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• Hepplewhite Stand #4: A Proper Edge

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Blog entry by Ron Aylor posted 12-18-2016 04:50 PM 1093 reads 0 times favorited 2 comments Add to Favorites Watch
« Part 3: Lay-Out & Rough-Cut Part 4 of • Hepplewhite Stand series Part 5: Mortises ... Finally! »

 
Before jumping into the mortise and tenon joints I thought it a good idea to make sure my chisels have a proper edge. For this project I need a 3/8 mortise chisel, a 1/2” firmer chisel for the half blind dovetails, and a 1-1/2” bevel edge chisel for the tapered legs.

A proper edge is actually quite simple. You need but two intersecting planes. Generally, the smaller the angle between the two planes, the sharper the edge and easier the cut. The smaller the angle, though, the less force it can take without folding over or blunting. Consequently, the harder the material you are going to cut, the greater the angle of the two intersecting planes needs to be. An edge for cutting both hardwoods and softwoods should be around 25-30 degrees. In my opinion some woodworkers obsess needlessly over angles and such. Close is good enough. The most important thing about getting a really sharp edge is that the intersecting planes must be as flat as possible and highly polished. If your edge isn’t polished like chrome, it isn’t sharp.
 

 
My sharpening station consists of diamond impregnated stones (course, medium, and fine), 1000 grit wet/dry sandpaper on glass, and a leather strop charged with chromium oxide. I use a honing guide to insure a constant angle while I work my way from left to right across the station, starting with the course diamond plate and ending up with the leather strop.

Sharpening by hand takes time and patience. Every time I being this process two motion pictures come to mind. First, The Shawshank Redemption starring Tim Robbins and Morgan Freeman. Freeman’s character Ellis Boyd “Red” Redding, the narrator of the film befriends Tim Robbins’ character, Andy Dufresne, a banker who is sentenced to life in Shawshank State Penitentiary for the murder of his wife and her lover, despite his claims of innocence. At one point in the film “Red” equates the arduous prison life to that of geology, ”… pressure
and time. That’s all it takes, really. Pressure and time.”
 .
 

 
It’s not until the end of the process that the second motion picture comes to mind … Radio, based on the true story of T. L. Hanna High School football coach Harold Jones, played by Ed Harris, and a mentally challenged young man, James Robert “Radio” Kennedy, played by Cuba Gooding Jr. Haunted by a childhood memory, Coach Jones befriends Radio, who eventually learns to read and receives a high school diploma. The scene that comes to mind is when Coach Jones and Radio are at the Christmas tree in the town square and Radio sees his reflection in a Christmas ornament saying, ”Big Radio in there … That’s a big Radio.”.
 

 
So, if the two intersecting planes are perfectly flat, polished, somewhere between 25 and 30 degrees …
 

 
... and I can make Barbie® spills ... I guess I can easily chop mortises!
 
Next up … mortise and tenon joints and tapering the legs. Thanks for looking, more to come!

 
Hepplewhite Stand #1: What's Wrong With This Picture
Hepplewhite Stand #2: First Things First
Hepplewhite Stand #3: Lay-Out & Rough-Cut
Hepplewhite Stand #4: A Proper Edge
Hepplewhite Stand #5: Mortises - Finally!
Hepplewhite Stand #6: Frame Members Sized for Tenons
Hepplewhite Stand #7: Tapering the legs
Hepplewhite Stand #8: Completed Legs and Drawbore Pins
Hepplewhite Stand #9: The Drawer
Hepplewhite Stand #10: Final Assembly

-- Ron in Lilburn, Georgia.  Knowing how to use a tool is more important than the tool in and of itself.



2 comments so far

View theoldfart's profile

theoldfart

9267 posts in 2291 days


#1 posted 12-18-2016 11:07 PM

Ron, I’ve found I’m better off with 30 degrees on the mortise chisel, twenty five on the other two.

-- "With every tool obtained, there is another that is needed" DonW ( Kevin )

View Ron Aylor's profile

Ron Aylor

1792 posts in 487 days


#2 posted 12-19-2016 12:29 AM

Kevin, I have but three mortise chisels, a 3/8” Marples, a 6mm Narex, and a 4mm Narex, all ground to 30°. All of my bevel and firmer chisels ( 1/4” to 1-1/2”) are ground to 30°, as well. I have three rather thin generic chisels (1”, 3/4” and 1/2”) all ground to a 20° bevel posing as quasi-paring chisels that hardly get used, as I seem to forget I have them!

If I have to mortise larger than 3/8” I use the old “drill a bunch of holes” method to remove waste and clean up with whatever bevel chisel fits the bill.

-- Ron in Lilburn, Georgia.  Knowing how to use a tool is more important than the tool in and of itself.

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