Thread: Plane sole flattening, again...

Originally Posted by D.W.

Is this going to get an engine turned finish at the end?

Nah, gotta be scraped

Every one that I've used has always developed stray scratches, too. Even if the wood is agreeable, something will always be scratching the bottom - stray grit, a staple in something, whatever it may be.

but the flatness remains!!

I think Rob fill find that the finer the bottom finish and flatness are, the easier it is to get consistent very thin shavings.

That's how one sells planes at wood shows. It's a little harder to use in rhythm in the shop, but there's something nice sometimes to finding out what the end point is. I still marvel a little each time I come across a new LN or LV plane (which isn't something I buy often these days), because I'm used to spending a half hour with each bench plane, or some similar amount, to get the sole where I want it, the cap iron cleaned up and the iron set up or back ground flat.

Then, you get a premium plane out, sharpen it in a matter of a minute or two, wax it, and it works a treat.

What about the data?

Nobody?

Originally Posted by rob streeper

What about the data?

I'll admit I didn't read it. If I read your chart correctly, you get more consistent thin shavings with a finer surface finish. That should be the case.

Especially freshly lapped with a more coarse surface.

Wait, the chart shows the standard deviation in what? Shaving thickness? And the surface finish is charted to standard deviation of shaving thickness? And that standard deviation settles in around 2 ten thousandths?

er, wait....I admit I didn't read all of the posts to this point. standard deviation in the planed surface. 2 1/2 ten thousandths? Got much better after shaving thickness normalized?

If that's what I'm reading, sounds about right, except I have no way to judge whether or not the standard deviation is typical because I couldn't measure it in the first place .

For those of us who aren't statistically inclined, could someone please explain the data in plain English?

What I think the data shows is that the thicknesser, Shelix equipped, produces a pretty flat surface which has deviations, which are palpable. When I adjusted the plane to take minimal shavings the standard deviation of measurements taken of the planed surface, not the shavings, seemed to settle. This result suggests to me that I gradually increase the cut depth and see what happens.

Originally Posted by D.W.

I'll admit I didn't read it. If I read your chart correctly, you get more consistent thin shavings with a finer surface finish. That should be the case.

Especially freshly lapped with a more coarse surface.

Reading is fundamental.

I think you'll find more surface deviation with thicker shavings, especially on a plane with a single iron.

Originally Posted by elanjacobs

For those of us who aren't statistically inclined, could someone please explain the data in plain English?

The standard deviations reported are for the measurements of the planed surface at 7 points each for lines 1, 2, and 3. The average SD is for all 21 points measured. I zeroed the gauge at the 0,0 point and measured each subsequent point, up to 7,3, relative to 0,0. This method of measurement reduces the influence of human factors, i.e. am I holding the plane flat during the pass etc.

What I'm seeing, I think, is that the plane produces a smoother surface (more consistent standard deviation) when it is set to cut a thinner shaving. Note that the data are taken after five cuts, thus the total removed is something like 0.004"-0.006". The earlier data had many cuts that were in the 0.004" to 0.006" range per cut. This suggests that more thin cuts are better than a few thickuns.

I predict that as I deepen the cut the standard deviation along each of the three lines of points will increase, we'll see.

Anecdotally, the minimum thickness shaving I was able to get with the plane lapped at 60 microns was 0.0015" to 0.002" thick. At 30 microns it is just a little less than 0.0001".

Originally Posted by D.W.

I think you'll find more surface deviation with thicker shavings, especially on a plane with a single iron.

I think so too. Since I was unable to get a shaving much below 0.002" with the plane lapped to 60 microns it may mean that a smoother bottom makes for a better product in the end. How smooth is smooth enough? As I wrote above, we'll see...

Just for FYI purposes, I honed the blade to 6000 grit with a 30^o included angle and lapped the back with 60 micron.