Chris Schwarz's Blog

Resharpening a Scraper Plane

Question: I’ve noted that you’ve recently mentioned that you’ve been looking into scrapers, so I thought that maybe you could answer a question that I have about scraper-plane blades.
 
Recently I acquired a Stanley #12 scraper plane and the three Lie-Nielsen scraper planes (modern versions of the Stanley #112, #85, and #212).  I am in the process of preparing and using these scraper planes to smooth the surfaces of the blanket chest that I made at Chris Gochnour’s Marc Adams School of Woodworking course.  I intend to thereby avoid sanding.
 
I intend to paint the chest (which is made of poplar) following the methods given in the painting article in the recent issue of Woodworking Magazine.
 
I am preparing the scraper-plane blades just as I would plane blades: both back and bevel, five DMT plates of grits from 120 to 1,200 followed by four Shapton water stones of grits from 2,000 to 16,0000.  The burnishing of the 45Ã?° bevels to produce a burr is being done with a Glen-Drake burnisher following the method of David Charlesworth (which is similar to the method given by Garrett Hack).
 
It is my understanding that when a scraper plane ceases to proceed shavings and starts to produce “sawdust” that I must go back to honing and redo the burnishing to produce a new burr.
 
Here is my question: How far back must I go in the honing sequence?
 
Certainly I need not go back to the DMT plates.  But, do I need to go back to the 2,000 grit Shapton water stone?  And, can I get away with only re-honing the bevel, or must I re-hone both the back and the bevel?
 
If you are able to help me understand how to do the refurbishing of defunct scraper-plane burrs I would greatly appreciate it.
  
- Dave Raeside

Answer: I have indeed been doing a lot of work on their care and feeding this year. In brief, they are like any other edge tool. All the same rules apply. The burr is strongest when it is turned from the intersection of two highly polished planes.

And so resharpening of scrapers involves exactly the same regimen as it would for a plane or chisel.

1. If the edge is only slightly degraded, I’ll begin with a polishing stone (8,000) and then turn the burr.

2. If the edge is mostly used up but still unchipped, I’ll begin with the 1,000, then polish, then turn the burr.

3. If the edge is chipped or otherwise damaged, I drop back to the diamond stones, grinder or other grinding abrasives. Then the 1,000, 8,000 and burnisher.

What I don’t do much of, is to try to resharpen with burnishing alone. My results have always been inconsistent. Occasionally it works. Usually I get a burr that is OK in some places and weak in others. Other times I get nothing but a trip back to the grinder.

I hope this helps more than it muddles….

- Christopher Schwarz

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