Welcome Guest 

Show/Hide Header

Welcome Guest, posting in this forum requires registration.





Pages: [1] 2
Author Topic: Cruck Frame No 1
Ken Hume
Administrator
Posts: 430
Permalink
Post Cruck Frame No 1
on: October 21, 2016, 19:54
Quote

Image

Following completion of the sill frame for the Oxfordshire Woodland Group cruck barn it was decided to select a matched pair of cruck blades from the storage pile and winch these up and into position on top of the sill frame. The winch fitted to the Land Rover proved it's worth by executing this task in short order.

Image

The cruck blades were pivotted on the centre cross sill to orientate them correctly with their selected "faces" up such that eventually when raised into position these will face out.

Image

A cruck mantle (tie beam) was selected and pulled from the stock pile together with a collar and these were then placed on top of the crucks in their approximate final position.

Image

We are now ready to position, level, line and plumb scribe the first cruck frame.

Ken Hume

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: November 1, 2016, 19:52
Quote

The top ends of both cruck blades were hewn square down to heartwood.

One of the cruck blades was raised on blocks matching the equivalent thickness of the other cruck blade and both crucks were then scribed to cut a lap joint towards the top end of the cruck blades.

Image

After the laps were cut the blocking was removed and then the top cruck blade was positioned over the bottom cruck and then tapped down into position to merge both cruck blades to form the first part of cruck frame no 1.

Image

This type of lapped scissor apex is generally recognised as being an Alcock type "D" apex with only one other of these existing in Oxfordshire and the adjacent county of Buckinghamshire. See :-

ALCOCK, N. W., 1981 Cruck Construction - an introduction and catalogue London : CBA Research Report No 42.

ALCOCK, N.W., MILES, D., 2013. The Medieval Peasant House in Midland England. Oxford : Oxbow Books.

Image

Once the cruck blades were locked together it was possible to position the head of a 5" diameter large rubber commander between the overlapping cruck blades that form the apex. This arrangement illustrates that the type "D" apex could easily accomodate a 5" - 6" dia ridge to which the common rafters will be pegged.

Image

Ken Hume - OWG

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: November 8, 2016, 14:02
Quote

The cruck mantle (tie beam) was then placed into position on the cruck blades on top off a levelled area.

Image

The line of the lap joint was scribed down from the cruck mantle to create line "a-b" and then a laser cross hair level was used to continue this line down the curved sides of the cruck blade with this illuminated line being overwritten by timber-frame trainee Nathan Bonnie using awl points and pencil.

Image

The 1st lap joint in the cruck was then cut out and the mantle dropped down into the lap housing to test the joint.

Image

The sides of the cruck lap joint were then cut by Mark Griffin to provide shoulders for the joint that could be translated and scribed to the cruck mantle joint.

Image

The cruck mantle lap joint was then cut -

Image

- and dropped down into the cruck blade lap joint.

Image

Ken Hume OWG

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: November 8, 2016, 14:33
Quote

Following the fitting of the cruck mantle (tie beam) the cruck collar was then moved into position and the same process employed to mark the cruck collar lap joints was repeated by Andrew Jarvis and Mike Jenn (Men's Sheds) to scribe the crucks & collar in very challenging wet weather conditions.

Image

Several days later when the weather had improved Course instructor H Russell then cut the cruck collar lap joints.

Image

Ken Hume OWG

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: November 18, 2016, 19:17
Quote

The rain eventually stopped and progress was then made by Andrew Jarvis laying out and scribing the first principal rafter -

Image

- followed by fitting the first principal rafter to the cruck mantle

Image

and then the principal rafter to the collar -

Image

and finally the principal rafter top was profiled with the Wetterling's hewing axe to match the cruck blade.

Image

Although the mortice and tenon joints were plumb bob scribed the laser level was used to check the accuracy of the old traditional work methods and this confirmed that the old ways are surprisingly accurate !

Image

The principal rafter was then pulled into joint with the cruck frame.

Ken Hume OWG

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: November 25, 2016, 19:54
Quote

The two principal rafters have been profiled and fitted to the cruck apex -

Image

and jointed to the cruck mantle (tie beam) and collar using mortice and tenon joints

Image

The frame even though not yet pegged is extremely robust.

