While on a long bus ride across coastal Uruguay, I got to thinking again about the problem of using my jig with water stones or oil stones. An earlier, very elaborate solution, did not work.

My jig must slide on a flat smooth surface in the plane of the surface of the stone. The problem is to produce this surface. The solution turned out to be quite simple: build a vice with one wide, smooth jaw. Put the stone in the vice, with the surface of the stone level with the wide, smooth jaw.

Well, I have made four versions of the vice now, slowly improving the design. This pages shows the jigs in the order they were built.

Contents

• Versions I have built:
  1. Version 1 - wood, one stone. The prototype, made of Ash, had all the features, but got very dirty when used with water stones. Do people wear hazmat suits when using water stones?
  2. Version 2 - plexiglass, one stone. This gets me close to the Tom Swift class. Worked well, but it turns out wood does not slide that well on plexiglas. This is not a problem when doing a primary bevel, but when I wanted to use the slips for the microbevels, the jig kept slipping off the slips.
  3. Version 3 - three stone, wood. Maple this time, rather than Ash, aiming for the slipperiest surface possible. The wide face was finished with Tung Oil, then waxed.
  4. Version 4 - one stone, wood, glass faced. This version is much longer - long enough to allow me to use the full length of a 12" bench stone, with an appropriate jig. The appropriate jig is pictured.
• Versions others have built.
  1. George Daiber has added a couple of refinements in his aluminum version of the stone vice that are well worth considering.
• Sketchup drawings. I have recently started using Google SketchUp to draw the various jigs I designed and built. The new Jig Geometry page includes sketchup models of a couple of tool holding jigs as well as models of a triple stone, glass surfaced stone vice.
• Design parameters What you need to know to make a stone vice.
• Error Analysis

Version 1

Top view of the stone vice holding a small hard Arkansas stone. You can tell from the length of the threaded rod that it will handle stones up to about 9" long. That is a Hock iron in one of my jigs resting on the wide side of the stone vice.
Side view. The vice is taller than it has to be. I have one very thick water stone, so I made the jig pretty tall. The plane iron jig could be taller, allowing you to make use of more of the wide vice face and thus more of the stone.
The end view, with detail of the sawn slots for the threaded rod. The washers beneath the nuts are inset a bit into the end of the vice, helping to keep the rods from moving up and down in the slots during tightening.

Using the Stone Vice

Check that the stone and wide face form a flat surface using a long straight edge. Assuming a 5" wide vice face and an 8" long stone, then an error of 1/32" (straight edge high or low) at the vice-stone junction corresponds to an error of .22 degrees, which is acceptable. Flat is best.

An error means that either the front support is not square to the top, or the stone ends are not square. The second problem is hard to correct with this design, but does not arise in the Version 3 design because the stones rest on wooden blocks.

The vice appears to be able to easily hold the stone well enough for sharpening with only finger tight pressure on the wing nuts.

With my particular hardware, turning the wing nuts turns the threaded rod inside the nuts on this end, but it still gets the job done. You might want to use wing nuts on both ends.

Experience

Version 2

The top view of the stone vice. The wide jaw is about 6" front to back, 8" across. The narrow jaw is 1" thick - laminated 4 1/8" thick pieces. This stone is less than 2" wide - unsuitable for plane irons in my opinion. A 3" wide stone is one the way (not here June 7, 2004).

This side view shows that the vertical pieces have only one section that actually touches the table top. The thickness is only necessary to prevent bending as you tighten the thumbscrews, not for support. With only one supporting piece it is much easier to joint to width. While you can plane Plexiglas, a 1" wide section is not that much fun. The plane iron is not at the correct extension for a primary bevel angle of 25 degrees. The jig is 2-1/2" tall under the blade, so the correct extension is just over 5-1/2". The plane iron edge is then over 6" from the bottom front of the jig, allowing use of a good part of the stone.

Version 3

First, the vice does not grip the stones, but pieces of wood just a bit longer than the stones, called stone supports here to distinguish them from the vertical parts of the vice, which are called simply supports. This removes any danger of breaking thin stones.

Second, because the vice grips the stone supports rather than the stones, it is no problem to hold several stones at the same time. This is a big advantage since there is no set up time between stones - all the oil stones are available all the time. In fact, you need only set up the version 3 stone vice once. When you are done, lift the stones off and put them away. Next time just put the stones back in the same place and you are ready to sharpen.

Side view. Notice the stone thickness - just 1/2". The wooden supports are just a bit longer than the longest stone. The threaded rod runs between the supports, at about half way vertically to balance the pressure. If you had stones of different thicknesses, you would vary the position of these rods. As before, set up is done with the stone vice up side down on a smooth surface. First place the stones between the rods, then the place the wooden stone supports on the stones, then tighten the screws. Since the stones are not held tightly by the stone vice, you have to be careful when you turn the stone vice over. In this version, the rods only go through the front of the wide jaw. This means not only shorter rods, but it also means that tightening the wing nuts does not put any tension on the wide face, and hence does not bend it.

Top View The top stone is a Norton medium India, the lower stone is a Norton translucent Arkansas. The third slot could be filled with another stone, or with a strop. You could strop with a smooth piece of wood - in my earlier stopping tests I used a piece of Maple. You could also glue a piece of leather to a piece of wood. In either case, since the surface of the strop is level with the surface of the wide vice face, you can strop using the stone vice, treating the strop as any other honing surface -- except you only pull the blade along a leather strop.

