Tool Sharpening 101
Equipment & Material
Equipment covered in this class includes the following:
Slow speed grinder
Whet stone
Burnisher
File
Material
Lathe Tools
Chisels
Hand Plane
Cabinet Scraper
General Safety Requirements
Mandatory:
Safety glasses (provided)
Closed-toed shoes
Remove dangling jewelry
Tie back long hair
Recommended:
Particle filter mask or dust mask
Tool Safety
Main causes of injury are:
Loose clothing getting caught in the slow speed grinder
Catching a tool on the slow speed grinder
Tools will be sharp
Tools will be hot after grinding
Hands are never close to cutting/drilling/turning mechanisms
ALWAYS unplug a tool before servicing it/ changing consumables
Grinding wheel should reach full speed before touching material
Ensure participants turn tool off before passing off to next person
Sharpening Tools
For all the tools we’ll be sharpening, we will be working with tempered steel. As we’re sharpening with the slow speed grinder, the tool will heat up. We need to make sure that the tool doesn’t get too hot, otherwise it will get damaged..
When the tool heats up, it will change in colour. If the tool is over heating you’re going to notice it on the corners first. If you go past the straw color you’re weakening the steel. When you start to notice this, dip the tool in some water to cool it down. You want to avoid seeing the blue colour. If it’s blue it means you are damaging the steel.
Using the Slow Speed Grinder
The slow speed grinder is used for sharpening lathe tools and chisels. The motor runs at 1000rpm, which is about half the speed of a conventional grinder (ie. what we have in the MetalLab). The slow speed reduces the risk of overheating the tools and damaging the steel.
The grinding wheel is made of white aluminum oxide, which is soft, runs cooler, and also reduces the risk of overheating the tools.
***Do not sharpen any of the tools we are using with the grinder in the MetalLab, or you may damage the steel. ***
This grinder is rigged so the wheel can move away from you, or towards you, depending on how it is plugged in. Make sure that when you’re sharpening the tools, that the wheel is always spinning towards you. You may need to change the connection if it is spinning the wrong way.
Diamond Wheel Dresser
As the grinder is used, the stone will become uneven and can have grooves form in the surface. Before sharpening tools, the stone will first need to be “dressed” using a diamond wheel dresser.
What it’s used for:
Evening out the surface of the grinding stone
Parts:
Handle
Diamond Bar
Important Safety guidelines:
Hold handle firmly
Bar should be at a 90 degree angle
Proper use:
Hold at 90 degree angle and move dresser side to side until stone wheel is even.
Lathe Roughing Gouge
The roughing gouge cuts on the front edge of the tool.
Before turning the grinder on, mark the end of the gouge with a sharpie
Line it up to the grinding wheel to match the angle of the tool
Slowly spin the wheel towards you, and check where the sharpie was ground off. You want to aim to be grinding the first two thirds of the bevel.
Once the angle is lined up, turn on the grinder
Leaving the tool in the same location on the wheel, turn it so that all edges are ground
If you notice the tool is starting to heat up, dip it in water, and then continue to grind it.
Once sharpened, it will form a burr on the inside. This can be sanded by hand with sandpaper.
Lathe Skew Chisel
The skew chisel is ground at an angle to ensure the entire front edge of the tool is sharp.
Repeat steps 1 to 4 as noted in the roughing gouge. With this tool, you can colour in the whole bevel, and grind it until the marker is ground off
Move the tool side to side along the grinding wheel, making sure it is positioned to avoid a catch
Grind one side, then flip the chisel over to grind the other side of the bevel
Make sure to dip the tool in water if you notice it heating up.
Lathe Parting Tool
The parting tool does not get much of a burr. Once it is sharpened on the grinder, it can then be finished on a wet stone.
Repeat steps 1 to 4 as noted in the roughing gouge. Colour in both edges with the marker, and grind until the market is ground off.
Move the tools side to side along with the grinding wheel. You should get a flat edge on one side.
Grind one side, then flip the chisel over to grind the other side.
Dip the tool in water if you notice it heating up
Finish up on the whetstone (see below)
Lathe Bowl Gouge
We will not be demoing the bowl gouge since MakerLabs doesn’t own one, however the steps and link to a video is listed below. The bowl gouge cuts on the sides of the tool, not the edge, so we need to use the Wolverine Jig for this.
Insert the bowl gouge into the wolverine jig and tighten
The base of the jig (pointy part) should sit in the adjustable guide for the grinder.
Line up the guide so the edge of the gouge meets the grinding wheel
Turn the grinder on, and rotate the gouge around so that all edges are sharpened, while keeping the gouge in the same general position.
Woodworking Chisels / Plane blades
Woodworking chisels and hand plane blades are sharpened with the slow speed grinder in a similar fashion to the skew chisel, in order to put on the primary bevel. This will only need to be done if there is damage to the chisel, or if it is super dull. Otherwise, it can just be sharpened with a whetstone.
Repeat steps 1 to 4 as noted in the roughing gouge. With these tools, you can colour in the whole bevel, and grind it until the marker is ground off. The bevel should be level.
Move the tool side to side along the grinding wheel.
Finish up on the whetstone (see below).
Using the Whetstone
Some tools require the use of a whetstone to fine tune them to their desired sharpness. This includes the lathe parting tool, woodworking chisels, and plane blades.
The whetstone we have is 400 grit on one side, and 1000 grit on the other side. It needs to be submerged in water for 15 minutes, prior to use.
We will be making some DIY whetstones that everyone will take home. These are made with contact cement, and wet / dry sandpaper on either side.
Steps for sharpening on a whetstone:
As the stone gets used, the surface will become uneven. Run a pencil across the whetstone to begin with. When using the whetstone, try and run the tools over surfaces that haven’t been used to keep it true. Once all the pencil marks are gone, the stone will be true.
Find the angle that exists on the tool, and rub it along the surface of the whetstone using a figure 8 motion. You should be pulling the tool towards you, not moving away from yourself (there is a chance that you can nick the stone or sandpaper if moving in the wrong direction).
For the tip of the tool, adjust the angle up a few more degrees, and continue moving it in a figure 8 motion.
Sharpening Cabinet Scrapers *AKA Put a burr on it
Cabinet scrapers are great tools to use small amounts of material, and can get into tricky areas where handplanes cannot. When purchasing a new cabinet scraper, or after using it for a period of time, you will need to put a burr on it.
Steps for tuning the burr:
Place the cabinet scraper in a vice with the cutting edge facing up.
Using a file, start at the edge furthest from you, and pull the file towards you along the top of the edge
Use a burnisher and pull / push the burnisher back and forth along either side of the top edge.
Fees
WoodLab Drop-In Rate: $45/day (12pm to 9pm)