[chrismahon]

We have two Japanese made Silky tree saws which, after 20 years of use, are noticeably less efficient at cutting than they were. I thought they were in need of replacement and they are not cheap. The reason I thought they had to be replaced is because the teeth are hardened by a process called 'ion implantation' which creates an extremely hard edge to the saw teeth and which is too hard to sharpen. Once worn away, underneath is a softer material which won't hold an edge.


Before splashing out €100+ on a new blade I looked into it more closely. Not all Silky saws are hardened with the aforementioned process. Some are 'just' (of exceptional quality) very hard steel which can be sharpened, but not with an ordinary file. Using an ordinary file will just wreck the file. What is needed is a diamond file and I have one but, although it does the job it is too cumbersome to use. So we've invested in a Silky saw file which comes with a lifetime guarantee. I'll report further when it arrives (€32) and I've tried it. From my efforts so far, the one edge that needs sharpening also needs a magnifying glass to see it!

[arobwk]

Yes please - do report on experience with the file idc. (I have a gomtaro apple which I believe is just called gomtaro "fine" these days:  I can't imagine the fine-toothed blade can be sharpened actually, but I'd be interested in knowing how you get on.)

[chrismahon]

I've just looked at the 'Silky Sharpening Instructions' from the site 'silky-europe.com' [member=152775]arobwk[/member]  and 'Gomataro' isn't on the list, so perhaps it can't be sharpened. However there is a symbol that appears on the blade (teeth with a file above) which denotes it can be sharpened, so if that's on your blade it's OK.


We have a pole saw with a curved 'Hayauchi' blade and a hand saw 'Yamabico' with a straight blade. Both of those are on the aforementioned list but not on other lists I've seen?


I've just looked on both blades and neither has the symbol on them, however it does appear on the label attached to/ wrapped around the plastic safety covers.

[arobwk]

Thanks for that [member=23925]chrismahon[/member] .  I couldn't find a link to sharpening instructions on the web-site, but the Gomtaro tooth pattern is rather complex and I can't see how could be sharpened actually.
Today's prices are a bit steep (phew!):  they did dip for a while after I bought my 1st Silky (wish I'd bought a spare blade back then).  However, they are very very good as you will know:  I can often cut through a 20mm branch with a single backward swipe of the Gomtaro 'fine' blade (hot knife thro' butter comes to mind). 
I smiled when I spotted Silky branded plasters offered as an accessory:  luckily I have not had any accidents, but not sure how useful a plaster would be if one really took one's eye off the ball when wielding a Silky ! Lol
   

[chrismahon]

The file arrived quite quickly at our local collection point (house is difficult to find) and was put to use immediately due to the terrible weather. It doesn't have a handle and one is essential to be able to control the file properly. Fortunately I have one.


Started with the Yamabico, which has the shorter (30cm) straight blade, although both blades have the same pitch of teeth, 6.5- 30mm (5.5 to inch). First job was to clean all the teeth with a wire brush and then clamp the first section firmly in the vice. There are three bevels on each tooth- forwards and backwards cut and a small one at the point. As the saw cuts on the backwards stroke the other one can be ignored. Close inspection of the teeth (X10 magnifying glass) revealed that only the tiny top one needed work. My, it is fiddly work. One slip of the file and you will blunt the edges of the adjoining teeth. All it took was one light stroke of the file towards the cutting edge though. All finished in an hour. Note that close inspection of a sharpened tooth and it looks blunt. That's the burr created with the file. It is very brittle and can be knocked off with a fingernail. I would suggest just trying a wood cut which will knock all the burrs off and then check the teeth.


The Hayauchi took a bit longer. It's 39cm long, but some of the main cutting backward edges needed work and they are particularly difficult. Noticed that one side of the blade was worse than the other, which may explain why the blade was getting stuck. So 2 hours of work later (with stops every 20 minutes) and it was finished.


If I had a blade that needed all the main cutting edges doing I would probably buy a new one. A clothes peg works well as an indicator of the last tooth sharpened, so you don't waste time trying to find where you had finished last time. Olive oil does indeed soften the sap buildup, but it still needs scraping off and of course you wouldn't apply it to the blade before it was sharpened.


We haven't that much to prune here now, so hopefully I won't need to do these blades again. I did read somewhere that the extra-hard file can also be used for sharpening axe edges- haven't tried that yet, but if correct it will be considerably quicker than a stone.