Video: How to centre a blade in the knife jig >>

Tormek knife jigs do not center the blade in the clamps. Because of that asymmetric bevels is a common issue.

This set of jigs is our solution to solve bevel asymmetry when grinding using the Tormek knife jigs.

Generally speaking, the jig is perfect for a blade which thickness at the spine is exactly twice the distance between the jig base plane and the jig centerline.

Where the blade is not centered in the jig, you get one bevel higher than other.

A thicker blade (i.e. where the blade centerline is above the jig centerline) results in a higher bevel on the base side.

Jig #1 - up to 3mm thick knives;

Jig #2 - for 3-4mm thick knives;

Jig #3 - for 4-5mm thick knives;

Jig #4 - for 5-7mm thick knives.

Jig #1

This is the Tormek Knife Jig SVM-45 as is. The Tormek Knife Jig SVM-45 has 1.054 mm offset from the centerline of the handle to the bottom of the knife clamp (the static part of the clamp).

Ideal for 2.1-2.2 mm knives, but well acceptable for 2-3 mm thick as well.

Knives thinner than 2.1 mm will get the top bevel higher, whereas knives thicker than 2.2 mm will get the base bevel higher; the further from the ideal thickness, the more noticeable is asymmetry of the bevels.

For knives 2 mm and thinner we use shims.

Measure thickness of the knife at the clamping spot, and divide by 2 - you get spacing to the centerline of the knife.

Difference between 1.1 mm and the halved blade thickness is filled with a shim.

Shim is placed on the bottom jaw (the static part of the clamp).

Example

Knife thickness 1.7mm, divided by 2 = 0.85mm.

1.1mm - 0.85mm = 0.25mm shim.

Jig #2

Obviously, for knives thicker than 2.2 mm you cannot put shims in the standard SVM-45 - for them we use the second jig where we milled away 0.5 mm from the static clamp (using an end mill).

Offset from the centerline of the handle to the bottom of this jig is 1.1mm + 0.5mm = 1.6mm

Ideal for 3.2 mm knives, but well acceptable for 3-4 mm thick as well.

Jig #3

The third jig has 1 mm milled off the static clamp.

Spacing from the centerline of the handle to the bottom of this jig is 1.1mm + 1mm = 2.1mm

Ideal for 4.2mm knives, but well acceptable for 4-5 mm thick as well.

Example

Knife thickness 3.9mm, divided by 2 = 1.95mm.

2.1mm - 1.95mm = 0.15mm shim.

Jig #4

The fourth jig is an adapted Triton Long Knife Jig with 3 mm milled off the static clamp. Triton jig has no offset.

Spacing from the centerline of the handle to the bottom of this jig is 3 mm.

Ideal for knives 6mm thick at the spine, but can be used for 5-7 mm thick as well.

Note that the Tormek long knife jig SVM-140 centers 3 mm blades, its offset to the centerline is 1.5 mm approx.

Instead of shims, you can simply put on where you clamp as many layers of a cloth tape, as needed to bring the spine of the blade to the "ideal" thickness for the jig.
E.g. if the knife spine at where you clamp has thickness 3mm, you use the jig #2 that has offset 1.6mm, and put 2-3 layers of cloth tape on the spine to bring its thickness to 3.2mm (the offset of 1.6mm x 2).