Another flat grind question

[Chiro75]

Now that I've got the hang of flat grinding (something that seemed impossible a month ago feels easy now... weird how that works) I have a question. As I put a distal taper into the knife, the point is obviously thinner than the area by the ricasso. Once I have my flat established and the distal taper in a nice place, then it's all a matter of thinning out the bevels. But, with a distal taper, I've basically created a wedge shape (look at the picture, which is highly exaggerated, but gets the point across). If I keep thinning the bevels and maintaining the taper, I'll never end up creating a uniform thickness in the knife. So, as I get closer to where I'll put the secondary edge bevel, the thickness of the edge is greater toward the ricasso and shallower toward the point. Do I leave it like that, heat treat, then just use the secondary bevel to clean that up, or am I doing something wrong? It's hard to explain in writing. The edge is thicker the closer you go to the ricasso. Is that how it should be, and the edghe bevel will simply be deeper at the ricasso and shallower at the point, or am I not tapering properly?

 

[blgoode]

You want something like this is what your shooting for.

 

[Chiro75]

Yeah, but how? To get that edge area evened up, that would mean no taper, but uniform thinness throughout the whole blade, no?

 

[BARRY JONES]

A distal taper is the taper from the guard heading out towards the point.

You should have a uniform thickness at the edge thruout the entire length of a flat ground blade, even with deep recurved blades. You can do that and get a distal taper, you just need to grind it in.

Me describing how to grind it right is very difficult. You will need to teach yourself how to properly twist your blade when grinding. The twisting is very minute. You'll feel it more than see it. The best way to learn it is by doing it. I taught myself how to do it.

 

[Chiro75]

I thought about having to twist the blade as I get closer to the ricasso, but then the knife isn't truly flat anymore, is it? That area would have a more angled grind than other parts of the blade. Or, are all "flat ground" blades really slightly compounded like that? I guess I may be getting hung up on the meaning of a flat grind!

 

[kenny]

chiro, you need to get the hang of this grinding so you can give me some lessons.

 

[Chiro75]

Kenny, as I've told you before, simply do nothing I do and everything I don't do and you'll have the best lesson ever! Drop me an email and maybe we can figure out some time to hang out. Did you get a grinder? I have a decent hang on flat grinding (despite this recent little tune-up I need to figure out) and a pretty good idea of convex grinding. I couldn't figure out flat grinding at all, and after about 5-6 attempts that turned into convex grinds, I all of a sudden "got it" and once you get a feel for it it's pretty easy to do it over and over again (on simple blade shapes).

 

[butcher_block]

i hold the angle of the blade and pivot while going to the tip not sure it its the right way or if it even helps might have some one take a picture or 2
to help explain what im talking about

 

[John Andrews]

Butcher block says it very well. I would think you would find it easier to flat grind than hollow grind. Maybe that's because I started out flat grinding, though. What kind of grinder are you using? That will have a lot to do with it.

 

[Chiro75]

Okay... this is hard to write about. In picture #1, I show, looking from above, how I move the blade right now when doing a flat grind. Starting at the ricasso, I grind and move the blade across the belt while also slightly bringing the ricasso area off the belt to establish a distal taper. Eventually the difference between the taper and the rest of the flat grind is so minute that it feels like I'm barely bringing the ricasso off the belt. But, throughout this I hold the angle of the blade constant, so the flat is in constant contact with the platen throughout, if that makes sense.

In the second picture, do I need to be compounding my motion so that I twist/rotate/modify the angle of the blade while I do this in such a way that the angle of the grind is steeper(creating a deeper cut) at the ricasso and a shallower angle at the point?

 

[Laredo7mm]

Now that I've got the hang of flat grinding (something that seemed impossible a month ago feels easy now... weird how that works)

So if you have gotten the hang of flat grinding, what is with all the questions?

I only know how to hollow grind, but I would assume it is similar on how to get the distal taper in the blade. The taper should naturally occur if your grind is straight and even because of the the profile of the blade. If your grind is consistant and even then the clip or tip will be ground thinner because they are not along the same line as the spine or edge.

For example if your blade is .125 thick and 1.0 wide and the tip is centered 0.5 from the edge and assuming a zero edge thickness coming off the grinder and the flat goes right to the spine:

The thickness of the blade at the spine of the tip is 0.0625 not 0.125. That is your ground in distal taper. The distal taper will only be where your knife profile geometry varies from the parallel lines of your spine and edge. So if you are grinding a straight razor where both lines remaing parallel, ther would be no taper.

Otherwise for a true full distal taper, I would think that the bevel would be compound angles.