6. Detailed Instructions – Laying Out and Cutting the Connector

Feb 08, 2021

 

 

Laying Out and Cutting the Connector

Laying Your First Log

If you’re working offline (in the forest), you can download the instructions here: Lesson 6 Laying Out and Cutting the Connector

This is a core Module and we highly recommend that you watch video 6 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!

In the previous module we went through the steps to layout and cut the receivers. Now we want to look at the process to fit the next logs to those receivers, including scribing the matching connector.

Laying a Log  

The complete process of “laying” each new log can be broken down into three main categories:  

  1. Lining up the Log,
  2. Scribing the Log,
  3. Cutting the log.

 

Lining up the Log

Lining up the log refers to the process taken to maneuver the log once it is set on the receivers to get it “Lined Up” into its desired position and ready for scribing. Before we can scribe, the log must be sitting in the exact orientation that we want it to rest once notched down. We want the top of the log to be reading level and the side faces to be sitting plumb at which point it is ready to scribe. When we scribe and cut the connectors the log then goes straight down in equal amounts on each end and remains in its same level and plumb orientation. Lining up the log is a consistent 3 step process that will be repeated each time we set a new log on the wall.

Remember each receiver that we cut is custom sized to a pre selected log that you chose. Set that pre selected log on its corresponding receivers now.

 

  1. Trim to length Ensure that there is adequate (extra) length at both ends of the log and trim it to rough length, so that it has an extra 2” of length at each end. (Building width + 4”). We build the complete walls with 2” of trim then finish cut all the tails once the shell is completed.

 

Trim, equalize, and plumb the log.

 

  1. Equalize the log Each time that we introduce a new log to the building we have the opportunity to check and adjust the top of our walls to ensure they are remaining level. This is accomplished by equalizing the log prior to scribing it. Equalizing the log simply means that we adjust one end of the log so that both ends of the log are sitting at an equal height from the floor prior to scribing.

Measure the total height from the floor to the top face of the log at each end of the log. If there is a difference in height of more that an 1/8”, use a wedge placed between the bottom of the log and the top of the receiver it is sitting on to shim the lower end up so that both of the top face heights are equal. The measurement to the top of the log is now equalized and in proper height alignment to be scribed. The gap between the bellies of the two logs may not be even from end to end after shimming but it is more important that the tops of the logs be equalized, as this is how we ensure that we keep our walls level as we build.

  1. Plumb the log As we mentioned above, before we scribe the connectors, the log must be sitting in the exact orientation that we want it be once notched down. Using a 24” level referenced on the exterior face of the log check to see how the log is sitting. Using another wedge placed under the end of the log, roll the log in or out slightly until the sawn or hewn faces are sitting plumb. If there is a minor twist in the timber split the difference so that each end is slightly out and the middle reads plumb. Draw a plumb line reference on each end of the log, this will be used later to check plumb after cutting the dovetails.

 

Always reference the exterior face of the wall logs when plumbing the log during the line up process prior to scribing.

 

Scribing the Log – Laying out the Connector (Lower Face)

Scribing the log is the act of accurately transferring the shape and parameters of the receiver below onto the log above so that we can layout and cut an exact matching connector.

**We recommend that you watch Video 6 prior to continuing with the following steps as it will help to clarify the techniques. Again, this is a repeatable process and you will have many chances to perfect the steps and practice them in exactly the same order.**

  1. Find the Scribe Setting With the log equalized we must now find our scribe setting. The scribe setting refers to the distance set between the pin point end and the pencil end on your scribes. This is simply the amount that you want the log to be let down after you have cut the notch.

To determine the scribe setting, measure the space between the underside of the log that we just lined up and the log below it. Measure the space at each end of the belly gap, just inside each tail. The most accurate way to measure this is by using the scribes themselves. Place the scribes in the space between the logs and open them up as much as you can. Do the same at the other end and compare. If there is a difference, and there will usually be a slight difference from end to end after equalizing, use the largest of the two settings and subtract ¾” from this measurement. This will give you your measurement for your scribe setting.

