Most BH steels are not sufficiently hard to hold their edge when the TOTAL angle is 25 degrees. The thin edge rolls to easily on soft steels.
The lower the angle, the thinner the edge. The thinner the edge, the sharper is can be made; all else being equal.
We're interested in only single-slice durability, but we don't need an edge so thin it rolls on bone impacts. Another factor to consider; a 'thinner' edge will slice with less effort, and more deeply, than an "equally-sharp" edge that is 'thicker'. You want to use the lowest sharpening angle that your BH's steel-quality permits.
It takes more effort to sharpen hard, quality steel, but it can be made sharper than softer steels (because the edge can be made thinner while still durable - long lasting - enough for our required single slice. It's also far easier to resharpen them to a 'truly sharp state' after use; because they 'dull less' during penetration.
If you're holding a precise angle, which should be no problem with all the jigs you've tried, the reason you're not getting the desired results is probably related to either the quality of the steels/stones you're using or the pressure you're applying; and I'd speculate it's the pressure you're using.
Especially on the courser grits, using too much pressure will result in deep microscopic gouges in the edge. It takes a lot of fine-stone work to fully remove these (and ALL fine stone work should be at light pressure; it's purpose is only to polishe the edge you've established with the previous stone(s). You also need to pay careful attention to the removal of any microscopic wire-edge that may be resulting.
As far as angle, on most commonly used BH's the best overall double-bevel angle ends up being 20 to 25 degrees on each side of the bevel, for a total edge-angle of 40 to 50 degrees. A single bevel should, ideally, be at 25 degrees (and zero on the other side) but this REQUIRES hard steel to work well, around R52 minimum. The maximum hardness for single-bevels is about R62, or the steel becomes too brittle. Around R57-58 seems about ideal. Most commonly used BH's range from a hardness from the low to high 40's; too soft for an 'ideal' single bevel, or a low-angle double-bevel.
A long reply to your question, but BH sharpness is an important issue. I see many self-purported 'scarry-sharp' broadheads that are not truly sharp enough.
Cangratulations in being conserned enough about your BH's sharpness. Try using less pressure between the blade and the steels or stones. It takes longer, so be patient. Once the bevel is correct, and the BH sharpened properly, it's fast and easy to re-sharpen them. Look at initial sharpening as a one-time task; good for the life of the BH, unless there's a catastropic event.
My other recommendation is, if you still have problems after trying low pressure and patience, is to pick up the phone and call Ron at KME. He knows sharpening well.
Ed
TGMM Family of the Bow
Topic: angle for sharp broadheads ?????? (Read 566 times)
