Stihl chain grinding angles

[Cedar Row]

I have searched through the site looking for Stihl chain angles, thought I'd try just asking. What angles do you use for stihl RS chain and RM chain. Apparently Stihl recommends 30/60 for RSC; 30/75 for RMC. I have been using 30/60 for all my Stihl chain. Any thoughts or comments about advantages or disadvantages of grinding angles?

 

[indiansprings]

We use a Stihl USG grinder, when new somewhere around 1200-1300.00 bucks, it is fixed at 60 degrees, we grind them at 30 degrees unless a customer specifies something different, some ask for a 25 degree angle, 90% get the 30 degree.

 

[Cedar Row]

We use a Stihl USG grinder, when new somewhere around 1200-1300.00 bucks, it is fixed at 60 degrees, we grind them at 30 degrees unless a customer specifies something different, some ask for a 25 degree angle, 90% get the 30 degree.

The key question I have is about the 75 degree angle for RMC. I have a Stihl data sheet that came with a new (from e-bay so it might not be real new, since Stihl seems to be eliminating the RM chain) RMC chain, and it lists 75 degrees as the top plate angle for RMC. Any good reason to use this angle?

 

[lambs]

No good reason that I can think of unless it's just to try and reduce their liability on semi-chisel, which they'll try to sell to everyone who walks in the door because it is supposed to be safer.

I run 30/60 on any semi-chisel, and 30/60/10 on full chisel.

I suppose you could try it at 75 and see how it performs. My guess is slower.

 

[MCW]

I run 30/65/0 on all the chain I sharpen apart from ripping. The 65° matches a file better, is less aggressive than 60°, and also seems to stay sharper longer. I actually don't mind 60° in softwoods but it still basically ends up as 65° after filing.

 

[Cedar Row]

Thanks, Lamb and MCW. It is good to be able to get information from people who actually have experience. The 65 degree sounds interesting, I may try that since I cut dead oak. I'm not going to bother to change angles for RMc and RSc chain. I'd rather run RMC, but it seems to be getting hard to find. I have read in posts on this site that quite a few people think RMC stays sharp longer.

 

[lambs]

It will stay sharp longer because it cuts from a "shoulder" rather than a "point", and the point can dull quickly in dirty wood. RS or chisel chain cutters look like a "7" from end to end. Semi-chisel or RM chain looks like a "?".

If you are cutting dirty wood, I'd use semi-chisel. In clean wood, correctly sharpened full chisel chain will cut faster.

 

[Cedar Row]

It will stay sharp longer because it cuts from a "shoulder" rather than a "point", and the point can dull quickly in dirty wood. RS or chisel chain cutters look like a "7" from end to end. Semi-chisel or RM chain looks like a "?".

If you are cutting dirty wood, I'd use semi-chisel. In clean wood, correctly sharpened full chisel chain will cut faster.

Good information!

 

[MCW]

Out of interest this is full chisel at the top, semi chisel in the middle, and chipper at the bottom...

 

[Duane(Pa)]

Awesome example!

 

[John R]

I grind my Stihl chains at 60/30/0, they cut good, never a problem.

 

[Fish]

Yeah, for sanity's sake I keep the angles 60/30, but I do the tilt on the full chisel and use my bi-directional motor as it should be used.

 

[Tommy Collins]

The key question I have is about the 75 degree angle for RMC. I have a Stihl data sheet that came with a new (from e-bay so it might not be real new, since Stihl seems to be eliminating the RM chain) RMC chain, and it lists 75 degrees as the top plate angle for RMC. Any good reason to use this angle?

I have satisfied my own mind that the 75 degrees is useless information which is misleading and confusing and has ruined a lot of rm chains.
It is not to be used for setting the angle of your grinder.
It is not the top plate angle. It is the side plate angle.
Let me explain....

On the RS chain ,full chisel,the portion of the cutter considered to be the side plate extends all the way up to the top of the cutter where the listed side plate angle of 60 degrees happens to be the setting you would use for your grinder.
Here's the difference...
On the RM,semi chisel chain ,the rounded corner portion of the cutter is not considered part of the side plate , the top of the side plate is located at the point where the side plate meets the bottom of the rounded portion of the cutter, at which point ,because of the curved gullet, the side plate angle happens to be 75 degrees.....useless and confusing information.
The evidence that RS and RM are ground exactly the same is that when filing you use the same diameter file, the same filing guide and use the same angles.
So....if you set your grinder at 60 degrees, use a properly shaped wheel of the correct thickness, grind to the proper depth the RM cutter will magically have a 75 degrees side plate angle...... as if you could measure it.