With the Australian Quick Build Kits it was decided to supply the rear flight controls in kit form to meet the requirement of AC 21.29 which defines the 51% rule.
One of the tasks assigned is to trim the skins to their correct width. The cut lines are marked at the factory using a standard offset of 10 mm. These could be cut using a guillotine or aviation snips and like most builder's I do not have ready access to a guillotine so snips are the only option.
A new set of Weiss snips were used on the top turtle deck skin with the lack of skill of the user begin more than apparent. The main issue was the witness mark and local distortion created near the tip, there had to be a better way.
A Sonex builder used a laminate cutter to open an aileron to add a trim motor - so if it can do that why not trim a sheet. A Olfa [P-CL] Heavy Duty Laminate Cutter was purchased with 2 packets of spare blades plus a length of 25 x 3 mm off aluminum extrusion from the local hardware store.
The strip was marked at the standard factory edge distance of 10 mm and then three [3] holes drilled using a sheet as a template. The factory punching is on a standard pitch so this should be a one time job.
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| Scrap from sheet |
The first job was to cut a slither off one skin that was not as tidy as this builder would like. The bar was fixed using three [3] clecos and two [2] pieces of dressed 50 x 25 x 600 l/g pine were placed on the underside of the sheet. These are positioned at either side of the cleco pins to support the sheet during the cut. The cuts are best achieved using a 450 mm [18''] strokes. The first few cuts are the most important, be light and accurate, continue the cuts until the sheet is penetrated to a depth of 60% or more. If longer cuts are required, move along the sheet and repeat the operation. At the completion of the cut fold the scrap to break it free, dress the edge with a flat file to remove the burr.The first and second images opposite shows a slither cut off one sheet that this builder wanted to tidy up.
The photos below shows the rudder skin begin trimmed on both sides ready for installation. The timber blocks in this case offered protection to the other side during the scoring operation.
Overall this builder is very happy with the final result and it is faster to do than write about.
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| Timber support |
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| Finished rudder skin |
