Tuesday, May 12, 2020

The Geometry of The Park-McCullough House Brackets



I have not measured nor carefully checked the brackets for their construction. The House is not open during this time of the corona virus. I will go another time.
The architect's perspective drawings of the House are part of the House' collection. I am curious to see if the bracket design is visible, and whether working drawings for the house exist.
I have heard that a mock-up of the bracket may exist. By June I hope to examine it.



I would like to understand how the design for the bracket evolved.
The shape was well known. It is one variation of the standard shapes used in classic architecture. Here it is in Plate I from Asher Benjamin's The Country Builder's Assistant, 1797, Greenfield, MA.  F is a cima recta molding; D , E, I and K are the reverse: ogee moldings. (and E have quirks; E has an astragal. K has a bead.)

Did a joiner suggest the Park-McCullough variation to the builder, the architect? Or did the architect, possibly his draftsman, draw it for the others?  Did they build a mock-up and improve upon it?








 Here's Edward Shaw conferring with his builders, from the frontispiece of his pattern book published in 1854, 10 years before this house was built.

I wrote blog posts about him here:
https://www.jgrarchitect.com/2012/02/edward-shaw-uses-tools.html
and here:
https://www.jgrarchitect.com/2019/12/english-construction-tools-1669.html

I've written about the House and its Barn being 'built to the weather'. Start here: https://www.jgrarchitect.com/2008/06/oirginal-green.html.

Tuesday, April 28, 2020

Practical Geometry Lesson 4b - The Old First Church







The circle, the daisy wheel, governs the design and frame for the Old First Church.
The circle was often used for the top of the window in the 19th century as well as just for decoration.  
I am sorry the images are tinged with green. This is one more presentation skill I have not quite mastered. Another proof reading is also necessary.  



Friday, April 10, 2020

PRACTICAL GEOMETRY - Lesson 3








The drawing of 'stepping off' is from Audels Carpenters and Builders Guide, NYC, 1923, p.640.

The holes in the daisy wheel are lower left, center, upper right.  There are others which do not photograph as well. This sheathing board was given to me by the crew that deconstructed the barns. It travels with me when I present on Practical Geometry.

Saturday, March 21, 2020

A Barn and its Daisy Wheel



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Not a very neat daisy wheel is it?



About 8" across, it was found during the dismantling of an upstate NY barn, c. 1790, scribed onto a board used to sheath the roof. The lines were drawn with a divider, not a marker. They can be seen in a raking light.The board is still in its proper place. This is a tracing made of the pattern carved by the pin of the divider.




The barn is probably the first of 4 connecting barns, c.1790. Green Mountain Timber Frames recently dismantled, repaired, and sold this barn for reuse.






It has modified gunstock posts, a 5 sided ridge pole, rafters spaced 38" on center.












The daisy wheel determined the framing layout.

The petals are the arcs of the radii. The points of the petals divide the circumference and locate the diameter. The sheathing board with the daisy wheel was a template, the reference for lengths and relationships. When it was no longer needed it became sheathing.

The master carpenter could rotate the daisy wheel first with one diameter  vertical and then with one diameter horizontal. He could use all 12 points and spokes. The radius and the distance between each point are the same length.



So how did the carpenter begin? He and the farmer knew the approximate size and location of the proposed barn. He decided on a width (the radius of his circle) and drew his daisy wheel.

Using the points on the circumference and a line, he marked the width and the rectangle of the circle  ( the 'x') - The green dashed lines show how he determined the length of the barn. The dashed red lines show the floor plan . 





The farmer wanted an English barn with a center door. The door needed to be a certain width for easy movement. 
Was 32' long enough? Would a 12' wide door give him enough working space on either side of the door? Would a 12' high wall work?  If that 12' were also the height of the barn wall there would be enough space for a lintel at the top of the door frame for strength. And what size are his timbers? 




He decided 11'-2" was wide enough, 12'-4" tall enough. The
carpenter laid out the door within the circle.
The width of the door is the radius of the circle, and the height of the barn wall.
The square laid out by the arcs of the radius.







The placement of the door lintel is set at the crossing of the arcs of the radius.




Since the door is in the center of the wall, the right side mirrors the left.  The arcs  - dashed red line -  locate the center of the circle to the right. 
The right side could also have been stepped off with a large compass.


 


The interior bents of the barn fit neatly into the daisy wheel geometry. The rectangle is laid out by the division of the circumference into 6 equal parts. The dashed red line shows the rectangle of the daisy wheel. While the layout of the barn is a traditional English pattern, dropped beams are the regional Anglo-Dutch vernacular tradition. They are placed using the same geometry as the lintel.






The end elevations fit into the daisy wheel too. Of course! interior and end bents need to be the same size. The plates are not dropped.

This is the first pattern I saw when I began to study how this daisy wheel was used in this barn. I thought the layout began here.
I now think he began, not with this simple end bent, but with the door.



The gable's ridge is 22' high.  22' is also the width of the bent, the side of the square which enclosed the gable end.

The roof pitch was determined by a square using the width of the barn as the dimension.
A carpenter used a framing floor to lay out his bents, mark his mortises and tenons.  This bent could have been laid out on the dirt floor of this barn using twine the width of the barn.   



The daisy wheel was the design for the barn. The carpenter knew how to use it.
The specific 8" daisy wheel probably was the dimension - measured across the diameter - used to locate the holes for the peg: they are all at 32" 4 lengths of the daisy wheel diameter.  The distance between holes for pegs on the braces appears to be 48", 6 lengths. 
Today I have no way to check this. I hope I do in the future.


3/21/2020: This post is a complete revision of a post I first wrote in 2014. 










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