Hand Sanding Questions

Col Defender

Col Defender

Joined
Nov 11, 2011
Messages
1,398
I watched Nick Wheeler's amazing video Sanding 101 today - twice. I am trying to see how much of his technique I can apply to what I do, given my lack of experience and minimal tool availability. I use a Sears 2x42 single speed belt sander and so far my knives are all convexed for two reasons. First it is all I really know how to do and am still learning that technique and second, when I have tried to use the platen and flat grind a blade it just bounces around and put dings in the blade. This may be a technique problem on my part, a limitation on the capability of my sander, or some of both. For now, I use the sander in the vertical position with the platen removed and do reasonably well on convexing.

So - the questions:

1. Should the hand sanding be done before or after heat treating? (I'm using 1084 if that makes a difference.)

2. Can I hand sand the convexed blade like Nick does if I just gently rock the steel or board on which the sandpaper is glued so it follows the contour of the blade?

Thanks to anyone who can give me some guidance here as I have a few blades (convexed to 600 grit on the belt sander) which are ready to be heat treated. UNLESS I LEARN I NEED TO HAND SAND THEM BEFORE THE HEAT TREATING.

sTEVE
 
A lot of guys grind the blades to 400 grit, and sand the vertical grinder marks out with 400/600 grit sandpaper, well...at least I do, then it goes to Ht and that is where the sanding really starts. A nice 600 grit finish, with ALL the previous grit marks taken out, looks great. But as you know, you can take it all the way up the scale. So question 1: yes, sand out the vertical grinder marks, and yes, the bulk of the sanding is done after HT.

As for question 2. Sure, that should work, but I'd use a light touch. I fix the blade to a board, then use my sandpaper with a hard leather pad. Hope some of this helps.
 
I mounted a glass platen between the contactwheels to get good flat grinds.
But if you have convex blades and want to hand sand them I'd make a sandingstick with a rubber on it so it forms to the convex you have
 
I have found that for a convex ground blade .25" plexiglass works well as a sanding stick. It is stiff but will curve to match the convex surface better.
 
Glass platen makes a world of difference on the 2x42. I flat ground about 150 knives with mine before I built a NWG. To answer your original question, I usually only go to 320 or so on the machine before HT, then to 400 on the machine afterward, then hand sand with 400.
 
Most of my knives are convex to some degree. I attach the sandpaper to a steel bar about 12" long, 1/4" thick, and 1" wide. I watch very carefully to see when the previous sanding marks disappear, and adjust my angle of attack to hit the areas that need it. You will quickly develop a feel for slightly changing the angle of sanding to hit different parts of the blade (spine, middle, edge), there is really no need for a padded backing. The nice thing about sanding a convex blade is you only have to hit the areas that still show the sanding marks from the previous grit instead of the whole width of the blade, which in my opinion is a huge time saver over sanding a perfectly flat blade. I rarely go over 220 grit before heat-treatment as I want to thin the edge down a good bit afterwards, so anything over 220 grit pre-HT would be a waste of time.
 
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