Posted 09 March 2012 - 08:37 AM
Hi Johnathan,
My 2 cents about handfinishing...
First,It's important to have a couple of different types oflighting at
the bench where you'll do your hand sanding. One of them should be hologen
because that type will show scratches from the previous grit better than
other types. The second type may be either florescent,or incandescent.
I grind through 120 X and try to be certain that all coarser scratches are
gone,and that the edge is of uniform thickness, and the blade's straight.
For hand sanding,position the blade at a convenient height and angle so that
you can apply pressure. the full length of the blade should be supported. For
safety, the tip should not be protruding where you can be injured by it.
The first sanding block I use is a plunge block...a block of micarta with the long
edges rounded the same as the radius that the plunge cuts are to be. A sheet of 120X
sandpaper is drawn tight over the block and held by a yoke. each side of the blade is
worked on the block to insure that the plunge cuts mirror each other.
The next step is with a hand held micarta block about 9-10 inches long, and 1 X 1 3/4"
wide. The edges are slightly rounded to match the plunge cuts.
With a strip of 120 X paper wrapped around the block start sanding from plunge to
tip. Push the sanding block one direction forcefully, then draw it back lightly.
Never scrub,as this can cause abrasive to loosen from the paper and roll under the block
causing deep gouging....Also the change in direction can cause the trailing edge do dig
in as it becomed the lead edge...another source of blade ripples.
120X may be the most critical,as it lays the foundation for each step that
follows
I use WD 40 as a cutting fluid through all hand sanding steps. Other fluids work also.
Once the 120X step is complete, I go to 320X. All thepapers I use are Rynowet. Their
320X is aggresive enough that 120X to 320X isn;t as much of a jump as it may seem.
To be most cartain of getting each step is done well, check by turning the blade so that
light and dark are visible in reflection, the line where they come together will show
any scratches that still need to be addressed.
Each grit of paper should be used in a different direction than the previous one, A change
of 20 or so degrees will be enough. Don't go across the blade any more than absolutely
necessary.
For 320 and finer grits a 1" wide sanding bar will do the job faster and shouldn't cause unevenness
if your technique is consistant.
If my final grit is say 1500, I use that same grit with a leather covered block, then a rubber block
and the same grit...and a light touch. Sometimes spend an extra 20-30 minutes on this step, on
each side.
I hope this is of some use...I'll check back later..
Russ Andrews