Saturday, 21 April 2012

Filing lamb’s tongues - inspiration from George Walker

A few days ago, I was starting one of the last stages on a pair of Bayfield rabbet planes - filing the lamb’s tongues where the chamfers terminate. As I was preparing to do this, George Walker immediately came to mind. Over the last several years, George has been introducing design as it relates to woodworking and furniture making. This is no small task, and (I think) is more challenging than the technical aspects of woodworking. George has been going to great lengths to demystify and break down design elements into more manageable pieces. Taking seemingly complex shapes and profiles and revealing the simple, building blocks behind them. It was the notion of breaking things down into simple elements that prompted this post. 

These 2 planes are scaled down versions of the full sized Bayfield I made last year. The original Bayfield was 1-1/4" wide and 9" long. The larger of these planes is 3/4" wide by 7-1/2" and the smaller one is 5/8" wide and 6" long. The 3 different sizes meant I needed to scale the lambs tongues accordingly.

A lambs tongue can look like a somewhat tricky detail to add, but when you break it down, it is really quite simple. You only need 2 files - a triangular file and a full round file.

The 2 arrows show the locations for starting with each of the 2 files. 

This photo show the setup. The plane is elevated on a block of cedar so I can take a longer file stroke. The clamps are somewhat centered so I have lots of room to work around the edges. 2 clamps so it does not pivot and scratch the metal surface.

These are the 3 files for the 2 different sized planes. The top file (1/4") is the round file I used on the original Bayfield. The second one down is also a full round - 3/16". The third file is a full round - 5.32". The file at the bottom is a triangular file with a flat on the edge. I used this same file for all three planes.

This is the first cut. Notice how the file is parallel to the plane. The black sharpie line is where I file too. I am not sure of the angle - I just do it by eye. I file to the sharpie on one side and until it looks right on the other side. It is really important that the triangular file is dead center on the top scribe mark. 

This is the round file in the center of the second scribe line. You want to maintain the same angle and keep it parallel to the body of the plane.


This is what it should look like. You can clearly see the triangular cut on the top and the round cut below it. Notice how the two cuts form a fairly crisp peak between them - this is when to stop filing. You will also notice that the flat edge of the triangular file is in line with the sharpie baseline.

With the round file, round over the peak - show above. And that is it - the lambs tongue is done. 


Well... not really... we have to file the rest of the chamfer without ruining the lambs tongue. I do this by using a file with a safe edge, and deliberately filing another peak above the lambs tongue (the black arrow). I am essentially making a fence for the file to bump up against. I like to file fairly fast - and this fence gives me just enough protection. 

The photo above shows the chamfered edge with the fence still in place.  


The fence now removed.

Once the opposite side is done and the top edge is done, it is time to do the rounded corner. 

The above photo shows what the rounded end looks like before rounding. You will notice that the flat chamfers meet at the center of the radius - this is a good sign and helps me know that everything is lining up correctly.

To file the radius, start with a coarse file and treat it like a series of flat segments. Don’t worry about getting it round yet - focus on keeping the angle of the chamfer consistent from one end of the radius to the other. Once it looks right (the above photo looked good to me)....

.... then you can use a finer file to start blending the flat segments into a rounded chamfer. 

The above photo shows the front corner. The chamfer has been further refined at this point - you will notice the texture has changed. This is the surface left from drawfiling. The corner is not quite right, but is very close - close enough to move to the last file.

This photo shows the fully shaped and polished chamfer.

And the other end of the plane.


The completed pair.

I will post photos of this pair of planes shortly.


Blogger David said...

Wow, Can't wait to see the entire planes!!! As usual, you do real nice, you are an inspiration to many of us!!

21 April 2012 at 13:05  
Blogger Pedder said...

Oh Konrad,

thank you so much for this tutorial! I love the lambs tongues from the first time i saw them and wondered how to do.


21 April 2012 at 14:26  
Blogger Cory said...

Fantastic! Thanks so much for this!

21 April 2012 at 18:09  
Blogger Kevin Brehon said...

Thanks for showing the way. If you are ever at a loss for something to post about, more on the metal work you do would be appreciated.

21 April 2012 at 21:36  
Blogger Jamie said...

You make it look so easy, and I know that there are many years worth of experience going into every detail of that lambs tongue, great post, I just love your work.

all the best


22 April 2012 at 03:48  
Blogger Matt Owen said...

Love the tutorials, Konrad! This one is fantastic. I agree with Kevin. If you're ever at a loss for what to post, showing us how you work is always appreciated.

22 April 2012 at 22:28  
Anonymous Chris Bame said...

Nice post Konrad,

Great tutorial on the lambs tongue. Love the way the infill works on that style plane.
Can you tell us a little about your files, brand, etc

Cheers Chris

23 April 2012 at 10:04  
Blogger Konrad said...

Thanks everyone.

Chris, the round files I use are nothing special - they are just chainsaw files. The triangular file is also pretty run of the mill... I think it is a Nicholson and pretty readily available.


30 April 2012 at 09:18  

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