Flatten plane sole - assembled or apart?

[Chris Griggs]

You'll never get there unless you spot sand, or better yet scrape, the high parts. Once you get things fairly well straightened out then it's time to lap the entire sole in order to *essentially* blend everything in. Learning to scrape is building a skill you could potentially use elsewhere, rubbing the whole thing around on sandpaper while it teeter-totters between different high spots generally making things worse isn't really building a useful skill. You've already lost four hours and in this amount of time you should have been able to almost achieve Lie-Nielsen or Lee Valley flatness on one plane at least, maybe one plus about halfway through another. It's like planing a board - you hit high spots to get the thing closer to a point of equality and then you start making full strokes, the corollary in sole truing being lapping.

This is a reasonably decent place to start:

http://www.amgron.clara.net/plane%20...ape%20105.html

By the end of all of this you'll probably wish you'd simply bought wood-bodied planes that take about ten minutes for a sole true up.

This is great info Charles. I have a big old Sargent 424 I never got as flat as I would have liked and have been looking for something better than lapping and or spot sanding. Thanks!

[David Weaver]

It's easier to use a 2x3 inch or so flat wooden block with very coarse sandpaper, but using the same marking setup that you'd use if you were doing scraping. Scraping will leave a lot of people who don't do it all the time breaking out bits around the edges of their planes and especially around the mouths.

The couple of jointers that I flattened I first blued the bottom with dykem, then ran them over the lap to find the high spots and put the plane upside down in the bench vise to spot sand. Blue again and repeat. It takes about 20 minutes or a half our to do a jointer this way, you can remove metal very fast with a 2x3 block of sandpaper with 80 grit heavy cloth aluminum oxide sandpaper on it, and the small contact area means the paper will work well until it's totally worn out. lapping a plane entirely on a long flat surface is slow going and as soon as the paper loses a little bit of tooth, the contact area is too large and it stops cutting effectively.

That assumes that you have a long and flat lap to do it, though - dead flat.

What took me 5 hours on the first jointer I ever lapped took about half an hour with this method, though, and the plane is probably flatter, even if it's not as pretty. Well, someone else has the plane now. The only thing undesirable about it is with that much dykem drying on a large surface like a jointer bottom, you need to have fresh air or some air circulation.

I had less luck with scraping in terms of speed.

[Charlie Stanford]

This is great info Charles. I have a big old Sargent 424 I never got as flat as I would have liked and have been looking for something better than lapping and or spot sanding. Thanks!

Good luck Chris. As David cautions, be careful at the arrises. Jeff Gorman's site is pretty much a must read, if you haven't visited there before.

[Chris Griggs]

Thanks guys. Mostly I just need to get off my butt and do it. I get by fine without having it dead flat (and w/o using it at all), but its such a lovely old plane I really want to get it performing ideal at some point...I'll "get round tuit" eventually by one method or the other.

Great site Charlie. I feel like I've run across it before but never really read though it. Just took a look at it. Lots of great stuff. Looks like a fantastic resource!