Thread: How long should it take to lap a plane iron

It could be the plate Jason. I have found that DMT plates stop cutting in too short a time, but others swear by them. I switched to Atoma plates and found them better, but not outstanding.

Remember that as the flattened area spreads, so the amount of work increases. When you think you're nearly there you still have most of the work to do (because you have to grind down an ever increasing area).

You may need to start with a coarser grit than the diamond plate provides. Try with an 80-120grit wet 'n dry on your table saw, jointer, glass plate or other guaranteed flat surface. Then you can move onto the diamond plate to remove the coarse scratches. If the blade is out a lot then it can take an extremely long time trying on a finer grit like that.

John

Yanis is right on the nose,it may take a long time but when done it's done forever.

Like Yanis said, rather than using up the diamond stone, get a few sheets of the coarse grade wet and dry sand papers, 60, 80 and 120 and glue them to a plate of glass. You have a much larger surface to work with and it should be faster. Save your stone for the quick sharpening of the cutting edge.

Can you put up a photo of the blade

As others have said start with coarser grit to get it flat. You have a hump on the back that has to be got rid of so go the sandpaper way to get it down. When you see the scratch marks all along the edge then a couple of finer grits then back to the stone. Some people even create a small back bevel to save a lot of work on a badly out of flat back.
Jim Davey - Woodworking Hand Tools - Sharpening Notes

Regards
John

if you are like some of the fanatics here, between 300 and 800 hours should have it done.

You should make yourself a holder with two bolts (50 cent hardware store type are fine) and a 2x4. It'll make the process faster and you'll not have bleeding fingertips - even if you use the same pressure as by hand, the pressure is off your fingers and onto your shoulders and triceps.

at 8:00 in this video...sorry I gave short shrift to it (it is almost free to make, and making a rough one is better because it will be covered with nastiness if you use it a few times):

https://www.youtube.com/watch?v=N_aN2jr5l5w

Use of it at 12:00 here

https://www.youtube.com/watch?v=v7w_UWbeBwg

You can disregard most of the information about flattening basket case irons, I have a large array of things to flatten an iron (and derek has not stopped by yet, but the long run of PSA paper stuck to a flat surface suggested above is what I recall derek recommending, and that is also good).

If you're just doing this once, I've found good quality paper aluminum oxide 8x11 sheets in 100 grit to be a decent starting point if a 1k stone isn't.

DMT hones don't tolerate much lapping with force, it pulls the diamonds out of the electro plate. Atoma tolerates it better, but they do feel dull after they've had a significant amount of use, they just don't seem to lose everything on the surface like DMT does. Whoever has the "science of sharp" blog did a good job showing a DMT plate, and showing that the "break in" is actually scads of diamonds disappearing as they break loose from the electroplate.