How to measure existing angle on thin knifes with groves in angle master

[John Thunderbir]

Manual states that on thin knifes, where bevel small and is too hard to set angle master to, set angle master to blade and half the bevel angle you desire. So with his thin knife, how do you measure existing edge angle with angle master groves. With this type of thin knife, the groves are measuring the blade not the bevel, no?
Thanks

[Ken S]

Welcome to the forum, John.

You ask a very good question. A standard, old favorite answer is to mark the bevel with a black marker. With the knife in the jig and the jig in place on the universal support (eyeball an approximate setting), rotate the grinding wheel about an inch by hand. Then lift the jig off the universal support and look at the bevel. Adjust the universal support with the micro adjust until the grinding wheel has removed the black market in the middle of the bevel. This is covered in the handbook under "replicating an existing angle". (different tool, same technique)

Ken

[Jan]

Welcome to the forum, John. 

It is difficult to measure the edge angle of a thin knife where the bevel is narrow *. The notches of the Anglemaster can be used when the bevel height is greater than circa 1 mm, which is often not the case for thin knives.

Ken has wisely advised you to replicate an existing edge angle using the marker method. For knifes thinner than 2 mm you have to adjust the USB for each side individually, because the knife jig works symmetrically for knives with blade thicknesses between 2 and 3 mm.

Tormek handbook on page 55 describes how to set an edge angle for a thin knife. You can start with an edge angle of 30° and you will see how the knife performs. In this case the angle setter should be set to 15°.

Good luck! 

Jan

*P.S.: In a topic: "Laser device for edge angle determination" I described my homemade laser goniometer. http://forum.tormek.com/index.php?topic=3104.0
But even with this device it is challenging to measure the edge angle of thin knives with narrow bevels. 

[John Thunderbir]

Thanks for the reply Ken and Jan. I will just ignore the groves on the angle master for my knives. A note stating the groves in the angle master are not to be used for knives might be an idea Tormek could consider. Thanks again. John

[Herman Trivilino]

Thanks for the reply Ken and Jan. I will just ignore the groves on the angle master for my knives. A note stating the groves in the angle master are not to be used for knives might be an idea Tormek could consider. Thanks again. John

There is nothing inherently wrong with using the notches on the Angle Master to measure a knife's edge angle. With good light, and perhaps also magnification, it can be done even for thin knives.

Matching the existing edge angle may not be all that important. If the knife has been previously sharpened, it's not likely that there's a consistent edge angle all along the blade, and even if there is, it may not match the original. One thing that's nice about the Tormek is that you have the precision and accuracy to choose your own edge angle. Whatever suits you best for your given purpose.

Recommended edge angles are just guidelines and need to be adjusted anyway for steel type and intended use. You might think that knife manufacturers take all this into account when they sharpen at the factory, but examination with good light and magnification reveals that in many cases the angle varies along the length and the bevel polish is not uniform.