No point in destroying the plane like in the Sellers video, as the old plane has lasted this long,
and probably would make a good user to add to your arsenal if you don't make the sole like a banana removing more of the toe and heel by lapping like that.
Lapping on a flat plate isn't foolproof, and if the plane is a cheaper variant compared with a Stanley or Record, it might not have hefty castings, meat on the sole if you will, and should it not be flat
you might only get one shot at getting it flat.
Getting anything flat means respecting the perimeter.
Don't trust anyone who won't show the results with feelers, like so...
You need to read up more on this, at least on the thread I mentioned,
as what I'm saying isn't any more difficult, will build knowledge which you will use,
and doesn't need such expensive equipment, as a flat surface is nothing if you don't use it as such.
Look with your eyes at the plane sitting like Cosman demonstrates,
use some hinging exercises to make note of the high spots,
paint the sole in marker and one small rub for 1 second to see, it should collarate with your findings.
If you keep rubbing on the lap for 5 seconds, you will loose the witness marks and abrade the toe and heel excessively should it be somewhat flat in the firstplace.
You can't trust what the witness marks tell you beyond say 2 seconds, and believing beyond this will lead to a convex profile, even though there still may be a troff in the centre.
Why? ...
Those shined up areas (toe&heel) will appear as high spots, so it just might give the impression that the plane is convex, i.e touching on the toe and heel,
when infact things are actually the opposite!.
Go back and look at the plane sitting on the clean plate if this is the case or
you risk going too far, try getting a feeler or whatever, or even just looking at the plane
sitting on the clean plate, and make note of the toe/heel
This is more important/notible on a no.5 compared to a no.4 plane, and so on,
and what will happen the longer the plane is the more it will be see sawing on the lap
removing where you don't want, you need to remove those high areas without removing the low ones on the perimiter, as abrasion on a lap like shown will always favour the edges.
So make note of it just sitting on the plate, and think about how you can remove only where is needed, which is highly unlikely everywhere.
For the non believers, they can colour in the plane and count how long the ink will last on the toe and heel, about three short strokes will show this on something flattish, and will take considerably more should one want to remove from the center everywhere,.
Best do nothing to the plane if unwilling to do this simple test.
Do some more reading if you intend to be happy with the work you wish to do to this,
as who wants the plane of shame lying around,
which took hours of unsucessful lapping, and was tolerable beforehand?
Nice to have Cosman's video to highlight this, as plenty of those videos are pure dishonesty
which I say with a bit of scorn, as I have experieced gasthly results by blindly following that rethoric, and led to the demise of more than one plane.
Took thicko here some time to realise what I was doing, as I simply believed that flat made flat.
If only I knew, just to simply look at what I was doing from a different perspective rather than beliving a misleading scratch pattern, (rabbit in the headlights job)
and make note of the toe and heel before it was too late, I wouldn't have some useless cast iron lying around.
All the best
Tom
