Wednesday, June 23, 2010

Centrolinead

A centrolinead is a perspective tool with adjustable Y-shaped legs branching from a main bar. The legs rest against two nails placed on the drawing board.
As it pivots up and down, the main bar changes slope. The resulting lines orient to a remote vanishing point that would be otherwise difficult to establish.


E.G. Lutz’s book Practical Drawing includes the diagram above.

Concept artist and illustrator Craig Elliott discovered an antique centrolinead dating from around 1890 (below). Note how the Y-legs branch from a point along the top line of the ruler. He reports:

“I did a little building facade and some windows to test out the Centrolineaid. It is such a breeze, even better than using a long ruler! I set the map pins at 3 inches from the HL and the blades at 30 degrees.

I did the verticals with a t-square and the 30-60 triangle shown. I think two or three of these would make darn quick work of a two- or three-point perspective drawing on a quite small drawing board. This board is about 24 x 32. Another benefit of this tool seems to be that it doesn't pop off the pin all the time like a regular ruler would- it is very steady on the 2 pins.

For the pins or nails, I used a paper clip with one end bent up, or even an upside down flat headed thumbtack taped to the board or paper. This is good for balancing a ruler on for perspective points on the board or for this operation.

You could also use a sheet of metal to draw on, even with a Borco cover, and Neodymium magnets about 1/2 cube size for the pins. They are so strong they won't shift.”

ADDENDUM
Check the comments for a lot more links and tips. Below is a scanned version of Craig's antique model, with measurements.
Thanks, Craig!
Craig Elliott’s blog post about his centrolinead

17 comments:

Bjorn Nelissen said...

That's awesome! I'm right now working on a perspective drawing and this tool looks like a real time saver!

Paolo Rivera said...

Why am I only hearing about this now? Great tip! (Although, I must admit, I do much of my perspective on the computer now.) Also, good call on the magnets. I draw on a slanted, metal board and have magnets attached to all my tools—my eraser never makes it to the floor anymore.

Johnnyburn said...

Digging around a little bit, I came up with this:
http://books.google.com/books?id=FetJAAAAMAAJ&pg=PA43#v=onepage&q&f=false

He mentions that the two arms are adjusted 'by trial,' and that 'the difficulty of adjustment' is a problem.

Also the author leaves a tantalizing clue about the priciple on which it acts and 'a simpler instrument for the same purpose' that can be found at another resource. I'll leave that discovery for another commenter.

Thanks for the post. I want to make a trip to the hardware store now.

Brian said...

Wow, that is pretty neat.

It would be great to use on 24 Hour Comic Book Day.

Time to figure out a homemade DIY version of it?

E.M. Gist said...

Brilliant, I get tired of loosing my perspective on larger paintings. I wonder if I could construct a frame to use on my easel based on this.

E-

MichaelJA said...

I was very lucky not too long ago when I came across a Klok Perspector table top. IIt did not come with the specially cut t-square that follows the bowed curve cut into the table top but all the lines and measurements are still very viewable and I got it for free!

Along with this the original purchase was for an Italian made pedestal with hydraulic lift center drawing table for $10.00!!! I learned when new this item is around a grand.

I still haven't figured out how to use the top for perspective drawing yet but what a find!

Mary Brewster said...

Does anyone have a diagram or drawing of the measured parts? It does not look very difficult to make one.

Craig Elliott said...

I actually did a tracing of the parts for Jim to try and make his own in the shop. I could make a measured drawing for people if there was interest. I'll post it on my site later today or tomorrow.

-Craig Elliott

Craig Elliott Gallery

Don Cox said...

I have a centrolinead which has a fixed, diamond-shaped head instead of two hinged arms. The head is marked with a scale of distances, and you put the pins at the marks on the scale.

The two sides of the diamond are used for the left and right VPs.

There is a full description, with a diagram from which one could be constructed, in "Perspective Drawing" by H F Hollis - an excellent little book.

I bought the instrument, which is made of thick Perspex (=Plexiglas) many years ago, but have never actually used it.

It is a nice thing to own, though.

Richard said...

The math and a well-made example.

http://lockyeardesign.com/Pages/Parametric/Centrolinead/01.html

Richard

Richard said...

Sorry cut off link

http://lockyeardesign.com/Pages/
Parametric/Centrolinead/01.html

DPetersen said...

I think that with modern materials (thinner rigid plastics) you could have the 'Y' arms coming directly off the main rule instead of off a 'T'. This would allow for a wider range for the tool. In extreme angles, the tool won't work as constructed.

Mario said...

Richard, I think the formula given in your link is not correct, should be:

tan(beta) = vp/d

mcahogarth said...

If someone made one of these, I would buy it. Alas, I have no skill with tools myself. :)

Susan Sorger said...

In his book "Architectural Rendering in Tempera" Richard Baehr, a one time well known Architectural Illustrator, provides instructions and specs on how to make a centrolinead out of metal. I bought the book in 2001 and had a metal shop make up 5 of them for me. I sold 2 of them to an Architectural Illustrator friend of mine. I never did use them as I started using SketchUp for my perspectives. SketchUp conveniently prints large perspectives on tile sheets of paper which can be taped together and transferred onto watercolor paper or whatever.
The book is now available as an Ebook here: http://www.ebooknetworking.net/books_detail-0471285129.html

Andre said...

Am I the only one who doesn't know how this centrolinead works? I must be stupid. Is there a more detailed explanation somewhere? Thanks.

Johnnyburn said...

I have collected some information about the math behind the centrolinead and a few methods for setting the angles on the rulers. It helped me to understand that the vanishing point, the studs and the ruler 'elbow' all lie on a circle. You can find it here.