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I have a Stihl chainsaw with the ROLLOMATIC E Standard 20" bar:

I picked up a Granberg Clip-N-Trim attachment, to help it go through brush:

The instructions say to bolt the comb to the bar. I see a circle in the bar about 6" from the end. Is it a knockout? Or a grease fitting?

Should I try to drill a hole through? I've heard that it's really hard, because the bars are made of hardened steel. Where would the hole go? I don't want to interfere with the nose sprocket, obviously. Or maybe I should find an alternate bar, just for this purpose.

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The Stihl I used had a similar small hole near the nose which was a grease fitting for the nose sprocket. –  Steve Armstrong Oct 25 '10 at 21:19
    
I was at the Stihl dealer yesterday, and looked at replacement bars. A 20" bar was about $50. They didn't have any in stock, but the other sized bars all had a hole in this spot. So I'm guessing it's a knockout, but I'm not certain yet. –  Jay Bazuzi Oct 31 '10 at 15:25
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up vote 2 down vote accepted

I'm not familiar with that particular bar, so can't tell you anything about that spot. However, if you intend to drill anywhere on the bar a normal drill bit is not only going to fail, it's going to get damaged trying.

If a drill is your only option you need to get a masonry bit and regrind the point to about the same shape and angle as a regular bit. Use an Aluminium Oxide wheel for that. Drill at a slow speed without applying too much force, preferable using plenty of cutting oil because otherwise the tip can easily get hot enough to melt the brazing.

An alternative to drilling is to use a carbide burr in a pencil grinder.

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