If we do not subtract the ¾” from the full belly gap measurement prior to scribing, then our log, once notched down, will drop too far down and the belly will contact the top of the log below. We want to be left with a ¾” gap between the two logs once notched down. By closing up our scribes ¾” we are taking less wood out of the notch meaning it will It be let down less and we will be left with our desired chink gap. As mentioned above, we subtract the ¾” from the largest opening between the logs. By doing this we ensure that the finished chinking gap is ¾” at the widest point and any variances get smaller not larger than the ¾”.

 

Scribe Setting = Largest Point of Belly Gap – ¾”

 

 To scribe the connector, we use our level and our scribes to mark out the profile of the receiver onto the log above.

  1. Draw 3 Exterior Vertical Lines Using a level, draw plumb lines on the exterior face of the log that define the width of the perpendicular log below. To do this hold the level plumb and pressed against the exterior face of the tail below to mark the outside width of building line.

 

First Line – outside width of the building.

 

To define the shoulder cut for the connector, hold the level plumb and pressed against the interior face of the tail below and draw a line.  Carry these lines up to roughly to the mid point of the log. Do not draw the lines all the way across face.

 

Second Line – shoulder cut line.

 

Using your level, draw a third line 3/8” to the inside of the shoulder cut (towards the centre of building). This is the line you will cut on, creating the chinking set back.

 

Third Line (Chinking set Back): 3/8” to the inside of the vertical shoulder line.

 

Three exterior vertical lines.

 

A Note on the Chinking Set Back (Line 3) – by overcutting the shoulders only on the exterior face of both the receiver and the connector, we are removing some additional wood that allows room to install a foam backer rod for insulation as well as a generous bead of chinking. Without this space we are limited to only a thin bead of caulking to seal the joint.

  1. Draw 2 Interior Vertical Lines Using a level, draw 2 plumb lines on the interior face of the log that define the width of the perpendicular log below. Carry these lines up to roughly the mid point of the log height, do not draw the lines all the way across face. There is no additional chinking set back line on the interior.

 

   

          Draw 2 plumb lines on interior face to define width of the log below.

 

Two interior vertical lines.

 

  1. Mark 4 Tail Tics With your scribes set at the appropriate size to result in a ¾” chink gap (as described above), you must make 4 reference marks, 2 on the exterior face and two on the interior face, that when joined up will define the slope of the receiver.

 

   

Mark 2 tics on exterior face (photo on left), and 2 tics on interior face (photo on right).

 

Starting on the exterior face, set the pointer of the scribes on the receiver tail below, at the furthest down hill point. Holding the scribes in a level position make a small arching tic that intersects the plumb line above (the first plumb line you made on the exterior face). Make a second tic at the top of the receiver slope that crosses the exterior shoulder plumb line (the second plumb line you made on the exterior face). Note: This tic crosses the shoulder plumb line not the chinking set back plumb line. Following this same approach, make two similar tics on the interior face that intersect the two interior plumb lines. If this is a full length log, repeat the same scribing process at the other end of log.

 

5 AND 4 Rule: Once you are done scribing, always double check that you have 5 plumb lines and 4 tics at each tail.  5 plumb lines = 3 exterior lines (including chinking set back) and 2 Interior lines.

 

5 and 4 Rule; 3 lines and 2 tics on exterior (photo above), 2 lines and 2 tics on interior (photo below).

 

Cutting the Log

  1. Remove the Log from the Wall Take the log off the wall and set it on some cross timbers so that it is at a comfortable working height. Roll the log over so that the connector to be cut is now facing up.
  2. Connect the Lines Before we can cut, we must connect all the lines and tics that we created during scribing. Using your square as a straight edge, first join up the reference tics on the faces. Draw a line on the exterior face that connects the two reference tics. This angled line must continue through the shoulder plumb line and carry on the additional 3/8” across the chinking set back shoulder line. The line must also be extended to pass through the 2” of trim and carry on to the end of log. Connect the two tics on the interior face in the same manner. Note that there is no chinking set back shoulder on the interior face. Next connect the interior face line and exterior face line across the end grain of the log. The tail faces are now defined!

