Plunge height relative to blade thickness?

[arsenius]

Is there a rule of thumb regarding how high your plunge line can be relative to the thickness of the blade, before it starts getting washed out and blending in with the ricasso? In other words, if you want the ricasso and spine (the flats?) to be visually distinct from the top of the grind, is there a maximum grind height you should attempt? Or is this just a matter of not running into the spine/ricasso when sanding?

I guess this would probably be a matter of angle, and I did see this. Is there a minimum angle that should be maintained to keep those areas distinct?

I also saw this little knife tutorial by Nick Wheeler, 1/16" and full height grind. But I think some of the distinction on that knife's plunge is in part due to the sanding scratches being at 90 degree angles to each other.

By the way, I'll be using files and sandpaper. I haven't made a knife in about 10 years, but I remember there were a couple of knives I ended up not finishing because I was so disappointed with the way the ricasso got washed out towards the spine. It was disappointing to toss all that work from hand filing, but the blades were just so ugly to me that I didn't want to invest more time in finishing them. I can't remember how wide those old knives were, and don't want to make the same mistake again!

I've designed a knife that is a little under 1 inch wide, and was planning on using 1/8" stock, but not a full height grind. Maybe 3/4".

[tryppyr]

Generally speaking, the ability to keep the bevels distinct from the flats is a function of your skill with the files and the sanding blocks/jigs mus more than it is a function of the angles.

It's certainly easy to mess up the line, but it's just as easy to get it back. One way to keep it sharp is to put a very slight reverse bevel on the flats. This slightly increases the angle between the primary bevels and the flats, making it more distinctive. It also gives you a way to fine tune the position of the line of demarcation more effectively.

[Hengelo_77]

Drawfile and use a hard sanding block.
Don't wrap a whole strip of sandpaper around it, only the bit that is in use and move it up when it gets dull.
If you want the difference between the flat and bevel to be realy clear you can do a "two tone finish"
Say 1200 gritt of the flats and 400 on the bevel
(or whatever comes to mind)

[arsenius]

Thanks guys, I'll just try to to my best to keep it clean. I'm sure my skills have only improved during my layoff!

[daizee]

Agreed with Tryppyr, you can keep them distinct as long as your tools are rigid and you are patient.
The contrast will depend on blade height, grind height, AND blade thickness. Also, if you use a filing guide (for files or belts), you will probably end up with a steeper plunge. Using a hard, FLAT block for finish sanding is important. Wood is not a great sanding block, but if you use wood, use the hardest you can find.

-Daizee

[Hengelo_77]

Nick Wheeler did a very good and inspirational WIP on hand finishing not to long ago.
(that's where i got the 'not wrap all the paper around the block idea)
That should help you out

[arsenius]

Nick Wheeler did a very good and inspirational WIP on hand finishing not to long ago.
(that's where i got the 'not wrap all the paper around the block idea)
That should help you out

Thanks Hengelo. That was a good tutorial (so thanks Nick as well!). Here's a link in case anyone missed it.

I was planning on using micarta for my sanding block, but after watching Nick's tutorial, I'm going to look for something stiffer like a piece of mild steel.

Also, I found this thread. Using a sander is tempting, especially upside down where I could hold the knife against it and keep it flat. But it seems like it may also be asking for trouble, since more powerful tools help you screw up faster.

[Hengelo_77]

I use brass. (since I had it laying around)
I have all different shapes and sizes.
I found that after draw filing with a single cut file and making sure there are no bits of steel between the teeth (brass picker) you can start with gritt 180.
I doubt if a hand sanding machine is much faster. Don't forget the time it takes to set the machine up and change the paper.