Sharpening Angles

[jteneyck]

Recently, there was a question about what sharpening angles people were using.  Like many folks, I replied that I used the angles recommended by the chain manufacturer.  There are three angles to consider, the top plate angle, the side plate angle, and the tilt angle for lack of a proper term.  The top plate angle and tilt angle are pretty clear to me and relatively easy to control no matter what approach you use, file or grinder.  The side plate angle is something that if you're hand filing you pretty much don't even think about.  You just match up the file with how it was milled by the manufacturer and file away.  If you're using some kind of filing aid then however it controls the file depth controls the side plate angle.  And when you use a grinder life is just as simple.  You just set the wheel angle to what ever angle specified by the manufacturer and you're all set.  WRONG, as I found out as soon as I got my new grinder.  I was always amazed that many chains have side plate angles listed as 85 degrees, such as a Stihl 26 RM2.  This seems like trying to pull a nearly flat faced tooth through the wood.  But when you hold the appropriate file up to a new chain tooth you'll see that the file nests into the tooth perfectly, and the angle where the file enters the tooth is much shallower than 85 degrees.  When I put this new chain on my grinder I found that I had to adjust the wheel tilt to about 50 - 55 degrees in order for the edge of the wheel to match up with the tooth.  Now a sharpened tooth looks just like a new one and the chains cut like they are supposed to.  So what am I missing about how the chain manufacturers are specifying the side plate angle? 

[Kevin]

I had to adjust the wheel tilt to about 50 - 55 degrees

I suspect you are confusing the top plate cutting angle which is between 50 and 60 degrees with the side plate angle which is 85 degrees.

[jteneyck]

The top plate angle is stated to be 30 deg.  I set this angle by rotating the chain holder to that angle, and the wheel was in perfect alignment with the front of the tooth.  The side plate angle is stated to be 85 deg.  I take this to mean you tilt the wheel to that angle.  But when I did that the edge of the wheel did not mesh correctly with the side plate profile cut by the chain manufacturer.  I had to tilt the wheel much further, to around 50 - 55 deg.  I'm sure I'm confused, but in what way?  Thanks.

[ladylake]

Just set your sharpener at 30* top  60* tilt make sure you get the wheel low enough so the side of the wheel  hits the face of the tooth and you'll have chains that cut good if the rakers are not too high. It's the top 25 to 30 thousands of the tooth that does all the cutting on a chiesel chain.    Steve

[Kevin]

There is a top plate cutting angle,60o and a top plate grinding angle.
The top plate grinding angle is 30o.
Also there is a side plate angle which is 85o.

[jteneyck]

Thanks for the feedback guys.  What you say, Ladylake, makes perfect sense on a chisel chain; that's how I set up my grinder and I get good results.  But if you do the same on a semi chisel chain, the grinding wheel does not mesh identically with the profile on the tooth cut by the manufacturer, at least not on the Stihl chains I have.  I had to tilt my wheel down even more, closer to 50 deg. before the wheel lined up the same against the side plate.  Set up like this, Kevin, the angle on the side plate where the tooth enters the top plate has to be 50 deg. also, and not the 85 deg. stated by the manufacturer.  It will be 85 deg. some place around the end radius of the wheel.  If you set up your grinder with a tilt angle of 85 deg., like is suggested by looking at what the chain manufacturers print on their chain boxes, and on Stihl's website, well, you're gonna be cold come next winter.  So they must mean some other angle, which may be the same as what you meant in your post as well, but until I see a drawing that shows how it all works I guess I'll remain confused.  In the meantime, I'll set my tilt angle to no more than 60 deg on these chains.  If you want to take another whack at enlightening me from my obvious ignorance, I'd be greatful. 

[Rocky_J]

Here's some general guidelines as published by Oregon. I prefer a bit more hook in the top plate, but I run the harder Stihl chain which holds an edge better. Oregon chain would dull too quickly at the filing angles I prefer.



And yes, published specs are not always best. But they are published for the lowest common denominator and usually have to pass muster with the corporate attorneys in order to minimize liability. If your preferred angles work better for you than the published guidelines, then stick with what works.

[ladylake]

I think with the grinder tilt set at 60 and the bottom of the wheel rounded some the side plate will end up curved like the wheel and it's hard to tell what the angle of the side plate is and it doesn't matter much just so long as as you get the wheel low enough. On low profile chains I'll form the bottom of the wheel level with the grinder clamp to make sure I can get the wheel low enough. The 2 biggest  mistakes people make are too high rakers and not getting the wheel low enough. jteneyck, thats a good one about being cold next winter.  Also when I first got my grinder I threw the manual away after reading it for 10 minutes and thinking this doesn't make any sence, these are grinder wheels not files.   Steve

[jteneyck]

Thanks for the drawing Rocky.  It must be true, but I still can't visualize how it can be so.  I'm going to have to try to measure the side plate angle for myself on a new chain, and then again after filing one and grinding one.  And I bet you are right about the lowest common denominator, because a chain filed/ground with more hook at the beak leads much better but has a greater tendency to kick back.  Thanks for the grinder advise Ladylake.  Concise and easy to follow - and I will.  And glad you enjoyed the humor.  Question:  On your grinder, is the centerline of the wheel in the same vertical plane as your grinder clamp when the wheel is cutting the tooth, or in front of or behind the clamp?  I think this may impact the side plate angle.  Not sure how mine is positioned and can't check for some time since I'm on the road for another 10 days.  Thanks again for you help.  Much appreciated. 

[ladylake]

Thanks for the drawing Rocky.  It must be true, but I still can't visualize how it can be so.  I'm going to have to try to measure the side plate angle for myself on a new chain, and then again after filing one and grinding one.  And I bet you are right about the lowest common denominator, because a chain filed/ground with more hook at the beak leads much better but has a greater tendency to kick back.  Thanks for the grinder advise Ladylake.  Concise and easy to follow - and I will.  And glad you enjoyed the humor.  Question:  On your grinder, is the centerline of the wheel in the same vertical plane as your grinder clamp when the wheel is cutting the tooth, or in front of or behind the clamp?  I think this may impact the side plate angle.  Not sure how mine is positioned and can't check for some time since I'm on the road for another 10 days.  Thanks again for you help.  Much appreciated. 

  I never checked that as I get good results with not tilting the base 10* back and forth.  I'd think the center line would change a little as the wheel wears , being on a pivot.   Steve

[Kevin]

The side plate angle is illustrated in the Oregon filing guide that Brian posted.
The difference is they are measuring from the back side at 5 degrees but when you measure from the front it becomes 85 degrees.
5 plus 85 = 90o.



Don't worry about this angle when grinding because there isn't a setting on the grinder for it.
It will be built into the wheel if the radius is right.