Drilling holes in guide bar

[Fence-Post]

This site has been really helpful and interesting to read. I'm making a simple Alaskan mill to get my feet wet, based on the mill in a video by David Groth cutting Redwood. The tree that I get to mill is a Cedar. I have a couple questions about drilling holes in the guide bar. In the Instructables the author said to drill the hole right dead center of the 6 dimples, but on the far end of my guide bar there are 4 rivets, and the hole would cut through part of the rivets. It seems like this might be problematic. Is there a bearing in here, and do I have to be careful about drilling a hole through the bearing? My guide bar is a Stihl Rollomatic E.

The bolt in the picture is 5/8". It seems like David Groth is using 3/8" bolts. Would it be fine to opt for 3/8" bolts here?

Thank you.

Instructable - Chainsaw Mill Build, Use & Tips n Tricks
http://www.instructables.com/id/Chainsaw-Mill-Build-Use-Tips-n-Tricks/?ALLSTEPS

David Groth's video

 

[Grande Dog]

Howdy,
Deciding where to drill on a laminated bar is a crap shoot because the center laminate is not a solid piece. If your width of cut isn't an issue, punch the assembly plug out of the bar, and use it.
Regards
Gregg

 

[BobL]

I use 1/4" high tensile socket headed screws on the bar nose and they fit easily between those rivets.
On the inboard hole I use 3/8" high tensile socket headed screws
The static bearing part of the roller inside the nose at that point is incredibly hard.
I found I had to use a freshly sharpened or new carbide masonry but, slow speed (120 RPM), lots of lube/coolant and very high pressure.
Drilling it all in one pass will create a large burr that can grab and shatter the carbide.
I found it best to drill it one way until the top breaks through and then turn the bar over and come in from the other side and go a bit slower when drilling out the final bit.
You may end up destroying the bit but that is the cost of making the hole - so if you have to buy some bits but a couple.

BTW Im not that impressed with David Groth's Video.
The working positions he uses will lead to operator fatigue and that leads to other problems.

 

[Kroll]

I drilled mine for 1/4". But went with 5/16". Why? Couldn't find my 1/4" tap. Only reason. Bolts to mill frame upright.
Are you using the bolt/threaded rod as the upright as in the video? If yes, I would use the bigger size for stiffness, to avoid flexing or bending. As Grande Dog said, bolt back further on bar if cut width not an issue. If it is, extend it past the nose with flat stock/bar.
This is just an idea. Pieces from the workbench. I would use aluminum bar. This would allow smaller bolt thru sprocket. And make sure its all tight! Would offer some protection from nose. Use drill press on bar, much easier than by handheld drill.

Kroll

 

[muddstopper]

To drill holes in the harden steel, you might try finding a m42 colbalt drill bit. One small bit might cost you $10, but M42 will drill thru just about anything.