Tuesday, March 13, 2012

Tech Tip Tuesday

Paddle making class has finally picked up pace!

The net to last glue-up of paddle blanks has taken place:

After the paddle stock has been dressed or the paddle blank is glued up as above, we then draw a centerline down the middle of the board or the glued up paddle.  We then use our templates to draw the blade outline onto the wood.  The bandsaw is then used to cut out the profile.  Because we have the templates, some of the students used a router to copy the pattern exactly.  Some used the belt sander to clean to their lines.  Some preferred a spokeshave for this operation.  All of these methods work - it is a matter of personal preference.


The paddle below has a special template that we're following with a pattern bit to create a curved ash edge on the cherry paddle.  This should be interesting.

The picture below shows the spacer blocks that were used to support the blade as this student roughed out the paddle on the bandsaw.  The shaft protrudes a bit and the blade would rock back and forth on the bandsaw table which would give poor results.  The spacer blocks are the same thickness as the shaft protrusion giving a level plane on the bandsaw table.  When this same student used a blade template and a router with a pattern bit to cut out the profile, the spacers and the shaft supported the template and kept it level so that the cut by the bit was square to the face.


After cutting out the blade profiles, we marked centerlines on the blade edges.  This is particularly important if you've put a tip on the blade as we have with some of these paddles.  The tip has a tenon extending into it of contrasting wood - we need to know where we are and how much material that we can remove without running into the tenon.  To do this, we mark two lines offset from the centerline on the edge that is half the  thickness of the tenon plus a bit for safety. (~1/16") At this point, we start using planes to thin and taper the blade to the appropriate shapes.  The bottom 1/3 - 1/2 of the blade is fairly flat while a bevel that runs from the centerline of the face of the blade to the nearest line on the adjacent edge.

The process is relaxing and with a sharp plane quickly generates a large pile of shavings:

Here's where we get to our Tech Tip Tuesday information...

The tool below is a somewhat rare animal and we're fortunate to have one for our spoon-blade oar and double-paddle builders.  It's a Stanley #113 Compass Plane. It has a spring steel sole that is adjustable for both inside and outside curves of gentle radii.  Most woodworkers rarely have use for an item like this.  It has the usual adjustments for the blade depth and angle that you're used to seeing on other bench planes, but the front knob does something neat.  It screws in and out to adjust the radius of curvature of the front part of the sole and via a small set of gears along the side of the plane, the rear part of the sole is adjusted at the same time.

By placing the sole against the bandsaw cut surface of the oar blades, we were able to set the radius of curvature on the plane to match.  Then it was a matter of a minute or two to achieve a smooth surface on the power face of the blades.  After a quick adjustment to change to an outside radius, the back of the blades soon followed.   An obscure tool, but a wonderful one to have around when you need it!

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