Setup

1. place the stone vice face down on a flat surface,
2. put the stones between the rods,
3. put the stone supports on top of the stones,
4. tighten the wingnuts to bring equal tension on all of the stone supports,
5. lift the stone vice with captured stone supports off the stones and place it face up on a flat surface,
6. put the stones back onto their stone supports,
7. check the stones and wide vice jaw for flatness.

Version 4

The problem does not arise when using a wooden jig and wooden slips on glass. It happens, by chance rather than design, that there is less friction between wood and glass than between wood and wood. So the jig stayed on the slips when honing on glass and I did not notice the potential problem.

I glued the glass to the wooden vice using the same glue I used to glue the glass to the backing boards for honing - Weldbond. See that link for a full how-to on gluing glass to wood.

Although I use this stone vice mostly for grinding primary bevels (so don't often use slips on it), I still decided to glue on a glass surface. The reduction in sliding friction is worth the extra effort. I put glass on both faces - it seemed to be no harder than just putting it on the long face, and dimensioning the shorter face to match. I used 6mm glass. Thinner glass would probably work just as well.

Note It is a little hard to see in the picture, but the stone is not actually gripped by the vice. In fact, it is resting on a piece of wood (a support) that is gripped by the vice. The support is about 1/16" longer than the stone, so the stone can be lifted out and switched end-for-end, or flipped over. The tension rod placement, the support thickness, and the stone thickness must all be taken into account so the that support is between the tension rods (not above or below) in use.

This vice holds only 1 stone. I found that I was always using the 3 wide vice with a single stone, so made the new vice 1 wide.

I used Version 4 when doing the second round of bench stone tests and it worked really well.

Sketchup Model of V4

This is a sketchup model of the version 4 jig, with dimensions.

The build order may be important. Make the vertical pieces first and drill two of them for the threaded rod before glue up. The holes should be aligned so that the threaded rod is about in the middle of the stone support board. The stone support board is a little longer than your longest stone.

If the threaded rod is too near the top or the bottom of the the stone support board, the jig will rack. Making the stone support board thick will mean the jig will handle a greater variety of stone thicknesses. Remember that there will be glass on the entire upper surface, so take the glass thickness into consideration when positioning the threaded rod holes.

Once the supports are finished, glue the wide piece between the two verticals, glue on the glass pieces and assemble.

George Daiber

The vice is aluminum except for the sliding surface, which is glass faced. George elevates the abrasive surface above the sliding surface and uses a matching elevation on the jig. He rests the jig on plastic slider to compensate for the raised abrasive. This allows him to use smaller back bevel angles.

The interesting innovations are related to the way the rods fit into the jaws and the shape of the stone support plate.

• Rather than run the threaded rod through holes in the jaws, George uses slots. This means that the threaded rods move with the plate. This allows the vice to handle a much wider range of stone thicknesses without racking. With my design, if the stone is too thick or too thin the jaws rack - throwing the vice out of flat. This design won't have that problem.
• For the movable rod mechanism to work best you must keep the rods in the middle of the support plate. George does this with slots in the side of the plate. There can be no racking. A slot is not essential - a rabbit would do.

• The third innovation is the shape of the ends of the plate. George uses water stones and water stones wear. Who knew! It turns out that when you flatten a water stone you may end up with a stone that is flat, but a stone that is tapered!

  If the plate has square ends this is a problem - the plate tries to be square to the jaws. This pulls the stone vice out of true, so it won't sit flat on the table. (Trust me to design a jig that makes water stones look bad!)

  If the plate has rounded ends it can accommodate the taper in the water stone. It can probably handle both lengthwise taper and side to side taper if there is a little play for the threaded rod in the slots.

  I have not seen a plate with round ends in action but will try it out for myself some day. Perhaps soon. For water stone users, this may be crucial!

• George originally found my site after being frustrated sharpening a bevel up plane. George now uses back bevels on all his plane irons.

Design Parameters

Error Analysis

If, for whatever reason, the stone surface is out of flat with the wide vice face, then honing will produce a rounded, rather than a flat, microbevel.

When the iron rests on the near end of the stone, there is a 1 degree error in the angle. When the iron rests on the far end of the stone, there is again a 1 degree error.

However, when the plane iron is half way between the two extreme positions the error is not 1 degree. It turns out that at the midpoint of the jig's travel, the angle at the edge is an extra 1/2 degrees (half of the amount of the error). So, over each jig motion the angle at the edge varies from 30 degrees, up to 30.5 degrees, and back to 30 degrees.

This means that only at the midpoint of the jig motion, when the angle at the edge is greatest, are you actually honing the edge. The rest of the time you are honing at a slightly lower angle, so you are honing a bit back from the edge.

The result is a rounded microbevel, not a flat microbevel. When you look at the iron to check for the presence and width of the microbevel, you do not see a single reflecting surface. Instead, since the microbevel is rounded, there is no angle at which it reflects the light particularly well. It looks like no microbevel is being formed.

I suspect that even the best hand honing produces this type of microbevel. Most people will vary the height of the back of the blade by more than 1 degree (which corresponds to lifting the back of a 7" long plane iron by about 1/8"). The result is a rounded microbevel.

Fortunately, if you build the stone vice so that all the legs are of equal height, the stone face will be flat with the vice face.

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