[OP]
Contributor
I was finally able to set up my surface grinder to establish the primary bevel of a handplane blade. It produced a superb grind perfectly square with the sides. I'll continue to work on my skills applying the secondary and tertiary bevels by hand using the Rob Cosman method but I'll NEVER grind a primary bevel again by hand.
grinding 001.jpg
Member
I'm missing something, I keep seeing posts about primary, secondary, and tertiary bevels. Is someone selling snake oil or do I need to be educated?Originally Posted by Steve Mathews
ken
Member
BTW, that is an impressive looking contraption in the photo, does it put a camber on the cutter?
Member
But you'll have grinding swirls that you will have to hone out!
(In case anyone wants to duplicate this method, I have a surface grinder surplus to my plant, that has been taken out of service. Unit is a Brown & Sharp, with (I believe) 48" table travel (it is a large grinder), factory rebuilt less than a decade ago. I'll let it go for around $25,000 and toss in fixturing to duplicate Steve's set-up, PLUS a diamond wheel, FOB DuBois, PA (one of my Hyaters will load it on your truck).
PLEASE NOTE: this is good natured ribbing! I do have a surplus grinder if anyone wants it. I have had my machinists or toolmakers precision grind handplanes for me, and makes n old Bailey like a new LN
Last edited by Tony Zaffuto; 07-23-2020 at 7:21 PM.
If the thunder don't get you, the lightning will.
Contributor
Normally, I'd give you a hard time about such a set up, but as an owner of a Tormek I probably should not throw stones
I also never grind primary bevels by hand and haven't for about 2 decades. I suppose you could say it builds muscle memory and character, but to me it falls into the same category as thickness planing. Why break your back to do what a machine can do so much faster and better? There is only so much time and muscle available.
Secondary bevels are worth learning to do free hand, though; once you get good at them, they take about 30 seconds. I haven't heard of a tertiary bevel in woodworking.
[OP]
Contributor
I wouldn't mind being given a hard time as using a surface grinder seems like an overkill for the task of grinding a handplane blade. But also having a Bridgeport mill and metal lathe I enjoy using them for any purpose including supporting my woodworking efforts. After not being satisfied with the results of hollow grinding handplane primary bevels I wanted to accomplish the same task using a surface grinder. The only thing holding me back was proper work holding. The 2 position sine plate shown is also overkill but it's what I had. You may be surprised to know that I paid less for my surface grinder and sine plate than what you probably paid for your Tormek. Check out Rob Cosman's videos if want to know more about tertiary bevels.
Last edited by Steve Mathews; 07-23-2020 at 9:16 PM.
Contributor
Ken and Andrew, look for the “Bevels” thread currently active for a discussion of the three-bevel notion: basic grind (say, 25°, flat or hollow), secondary hone @800 or 1000 grit (I use 33° for standard chopping work, 28° or so for paring), and final polish on an 8000 stone (35°, or 30° for paring). You can go 7 or 8 resharpenings before the need to regrind.
Contributor
This like thought DejaVu. I am learning to grind square on bench grinder. While doing so, I imagined why bench grinder? Why not just use a surface grinder and get precise result.
Did a quick search on Craigslist, saw the prices, and then built a wood jig (that Derek suggested in another thread). I am now content with approximate angles.
Well some day!
[OP]
Contributor
Stay the course on your search for a surface grinder if you want one. They're available at reasonable prices if you're persistent.
Nice setup Steve. If I had that sort of thing available I would certainly take advantage of it. Not really in the cards for me. I have multiple irons and can't remember the last time I had to grind a primary. I guess I sharpen and touch up often enough that it just occurs as a matter of course. The next damaged iron or used plane restore I run into though, will have me dreaming of your setup ;-)
"A hen is only an egg's way of making another egg".
– Samuel Butler
Contributor
Something is eluding me… For me, when blade acquires a secondary bevel from freehand sharpening it is the main reason the blades is brought back to the grinder to reestablish a single flat bevel whether it is 15º or it is 30º. To me it is easier to have a single bevel to hold to the stone, hone and be done.
This method doesn't seem to take an inordinate amount of time. The edges on most of my blades seem to hold up well.
Cutting some 3/4" mortices with a recently purchased chisel has been more of a challenge to swing a mallet than the sharpening:
USN 3:4%22 Chisel Mortising.jpg
Finding a 3/4" pigsticker has been difficult so this had to do the job.
After honing to a 25º flat bevel this chisel cut a 4" long mortise 2-1/2" deep without needing to be sharpened. After the mortise was cut, it was back to slicing thin paper after only a few minutes of freehand honing on my oilstones.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
Member
Jim,
This multiple bevel thing has me cocking my head like a GSD pup. I think I've traced it to a Rob Cosman video. Whatever, there sure must have been a bunch of folks that watched that video.
ken
Contributor
It may even be older than Rob Cosman. Freehand sharpening can lead to a convex face on a flat bevel if care isn't taken during honing. This is where a coarse stone or abrasive sheet can be appreciated. In lieu of a coarser abrasive it is possible to lift the blade and hone a small area in order to return to work quicker.
It is like the ruler trick on the bevel.
With two bevel threads, (is a sharpening thread by any other name still so keen?) it is difficult to keep clear which is which.
Examining the scratch pattern on the bevel after every few strokes makes it possible to see where the stone is having an effect. This allows one to adjust their grip to evenly distribute the stone's work on the face of the bevel.
My softest Arkansas stones produce a satin like finish. The stones graded soft & hard Arkansas from Dan's Whetstones produce a reflective to mirror like finish. The Black Ark from Dan's produces a mirror to hazy grey finish.
Usually my blades, other than lathe tools, are not ground unless the bevel becomes convex or my freehand bias has given them too much skew. The blades having been ground the most in the past two decades have been ground three times or less. Most of my blades are still on the original grind from when they were first acquired.
My shovels are likely to be ground more than my woodworking tools and that is still at most every year or two.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
Contributor
FWIW, my great uncle taught me that using a secondary angle when polishing makes it faster. I'm not sure when he learned it, but I'm certain it was before youtube
It also depends on what I'm sharpening.
~mike
happy in my mud hut
Contributor
This holds true until the secondary bevel begets a tertiary bevel begetting a quaternary bevel begetting a quinary bevel and so on until one has to take the time to regrind.using a secondary angle when polishing makes it faster.
Yes, two or three strokes on a small edge is likely faster than five, ten or fifteen strokes on a full bevel. How many times can the smaller bevel be honed before it requires more care to stay on the small bevel?
Being able to walk up to stones on a bench taking a few passes over a couple stones is likely quicker than setting a blade in a holder, checking the angle, running it over a stone, removing it from the holder and getting back to work.
To each their own choice of what works for them, but remember, YMMV!!!.png
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
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