Bevels with file jig help

[Josh Conder]

I have done several thinner blades (.125) on this jig with no issues, but this is the first time doing something a little thicker (supposed to be.156 but it’s more like .165) and I am having issues getting the jig to take off material at the same rate on the last 1/2” of the blade. Trying to figure out why this is before I get to my scribe line everywhere but the tip. The only thing I have done differently is going for an angled plunge line so the blade is all the way to the left of the jig with the tip being in the center. Could this be the issue?

 

[O.L.C.]

I have had some issue with this too. Maybe not the right thing to do, but I swing the tip out towards you a little. The only thing I can think of is that the as you bring the file around the curve of the blade it doesn't cut in the same. Like when you use a belt grinder you move the knife with the curve of the blade.

 

[kuraki]

Yes. What OLC said. Think about it, the surface you're working on is a different distance from the guide pedestal. Swinging the tip out towards you will get you closer to the same distance and therefore the same relative depth/height/angle.

 

[kuraki]

To illustrate the issue, here's a mock up.

When you're doing the straight portion of the blade:


I have it constrained to follow that edge. That's your bevel angle, and while it does change slightly as you move radially relative to the center of the pedestal of the guide, the significant change you're having trouble with is this:



Constrained to the straight edge and moving over the tip, you see this gap appear. You maybe don't notice this when filing, because your guide isn't constrained like the model, and the file just moves down to close that gap.

What happens to a right triangle when you shorten one of the sides? The angles of triangle change.

 

[AVigil]

measure the distance from your pivot to the edge, then move the tip to about the same distance from the pivot.

Go slow with the file see if any adjustment to be made.

 

[Josh Conder]

Thanks guys. I am going to make some adjustments here shortly and see how it goes. I did make sure that the file was contacting the full length of the bevel and not hitting the jig though.

 

[kuraki]

Thanks guys. I am going to make some adjustments here shortly and see how it goes. I did make sure that the file was contacting the full length of the bevel and not hitting the jig though.

That's good? No one thinks that's causing your problem. It's just geometry.

 

[Josh Conder]

Ah ok I thought that was what was being shown in the last illustrated drawing.

 

[AVigil]

GEOMETRY

Once you realize the distance at the tip and at the flat edge are not the same you will see why you have the problem

 

[kuraki]

 

[Josh Conder]

GEOMETRY

Once you realize the distance at the tip and at the flat edge are not the same you will see why you have the problem

I have made the adjustment where the tip and the edge are at the same distance from the pivot point. The only problem is at that angle the plung line is going towards the handle.
https://imgur.com/a/Rk57HCU

 

[KnuckleDownKnives]

I have made the adjustment where the tip and the edge are at the same distance from the pivot point. The only problem is at that angle the plung line is going towards the handle.

You're not going to be able to file the entire length and tip at the same time and have a consistent bevel. you're going to need to change positions filing the flat some then the tip to catch up, then the flat and vise versa. Make sure you have a center line on the edge and since you have a line for the bevel just keep filing and changing to keep it consistent. That's one of the downfalls to doing it like this. You cant do it in one step and keep the geometry correct.

 

[kuraki]

You're not going to be able to do everything in 1 single setup to get the end result you want. Scribe out what you want the grind to look like, set up to file the plunge and straight edge. Take it to the scribe line. Then reposition to do the tip and take it to your scribed line.

 

[Josh Conder]

Ahh ok. Thanks for the help guys. I apologize for my ignorance I’ve always enjoyed working with my hands, but I’m a noob at this.

 

[AVigil]

what they said

 

[Natlek]

I have done several thinner blades (.125) on this jig with no issues, but this is the first time doing something a little thicker (supposed to be.156 but it’s more like .165) and I am having issues getting the jig to take off material at the same rate on the last 1/2” of the blade. Trying to figure out why this is before I get to my scribe line everywhere but the tip. The only thing I have done differently is going for an angled plunge line so the blade is all the way to the left of the jig with the tip being in the center. Could this be the issue?

Fix blank in a normal position, grind the bevel .After that /last/ you can file plunge line in any angle you want .I don t like that jig .............file catch the edge of wood ,that's part of the problem .I would mount another one wood board where you fix knife ....... shorter one .Now it is to low for comfortable filing ............Why you fixed blade that deep on jig ? Fixed it like this
Something like this ..........