Bearhawk 4 Place Plans #1582

Entry: Tue Feb 11 2020

Tools and rib flattening / evaluation

Right now my primary task is to evaluate the condition of the existing ribs and decide whether to keep them or remake them. The ribs that were included with my materials kit were all scratchbuilt and all have been flanged and initially fluted. Most but not all have lightning holes cut and flanged too. Currently I'm missing all the flap nose ribs and several flap ribs. All of this is complicated by the fact that no forum tools were available or supplied with the kit, and none of the ribs are laid out for rivet locations.

In order to determine if the work as built is sufficient to continue of weather I need to reconstruct these parts I need to first get them flat and the flanges trued up to 90 degrees. To do so i'll need tools to work the lightning hole flanges, a fluting tool, and a method to layout the missing rivet locations so I'll know where it's safe to add additional flutes.

Tonight I made a "bob stick" which is a simple 3/4", 3/4". 6" hard wood stick with the nose profiled and notched to allow for working of the lightning hole flanges. Then I moved on to make a bench mount fluting tool similar to the straightening tool I made a couple days ago. While I got the concept right here i'll need to remake the anvil with the dowel for fluting since I left to much space between the table surface and the end of the dowel.

The final thing I did this evening was create a rivet spacing template out of a role of acetate film. to do this I rolled our the film and drew a center line. Along this line I marked a perpendicular line at one end to represent the spar web center line. From this reference mark another parallel 3/4" down and the repeated with additional parallel lines each 1.5". From this initial template I was able to trim off a 1/4" strip that can be aligned and taped to the rib flange for rivet location layout.

Next up:

  • layout rivet locations on tip ribs
  • fix flanging tool
  • flatten and trueup tip ribs
  • compair ribs to full size rib plan.

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This post is from Bearhawk 4 Place Plans #1582