Academy Notes and Tips - Clean Cuts

Academy Notes and Tips

MAR/APR 2004
Volume 47/Issue 2

IN THIS ISSUE
Project Articles
• Strip Laminate Bending
• The Turned Hall Tree
• Two Great Kitchen Gift Items

DEPARTMENTS
• Ask Smitty
• Owner’s Gallery
• Letters from Owners
• New Baby Workshop Calendar

Academy Notes
Clean Cuts - Pt. 5- Sharpening Jointer, Molder & Shaper Knives

Service Pointers
Troubleshooting the Shopsmith Lathe Duplicator

Safety Tips
Safety Cans for Flammable Liquids

What's New
Check out our New Shopsmith Website

EDUCATION
• Find A Shopsmith Woodworking Academy Near You
• National Woodworking Academy in Dayton, OH

ONLINE CATALOGS
• Online Accessory Catalog
• Request Printed Accessory Catalog
• Online Replacement Parts Catalog

MARK V INFORMATION
• Find A Shopsmith
MARK V Demo Near You
• Request MARK V Information Package

LINKS
• Links Worth Visiting
• Free Woodworking Tips

FEEDBACK
Contacting Shopsmith

From the Shopsmith Woodworking Academy
Clean Cuts -- Part 5--Sharpening Jointer, Molder & Shaper Knives
Printer friendly PDF copy of article (607K)

Fig. 1 Using a straightedge over a piece of waxed paper as a guide, lower the infeed table until it is level with the bevel of the cutting edge.

Next, lower the infeed table about 1/8" so that the bevels of the cutting edges are exactly level with the infeed table surface. Use a straightedge resting on a piece of waxed paper as a guide (See Fig. 1).

Wrap a well-dressed, flattened oilstone (a medium India is best) in waxed paper, leaving about 1" of the end of the stone exposed. Place the wrapped end of the stone on the infeed table so the exposed part of the stone rests precisely on the bevel of one of the Knives. No part of the exposed stone should contact the infeed table surface.

Fig. 2. Wrap an oilstone in waxed paper, leaving one end exposed. Place it on the infeed table so that the exposed part of the stone rests on the bevel of one of the knives.

Hold the Cutterhead drive shaft with your left hand and move the stone across the Knife with your right hand. Take long, even strokes from side-to-side (See Fig. 2). Count the strokes so that you can hone all three Knives evenly. How many strokes should you take? Usually 15 to 25 is enough. If you need more strokes, it usually means that you're using the oilstone incorrectly or that your stone is not properly dressed. It might also tell you that you're waiting too long between honings.

Fig. 3. To finish honing each jointer knife, stroke the front or face of the cutting edge with a hard Arkansas oilstone.

Repeat this process for the other two Knives. Clean your stone frequently with Honing Oil. Squirt a generous amount onto the stone, rub it in to loosen the swarf and wipe it clean with a soft rag. Touch up the burr on the Knives with a few light strokes using a Hard Arkansas stone (See Fig. 3). Remember...take no more than a few strokes.

Prior to using your Jointer after honing the Knives, check the height of the cutting edge of each Knife with a straightedge, as described in your Jointer Owner's Manual.

Regrinding Jointer Knives
Regrinding must occur when Jointer Knife edges have been chipped or damaged...or the bevel has become rounded after repeated honings. Since the Knife leveling screws in the Shopsmith Jointer eliminate the need for match-grinding each Knife to precisely the same width, this is a fairly simple task.

Knives that have been reground to less than 11/16" wide should not be used in your Shopsmith Jointer, since the locking wedges will not be able to hold them securely in he revolving head. Furthermore, Shopsmith Jointers require Shopsmith Knives. Other brands just won't seat properly in the Cutterhead and can pose the danger of Knives flying out of the machine at tremendous speed.

As a point of information, Shopsmith Jointer Knives are factory ground with a straight bevel at 45-degrees. This is a multipurpose cutting angle that will produce smooth cuts at a variety of speeds in both hard and soft woods. The straight bevel (rather than a hollow-ground bevel typically produced by a grinding wheel) offers more steel backing up the cutting edge. This helps to produce a longer-lasting cutting edge.

Depending on the materials you work with, you may wish to change this angle slightly. If you work entirely with soft woods, 47 to 48-degrees will give a smooth cut. If you work entirely with hard woods, try grinding your knives at 42 to 43-degrees.

Stationary Grinder or Disc Sander?
If you use a Grinding Wheel to regrind your Knives, it's important that the wheel be very well-dressed beforehand. A rounded-over or clogged-up wheel cannot produce a straight, true edge. Keep in mind that using a Grinding Wheel on Jointer Knives can be a complex and dangerous process. First, Jointer Knives are narrow and difficult to hold safely during grinding. And secondly, match-grinding all three Knives without a special holding Jig can be practically impossible for all but the most skilled tool grinders.

Continue . . .