Bench Chain Grinder - Specific Question about Grinding Rakers

[Mauser]

This post is NOT about the pros or cons of using grinders or files - it is a question very specific to the instructions for the Oregon 410-120 grinder, and it only applies to dressing the large wheel for setting the depth gauges.

The instructions on page 28 are quite clear on how to set up the grinder for setting the depth gauges, but one part of it just seems kind of dumb or pointless:

After mounting the 1/4"wheel, it says to adjust the tilt angle of the motor unit to between 75-80 degrees - this places the angle of the wheel fairly close to straight up and down. It is important to note here that this unit CAN be set to 90 degrees, which would be exactly straight up and down.

After setting the tilt angle to 80 degrees, the next step is to put the supplied dressing block in the chain vise and use it to shape a perfectly straight and flat bottom to the grinding wheel that is horizontal to the chain surface (exactly like you would be holding a file on a fixed depth gauge tool). After dressing the wheel, looking straight on it has the shape something like an upside down 7.

And that is it - after you dress the wheel so it is flat on the bottom, you just use it like a file to grind down the top of each of the rakers. You would still have to manually round off the front of the rakers after the depth was properly set.

But here's the question: WHY would they want the tilt angle set to 80 degrees before dressing the bottom of the wheel flat instead of just doing it at 90 degrees? Either way, the part of the wheel that grinds on the rakers is totally flat and horizontal, so what is the point of having the wheel tilted slightly instead of just square like a normal grinding wheel would be?

 

[Saw Fixr]

Are you 100% sure the wheel will hit the raker without contacting the chain/tooth stop first when set at 90? Pretty sure mine wouldn’t clear, and I have the same grinder, bought last year. If it will indeed clear, go for it. I’ve also found that setting the chain vise at 30deg, Didn’t burn the rakers, but sometimes when the clamp was set to straight, straight it would burn. Stihl chains seem harder than Oregon to me and therefore can burn easier.
I ended up dressing my raker wheel off with the head tilted at 30 degrees, so I just change wheels and go. Otherwise, next time you tilt the head to 80, it’s really only 80ish and it won’t be exactly the same angle as last time, and you’ll only be grinding with a thin line of the wheel.
Best of luck to you.....

 

[Saw Fixr]

Actually, I’m not sure i answered your question. I’ll try again.....
Regardless of the tilt angle of the head, the wheel will always be flat at the grinding surface. But with the wheel straight up at 90, you’re grinding at a right angle (perpendicular) to the raker tooth in the clamp. There’s probably a pretty high amount of right angle down force at the clamp/raker/tooth clamp area, and there’s probably a pretty good chance the raker could “chatter “ in the vise. Not sure of the difference it matters.....
However, with the wheel tilted at even a slight angle, the wheel at the grinding surface, although flat, is grinding at say, a 10 degree (with the wheel at 80) angle to the raker tooth, if you were to look straight down. There’s less force at the grinding surface because the wheel’s at an angle to the tooth,Not perpendicular to the tooth. Less likely to chatter, or burn....
Just my opinion, but I used to be in the cylindrical grinding industry, and it’s vaguely similar to that process, in some ways......