One of the early skills that is difficult to master in knifemaking is grinding bevels. There are many methods from free hand grinding to using jigs. One of our favourite techniques in getting a clean, consistent result is push stick grinding, one we teach in all our classes. This method was taught to us by ABS Mastersmith Shawn McIntyre.
Its very simple requiring just a rest on the grinder and a suitable push stick. Its suitable for anmost any blade shape and allows you to grind even consistent blades on both sides. By changing the flat platen to a wheel it can be also used to do hollow grinding.
Materials and Tools Needed:
- Belt grinder with flat rest
- Knife blanks to practice on. The knife blanck should be profiled with a smooth spine
- Push stick
- Safety gear (gloves, goggles, ear protection)
- Waterproof Marker
What makes a good push stick?
As a staring place, some timber measuring 12mm x 8mm x 250mm with a 5mm point grond on one end. Somthing sturdy and sacrificial. You will develop your own preference for the size and shape of the push stick.
Preparation
- Safety First. Put on safety gear. Ensure your workspace is well-ventilated and clear of obstacles.
- Mark the center of the Blade. Use a marker to colour the edge in. Scribe a center line down the length of the edge. This can be done with either a centre marker, a height gauge, or using a drill bit the same width as the blade.
- On each side draw a line parallel to the cutting edge 8mm below the edge. Repeat at 8mm intervals down the side of the blade until you get to the desired bevel height. This will be the path your push stick will follow.
- Grind a 45 degree angle along the edge, making sure the centre scribe line is still visibile
Setting Up the Grinder
- Belt Selection. Start with a used 50 grit ceramic belt: Sacve the new belts for grinding after heat treatment.
- Attach the tool rest at 90 degrees to the platen, for easier grinding the tool rest is around 50mm wide and smooth.
Set the Blade
- Place the spine of the blade flat on the tool rest
- Have the edge touch the belt and bring the spine out about 5mm from the belt. This creates a slight angle on the blade
Using the Push Stick
- The push stick focus' the pressure at a particular point on the blade
- The push stick needs to be in the middle of the belt to make a flat even grind
- The pust stick is anchored on the edge of the tool rest.
- Pressure is applied with the index finger on the push stick. The push stick does all the work
- Where you point, is where you grind.
- The hand holding the tang pulls the knife staight along the belt, avoid twisting the blade
- The angle is set by the push stick
Grinding the Blade
- Run the grinder at full speed.
- Gently position the blade as described above.
- Grind from the plunge area towards the tip.
- Check the grind after each pass and adjust as necessary.
- Look at the edge to make sure you dont grind past the middle line. You should always be able to see the scribe line.
- When you are almost at the middle scribe line. Move the push stick down to follow the next lower line.
- Stop before getting to your final level.
- Leave about 5 mm unground in front of the plunch line area, you can combe back later to do this on a higher grit.
- Cool the blade after a few passes in water. If you are grinding a heat treated blade, cool after each pass.
Refining the Grind
- Change the to 100 grit, turn on the grinder
- Gently introduce the blade to the platen , allowing the balde to find the bevel
- Press firmly on the push stick and follow a middle line
- Repeat until the 50 grit scratches are removed and there is an even finish
Trouble shooting
- If you have a uneven grind, you aren't pushing consistently with the push stick
- If a smile appears (the grind line is not flat), then you are not pushing in the middle of the platen
Extra Tips
- Practice, practice, practice. Try and do a number of the same shapes in a row to get used to the system.
- Straight backed knives are easier to get an even grind
- Narrower blades are easier to grind than wider blades.
- Be confident and press hard, light presses give facets rather than even bevels
- Grind first with your non dominant hand, the use you dominant hand to match the side. Its easiser than doing a great first side and use your worst hand to match it.
Safety Tips
- Always wear protective gear.
- Keep your hands away from the grinding belt.
- Regularly cool the blade to prevent overheating.
- Work slowly and methodically to maintain control and accuracy.
Click the pictures below for a larger image
