5. Detailed Instructions – Laying Out and Cutting the Receiver

Feb 08, 2021

 

Laying Out and Cutting the Receiver

(Practice Makes Perfect)

If you’re working offline (in the forest), you can download the instructions here: Lesson 5 Laying Out and Cutting the Receiver

This is a core Module and we highly recommend that you watch video 5 prior to reading the notes. Learning the layout steps through written instruction alone can be quite challenging but if you’ve watched the demonstrations and explanations in the video, you will be able to follow these steps and repeat them!

It’s almost time to fire up the chainsaw! Before we begin building the log shell, we want to go through the layout and cutting procedures on some practice timbers.  The following are some terms and skills that we will be dealing with once we start cutting.

 

Practice timbers are set up!

Chainsaw Techniques and Terminology   

Notching: Notching is removing the required wood from one log to create an exact shape that allows it to be closely fitted together with another log in a secure, tight fashion. This forms the locking connection in the corners of a building. Most notching techniques require that shaping be done to both the members being joined together (the receiving face of dovetails, or the saddles on round logs). Notching is done primarily with the chainsaw and with a chisel, or a small grinder used to finish to the line.

 

Notching

 

Brushing: Brushing is a chainsaw technique used to further smooth out a sawn surface, usually prior to grinding. This is done by holding most of the weight of the chainsaw in your arms so that the teeth barely contact the surface of the wood. With the bar held in the bucking orientation, the saw is moved side to side across the wood surface to be flattened. When brushing, the teeth of the chain are used more as a planer than a sawing tool. Accurate and efficient brushing is one of the most important skills for a log builder. It is also one of the more tiring movements.

 

 

Brushing

 

Slabbing: When cutting a log along its length (with the grain) it is referred to as ‘slabbing’ or ‘ripping’ (sometimes called ‘flatting’). Typically, this is done to create a lengthwise flat section on the log. Examples of logs that require slabbing include:

  • the bottom side of the first round of logs: they need to be flat to sit on sub floor,
  • the bottom of a window opening in the ‘sill log’ and the top of a window opening in the ‘header log’,
  • the cap logs need to be flatted to a matching finished height.

A powerful chainsaw is helpful for slabbing, as well as a ripping chain; a chain designed specially for cutting with the grain.

 

   

Ripping

 

Bucking: Bucking is cutting perpendicular to the log’s length, also known as cross cutting (as you would cut firewood). It is used for rough cutting logs to length and when finish trimming log ends once the building is complete. Being able to make a clean, plumb end cut on a log is an important skill in log building. It requires good technique, much practice, and a properly sharpened chain.

 

Bucking

 

Plunging: Plunging is inserting the bar of the saw into a log tip first. This is done when cutting a mortise or a blind notch. Caution must be taken when plunging because you are working in the kick back zone.

 

Plunging

 

Kickback:

When the momentum of the chain is stopped by the log, the energy is transferred back in the opposite direction; it can cause the chainsaw to be thrown back toward the operator. The top quadrant of the bar is considered the “Kickback Zone”. It is recommended that working with the tip of the chainsaw is avoided. However, there are times in log building that it is necessary. Always work on the bottom side of the tip; be aware that kick back is a potential and never let your guard down.

 

Scribing: Scribing is the act of accurately transferring the shape and profile of the receiver below onto the log above so that we can layout and cut an exact matching connector. In dovetail construction, scribing is done with the level and the scribes.

 

Scribing

 

Scribe Setting: Scribe setting is the distance that you set between the two points (steel pin and pencil) of the log scribes when marking out the connector. This is simply the amount that you want the log to be let down after you have cut the notch.

The Chinking Gap: The chinking gap is the space remaining between the bellies once the logs are notched down; typically it is ¾”. Once the log shell is completed, the chinking gaps will be fitted with a foam backer rod and sealed with a layer of chinking material.

Grab your tools. Watch the video to see how to set up your practice station using some short logs and you can go through the following steps with us on your demo blocks before we hit the big money logs!

As previously described, we know that each completed dovetail joint consists of a receiver cut on the lower log and a matching connector cut on the upper, perpendicular log. The layout of the receiver and the connector are the two core procedures (Lesson 5 and Lesson 6) for creating the dovetail notch. Though there are numerous specific steps for these 2 layouts, once you’ve mastered it, it is the repeatable process used throughout the building. Let’s take a close look at the layout and cutting steps for each face of the completed notch.

