Whilst I am waiting to hear back about my dimpling/countersinking query, I made a start on the HS ribs.
First I had to notch the inner forward ribs so that they can fit between the angle reinforcements on the forward spar. I marked these the day before so I clamped them to the bench, then used a #21 drill to make a hole in the web where the notch radius needs to be.
Then using left and right snips where required, I carefully cut the aft flanges. I cut “long” so that the remaining flange was going to be too big. Better to not cut enough than to cut too much! Lots of builders have mentioned that they cut too much and had edge clearance problems with future rivet holes.
I carefully bent the bits that needed to be removed flat and using the snips again, cut the sections away.
A quick check against the plans and you can see I have more flange than what the plans call for.
Using the Scotchbrite wheel, and sanding disc on the linisher, I was able to carefully grind the rough edges back to the marked lines.
Here’s the result. Two notched ribs.
Next, on to deburring all the ribs. I used by deburring tool (or whatever the proper name for it is) on all the edges.
Then I used the Scotchbrite wheel to smooth all the edges I could reach. For the fiddly little corners, inside edges and lightening holes, I tried a couple of different things to break the edges (including a die grinder with 1″ Scotchbrite wheel). I ended up using my needle files in these tricky spots as they gave me the best control and feel and had the least amount of risk in something going wrong. The die grinder scared the hell outta me! It jumped when I was trying to break the edges in a lightening hole and scuffed the rib web. Nothing bad but it illustrated the potential for things to go horribly wrong. The needle files worked great.
I managed to get one rib completely deburred, and the rest all given a once over with the deburring tool and Scotchbrite wheel. These should keep be busy for a couple of hours. Then it’s fluting time.
Build time 1.5 hrs.