InqRouter - Rotary Tool Holder 2023-02-10

[Inq]

Inq submitted a new resource:

InqRouter - Rotary Tool Holder - Tool to help creating tighter curved DTFB panels

Introduction
This is a 3D Printed stand that holds a very specific Dremel style tool such that it can be used as a router with a constant depth and perpendicular. Using it against a ruler, you can get strait line.
View attachment 234749

Why...
I have a need to curve DTFB tighter than I can do by simply using the table edge technique, yet a larger curve radius than I can get using the double bevel, crease technique.
View attachment 234750

I bet others might...

Read more about this resource...

 

[Inq]

Would anyone have any data on how tight a curve you've been able to get out of DTFB with one side removed and using the table edge technique (TET), but not using creases or cuts? I'm trying to come up with some guidelines for curvature and when someone would need to transition from TET to using this tool. And after that to estimate the depth and spacing between cuts to achieve as smooth a curve as possible.



Thanks!

 

[Inq]

Cura Settings I Used

Layer Height/Initial Layer Height = 0.25 mm
Wall thickness = 0.8 mm
Top/Bottom thickness = 1.0mm
T/B Pattern = Concentric
Infill = 15%
Infill Pattern = Cubic

Build Plate Adhesion and Support aren't needed.

ABS Plastic weight = 20 grams.

 

[Merv]

...have any data on how tight a curve you've been able to get out of DTFB with one side removed...

With one side of the paper removed you can fold DTFB back on it self. There was a guy named Ed, on a YouTube channel called Experimental Airlines, who would do that. He hasn't posted in a long time.

Have you tried cutting DTFB with your setup? Im thinking cutting out planes. If it cuts well, just follow the line. If you want to get fancy, mounting it on a cnc machine.

 

[Inq]

With one side of the paper removed you can fold DTFB back on it self. There was a guy named Ed, on a YouTube channel called Experimental Airlines, who would do that. He hasn't posted in a long time.

I've made the FT Storch and my current Fokker D.VIII use that technique and cut double bevels and yes... it give a very nice leading edge to small airfoil planes. The reason I think I need this tool is for an airfoil shape that is considerably larger. The leading edge curvature has a radius of about 0.5 inches. I've not been able to curl single side DTFB that tightly without it buckling and creasing. Big foil is at the centerline and the smaller is about 15" out the span... Further out the wing, I probably can just use the double bevel technique.

Have you tried cutting DTFB with your setup? Im thinking cutting out planes. If it cuts well, just follow the line. If you want to get fancy, mounting it on a cnc machine.

I hadn't, but just now... I've uploaded the full size image so you can zoom-in on the edge. I guess there might be some use for doing this, but anything near strait, a razor blade gives a far nicer cut. With lots of curves, this might be a cheaper option, but I think the needle cutter described here on the forum would be a far better solution than using this. Besides, putting this on a CNC and cutting a whole plane would be far messier option than the needle cutter.

 

[Merv]

Here is the video to make the airfoil you want.

 

[Tench745]

I have successfully rolled strips of DTFB into cylinders about 3/4" OD without kinking. It gets trickier not to kink something as the pieces get bigger.

 

[Inq]

I have successfully rolled strips of DTFB into cylinders about 3/4" OD without kinking.

That's good information. Although the OD on the biggest foil (root) is 1", it'll transition below your 3/4" about 25% of the span. Obviously, the curvature gets bigger as it moves away from the leading edge. Your 3/4" gives me a good idea where I can stop grooving it and rely on rolling the DTFB.

It gets trickier not to kink something as the pieces get bigger.

Does this mean when the pieces get longer?... as in a 30" long tube and 3/4" OD???

 

[Tench745]

Does this mean when the pieces get longer?... as in a 30" long tube and 3/4" OD???

Yes. As the piece gets longer it gets more difficult to support the whole length adequately to keep it from kinking. However, it is not too difficult to work the bend in incrementally. And, like Merv mentioned, the foam can be bent completely back on itself with just a little effort.
If you have the opportunity, watch some builds by NumaVIG. He uses raw XPS foam for most of his builds, reinforces the outside of bends with tape and rolls them around a tube for support. After the bend is in, you can safely remove the tape. We who build with DTFB don't need to bother with the tape, because our XPS foam already has paper on it to support the bend.
Here's a link to the portion of his P-40 build where he builds the wing.

 

[Inq]

and rolls them around a tube for support.

That's a good idea... I have plenty of PVC pipe laying around. Now, it'll be useful!