From: hsc@sybase.com (Howard Cohen)
Newsgroups: rec.woodworking
Subject: Re: need help using a scraper
Date: 13 Oct 92 20:25:28 GMT
Distribution: na
Organization: Sybase, Inc.

Bennett's description of the belt-sander method of preparing a scraper is
a good one.  I too was having a lot of problems getting a good edge on my
scraper, but then I discovered two very important things:

	- you won't get good results filing a straight edge on a scraper
	  unless you use a "mill file".

	- You won't get a good rolled edge unless you use a legitemate
	  burnishing tool, or a very hard piece of steel like a 3/8" drill
	  bit.

For a long time I tried to use a "file" to put a straight edge on the
scraper (before attempting to burnish it).  Well, all files are not the same.
There are woodworking files, and there are metal working files.  You don't
use one for the other purpose and expect it to work.  It doesn't work, and
its not surprising.

A mill file (I hope I'm using the right term here, my appologies if I'm 
using the wrong term) is a file with very fine teeth.  When I use a mill
file on a piece of metal, it feels as though I am pulling a violin bow
across a violin.  It has a drag, but does slide along.  If you look at the
metal being filed, it is clearly being removed, even though you aren't
using much force.  The trick is that the fine teeth do the work.  It doesn't
take a lot of work to put a square straight edge on the scraper (unless you
have curved the edge using the belt-sander technique, which Bennett did
mention could happen).

By contrast, a wood file has much larger teeth.  These work great for wood,
but are far too big for metal.  The big teeth slide over the metal and
don't do much good.  In fact, you may damage or *ruin* your woodworking file
if you use it on metal.  The danger is that the teeth can become rounded over.

Another thing about files, don't "pull them back and forth" across the work.
Files are meant to be used in one direction (OK, within say +/-45 degrees of
this one direction).  If they are designed to cut on the push, then don't
pull them across the work, you'll just bend the teeth over and ruin the file.

With woodworking files, it seems OK to push and pull, because the wood is
so much softer than the file, but over time, the teeth will be negativelu
affected.  With a metal working file, the negative effects happen much
sooner (depending upon the metal being filed).

This is why some people say that you can learn a lot about how experienced
someone is with metal working/wood working by watching them use a file.
As with all things, its possible to know a lot about one area and not much 
about another, so I don't place much credence in such quick assessments.

For burnishing, I tried to use different things I thought would work.  I
bought a "burnisher" at an art store.  It was for burnishing rub-on 
transfers, and was significantly softer than my scraper.  I finally broke
down and bout a $10 burnisher from a mail-order catalogue.  What an
incredible difference!

If you buy your scrapers from Woodcraft, they will send you a sheet of
instructions on how to sharpen them.

	Howard
-------------------------------------------------------------------------------
  Howard "I wood if I could" Cohen
  hsc@sybase.com  {pacbell,pyramid,sun,{uunet,ucbvax}!mtxinu}!sybase!hsc
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Newsgroups: rec.woodworking