[ame=“http://www.youtube.com/watch?v=X7qJjj2RNvE&feature=related”]Made in Germany | German Airplane Manufacturer Grob - YouTube[/ame]
[ame=“http://www.youtube.com/watch?v=wmxzcyZN9Nk&feature=related”]Examples of GROB composite technology - YouTube[/ame]
The second video was really neat.
It did raise a few questions, though:
- 2-4 minutes in: What is ‘blast drilling’? It seems they are drilling the compressed span with a drill that bolts to various parts of the ‘compression jig’.
- Also why was the span constructed of cloth woven on the spot - and not from precut strips?
Lastly, around 7min they drill a few holes with a cordless drill and then deburr. Can normal deburring tools be used with carbon fiber?
Nice Vid. That last bit of drilling looks like it would create a few delams!
1: NO idea what that blast drilling was. Looked like a water cooled reamer. Odd contraption.
2: there are many composite specific composite tooling bits. Some are normal steel tools, but most are coated in carbide/CVD. You can try anything, and see if ti works 
3: The spar section was just a tow coater, it was NOT a weaver. It just pulled and wetted out specific lengths of tows, almost like pre-pregging strips for them to use.
I noticed that they do wet layup. Scary for a AIRCRAFT!!! But it looks like they do a good and correct job at everything, so I’m sure they are good.
I thought the same thing! I wonder how much the honeycomb gets filled with resin?
- “Blast drilling” looks like an “old school” way of doing it. Now days quackenbush or winslow style drills that applys feed pressure to the drill / rheemer via hydraulics. These are very expensive and often unpractical.
Given a drill guide bushing and step rheemers it is very easy to drill perfect holes without the need of an automatic drill. That device they are using is not common and most likely is an adaption for an in house fixture.
Standard cobalt drills and a final straight flute rheemer is a common way to drill composites without de lams or chipping holes.
Standard counter sinks and micro stops are used but… De blurring tools are typically composite specific than their sheet metal counter parts.