recording a moulding

[bugbear]

It's easy to record a moulding if you don't mind cutting it - just take a cross section at an intact point and trace.

But recording the middle of a moulding (or moulding plane sole :wink: ) is harder, but desirable;
the ends are often damaged, or the piece may be too precious to cut.

I thought of a way to do it, that may be more accurate than a profile gauge (since
the pins are of finite, non zero width).

If the plane is held at an angle, a light boundary will record the profile. The easiest
light boundary to use would be a laser level or laser line, but since I don't have one,
I improvised.

In a dark room, I set up the moulding plane, inverted at 45 degrees, held in a drill vise.
I placed a LED torch long way off (further than the diagram shows) to emulate a point source
to reduce penumbra size, and placed a card shield in the way to make a light/dark
boundary.

I then placed a camera above the plane looking down where the boundary hit the plane, and took
a photo.

The only plane I have with a non flat sole is a reeding plane (don't ask).

Here's my trial photo;

That's stretched by roughly 1.414

This is scaled (in Gimp) to correct the stretch;

It's not perfect, but that's literally the first attempt at using this technique. Sadly the plane
has some sole damage where the shadow was.

Comments, suggestions and (especially) improvements welcomed.

BugBear

 

[AndyT]

That looks interesting and useful but I'm not entirely sure what I am looking at. Could you add a few normal photos of the somewhat unusual plane?

(And how come you have no ordinary moulding planes!?)

 

[bugbear]

That looks interesting and useful but I'm not entirely sure what I am looking at. Could you add a few normal photos of the somewhat unusual plane?

Your wish etc. :ho2

You start off using the fence, but when you've made the first reeds, you remove the fence (note the screws), and the plane is guided by the reeds it's already created; you can thus create as many reeds as you like across a surface.

(And how come you have no ordinary moulding planes!?)

I don't have any foreseeable use for one, and if I had one, I would feel obliged to sharpen
it to perfection, which would take ages.

BugBear

 

[xy mosian]

Now that is good, clever, thinking. I especially like the reference to the 45 degree angle with the resulting, known 'stretch'. It is, if I'm right, using similar principles to the method of striking corner profiles in Butt and Scribe inner corners in skirtings.

I wonder if, with the plane lodged at the bed angle, the result would be exactly the shape of the iron edge. Without scaling?

xy

 

[bugbear]

I wonder if, with the plane lodged at the bed angle, the result would be exactly the shape of the iron edge. Without scaling?

I think the answer's yes. It's clearly correct in the extreme (and unhelpful) cases
of 0 and 90, and it seems to be correct in the simple case of 45.

I see no reason all the intermediate angles shouldn't work too.

BugBear

 

[Angusdog]

Cling film and bog? Cheap and versatile.

 

[bugbear]

Cling film and bog? Cheap and versatile.

What's "bog" (apart from cheap and versatile )?

BugBear

 

[Mike.S]

Cling film and bog?

??

Cling film wrapped around plane and dipped in plaster of paris (or similar) to make a negative?

Or put cling film over the toilet and laugh when someone uses it

 

[bugbear]

The setup with a laser level would be almost absurdly simple:

BugBear

 

[xy mosian]

In the end I suppose the method chosen to get hold of this profile is down to what is available.
I could see that any method involving 'casting', plaster of paris etc., might lead to problems with a cut edge crumbling in an attempt to get a clean cut.
Such a cut would be necessary to have a profile to trace, or draw around.
Still, the job only comes to a halt when no suitable methods can be found, all alternatives are worth knowing about.
xy

 

[AndyT]

I think the clever aspect of this method is that it produces a record of the moulding, which is then easy to store, enter in a database, share, compare etc. Ideal if you want to compare mouldings used on windows in one part of the country with those used in another, or at a different period, for example.

Making a physical model of a moulding is useful if you need to reproduce it, but not much help as an abstract record.