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In the Shop => Knife Sharpening => Topic started by: Greybeard on January 17, 2022, 07:03:31 AM

Title: Knife jig offset another solution
Post by: Greybeard on January 17, 2022, 07:03:31 AM
I use the Triton style knife jig and as posted in earlier threads, this has zero offset and this is problematic on thicker blades.

A solution I am trying is to 3D print a collar that goes over the shaft that has basically a crescent shaped portion on one side of shaft, with thickness equal to blade thickness being held.
Example my prototype has a 2 mm thick crescent for 2 mm blades. This shifts effective jig centre line by 1 mm to centralise blade. The outside radius of crescent portion is same radius as shaft, so no issues with any tilting to sharpen tip of blade etc.

These images might assist.
Title: Re: Knife jig offset another solution
Post by: Greybeard on January 17, 2022, 07:10:44 AM
posted error- deleted
Title: Re: Knife jig offset another solution
Post by: cbwx34 on January 17, 2022, 02:26:30 PM
Looks like a good idea... jvh came up with something that is similar...

https://forum.tormek.com/index.php?topic=3918.0

Title: Re: Knife jig offset another solution
Post by: Greybeard on January 18, 2022, 08:26:39 AM
The eccentric bush you linked to is a really great idea. It might give minor variation on blade tips when tipping to sharpen the end?

The above spacer keeps same outside diameter for both "tipping" faces on the tool rest, and I can have multiple units for different blade thickness.
A 2 mm offset for 2mm blade etc, and being 3D printed, thought idea might suit some hobbyist without metal lathe. No dialing in required, just pick the thickness version as required.
Title: Re: Knife jig offset another solution
Post by: Perra on February 07, 2022, 09:59:56 PM
I'm been working with this problem also and come up with this solution.
I have tried to seek simplicity and not to destroy any existing characteristics. Everything on the jig works as usual.
The principle is to be able to use eccentricity to move the center of the shaft of the jig and thus center the knife holder after different knife thicknesses. Cut of the jig in appropriate place. Insert a 6.0 mm shaft pin that sits 2.0 mm out of the center of the shaft, which allows me to move the center of the jig 0 - 2.0 mm by turning the bracket. This allows me to center knives in the jig up to 3.1 mm out of the center (about 1.1 mm is available right from the start)It gives me the opportunity to center knives that are up to 6.2 mm in thickness. And also knives that are thinner than 2 mm. The process is simple. I put a knife in the jig, place as usual on the T8, measure both sides with the WM-200 and note the angles. Then turn the bracket until I get the same angular value on both sides. (Halves the angular difference) Lock with the locking screw. Insex M4. Maybe grind/lathe a small v-groove in the shaft also so the locking screw also locks axially. There will be a small side movement on the knife and there will be a (theoretical) angular error when tipping up the tip. But I can't see it's a practical problem! The next step is to measure and mark (draw in) positions on the two axes for different knife thicknesses, then you can theoretically center the jig in advance if you know the thickness of the knife where it is clamped. Rework requires some craft work but, on the other hand, costs almost nothing. Cutting, drilling, threading + one 6 mm pin (one M6 bolt goes well) and a locking screw M4 I did not press in the pin but threaded M6 and screwed it in.  I have not noticed that it weakened or in any way became unstable in the jig when grinding.  This is a possible jig solution for knifes with different thicknesses, maybe not for knives that have a tapered blade.
Title: Re: Knife jig offset another solution
Post by: Greybeard on February 13, 2022, 08:02:11 AM
Good idea- Similar way to get offset effect and fully adjustable.