Plane Irons: hollow or flat grind?

[Narayan Nayar]

I'm relatively new to hand tools. I used to tell people that I'm "working my way up to hand tools". In the last year or so I have slowly gotten myself into handplanes.

I've never really gotten the hang of sharpening. I can do a decent enough job on my waterstones, but every once in a while I inspect someone's plane iron or rewatch my handplaning DVDs and notice significant differences in the polish of others' irons. Also, sharpening seems relatively effortless for some people. I am not one of those people.

I brought my #8 to a local woodworking store the other day and showed it to a few people who I know do very good handtool work. Their advice on sharpening varied, which I expected. Two people said that a hollow grind such as that made by a grinding wheel would help immensely with the time I spend sharpening. Another person said that flat bevels with a microbevel are actually better. A passerby said it really doesn't matter as far as planing is concerned, but that dealing with chips and changing angles is much easier on a powered system. He uses a lapsharp.

There's a no-sales-tax sale going on this weekend, so if I'm going to get one of these systems, I might as well do it tomorrow. That said, it really is an "if"--there's some part of me that doesn't want to retreat from stone sharpening exclusively, but if through such a tool I can spend more time working with my tools than ruining them with my pitiful excuse for a sharpening technique, I may well spring for it.

So, hollow or flat grind, Jet, Tormek, or Lapsharp? (I've read all posts regarding the systems--I'm really more interested in the hollow vs. flat, but if some of that has played into your powered sharpening system decision, I'd like to know about it).

Thanks in advance.

[Deirdre Saoirse Moen]

I have a Tormek and I love it. The hollow grind makes it faster to hone, with or without a microbevel. I really love a wet grinder; the Tormek is built sturdier than the Jet.

[Mike Henderson]

Unless you're going to do an awful lot with hand tools - which would mean a lot of sharpening, you really don't need a powered sharpening device. If you're having problems and don't have a jig, I'd recommend buying the Lee Valley MKII jig (not the powered device) and trying that before you shell out a lot of money on whatever powered device you choose.

A hollow grind can reduce your re-shaprpening time, but there's another way to do the same thing without a hollow grind - that is to use a microbevel.

If there's any way for you to get some professional instruction in sharpening, such as by taking a class at a community college, or attending one of the private classes that are available, I think you'll find that you really can sharpen with a few stones and get excellent results.

If you decide that a powered device is the way you want to go, you can sell the LV jig and the water stones on eBay and get most of your money back. And don't worry about the sale on this weekend - sales come round pretty regular.

Mike

[jonathan snyder]

I agree with Mike, Try the LV MKII jig. I thought I was sharpening challenged too. I just got the LV jig and some of their micro abrasive sheets and I am now putting an edge on my chisels and plane irons that I can shave with. I have been following the sharpening schedule in the recent FWW article. When the edge dulls, I can re-hone it in a minute or two.

Jonathan

[Narayan Nayar]

I just got that jig and started using it a few days ago. It certainly makes some things easier, though the first time I used it I didn't realize how hard the clamp had to be screwed down and before I knew it, I had an unintentional skew in the plane iron. Good thing it was my practice iron.

One of the guys at the local woodworking store said I could take a private lesson with any of the instructors. I might just do that...one of the reasons I wanted to get into hand planing in the first place was for surface preparation prior to finishing, and one of the instructors is supposedly very good at both.

Cheers, folks.

[Mark Rios]

I'll put in my vote for the (updated version) LV MKII as well. It almost makes the set-up a no-brainer. And perfectly repeatable as well.

Once the plane iron is ready to use, all you should need to do is touch it up every once in a while, depending on the use.

[Ian Gillis]

I like the hollow grind I get with an 8" grinder. I have a 6" and that's just too hollow for my taste. I added a 1" wide Aluminium Oxide wheel - the green/grey silicon carbide wheels that come with just heat up and glaze too quickly. I recently added a LV grinding guide, initially for my turning tools, but it has improved the bevels on my plane irons and chisels also.

Any day now I'm going to finish work on the treadle and toolrest for a 20" stone I bought at a yard sale (doing Tim Allen ape noises). Then I'll be the galootin'est guy east of the Rio Grande. I was already intending to do a review on my UR-Tormek, wif pics

[nic obie]

Any day now I'm going to finish work on the treadle and toolrest for a 20" stone I bought at a yard sale (doing Tim Allen ape noises). Then I'll be the galootin'est guy east of the Rio Grande. I was already intending to do a review on my UR-Tormek, wif pics

Pics,

we need pics.

[Clinton Findlay]

Flat or hollow grind -
My opinion is that there is no difference between the two.
Its more a matter of what you are using to achieve the grind. A beltsander, stone or scarysharp gets a flat grind, a wheel makes a hollow.
My preference is for the hollow grind, but I don't really care.

[Leif Hanson]

Here's something I wrote a while back on hollow grind vs. micro-bevels. I think the graphics are pretty self-explanatory... There's no appreciable difference between the two, when done properly - at least IMO. It's more a matter of what sharpening equipment you have on hand.

The Difference Between a Hollow Grind and a Micro-Bevel


Hollow Grind

A hollow grind simply refers to how the wheel cuts the bevel on the edge of the tool (this graphic is a bit exaggerated):

It's the same basic idea as a microbevel - but instead of creating an additional, smaller bevel, you are removing the bulk of the existing bevel by imparting a curve to the middle of it. The end result is basically the same - less material to hone off by hand at the stone.

Micro-Bevels

Here's a graphic of a microbevel:

Which method you use usually depends on what tools for sharpening you have available for shaping the initial bevel on the edge. I have a Tormek for shaping bevels, so hollow grinding is the norm (the same would be true for any vertical wheel grinder). Someone who uses a belt sander, LV Mark II, or LapSharp (or non-powered on stones or sandpaper on glass) would obviously choose the micro-bevel approach. Either way, a truly sharp edge come with honing, not shaping - for that I personally prefer oil stones.

I have used both methods - edge retention for each is the same, IME. The main difference you have experienced might be simply the angle the beveled edge is ground to. If the angle is too shallow, then the steel won't hold an edge well... Too steep of an angle, and the chisel is harder to push through the wood. Better steel in a chisel means it can hold an edge better at a shallow angle, which is the main difference between a premium chisel and a cheap one.

I shoot for 20 to 25 degrees for a paring chisel (no mallets!), 25 - 30 degrees for a bench chisel (light mallet use) and 30-35 degrees for a mortising chisel (heavy mallet use).

It's a good idea to be conservative on how much material you remove from any tool. Grinding a new edge on a tool should be performed only when absolutely necessary; keeping an edge sharp with regular maintenance will usually make re-grinding the edge un-necessary except after very long periods of use. More than that and you waste good metal, shortening the life of your chisel or gouge unnecessarily. They can wear quickly if over-sharpened.

Hope this was useful information.

[Narayan Nayar]

Leif--I have in fact seen that post of yours; I have archived under a topic called "sharpening". Thanks--the illustrations are really helpful in understanding the differences between the two concepts.