There was a recent thread discussing scraper angles which I was going to bump, but as it is rather long I will just reference it here.
https://aawforum.org/community/index.php?threads/no-battles-please.16601/#post-167475
So here is my question. Suppose that you want to make a 70° negative rake or double bevel scraper. There are several ways to grind the top and bottom bevels to get to 70, here are three examples (top & bottom angles): 10° & 60°; 35° & 35°; 60° & 10°. Each of these grinds will give a 70° included angle, but in the first instance the tip will be directed more toward the top and in the third instance the tip will be directed toward the bottom. In the middle instance the tip will be directed parallel to the tool shaft.
Although the included angle is the same, I am thinking there will be differences in how the 3 options would perform. I have never seen anyone use or advocate option 3 and find it difficult to imagine that it would be that successful a grind. Between options 1 and 2, the middle approach has the advantage of being easier to implement and maintain, and it's reversible. But I wonder if there are any performance advantages or penalties to consider between either of the first two options?
https://aawforum.org/community/index.php?threads/no-battles-please.16601/#post-167475
So here is my question. Suppose that you want to make a 70° negative rake or double bevel scraper. There are several ways to grind the top and bottom bevels to get to 70, here are three examples (top & bottom angles): 10° & 60°; 35° & 35°; 60° & 10°. Each of these grinds will give a 70° included angle, but in the first instance the tip will be directed more toward the top and in the third instance the tip will be directed toward the bottom. In the middle instance the tip will be directed parallel to the tool shaft.
Although the included angle is the same, I am thinking there will be differences in how the 3 options would perform. I have never seen anyone use or advocate option 3 and find it difficult to imagine that it would be that successful a grind. Between options 1 and 2, the middle approach has the advantage of being easier to implement and maintain, and it's reversible. But I wonder if there are any performance advantages or penalties to consider between either of the first two options?