A Job for the Square or the Level? 

When marking out the receiver and the connector tails, we must use both the level and the square. We use each for a specific purpose in the layout. The 24” level is used when we are marking vertical plumb lines and horizontal tail lines on the interior and exterior faces of the log. The 24” framing square should be used when marking the shoulder lines that are connected across the top and bottom faces.

 

Familiarize yourself with the orientation of the different faces of the log, and the names used to describe them.

 

The wider, longer 24” portion of the square is known as the blade. For the most accurate layout, the blade side should be used to register along the edge of the timber and the tongue, the narrower, shorter 16” portion is used as a guide to make our marks against.

 

Laying Out the Receiver (Upper Face)

** These steps will be easier to visualize after you’ve watched the video; it is a repeated process that will take several times to perfect. But don’t worry, you’ll get many opportunities to master it.**

A receiver profile must be cut on the upper face of the log to prepare it to receive the next perpendicular wall log. Follow these steps to lay out the receiver. View a full demonstration of the layout process in Video 5.

  1. The first thing we need to do, before we layout any receivers, is choose which log will be fitted onto the receivers that you’re about to start. Choose the next log that is going to go on the wall and measure the exact thickness of this log at each end where the joinery will happen. There can be subtle differences from one timber to another based on milling quality and moisture content etc. By laying out each receiver based on the next log’s specific width, it helps us maintain accurate building widths as we build the walls up. Jot that measurement down on the top of the log where the receiver will be cut. This measurement will be used to lay out the length of the receiver later in Step 4.
  1. Prior to beginning any receiver layout ensure that the log is cut to “rough length” with approximately 2” of additional trim left on each end (building width plus 4”). We build the walls to full height leaving the extra length on all of the tails. This gives us a little bit of tolerance when lining up our logs prior to scribing. Having the extra sacrificial length on each tail during construction also allows us to be able to pound on the end of the logs with the hammer to assist in moving them during lining up. With the additional length we don’t have to protect them from marring the vulnerable end grain since the damaged fibers will later be trimmed off. Once the walls are completed to their full height then we trim all the tails from top to bottom.
  1. Always start the receiver layout on the exterior face of the timber and at the outer dimension of the building width. Using a level to carry up the location from the log below (*see note below for first half log) and make a small but visible reference mark on the exterior face where it meets the top side of log. This mark will then represent the outer dimension of building length.

 

Start receiver layout on exterior face, at the outer corner.

 

*If this is the first half log of the building, then you will measure and mark appropriately the outer dimension at each end of the log based on the building width. Watch Video 7 and refer to Lesson 7 in the First Half Round Module.

  1. Measure in (towards the center of the log) from the building width reference tic made in step 3 the appropriate distance that will define the width of the receiver as well as locate the shoulder vertical line. This distance is the measurement that you obtained and noted in step 1; it is the thickness of the next perpendicular wall log to be scribed to the receivers we are laying out. Mark the location with a tic on the exterior face. This mark will now define the shoulder location (the vertical cut).

 

Measure in to define the width of the receiver.

 

  1. Using a square, transfer this location across the top face of the log and make a tic on the far side of the top face. Do not draw this line in solid, just make a second tic.
  1. On the exterior face, move in (towards the center of the log) a further 3/8” from the second reference mark (the shoulder location established in Step 4) to define the chinking set back gap. Using a level draw a plumb line down from this point, on the exterior face to roughly the centre point of the log face. Also square a line across the top face of the log roughly to the midpoint of the log thickness. This defines the shoulder of the notch on the exterior half which includes the chinking set back.

 

Move in a further 3/8” to define the chinking set back.

 

   

Draw a plumb line down the face and a square line across top to midpoint.

 

  1. To mark the shoulder location on the interior face, draw a plumb line down from the tic that was transferred across the top face in step 5.

 

Use the tic from step 5 above for the interior face plumb line.

 

Carry the plumb line to the centre of the face on the interior face.

 

Carry this plumb line down to roughly the centre of log face. On the top surface of the log, draw an angled line that connects the top of the interior plumb (shoulder) line to the line that was drawn earlier from the chinking set back, to the mid point of the top surface. This defines the interior shoulder.

 

 

Draw angled line to connect interior plumb line to exterior chinking set back line.

