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Can anyone clue me in as to what sort of included angle a straight razor should have at the edge? (I understand that it varies, so rough ranges would be more than good enough.) Industrial razors are often in the 30 deg. range, so I'm assuming that it's a fair bit under that.
Cheers.
~ Karl
My vote would go for 16 +- 3 degrees, there lots of variables.
Here is a thread.
http://straightrazorpalace.com/razor...zor-angle.html
Charlie
The consensus among those who know is somewhere in the range of 16 to 18 degrees.
feather blades are at 22degrees per Tim Zs study
and i have had nothing but problms when running at under 14 degrees
hows that for a range
Hey, thanks guys.
I'd tried searching a few times, but hadn't found that page yet.
I used to work in an industrial testing lab, so my fallback plan would be to measure mine, but it's nice to see a variety.
BTW - I'm not on here often, but accurate measurement and metallurgical funkybusiness are some of the few things that I do actually know a useful amount about. I'm always happy to chat about that stuff.
I doubt manufacturers actually measured the angle… but throughout the history of making razors, most (if not all) manufacturers adhered to the proportion of the blade about 3.5 times the thickness of the spine.
So for example: 4/8th would be bit over 1/8th inch spine, 5/8th would be 3/16th inch spine, 6/8th razor would be a bit under ¼ inch spine, 7/8th to 8/8th razor would be about ¼ inch or more spine thickness.
They would start with a bar of steel about the width of the spine of the finished razor (I guess 3/16th and ¼ in thickness was the common sizes of steel supplied in those days), and simply forge the blade a bit more than the desired width, then after grinding, finishing and sharpening the razor would be somewhere about right.
But as you can well understand, “early” razors were all forged and ground by hand, and variations will occur, so there may not be a precise figure for the angle. However, as manufacturing techniques became more modern and efficient… they still stuck to the 1 to 3.5 proportion... because it worked.
Thank you! I can work with that --Quote:
I doubt manufacturers actually measured the angle… but throughout the history of making razors, most (if not all) manufacturers adhered to the proportion of the blade about 3.5 times the thickness of the spine.
with a blade that's 3.5x as wide as the spine,
the included angle is 16.3 degrees.
[The arithmetic:
the thickness is 1/3.5 of the blade width, so
the half-thickness is 1/7 of the blade width, so
the half-angle is arctan (1/7) = 8.13 degrees, and
the angle is 16.26 degrees.
Charles
It is the golden razor ratio if there ever was one :)Quote:
Originally Posted by cpcohen1945
Yes, but imagine a circle with centre in the middle of the blade with radius Z (Z to the spine and Z to the edge).
Now, if we place this imaginary circle around the blade and now imagine that it is a disc of height A, we can work out the volume of this encompassing disc as follows:
Volume = area X height
Area of a circle is Pi X (radius squared), which is, in our case,
Pi x Z x Z
So the Volume must be
PiZZA!
Ergo, when thinking of the best angle for a razor, it is best to have a pizza.
Math don't lie.
James.
Should the pizza be 3.5 x as wide as it's crust?
Whilst poking around a couple of weeks ago, I had read that Hart Steel uses a 14.2 degree angle so that it is a 15 degree when using tape. But for the life of me I can't seem to find that on their website. Maybe it was here. Maybe it was something I had fabricated in my own mind:shrug:
When the Harts were introduced some of the cognoscenti groused about the thickness of spine to width of blade aspect ratio. They noted that the included angle was 13 and change degrees: too thin, too thin they said and unsharpenable with that delicate O1 steel - all of which makes one wonder how the razor makers were able to get such good edges on them.
I think they look just fine and shave very well.
:beer2:
need to add that so far in my testing that SS razors like a bit more angle then there carbon brothers
I doubt manufacturers actually measured the angle… but throughout the history of making razors, most (if not all) manufacturers adhered to the proportion of the blade about 3.5 times the thickness of the spine.
So for example: 4/8th would be bit over 1/8th inch spine, 5/8th would be 3/16th inch spine, 6/8th razor would be a bit under ¼ inch spine, 7/8th to 8/8th razor would be about ¼ inch or more spine thickness.
I agree with Smythe here. When I make razors I like to stick to these guidelines. most of my razors are 1/4 spine and 8/8 blade. I have found that even a little thinner on the spine makes honing difficult and a couple layers of tape are needed to beef up the spine.
These guys are giving you some good info
Bob @ OCD Razors
So, if I've got a Bill Coffey custom straight that has a blade that is 24mm from spine to cutting edge and had a spine that is 3.2mm thick (7.5:1 ratio), is that out of proportion? If so, that would explain why I haven't been able to hone the damned thing to a shaveable edge.
It sounds as if I need a few layers of tape to get the spine up to around 7mm.
Arrrh, it's been so frustrating trying to get a shaveable edge on it.
Actually, the measurement should be from the lower edge of the honing flat to the edge, not the top of the spine. Notwithstanding that, it sounds like you razor has a very narrow included angle (maybe 8 degrees?).Quote:
Originally Posted by johnmrson
I'll defer to our more mathematically gifted members for confirmation. FYI, there are a couple very long threads about this very topic that go into great detail.
OK, that still makes it 19.5mm to 3.2 mm or a ratio of 6 times. That's still way out of the 3.5 times.
The first run of Hart's were 14.2 degrees. That worked great if manufacturing tolerances were kept tight. If the blades got much wider than 3/4" the angle would be too acute and edge holding would suffer.Quote:
Originally Posted by KingsRam
The current Harts are 16 degrees. That way if a blade is a little too wide, the included angle doesn't go below about 15 degrees.