Builders Data Base
Building The EMG-6 (CNC Drilling and Cutting Fuselage Boom)
We've recently started working on the kits for the fuselage boom. The majority of the fuselage boom is built from 2024 T3 aluminum .040" thick and all the components are CNC cut on the CNC router and bent using the CNC press brake. Using the CNC router to cut sheet metal and drill it is not the most efficient method, but provides us a cost-effective method to produce the parts with CNC accuracy. There are a total of 5 different sheet-metal patterns that produce parts from 4 x 8 sheets. Each sheet has from between 6 to 20 different toolpaths. In the video which is all time lapse photography it happens quickly but in reality each sheet requires between 3 to 5 hours of drilling and cutting time. The sequence of events requires drilling 4 locations on the sheet that gets screwed to the MDF tabletop. Then the drilling proceeds to drill all of the locations on the sheet that are required to hold down small parts or hold the perimeter of the fixture while the cutting is being completed. This is usually between 100 and 200 holes all of which have to be screwed to the tabletop manually. the next step is the remaining holes need to be drilled where rivets will be placed during construction. Depending on the sheet this will usually be between an additional 800 to1000 drill holes. The next steps are 2 to 3 different toolpath cutting out the interior components such as lightning holes. Failure to have a screw in each one of the small components can oftentimes lead to that part flipping up and jamming the CNC router or breaking a cutting tool. Next all of the exterior components are cut and then we follow up with the detail work of cutting the small components. Then all of the screws are removed from the components and stacked and organized ready for bending. The tabletop is then cleaned and the next sheet is put in place for the next series of parts. After 5 sheets have been cut on the MDF tabletop the surface is destroyed from the router and drill bits cutting .125 inch into the MDF that the entire tabletop has to be resurfaced and an additional 5 sheets can then be cut. After 20 sheets are cut the MDF sacrificial tabletop has to be replaced and the process can be repeated again.
Bending Sheet Metal Part 2
In today's episode, Part 2 of bending sheet metal for aircraft, we are going to be taking a look using and setting up an aircraft sheet metal finger brake. This is a companion video for technically speaking article published in the June 2017 sport aviation magazine https://electricmotorglider.com/2017/06/01/bending-sheet-metal-part-2/