Cutting a large diameter notch in 1/8" angle

[Andy Walker]

Hey all...

I'm looking at part SNX-F10-02, which is an angle cap in the forward fuselage with a large notch cut in it for a control rod to go through. I have the part, but since I'm making the lowered seat mod I have to make a second notch closer to the center (Sonex has confirmed the part is plenty strong to just make another notch and call it good).

The issue is that the notch is, IIRC, 1 1/4" wide and fully radiused. I'm not sure how to cut this. I might be wrong, but I don't think a fly cutter will go through 1/8" angle, so what's the best way to cut this fat notch and make it pretty? Unibit?

Thanks!

[falvarez]

I haven't built that piece yet, but because only part of the hole is on the angle, I would probably just go with drilling as large of hole that I can that fits on the angle (with the unibit), then cutting out the rest with a bandsaw and filing. I've filed so much aluminum now that I've just given in that its part of my build process :)

But because I'm a bit of a perfectionist, once I've roughed out the cuttout using the above steps, I usually find a pipe or something round laying around, wrap some sandpaper around it, then smooth out the curve that I've been filing.

Let us know what you find that works well here.

Frank
Sonex #800 - Scratch Building

[Andy Walker]

I think most common unibits only go to 7/8" or 1", so you'd still be left with quite a bit of filing and sanding...sounds like a couple hours' work. Just for my own education I'm going to hook up the fly cutter and try it working very slowly on a piece of scrap 1/8" plate...I'll let you know what happens. I just love how well the flycutter makes holes, so if I can save time doing it that way I will.

I guess another option would be to use a fine-tooth holesaw on the benchpress. That could go sideways really fast though...I don't think I'd try it.

[N111YX]

Andy, I used this tried and true technique many times. It does not take as long as you might think. I like to clean it up with a Dremel or 1.5 inch sanding wheel in a drill...

[Andy Walker]

Andy, I used this tried and true technique many times. It does not take as long as you might think. I like to clean it up with a Dremel or 1.5 inch sanding wheel in a drill...

I did not think of that! If the fly cutter doesn't get it, I'll do it that way, thanks Kip!

[XenosTed]

Andy, I have a power nibbler with a diamond cutter. You are welcome to use it. It cuts very fast. You don't have time to say "whoops". You might want to practice.. It fits a regular drill. Call me if you want to try it.
Xenos Ted

[Andy Walker]

Well guys, it turns out a fly cutter *does* work on 1/8" angle! It took about 3-5 minutes of steady, moderate pressure (too much and it will stick as you might guess), but in the end it makes a very nice, near-perfect hole, just as it does in sheet metal! The surrounding metal got warm but not hot, and I did not notice any wear on my cutter afterwards. It does make a lot of coarse shavings though!

So in the future, if you need a perfect hole in 1/8" metal, consider the lowly fly cutter. Now I'm off to make the actual part!

Thanks for the offer Ted, it looks like I won't need it though. :)

[XenosTed]

Andy, I am glad you got it done. Watching someone use the power nibbler reminds me of watching one of those guys who carves beautiful art with a chainsaw (scary). I saw it at Oshkosh in '99 and bought one on the spot (overpriced) but, wow, it came in handy later. Have to use much lube on AL, as usual.
Keep up the good work.
Ted