flattening the sole of a bench plane

[J.A.S]

Derek,

I hope you'll forgive me if this is a hijack.

In Hack's The Handplane Book, and elsewhere, I've seen it suggested that, while lapping, the plane should not be held by knob and tote, but around the frog area. Is this what the rest of you do?

I just wondered if, while lapping the sole, it might be better to hold the plane as one normally would, in order to make it flat in the same conditions that it would be used.

Jeremy

 

[Frank D.]

Hi Jeremy,
It's a good idea to hold a plane near the frog when you flatten a sole. You shouldn't be looking to reacreate the same conditions as when you plane because planing wood and flattening the sole are completely different operations. If you hold the plane by the handles while flattening the sole you will exert more pressure on the front and the back which will cause the sole to rock and be convex along the length. What turns out to be an advantage while planing definitely can turn out to be catastrophic while flattening, because in one operation you're taking off wood under the sole; in the other you're taking off the sole.
HTH,
Frank

 

[J.A.S]

Thanks, Frank!

You've soled me :roll: .

The query only came into my head while looking at Dunbar's Restoring, Tuning and Using Classic Woodworking Tools. In one photo, he's lapping a plane sole, while holding the plane by tote and knob.

Jeremy

 

[Anonymous]

This brings up the interesting point of static vs. dynamic. The methods used to check a plane sole (reference plate or straight edge) have the plane static with no external force applied. A plane in use has many dynamic forces applied.
Jeff Gorman has shown a metal plane can deflect with a moderate amount of downforce. His tests didn't consider the dynamic forces of a plane in action which would be much greater (that's why we need heavy benches!). Too, the wood we plane has irregularities of more than .0015" or we wouldn't be planing it :wink: .
The conclusion I reached from this is that the act of planing forces the plane to try to conform to the surface being planed. Ergo that sole that checked out superflat with a straightedge is not that way during the planing process until the planed surface itself approaches the same level of flatness.

 

[Philly]

Roger
I agree with you-you only have to vary the amount of pressure whilst planing to see the difference. I am sure this has a big effect on the performance of the plane.
You watch DC planing in his second vid-He doesn't just effortlessly slide the plane over the wood, there is some serious, calculated pressure being applied. Obviously technique is a big part of planing and has a large effect on the final surface quality.
Just my thoughts,
Philly

 

[Alf]

You watch DC planing in his second vid-He doesn't just effortlessly slide the plane over the wood, there is some serious, calculated pressure being applied.

And it's not being applied to the front knob either... :-k

Cheers, Alf

 

[bugbear]

I suppose I'd better say...

I think this is the most accurate and fastest way to flatten a sole.

http://www.geocities.com/plybench/flatten.html


BugBear (who's sure Alf's been expecting this)

 

[Alf]

BugBear (who's sure Alf's been expecting this)

Who, me? Not at all... :^o :wink:

Cheers, Alf

 

[Philly]

Hmm
Interesting stuff. So lapping by hand gives you a slightly convex sole (didn't DC say this is better than concave??). But by how much?
And how much would it cost to take your plane to a machine show and have them mill the sole flat? Anybody done this?
I see on the Dick website that they offer a similar service.
It all comes down to your reference surface, though. Float glass may be flat but you sit it on an uneven surface and is it still flat?? Any suggestions? In BB's link the Guy mentioned he put the glass on a thin rubber mat-doesn't that defeat the object?
If you can get 1 thou shavings is your plane "flat" enough?
Cheers
Questioning Philly :-k

 

[mudman]

Hmm
Interesting stuff. So lapping by hand gives you a slightly convex sole (didn't DC say this is better than concave??).

Convex would be bad as you are effectively shortening the length of the sole. However, a slight concavity would not be too bad as the toe and heel still retain contact. The effect in this situation is to limit the ability to produce those gossamer-like shavings to the amount that the sole deviates from flat at the mouth. So if this is 1 thou, then you can still get the 1 thou shaving. Of course if it is too conves, then this will limit the planes ability to press the wood fibres down ahead of the blade and you won't get a very nice finish. I seem to remember reading that it doesn't have to be completely flat, but must contact the wood at toe and heel with a slight bump infront of the mouth to ensure contact here as well.

 

[Jake]

I was imagining the convexity/concavity being side to side not front to back.

 

[Anonymous]

And how much would it cost to take your plane to a machine show and have them mill the sole flat? Anybody done this?

Any suggestions?

If you can get 1 thou shavings is your plane "flat" enough?
Cheers
Questioning Philly :-k

Ok

Milling won't give a particularly good surface and I would recommend surface grinding by a local engineering shop if you don't want to flatten it yourself. I have had this done at work on some very distorted chisels and it worked very well. I would expect to pay around a tenner in a machine shop

My suggestion would be to buy LN or Clifton as all that I have bought came perfectly flat :wink:

Or, veritas - mine (3) all needed a little work and were lovely and flat after 5 minutes on wet 'n' dry.

I would say that 1 thou shavings are pretty thick and you should be ashamed of yourself #-o Get into the workshop and flatten the soles of those planes :lol:


In my experience, using 80 grit wet 'n' dry followed by 120 grit (lube with oil or washing up liquid/water 1/10) gives a flattened sole in 10-15 minutes max. provided the sole is not too bad to start off with.
When I worked on the #6 and #7, I used a linisher (like an upside down belt sander) to get it pretty close and then 80 followed by 120

 

[bugbear]

Float glass may be flat but you sit it on an uneven surface and is it still flat?? Any suggestions? In BB's link the Guy mentioned he put the glass on a thin rubber mat-doesn't that defeat the object?

This is normal - you want the glass to be your reference, not the surface it's on. You therefore try to support the glass uniformly. Since you don't have a flat rigid surface (that's why you're using the glass) you use a conformant surface. It won't support the glass 100% uniformly, but it ain't bad.

BugBear