I posted this on Fit and Finish, but thought I'd put it here too.

I know various forms of this discussion have gone around before, but I have been noticing some "new" things.

Once I get to 220 grit on a platen, the joint of the belt is higher than the grit and so is very bumpy and cuts ladder pattern type grooves into my blades. Any one else? Ideas? Solutions?

The higher the grit, (on a platen) the lower the control. True or just my imagination?

Finally, I seem to have gotten mostly over the two inch mark, but am still bothered by his little brother. I am thicker at my plunge cuts and start to thin out after a couple of inches. The transition is smooth and flat, hence no two inch mark. But, when I got to sharpen on the belt grinder, I get a dished out part where the blade is thinner. Any one else? Any ideas?

Those of you who do a lot of hand finishing (Terry Primos mentioned this), when and with what do you start? Do you file everything in, or go to hand finishing after 60 grit, etc.?

I know this is long. Thanks for your patience.

John Frankl

If your getting that "joint jump" out of your belts, I'd say it's time to seek out a higher quality belt. Sometimes the platen set up on a grinder will be a partial cause, but most often it is splices that are not as good as they should be on the belts.
As for me, I grind in the following sequence.....
-50 grit
-120
-220
-400
-600
Usually be the time I reach 400 the edge is sharp. (the 600 is used more to reduce hand sanding than anything) Then it's on the bench where the blade is hand sanded with 400 until ALL the grinder scatches are removed. Then the same is accomplished with 600 until all the 400 grit scratches are gone. I etch nearly everthing I do, so from the 600 hand finish, the blades get an etch in ferric chloride.
The trick to this grinding thing is to keep an even thickness throughout the grinding process, from heavy all the way down to fine belts. If there is an area on the blade that tends to remain thicker, then work more on that area until the thickness is even for the length of the blade. Do this with each successive grit belt, and you will find that things will fall into place.
Many folks don't want to take the time to do the proper hand sanding, opting instead to attempt to finish out all the way on the belt. Take a look at the higher end blades/knives, there is a reason that they are high end. The maker has put in a great deal of time and effort on the finish. I personally think that there is no substitute for the look and finish that hand sanding obtains. I suppose the best way to describe it is you can see the "soul" of the knife. It's just that little something extra that draws you to it, and offers a warm glow and/or feel.

a platen cushon will also help on grit size down to 1200 grit or better with good belts like 3m 307ea cheap belts give cheap performance, good belts pay for them selves in a lot of ways
Gib
www.cactusforge.com (http://www.cactusforge.com)

thanks for the replies.

I try to avoid cheap belts as well. The 220 in question is a Klingspor J-flex. Any suggestions for replacing this with something better?

John

I'm a big Klingspoor belt user. I've never had the problem you mention with their 220s. Let's take a closer look at things to see if we can determine why it's happening in your case.
1. What type of grinder?
2. What type/material is the platen
3. Are the ends of the platen squared or rounded? (top and bottom ends where the belt comes onto and leave the palten)
4. Does the belt ride on the platen during operation, or slightly away from the platen?

We'll figure this one out!

I had this problum when I started out to, Bob Engleth in formed me one day to use two platens one bare for roughing and one with a cushon to finish with any belt under 220x no more trouble.
Gib

What kind of cushion do you use?

I also have a problem with belts jumping at the splice. I use a high temperature glass platen; while it's very flat and gives a good flat surface, it does jump when the splice passes over it.

I use a cushon that I get from K&G knife finishing supplies.
It is a belt that one side is filled with grafite and cemented to the platen with 3M contact cement, when worn just pull it off and put on another works great Gib

I feel your pain John. My observation is that as my own skill in grinding increases, so does the belt grit that I can use with acceptable control. My belts knock and slap a bit too as the seam comes around, but it doesnt seem to bother me. I dont finish up too fine before HT (120), and after HT often knock the black off by hand using a 180 on a leather covered block before going back to the grinder to take that last bit off with a fresh 120 belt. Thats about all I do before I go to hand sanding. I consider a Hardening successful if I am able to get a glass hard blade with out significant scaling. A clean blade out of the hardening quench helps tremendously in subsequent steps. Plus indicates to me Ididnt over heat in the hardening. Some folks use a borax wash etc. but I simply dip the blade (at a black heat) in the quench tank as I take it through its normalizing routine. The oil leaves a soft layer of carbon on the blade that comes right off and seems to protect against scaling. Come to think of it, the STYLE of blade you are making has a lot to do with what is appropriate, useful and good. The etching helps a lot. hard toi describe but it really adds something.

Ed, You gave me some good questions. I will try to answer.

1. What type of grinder?

Bader BM2. Springs are weak and tracking is less that ideal.

2. What type/material is the platen?

On one it is whatever the factory suppies. Mild steel perhaps.
On another there is a fully hardened piece of D2 attached.

3. Are the ends of the platen squared or rounded? (top and bottom ends where the belt comes onto and leave the palten)

I'll have to check. The D2 ones seem rounded from wear. But I don't know if it was rounded originally.

4. Does the belt ride on the platen during operation, or slightly away from the platen?

Seems to be on platen, but who knows. The weak springs and tracking may mean it is slightly off. I'll check.

Thanks,

John