[Read!] Restoring a New Hand Plane to Accuracy

I started working the blade of the plane, heres how the blade blued up after a few lapping cycles.
the lapping was achieved by laying 400 grit wet/dry sandpaper on the surface plate.
by adding some glass cleaner as the wet agent and a coarse grain foam sanding block as the makeshift work holder.
the coarse foam block almost adheres to the blade and makes the lapping a lot safer than trying to push the blade by hand.
i surmise that it would also apply a more even pressure over the surface of the blade as well.
pictures of the rubbings



it's gonna need some work!

I'd always been taught that the proper (only?) way to do "square" and "dovetails" required perpendicular or tapered reference artifacts to make rubbings just like you do on flat surfaces on a surface plate so you get the entire plane. If your angle plate (I've never heard it called a milling knee) is truly perpendicular it will work fine for a reference surface. Unfortunately cylinder squares only provide a single line contact if the part is good (single point if it's bad).

When I measure a plane on a CMM I have to tell it how many points to take and where to take them then it creates a plane based on the average location of the points it touched. It also tells me the range between the highest point and the lowest point taken. For scraping purposes we only care about the highest points and they all need to fall into the same plane. That's almost impossible without a single reference surface.

I have never done it but have heard that if you work with two angle plates by scraping them in together and make the rubbings on one surface while rotating the other surface 90 degrees in between rubs that you eventually end up with two perfectly square surfaces. There is an old book (1955) that is considered the bible of scraping called "Machine Tool Reconditioning" by Connelly that used to be rather expensive and tough to find. It's being reprinted again but it's still about $100. http://www.machinetoolpublications.com/ You might be able to locate a copy in a public library.

great info, thank you!

Catching up on some photographic insertions to the thread, Enjoy!




Looks like the effort is producing results, the nose and heel are starting to show signs of blue!!!

Ulma Doctor said:

I started working the blade of the plane, heres how the blade blued up after a few lapping cycles.
the lapping was achieved by laying 400 grit wet/dry sandpaper on the surface plate.
by adding some glass cleaner as the wet agent and a coarse grain foam sanding block as the makeshift work holder.
the coarse foam block almost adheres to the blade and makes the lapping a lot safer than trying to push the blade by hand.
i surmise that it would also apply a more even pressure over the surface of the blade as well.
pictures of the rubbings



it's gonna need some work!

Click to expand...

The blade should go the other way with the bevel to the rear.

thank you for the info-
i didn't catch the fact that the blade was installed backwards

Be careful about scraping planes with the blades and keepers removed. When re-installed they can twist and flex the body and then it will be out of alignment.

I was taught in shop class to flatten a plane with all parts installed and tight but the blade retracted so it didn't extend past the base.

thank you,
when i have the blade flattened out and the pillars scraped, i'll reinstall the blade and perform adjustments.

Another good tool for holding work for lapping is a mason's "float". It has rubber backing with lots of little holes that can apply a vacuum to the workpiece when moistened.



Although I've always used mineral spirits for this purpose, I've read that kerosene is very good for lapping (also very smelly).

Holescreek said:

...I have never done it but have heard that if you work with two angle plates by scraping them in together and make the rubbings on one surface while rotating the other surface 90 degrees in between rubs that you eventually end up with two perfectly square surfaces...

Click to expand...

I don't think that works, I believe that three plates are required to get a flat surface. (I watched a friend hand-lap a telescope lens into spherical surface by lapping two glass blanks together while changing the angle between the two.)