Scribing timbers for structural timber frames

Select, fit and use the appropriate Personal Protective Equipment (PPE), store, maintain and report defects in training and work equipment.

Will be able to Identify the correct PPE and understand storage, maintenance and employer damage reporting procedures for:

• safety footwear
• safety gloves
• safety eyewear
• RPE/dust masks
• knee protectors
• hearing protectors
• hard hats
• high visibility clothing

Be familiar with Provision and Use of Work Equipment Regulations (PUWER) regulations, workshop hazard identification, safe working conditions.

Select the most appropriate scribing technique

Take into account the context to decide which method is most suitable for the task including:

• plumb scribe
• square rule
• distance scribe
• boxing

Safely lift, move, position and secure timbers as required

Explain the health and safety requirements for safe manual handling

Prepare timbers in readiness for scribing

Describe how to assess twist, flatness and condition of timbers at joint location and how to rectify or prepare timber as required for the chosen scribing process

Demonstrate stack/lofted scribing, mark out and loft a lay-up in readiness for plumb scribing

Explain the following techniques and principles

• laying out over full size marks on workshop floor
• use of stools and bearers
• use of setting out lines on timbers
• levelling techniques
• precise location of datum points on reference lines and on timbers
• principles of lofting or stacking timbers
• use of wedges and packers to accommodate varying thicknesses and twists in the timbers

Demonstrate plumb scribe timbers

Explain the following techniques and principles

• referencing horizontal and vertical planes in lofted timbers using levels and plum bobs
• the use of dividers and rules to establish vertical displacement between timbers to be scribed together
• the use of scratch awls and other marking equipment
• aligning a reference plane to remote marks by eye and by using a straight edge
• significance of eye position when referencing plumb and level planes
• the procedures for referencing/adjusting the square end of a brace or strut tenon to the square end of the mortise to be cut

Demonstrate box scribing, box a timber and mark up scarf joints

• Describe the method to establish chalk/ink lines on a timber to produce two perpendicular intersecting reference planes
• Explain choosing datum points to form boxing/reference lines at appropriate length.
• Describe marking out joints using a roofing square with reference only to boxing lines.

Demonstrate remote scribing, establish position and angle of the joint to be cut using remote scribing techniques and copy an existing timber

• Explain how to establish a reference level to ascertain the relative pitch of the joint surface
• Describe how to establish a reference line to ascertain the deviation of the true shoulder of the timber to be jointed ie to calculate the true length of the jointed timber
• Explain how an existing timber can be reproduced from another such that its contact points within a frame are identical.

Demonstrate square rule scribing, establish a reference line on timber, create housings of standard length, depth and width with reference to marked lines and positions

• Explain how fixed reference lines on principal timbers can be used to standardise the length of intermediate timbers
• Describe how the width and depth of the intermediate timbers can be standardised at the joint position making all such timbers interchangeable.

Demonstrate the “two foot rule” scribing and use second-fit scribing techniques to fit a timber to an existing mortise

Explain how a fixed reference line can be used to re-fit a joint by scribing an approximated joint for a second time in situ.