saws

tyb525

From my experience, a good hand filing job cuts better than a chain straight of the grinder. However, someone that knows how to set up a grinder real well might say different. I don't think you can "harden" the cutter by grinding, however I know you can soften the tooth (when it turns blue) from too much heat.
LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

beenthere

south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

smalldog

Whoever my neighbor was having sharpen his chains, would do a poor job and HARDEN the cutters so a file would hardly cut them. I only file my chains and love how they cut vs. a bad grind job.
Hang in there body...just a little further to go.

tyb525

Could someone explain how grinding can harden a chain? (just curious)
LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

smalldog

TYB525...I know what you are getting at. To draw back tool steel after you harden it, you might heat it to a straw color and let it air cool. Maybe if someone fits a coolant hose onto their grinder, then they would be heating and quenching when they rush the grinding process. All I know is the neighbor would get a great deal on a grind job, then it would be so hard a file wouldn't touch it. Too bad it wasn't a quality grind!
Hang in there body...just a little further to go.

Ianab

What may be happening is that it's only localised heating at the spot where the tooth is being ground, the edge does actually get yellow hot for an instant, then the heat is instantly drawn away from the spot by the rest of the mass of the cutter. It's not like annealing where you heat the whole piece and then let is slowly air cool. It's more like a quick heat and quench cycle, and that certainly can mess with the hardness.

I prefer to hand file myself as there is no risk of overheated unless you are the "Flash"  :D

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

Al_Smith

Most high carbon bearing steel will harden if you reach critical temperature which is around 1400 degrees . About the color of a pumpkin .It the case of a chain it will only be a "case " hardening of a couple thou deep .Still though it would likely be around 60 Rockwell C which is harder than a file can cut .

With any grinding the secret is keeping a sharp wheel .Meaning that the wheel is free of grinding dust which loads the wheel and instead of removing stock it just tends to heat it up .Probabley the best advice I could give is to dress the wheel frequently .

ladylake


Seems like these hardened chains should hold there edge longer? Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

smalldog

Yes, you would think this would be a good idea except when you want to file a chain out in the field. Also, there are burrs left on the cutting edges where the metal was quickly "mashed" over. (nasty) I'm still trying to teach him to file his own chains.
Hang in there body...just a little further to go.

jteneyck

If your chains cut well after you grind them, why bother filing them?  Just take a couple extra with you for the day and change them out if one gets dull.  Takes two minutes to change and you're back cutting with a fresh chain.  I can file OK, but with a grinder I get consistent tooth shape and length so, for me, the chain cuts better. 

Back to grinding, the OE's must grind chains while flooded with coolant so the teeth don't blue or harden.  I think it should be possible to mist or drip water onto the grinding wheel yourself, but I haven't tried it yet for fear of frying my grinder.  Has anyone done this? 

postville

I did set up a mister and it helped. Now going to try a Borazine wheel.
I have filed for years and get good results. Trying this now as I am getting back into logging and firewood for some retirement income.
My big area of trouble with dulling is bucking logs in the yard. We have a lot if flinty rocks in the soil here and barely a touch is too much. If the log is straight I can roll it to finish up but a lot of the cull trees are too twisty to roll. Bob
LT40 25hp Kohler, Gehl 6635, Valby grapple, Ford 4600, Farmi winch, Stihl saws

1270d

In my experience when grinding a chain, if the cutter turn blue, it is hard enough to resist a file.    On the other hand i have intentionally done this on square ground chain.  It will hold an edge better in dusty or slightly gritty wood.   it was called "getting a good burn" on the tooth when explained to me, and it worked.   When doing it though make sure to keep the cutting edge free of burrs.    the blue, or hardened, surface can be removed by bumping the edge again with  the wheel.   Removing the color seems to make the chain file friendly once more.

northwoods1



Bob is it hard to file immediately after you grind it or after you have ground it and used it and dulled it again? Sometimes a saw chain will be hard to get the file started on but after the file begins to bite it is not a probelm, this happens particularly when the tooth has been dulled. It has to do with the fact the surface of the tooth has a different finish that the file will not bite into, nothing to do with tooth hardness being affected. I find it is important to not let the chain get to dull but give every tooth a couple licks every time I fill up with gas. If your cutting dirty logs in the yard, what I would do is have an extra saw with a used up chain for that task. Keep the good sharp chain for clean wood. I have never seen any need to mechanically sharpen a saw chain especially with the shorter bars we commonly use around here. It only takes a few moments to sharpen with a file, I sit the was on my lap while I do it and always use new files, they can be cheap but they have to be new. I get swedish made ones for less then $1 per.

