Now that the canard "center-section" was complete, it was time to hold it down onto the canard jig and bond the tip extensions to it. This assures the canard is perfectly straight (and no twist) when the canard is glassed.
The canard jig is composed of 9 identical jig blocks (known as the "K" jigs in the Roncz plans). I had my jigs CNC'd by Eureka (www.eurekacnc.com).
Page C-2 in the plans shows the spacing required between the jigs (one at BL 0, 26.5, 53, 55 and 63). The problem here was that the outer most jigs had to be 126" apart... my workshop table is only 96" long. Ok, so how do we build a perfectly straight 130" long canard on a 96" long worktable?! Let me show you...
First, I purchased two of the straightest 12ft 2x4's I could find at my local hardware store. I then cut six 6" long 2x1 pieces and used them to build a "railroad" like fixture on my table (as shown in the picture below). I made sure that none of the cross members were located where a jig will later go - you will see why this is important in a minute. Once I had this railroad jig assembled, I secured the entire assembly onto my workbench using 3" long drywall screws every 2ft or so.
I then drove a 3" drywall screw at each end of the aft 12ft 2x4. This allowed me to stretch a very tight string spanning the full 12ft length...
Hard to see in this picture, but notice how I purposely drove the screws as far aft as I could to give me more platform room to place the "K" jig on. The string will serve two purposes: 1) to make sure all of the blocks' ends are aligned with respect to each other, and 2) give me a reference line so I can shim the aft ends of the "K" blocks to the same waterline.
I drew a straight line across all 9 "K" blocks aft ends... it's important that the line drawn is at the same waterline for all 9 blocks!
I then marked the appropriate buttlines onto the 12ft 2x4's (one mark at +/- BL 0, 26.5, 53, 55 and 63), butted a "K" block up against the tight line... and used squeegee cards to shim the aft end of the block until the mark aligned with the string.
Ok, so the string assures me all the blocks will be aligned (with respect to forward or aft of each other) and that the aft end of the blocks will all be at the same waterline... but what about the forward end? How can I make sure the front ends are all at the same waterline (i.e., so that they are all level with each other and that there is no twist)?
Well, to help me with this one, I created the first ever i-Jig level. I downloaded a level tool app on my old iphone.. and gently clamped it to one of the "K" blocks (it doesn't matter which block, since they are all identical thanks to Eureka's amazing CNC precision!)
Here's a close up...
Some buttlines required 3 squeegee cards.. others required 6... but in the end, all "K" blocks were shimmed so that they would ALL be at 2.3 degrees. Again, the 2.3 degree number is irrelevant, as long as all blocks are level with respect to each other.
At this point, the shim cards were simply resting on the 2x4's. One large sneeze and all this work would have to be repeated. So I used my hot glue gun to permanently hold all the shim cards in place.
I used the block to weigh the shim cards down as I applied the glue.
After glueing all the shims to the 2x4's, I re-checked level with my i-Jig. 2.3 degrees on the money for ALL 9 buttlines!
Before permanently bonding the blocks to the shim cards, I decided to do a fit check. So I lined up the 5 "K" jigs that hold the canard center-section, and placed the center-section onto the unsecured jigs. I then placed heavy boxes on top of the canard to weight it down onto the jigs.
Here I am checking to see how straight my center-section currently was... and it looked good! Realy good! The blocks pretty much self aligned themselves perfectly straight with the tight string without me having to do anything!
Happy with the alignment, I used more hot glue gun to bond the jigs onto the shim cards...
I should note that prior to applying glue, I made sure the jigs were square with the tight string.
Here is a top view showing how the aft end of the jig hardly touches the string.
The plans say to set up ALL 9 blocks, bond the center-section to the jig, and then bond the tip extensions, aligning them by using the jig. I did not like this approach and decided to change things up a bit. Using the jig method does not assure I would match the tip ends 100% with the center-section. Instead, I did the following:
I started out by covering the outer most center-section jigs with plastic wrap. This way, they would not get damaged in the event of micro runoff.
I then placed the outer most tip extension jig in its proper location. Notice how I did not secure it to the shim cards - I left it unsecured and floating.
I then placed heavy boxes on top of the shear web to weigh the center-section of the canard down onto the jig. I also placed the 1.25" dia pipe on the trailing edge of the canard, leaving at least 6" of overhang on both sides. This overhang will allow me to clamp the tip extension up against the pipe, assuring that it will cure 100% flush with the center-section portion of the canard.
The setup looks something like this...
I then micro'd the mating surface of the center-section tip...
And micro'd the mating surface of the tip extension...
With the aft end clamped, I used my thumb and pointer finger to make sure the leading edge was flush... we are talking about very very small adjustments here. Once I found the sweet spot, I stuck a toothpick in from one side to hold it in place.
I then repeated this procedure for the other end.
I then cleaned off as much micro runoff as I could..
Here is a close up of the clamp showing how the pipe assures the tip extension aligns flush with the center-section portion of the canard...
I let it cure overnight. The next day I removed the heavy boxes, clamps and pipe. The tip extensions were 100% flush with the center-section! The canard is now 130" long!
Next step will be to secure the outer most "k" blocks, bond the canard to the jigs, prep it for glassing, and glass the bottom of the canard!