Kanaban Lapping Plate FAQ’s
Hand lapping is a process for imparting smooth and flat surfaces on hard materials to extremely close tolerances. The abrasive embeds itself in the soft face of the lapping plate, rather like the way your gums hold your teeth, and the other end cuts into the harder material as it skates across the top; gradually imposing the surface geometry of the soft lap onto the hard workpiece. Unlike a bonded abrasive like a stone, the lap will not exhibit any wear and will hold its shape indefinitely.
Will it give me a mirror finish?
Flat and polished are not quite the same thing, a ball bearing is polished, but it's not flat, however, as a surface approaches absolute flatness it must, by definition, also become increasingly smooth and will eventually reflect light. We tend to switch to polishing stones long before that point to avoid the risk of ‘wiping’ the workpiece into the lap, which would both damage the lap and spoil the work. What you will find however, is that a lapped surface polishes very readily because it is so uniform.
Will the lap not wear away?
As long as you only use it to lap hard things, then no. In lapping, the harder material is abraded away while the softer material holds the abrasive and retains its geometry. If you try to lap soft iron or non-ferrous metals there is a risk that they will seize control of the abrasive, which will damage the surface of the lapping plate.
Can I lap my plane sole on it?
No, see above. For plane soles we recommend using sheet abrasives on float glass.
Will it take the massive bump out of my eBay chisel?
The lapped item needs to be reasonably flat or concave to begin with, convex surfaces tend to wobble around in search of stability and should therefore be rough ground prior to lapping. To remove a bump, grind it against the single line of contact with the outer circumference of a grinding wheel that is wider than the blade, using a circular motion to avoid forming a groove.
Can I flatten my stones on it?
No, the only time we recommend rubbing a sharpening stone on a lap is to remove any high spots if the surface has been damaged. Sheet abrasives or coarse diamond plates are much better for maintaining your stones.
How hard should I press?
Mechanical lapping machines apply 2psi which is barely enough pressure to maintain contact, you are looking to replicate that by hand. Pressing down hard will crush the abrasive prematurely and risks undesirable ‘wiping’ which is where the workpiece contacts the lap. The idea is to let the workpiece float on a thin layer of grease and abrasive.
What happens if the surface of the lapping plate gets damaged?
Minor dings and scratches can be gently stoned out using a fine oilstone. As long as there is nothing standing proud of the surface it will remain functionally flat.
What abrasive should I use?
We recommend Chemico grinding paste, which is silicon carbide in a lithium grease base. let down with a little WD40 as necessary,
Is it stainless?
Absolutely not, low carbon steel is not corrosion resistant, we recommend using oil based media and storing your lapping plate lightly oiled, protected with fresh VCI paper, and kept in a warm dry place.
Benefits of Lapping plate
fast and accurate
low ongoing costs after initial investment
Increases the effectiveness of, and minimises wear on your stones
Hard metals only (blades)
Benefits of abrasive film on glass
Very accurate
Disposable / replaceable
OK for hard metals, soft metals, sharpening stones
Benefits of Diamond Plates
Durable and portable
Coarse ones can be used to flatten stones