Chain sharpening...

[difflock]

Hmmmm,

I know chain saw chain techonology is more advanced than blacksmithing Treequip

BUT

I stand by what I said in respect of hardening and tempering.

Albeit from 30 year old memories, backed up by subsequent experience.

Red heat applied to steel and allowed to air cool will loose the HARDNESS that is induced by the "quenching", which effectively locks the molecular structure of the steel into a harded finer grained state

see SEM photos for furthur elucidation.

Tempering is the process wherby some of the induced hardness is relived, by application of a lower carefully controlled temperature.

Classicaly to jump to another metal, copper is easily work hardened by hammering, one then softens it by heating and allowing to cool naturally.

Repeat the process as often as necessary.

So if one red heats a steel cutting edge, and does not quench one loses all hardness.

cheers

marcus

PS

I will now Google "hardening & tempering"

Erm

I suspect the comment about being unable to file the chrome on the tooth is erronous, otherwise there would be a several millimeter strip of chrome standing free after the steel tooth is eventually sharpened down to the wear guide

This does not happen, therefore the "chrome" must be filable.

By deduction, based on personal experience.

Cheers again,

Swithering to book ferry ticket to the APF, really must decide soon.

Edited September 11, 2012 by difflock

[treequip]

Hmmmm,

I know chain saw chain techonology is more advanced than blacksmithing Treequip

BUT

I stand by what I said in respect of hardening and tempering.

Albeit from 30 year old memories, backed up by subsequent experience.

Red heat applied to steel and allowed to air cool will loose the HARDNESS that is induced by the "quenching", which effectively locks the molecular structure of the steel into a harded finer grained state

see SEM photos for furthur elucidation.

Tempering is the process wherby some of the induced hardness is relived, by application of a lower carefully controlled temperature.

Classicaly to jump to another metal, copper is easily work hardened by hammering, one then softens it by heating and allowing to cool naturally.

Repeat the process as often as necessary.

So if one red heats a steel cutting edge, and does not quench one loses all hardness.

cheers

marcus

PS

I will now Google "hardening & tempering"

Erm

I suspect the comment about being unable to file the chrome on the tooth is erronous, otherwise there would be a several millimeter strip of chrome standing free after the steel tooth is eventually sharpened down to the wear guide

This does not happen, therefore the "chrome" must be filable.

By deduction, based on personal experience.

Cheers again,

Swithering to book ferry ticket to the APF, really must decide soon.

 

 

If you have ever made close observation if a tooth while filing it the chrome flakes away, it's erroneous to assume that a few microns of chrome could possibly form "a several millimeter strip of chrome standing" chrome Comes out at over 72 on the rockwell scale, find a lump of chrome and a file if you want, you may be able to dig through a small portion but it will cost you the file. Grinding is the only sensible option for dressing chrome.

 

Well whatever

 

I will leave you with this, if heating to red and allowing to air cool softens steel why is a badly ground tooth (heated to red and allowed to air cool) as hard as hell?

[Rob D]

When a tooth is ground so it gets very hot it does seem to get very hard indeed to the point it can strip a round file.

 

 

Grinders are fast but you usually have to take the chain off to grind the chain - by the time you have it off the bar and back on again you can usually have touched up the chain by then anyway....

 

But they work well if the chain is damaged.

[Ty Korrigan]

Back again, short day today.

After a days work I usually clean the and sharpen some of the saws.

As the saws are partly dismantled for cleaning the time to take off the chain etc it changes nothing.

I was thinking of the grinder to save my aching elbows as well as time.

Also, each saw has 3 chains allocated to it and so we normallly just change chains in the field except when I've been too tired to sharpen any at the workshop.

Stumpgrinding eats chains...

Although I clean off the bark with an axe beforehand the chains still take a beating often losing half a tooth on one side only.

I just can't face sharpening a whole half chain at the end of the day!

So then...

I like sharpening but not that much to take up my evenings.

Should I buy a grinder to save time and elbows or just put up with hand sharpening?

May have to vote on this one!

Ty

[treequip]

If you are only cutting stumps and you are going to grind the chains you might want to look into carbide tipped chain, it's difficult to sharpen in the field but if you are carrying a couple of chains per saw its worth considdering.

 

It will put up with dirt better than standard chain but it won't like inclusions, which can rip off the carbides and leave you with a cutter less chain

 

You will also need a green grit wheel rather than a standard grinder wheel.

[Ty Korrigan]

Ah, that all sounds to be good advice but can I ask...

What do you mean about 'inclusions...?'

Metal, stone etc...?

Ty

[treequip]

Ah, that all sounds to be good advice but can I ask...

What do you mean about 'inclusions...?'

Metal, stone etc...?

Ty

 

Yes, mostly steel in the form of nails, rather than blunting the tooth it tends to rip the carbide cutter ( they are braised on) clean off the cutter body. You shouldn't have too much of a problem with nails, they tend to be washing line and fence material, you will seldom find them in the last cut before grinding.

[spudulike]

My observations on the correct grinding of chains -

 

1) Only lightly touch the chain with the grinding wheel before lifting it again, keep "brushing" the chain with the wheel to avoid overheating - if the cutter glows with orange heat then forget it, you will only ever be able to grind that chain in future.

 

2) The grinding disks after a period of use will become less effective - you will see this as less sparks coming off the grinder - the disk has become glazed, solution - break the glaze, I use a diamond file but am sure there are a number of other methods. You will se a big difference in sparks after doing this.

 

The tempering argument - the cutter is small and doesnt hold heat well, if you overgrind it, it will glow orange and then cool rapidly and will under temper the metal leaving it damn hard and normally blue. Best solution is to grind as above with care.

 

I only use a £30 grinder but it does the trick as I use it with care and precision - any beat up chain is brought back in to spec faster and better with a grinder - light touch ups or tickles can be achieved with a file in field or workshop - thats my opinion for what its worth:thumbup:

[treequip]

My observations on the correct grinding of chains -

 

1) Only lightly touch the chain with the grinding wheel before lifting it again, keep "brushing" the chain with the wheel to avoid overheating - if the cutter glows with orange heat then forget it, you will only ever be able to grind that chain in future.

 

2) The grinding disks after a period of use will become less effective - you will see this as less sparks coming off the grinder - the disk has become glazed, solution - break the glaze, I use a diamond file but am sure there are a number of other methods. You will se a big difference in sparks after doing this.

 

The tempering argument - the cutter is small and doesnt hold heat well, if you overgrind it, it will glow orange and then cool rapidly and will under temper the metal leaving it damn hard and normally blue. Best solution is to grind as above with care.

 

I only use a £30 grinder but it does the trick as I use it with care and precision - any beat up chain is brought back in to spec faster and better with a grinder - light touch ups or tickles can be achieved with a file in field or workshop - thats my opinion for what its worth:thumbup:

 

Can we please get away from tempering, you can't temper over temper or under temper it. Tempering is for treating high carbon alloy steel that has been hardened by heating. Cutter bodies are made of bog ordinary mild steel, it can be hardened but it dosent posess the exotic alloys that respond to tempering.

[Le Sanglier]

Thank you the responses so far.

So, I guess the technique is to touch light and fast several times rather than holding the wheel to the chain continiously.

Basically, at the end of the day, I have several chains to sharpen and what I really want to do is go home...

So I am considering buying a grinder from Honey Bros (£450+v.a.t+

If I win time then over just a few years it will have paid for itself and also helps my tendonitus.

Cheers

Ty

 

Ty, I bought an Oregon grinder over here for €150 perfectly adequate.