 

Note the orientation of the shoulder lines on the top face showing the chinking set back on the exterior half, and the angled shoulder line from the interior half.

 

  1. With the shoulder lines complete, we now draw in the horizontal tail lines. Always start the horizontal tail layout on the interior face. The first layout mark is the receiver face height. To find this point measure up from the top surface of the perpendicular log below (or the floor if it is the first log) an amount that is:

1/3 of (the height of the next log + a chinking gap)

For example, if we are using 12” tall logs and a ¾” chink gap, one third of 12 ¾” would be 4 ¼”.

*This formula will be used to determine the receiver face height for every receiver cut in the building.*

 

Mark the receiver face height location on the interior face of the log from the top surface of the perpendicular log below. Then using a level, draw a horizontal line at this height across the log face from the interior plumb shoulder line to the end of the log. Remember that if we are using dimensional timber throughout, then the shoulder height will be the same measurement for all of the receivers.

 

 

Mark the receiver face height on interior face and draw a horizontal line to the end of the log.

 

Receiver face height “X “will always equal: (height of the next log + a chinking gap) divide by 3.

 

  1. On the end grain of the log, using a level, carry a horizontal reference tic across the width of the log. Do not draw in a solid line, only make a reference mark.

Horizontal reference tic.

 

  1. From the reference mark on the end grain drawn in step 9, measure down the appropriate ‘notch drop’ amount based on the thickness of the logs being used. For example, 2 ¼” notch drop for 8” thick logs: refer to the table of common notch drops on the Half Dovetail diagram in Module 2. Draw an angled line across the end grain that connects the first tic from the interior to the lower tic at the exterior of the log end. This defines the slope of the receiver.

Measure your notch drop.

 

Draw angled line across end grain.

 

Notch drop angle drawn on the end grain, (the lower connector is shown for reference sake only).

 

  1. On the exterior face of the log, use your level to draw a horizontal line that starts at the end of the sloped line on the end-grain, and continues to the vertical chinking set back line. The receiver layout is now complete!

    

Horizontal line connecting sloped line to chinking set back line.

 

The horizontal receiver line on the exterior face completes the receiver layout. (The lower connector is shown for reference sake only).

 

  1. Always double check your layout before you start cutting especially while you are familiarizing yourself with the layout process. The main 3 things to check are (1) that you have a connected series of lines that outline the complete receiver, (2) that the receiver is sloping to the exterior of the building, and (3) that the chinking set back lines are properly laid out as we saw in step 7.

 

Always execute the layout in exactly the same order so that it becomes a well learned and easily repeatable process.

 

When first reading through these steps, the layout can be daunting. We highly recommend that you watch the videos and use these written steps as a reference. Ensure that you repeat them in the same order each time so that they become habitual. Refer back to the videos and the notes as often as you need to.

 

Using the Chainsaw as a Finishing Tool

The chainsaw is a very effective tool for quickly chewing through a piece of wood. It can be helpful and timesaving but it can also make a mess of a piece of wood very quickly if not used with proper skill and technique. The role of the chainsaw in the log builder’s tool kit is to remove the bulk of the unwanted wood efficiently. The chain has no aversion to crossing our precious pencil lines and it is up to us, as the operators, to develop the skills that will keep the powerful tool on the right side of the line. One crucial step to cutting crisp straight lines with the chainsaw is scoring.

Scoring the Line

Before we make any cuts with the chainsaw, we want to score all pencil lines that we will be following. Scoring the line means cutting along all relevant pencil drawn lines with a sharp knife prior to cutting with the saw. The chainsaw is an aggressive tool that easily cuts through the wood but it isn’t an inherently smooth cutting tool. By scoring the lines, we are severing the fibres on the surface of the faces of the timber at the exact location that we want the cut to be clean and crisp. This means that if there is any breakout from the chain (and there will be, especially when cross cutting) that it only runs as far as the score line and then stops. When scoring, it is advised to pull the knife blade along the line in short ¼” bursts instead of trying to run a continuous straight line. It is helpful to make a first pass without pushing too hard, as this is easier to control. Make a second pass exerting more force as you follow the guide of the first pass. This can be a tedious step (especially in dryer wood) but it is an important one so take your time and score deeply.

 

                 

Note the tear out on the side where it was not scored before being cut with chainsaw.

 

Cutting the Receiver 

View a full demonstration of cutting the receiver in Video 5.