Image

The final primary timbers needed to frame cruck no 1 are the side wall posts. These timbers will be jointed to the underside of the cruck mantle (tie) beam and then profiled and skew pegged to the side of the cruck foot.

Image

Checking the hewn timber stock pile reveals that these timbers have not yet been hewn and so its off to the woods to fell a suitable tree that will yield the necessary stock.

Ken Hume OWG

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: November 28, 2016, 20:23
Quote

The felled larch tree was bucked into 8 ft lengths and extracted to the bunks for hewing conversion by Nathan Bonnie.

Image

The finished wall post was laid up over cruck frame no 1 ready for mark up and cutting.

Image

Ken Hume OWG

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: December 4, 2016, 08:42
Quote

After layout and scribing of the first corner post for cruck number 1 it was determined that this would require to be tapered at the top end to more closely match the end dimensions of the cruck mantle.

Image

Cutting the post taper with the Wetterlings hewing axe was undertaken a little more care and caution than usual removing a number of skinny layers to produce the required profile.

Image

The pink Douglas Fir heart wood is now more evident.

Image

The 2 corner wall posts and 2 door posts have now been hewn and laid up for scribing.

Ken Hume OWG

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: December 12, 2016, 09:03
Quote

Given that the corner and door posts have been converted from a recently felled larch tree then cutting and jointing these green timbers into air dry components (tie beam) needs to be taken into account. This essentially means making "tight" close fitting joints that are bound to loosen somewhat as the post material dries.

Image

The post tenons and shoulders have been planed down until a slight interference fit is acheived requiring the joint being pulled up tight using a come-a-long.

Image

The door post head joints are housed to ensure good bearing over their width & depth and to ensure that these posts are not free to rotate under the action of door opening.

Because both the cruck mantle [tie beam] and door post are made from waney timbers it has been necessary to employ "double cutting" of same. In this process the tenon is only partially cut to length and then offered up to the mortice with the gap between the tenon shoulder and mortice housing then being measured using dividers and then this gap dimension being transferred to the post to define the line of the finished tenon shoulder cut - this results in a perfect shoulder fit.

Ken Hume OWG

Ken Hume
Administrator
Posts: 430
Permalink
Post Re: Cruck Frame No 1
on: December 15, 2016, 20:54
Quote

The door posts are fitted into housed mortices (top & bottom).

Image

The top tenon on the door post is partially inserted into the housing ready for "double cutting".

Image

The gap between the housing and top shoulder is measured using dividers and then this is applied to the underside tenon shoulder and then the double cutting allowance is cut to the scribed line

Image

The bottom of the door posts are cut with 2" long stub tenons. These are not pegged but fit into a mortice cut in the sill housing.

Image

The top of the sidewall (corner) posts is cut and scribed around the cruck mantle (tie beam) to ensure maximum bearing around and on top of the post due to the excessive waney edge present on the smaller end of the cruck mantle. The post top is cut with a 6" wide tenon and a bare faced shoulder to help reduce any weakness in the cruck mantle due to the mortice needed for same interfering with the principal rafter mortice cut into the top surface of the mantle.

Image

The bottom end of the sidewall post needs to be cut with a profiled end that matches the slope of the bottom of the cruck blade together with a step lap seat that will carry the vertical downwards post load. The Wetterlings hewing axe was used to remove the surplus wood in short order.

Image

The sidewall post and cruck blade will be joined together with two stout oak pegs - one horizontal through the set lap housing and a second driven at a downwards angle to prevent the joint moving apart i.e. as load increases the sidewall post this will tend to slip down the angled peg towards the foot of the cruck blade.

Image

Cruck Frame No 1 nears completion with only the second sidewall corner posts needing to be scribed and fitted.

Image

Ken Hume OWG

Pages: [1] 2
Mingle Forum by cartpauj
Version: 1.0.34 ; Page loaded in: 0.029 seconds.

Events Calendar

September  2018
Mon Tue Wed Thu Fri Sat Sun
   
  1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

Training

Download our .pdf here.

Up Coming Events

Annual General Meeting Saturday 15th September 2012 will be held at Wytham Wood, please contact us for details.