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I'm considering adding access holes with covers to my STOL 750 so I can inspect and clean the area aft of the Rear HT Frame without removing the rudder! This is discussed in another topic located here: Those Darned Daubers!.
I've been reviewing forum topics and videos to determine how best to cut the access holes in the 0.020 fuselage skin. Jon Croke with HomeBuilt HELP.com has some videos in his free "Tip of the Week" archives that reviews several different methods and tools for cutting holes in aluminum. However, I've never seen mentioned anywhere that a Dremel tool with the router attachment might be a good alternative method.
I just happened to have one of those Dremel accessory kits with the router attachment and an assortment of cutting bits:
I tried all the pictured bits and they all seemed to make acceptable cuts in a piece of 0.020 6061T6 scrap. The three spiral-cutting bits on the right seemed to leave a little more roughness or chatter marks than the two high speed cutters with vertical teeth on the left, however, any of the cuts looked like they would easily clean-up with a file or a small drum sander chucked in the Dremel. The larger-diameter cutter (Dremel # 115) pictured chucked into the router attachment made the cleanest cuts of all with minimal marks or roughness on the edge - in fact, I could comfortably and smoothly rub my finger along the edge of the cut with no filing or sanding at all!
This looks like an ideal way to make curved cuts in thin sheet aluminum - especially large diameter round holes in sheet material that is already installed and can't be taken to the bench to use a fly cutter in a drill press. I'll probably make a hardboard or plywood template that I can tape to the fuselage to guide the router rather than try to free-hand it and also practice on some scrap before making the cut in my beautiful paint job! I'll also mask the area with tape and cut through that to protect the paint.
I posted this because I have never seen this technique mentioned. I'll bet 90+%, if not !00% of homebuilders have a Dremel tool, so it would seem obvious that someone has tried this before! Just wondering if anyone has been there/done that and how it worked for them, or, more importantly, why this doesn't work or is a bad idea???
I have to tease you a little bit here John: Quite bein so sceered of that pretty paintin you gots on your Plane. You are asking questions that you already know will work. I usually go to a router with a template for all my cutouts and shapes, but I have seen dremels used with good results. My only suggestions would be to definity use a template, protect the surface, and I would use a carbide bit in the dremel and lubricate the cut with paste or solid stick Beosheild.
Tease accepted, Dan! ;>) It just seemed odd to me that I've never heard anyone mention using the Dremel!
Thanks for the suggestions and glad to hear the Dremel worked well for you! I was just watching a YouTube video (presenter wasn't using a Dremel) but he mentioned also to avoid masking tape on the cut line - claimed it would gum up the cutter?
the glue will gum up a cutter, but by using a lube such as boesheild it will usually release most adhesives and is not a problem.
I have seen a few videos of a dremel being used ususlly to install an access panel on the bottom of wings after the fact like you are wanting to do.
Using a Fly Cutter Chucked in a hand drill, Just a minute: but turning it by hand, not the power of the drill will cut some nice round holes in .016 (701) and .022 (750) for fuel tanks and holes in skins for filler neck, just takes patience, but you get what you were looking for w/o damage to Al or missing fingers. I drilled my 701 gas tanks using this method on a drill press, but I took the drive belts off and unplugged it, and turned it by hand. I had previously made a foot pedal to pull down on the drill press handle.
Just today cut four holes with power drill and fly cutter! Worked fine. Only lost a little skin, nothing that won’t grow back. Gloves might’ve been a good idea. Cuts look clean, no extra, unwanted scratches on metal.
John, thanks for the reminder of using Dremel with router attachment. I have a couple of access panels to cut in wings for fuel fittings access and was not certain how to go about it.
Has anyone successfully used a Roto Zip to cut access holes?
John I used my Dremel to cut access panels in my wings, it worked just fine. I posted a picture or two on the 701 forum about three years ago. Gotta keep a firm grip on it, I like Dan’s suggestion to use a lubricant. I cut just inside my scribe lines to be safe and dressed to the lines with a file, but the bit I was using made a slightly rough cut.
Which bit did you use in the Dremel?
I used the long spiral bit, the third from the right in your photo.