  1. Score all of the cut lines except the notch drop that is drawn across the end grain it does not need to be scored.
  2. Always cut the shoulders (the vertical cuts) first. The shoulders are cut in two steps. Following the shoulder score line, we cut halfway through the log width from the interior side of the log and the remaining half from the exterior side. It is important that these cuts meet at approximately the centre of the log width and that they remain in contact through the full height of the shoulder cuts. It is ok if these cuts overlap a little as this will all be hidden after the wall is complete. Once the shoulder lines are cut, this defines the stopping point of your next cut which will be along the horizontal face lines.

 

   

Always begin with vertical shoulder cuts.

 

  1. Cut along the horizontal lines that define the face of the receiver. Depending on which end of the log you are cutting, you may be standing facing the interior or exterior face of the log. Prior to starting the cut, ensure that you are holding the saw with the motor facing up, and that you will be starting the cut with the bottom of the bar. This will mean you are on the proper side of the log. If the top of the bar is closest to the end of the log when the motor is in the upward position, then step around to the other face of the log to start the cut.

Start with the bar entering the wood at the corner of the log that is closest to you, where the horizontal face line meets the angled notch drop line on the end grain. Depending on which end of the log you are cutting, the bar will have to be angled in an upward or downward position to follow the notch drop line.

 

Start with the bar entering the wood at the corner of the log closest to you.

 

  1. It is a practiced skill to be able to cut accurately while following the horizontal face line as well as the angled notch drop line. Work your way along each line a little at a time until you have the proper angle established. Because you can only see one face of the log at a time it is important to make this cut in short rocking motions, alternating cutting action from one face to the other. Cut a couple of inches along the line that is readily visible to you, moving the bar only on this face of the log. Now set the dogs of the saw (the metal teeth) into the face of the timber. Don’t worry, the marks left from the dog teeth will be on the waste side of the cut. Lean over the timber so that you can see the horizontal cut line on the opposing face and rock the bar so that it cuts a couple inches along the far line. Repeat this alternating process until you reach the vertical kerfs of the previously cut shoulder lines.

Care must be taken when leaning to view the cut line on the far side of the log. Do not lean any more than necessary and maintain a safe distance from the saw bar.

You do not want to finish this cut with the chain meeting both interior and exterior shoulder cuts at the same time as this can cause the bar to jump into the kerf of the shoulder cut making an unwanted scar on the log. Instead, continue the rocking motion cutting a little at a time on each side, and meeting the shoulder kerf one face at a time. It is good practice to leave a small triangle of holding wood and pry or “pop” the tail waste piece off with the bar. This will provide you with more control when the vertical and horizontal cuts intersect. The holding wood can easily be brushed down once the waste block is removed.

 

Notice the holding wood in the notch.

 

  1. Carefully brush the surface of the receiver face with the chainsaw. Once you are practiced at the skill of brushing you will be able to work right down to the score line. Be careful when brushing in the corner where the horizontal face and the vertical shoulders meet. Take care not to tip the bar and nick the shoulder. A chisel can be used to clean up the intersection if desired.

 

Carefully brush the surface of the receiver.

 

  1. A final clean up of the shoulders and receiver face is done with the 4 1\2” grinder. Our goal is to precisely remove all the material above the scored line without taking away the line. When grinding, work your way from the outer edge of the receiver face in towards the center, doing so from each edge of the tail. This will allow you to be able to better view the critical area of face without the grinder disc blocking your line of sight.

 

Final clean up with the grinder.

 

  1. Keep in mind that the only visible mating surfaces of the joint, once fitted, are along the tail on the exterior face and along the end grain. For this reason, we want to concave the surface of the receiver slightly to encourage the outer visible edges to be very tight and avoid hang-ups in the center of the tails when the receiver and connectors meet. Check for an appropriate concave after completing the receiver by drawing your square along the length of the tail. The square should only contact the outer edges and there should be a visible space under the tongue through the center of the receiver. Remember that this gap needs to taper out and disappear before the square reaches the end point of the mating surface of the tail. If the concave carries past the point where the edge of the connector will sit, this will result in a visible gap in the joint.

 

Look for the concave gap!

With the receivers completed, it is time to get on with the fun: scribing your first log!

 

If you’re working offline (in the forest), you can download the instructions here:

Lesson 5 Laying Out and Cutting the Receiver