Guys have told me before that they think there chains get harder if the cutter turns blue either through use on a harvester or by grinding to fast. To my knowledge, all chains are made of oil hardening steel, which means that the only way you can harden that cutter is to heat it to at least critical and then quench it... other words it will only get softer by overheating and then cooling in the air.  Overhearing can only remove the temper and make it softer. Oregon chain for instance is made from an O1 alloy they specifically developed. impossible to harden it by overheating and it cooling in the air...

Al_Smith

Well yes ,true to a point regarding O2 .However it will "wear " harden as will most tool steels .It would stand to reason that if a person ground using a clogged wheel you could experiance some wear hardening .Maybe only a couple thou  deep but enough to cause you fits with a file .

I do lnow that if you machine off most tool steels with a lathe you want to make sure you are rolling a chip in order to pull the heat of machining out of and away from the part .If you keep on just scratching it pretty soon with each succesive pass it just gets hard as a rock .Keep it up long enough you have to switch from carbide to ceramic cutters to cut it .Fact is before I knew better I've had smoke rolling of a ceramic cutter on A2 .Now that is hard .

northwoods1

Quote from: Al_Smith on April 17, 2011, 11:53:05 AM
.Fact is before I knew better I've had smoke rolling of a ceramic cutter on A2 .Now that is hard .

Well yes, A2 is an air hardening alloy, the A denotes that. O-1 is an oil hardening steel saw chain is made out of oil hardening steel as far as I know.
I think the reason that a file won't touch a saw chain in some cases is because of the polish that can form on a tooth. It becomes, not harder, but more polished.

Al_Smith

My point was in spite of the fact that in theory A2 should be heated to crtical  and held for a period of time ,it will wear harden .It won't be very deep ,just enough to drive you nuts if you attack it with a file .

You can do all kinds of stuff with steel that really isn't the normal practice .I've taken A2 to 1400 with a flame, held it for 5 minutes and tossed it in a buket of oil .Then reheated and drawed it back to straw color .It worked out hard enough to hold up for a spur sprocket on a gear drive saw .Hill Billy metalurgest ,works for me . :D

northwoods1



Al smith, my point is why are you talking about A2 :) chainsaw chain is not made out of air hardening steel.
Tyb525 is correct, no one can explain to him how grinding can harden a chain because, well, it is not possible.
I think it has to do with the amount of polish on the tooth, especially with a dulled cutter. If you take 2 pieces of steel, one for example that has a surface that has been just cut with a bastard file and retains that surface, and another that has a more highly polished surface especially if that surface was created by use wear, a bastard file will have a harder time cutting the polished surface. But that is not because it is harder.
The phenomena of a saw chain becoming in a state where it is hard for a file to bite into is not because the tooth has become hardened.
 

postville

Northwoods and all, I think I will go back to hand filing and save the grinding for badly damaged chains.
I take your point on polished surface as the file will bite after getting past the hard edge.
Funny how sometimes the old ways are still the fastest!
LT40 25hp Kohler, Gehl 6635, Valby grapple, Ford 4600, Farmi winch, Stihl saws

Al_Smith

Quote from: northwoods1 on April 17, 2011, 07:19:22 PM


Al smith, my point is why are you talking about A2 :) chainsaw chain is not made out of air hardening steel.
   
I just interjected that for a thought ,I know chain isn't made of A2 .Ha I used to kid Wolfie who goes by "Raised by wolves " and  is a tool and die maker by trade .Anyway I'd drive him bonkers with some of my hardening methods which are more hayseed that protocal .Then too I was not making parts for the space shuttle or an atomic bomb,just a danged saw part .All in good humor . ;D

Gary_C

There is another very good explanation for the difficulty in filing a chain after grinding.

When you grind a chain, the wheel comes down at an angle and makes a flat face on the cutter. Yet when you file a cutter, the round file tries to make a concave face on the cutter. So you will not touch the cutting edge of the cutter till you re-establish that concave face. And the lower you let the file get on the stroke, the greater the concave needed to re-establish that cutting edge. 
Never take life seriously. Nobody gets out alive anyway.

Thank You Sponsors!