 

 

Connect the 2 reference tics on exterior face, notice how it extends to the end of the log.

 

 

Connect the 2 reference tics on interior face, notice how it extends to the log end.

 

Lastly, we need to connect the shoulders from the exterior to the interior across width of the log. Using your square, draw a line across the top face of the log running from the vertical chinking set back line on the exterior face to the approximate center of the log thickness. It may be necessary, to extend the length of the interior shoulder line so that it reaches the upper corner of the timber. If so, use a straight edge placed on the existing line and carry it up the remainder of the face to the top of the log.

 

Using your square, draw a line across the top face of the log running from the vertical chinking set back line on the exterior face to the mid point of the top face.

 

Using a straight edge, draw an angled line that connects the interior shoulder plumb line with the chinking set back square line (the square line that was just drawn across the top face to the midpoint). These lines should meet roughly at the midpoint of the log width.

 

Using a straight edge, draw an angled line that connects the interior shoulder plumb line with the chinking set back square line.

 

Notice the angled line connecting the chinking set back square line with the interior plumb line.

The connector tail is now fully drawn!

 

  1. Score the Lines Scoring is the same process as we described in the previous Module 4 – Cutting the Receiver. Don’t neglect this step as it is a crucial step to cutting a clean line.
  2. Cutting The steps to cutting the connector are essentially the same process as cutting the receiver. The only notable difference is in the orientation of the angle cut of the tail. The angle of the tail on the connector is, in theory, the exact same angle as the receiver since one was scribed from the other but the receiver cut angles across the width of the log while the connector angles down the length of the log.

The Receiver and the Connector both run at the same angles, only perpendicular to each other.

 

One note of caution when brushing the connector tails: be aware that the angle between the shoulder and the tail face is less than 90 degrees. Therefore, the saw bar must be tipped away from the shoulder while brushing the connector tail face to allow the saw chain to get into the corner without inadvertently scarring the shoulder with the chain.

 

Check the Final Fit

Once the connectors are cut, place the logs back on the wall. When you are inspecting the fit of the dovetails, the two main characteristics to look for are plumb and tight. Firstly, using the previously drawn plumb reference lines on the end grain, check that the log is sitting plumb now that it is notched down. Secondly, inspect the fit of the two mating faces. The joint where the two logs contact each other should be crisp and tight with even contact across the visible surfaces.

If there are any corrections that need to be made to improve either of these factors, we do so by removing high spots with the small grinder. The log is lifted off the receivers, moved so that it is not hanging above the work zone, and the modifications are made on the receiver face. We only work the receiver because this means we do not have to set the upper log down and roll it over each time to get at the connector.

The flatter and smoother we can make our faces the better the chance we have for a perfect fit the first time and what a great feeling that is! Some logs are more stubborn than others and it may require removing and finetuning the tail several times to achieve the ideal fit. I would like to challenge you and encourage you to take the time required to make your tails perfect every time. Think of it as leaving your signature on every joint you fit.

For some tips and techniques on finetuning the fit of your tails, view video 6B.

 

 

Using some short practice pieces, go through the full process of layout, scribing and cutting for both the receivers and the connectors. We recommended that you do this several times until you are comfortable with the procedures (in the correct sequence) and skills before beginning your full length logs.

 

The following pages contain our 10 Steps to Laying a Dovetail Log Guide as well as a Dovetail Cheat Sheet to help remind you of the most important things to keep in mind when fitting your logs. The overall process is straightforward but there are many specific steps involved that need to be executed in a particular order. 

10 Steps to Laying a Dovetail Log Guide

Dovetail Cheat Sheet

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

Lesson 6 Laying Out and Cutting the Connector