3D printing of aircraft parts

[Geoff_H]

I noticed in another thread that a discussion on 3D printing came up. I have been experimenting with printing various parts for my project. I have found that the weakest part of a printed part is the layer bonds, hence I would not use it for undercarriage parts, but for throttle quadrant rudder pedals and the like it seems to be OK. Weight is significantly lighter than aluminum parts owing to the lower density and 'honeycomb' style centre. The minimum material that could be used is nylon. Printing nylon is not for the faint hearted with much experimenting to get an acceptable product, dimension and surface finish often lead much to be desired. However my products are getting better as I solve each problem. I have had to modify my printer several times to improve the part quality. I designed each left using 3d AutoCAD then transfer the design to an appropriate language for the printing, quite cumbersome.

 

With time I expect to be making parts that can be service sensitive in requiring strength and endurance. Maybe undercarriage parts one day.

 

 

[Downunder]

Very interesting Geoff. So you are using nylon then?

 

 

[Geoff_H]

Yes. The temperature is destroying my Teflon guides, but I have a metallic hot end on the way. One of my big problems was curling and separation of the part from the bed. I did some bed temperature measurement and found that the bed temperature was between 20 & 30 deg C below the measured temperature. Getting much better results now. Only nylon has the temperature strength and chemical resistance required. Early parts split along laminations when hit with a hammer on the vyce. To get better built quality I am building a thermal box for the printer

 

 

[old man emu]

Do you have automatic bed leveling on the bed? If so, is the testing sequence built in to your G-code?

 

 

[Geoff_H]

Never tried the auto adjust features. I always watch the first layer very carefully and adjust as required to get best bed adhesion. I manually adjust temperatures during the print, I should put the changes in the GCode. I must do this one day. I spend heaps of time watching the print.

 

 

[facthunter]

Slight advance on Papier Mache? Nev

 

 

[old man emu]

What brand of printer are you using?

 

 

[facthunter]

Brother........ Nev

 

 

[old man emu]

Oh! I got a Canon on HP

 

 

[Geoff_H]

I have a modified Aldi Cocoon.

 

 

[old man emu]

Interrresting. What size print plate?

 

 

[Geoff_H]

At present it is 200 x 200. I use hairspray on glass for nylon and a variety of fiber based plates for other materials. For PLA I use masking tape.

 

 

[old man emu]

Geoff - Check you PMs in a couple of minutes

 

OME

 

 

[Geoff_H]

I tried to print a flap. Each segment to be made so a thin section aluminium tube could hold together each 200mm length of flap. To get it light I had thin walls of the flap. Printed one in nylon. It did not work, the youngs modulus of nylon is low compared to aluminum. With equivalent weight the nylon part was not Ridgid enough and flexed significantly.... Maybe a different material for printing will help some day.

 

 

[Vlad]

Hi Geoff,

 

I am building an aerial dispensing canister prototype. Basically it's a 20"+ aluminum tube with electric activated covers on both ends. It comes relatively heavy even without useful load. Is it possible to imbed a metal mounting rings while nylon printing the tube?

 

 

[Geoff_H]

This is a picture of the test part for the feasibility of a nylon printed flap. Notice the curve of the leading and trailing edge this could be remedied by a themally constant environment, or a heated box around the printer. It is light but not strong enough.

[Geoff_H]

This is a picture of the test part for the feasibility of a nylon printed flap. Notice the curve of the leading and trailing edge this could be remedied by a themally constant environment, or a heated box around the printer. It is light but not strong enough.

 

 

[Geoff_H]

One of the reasons for experimenting with nylon is its great engineering properties. One is its low coefficient of friction, that makes it good for low speed gears and similar. Having a lower interlaminar strength, similar to glass/epoxy structures. Hence design features such as shear stress needs to be taken into account, with metals the shear stress is so high that it's not usually needed to be calculated. Nylon is great for low speed gears where the laminations are at the vertical plane to the axis. The dimensions maybe not great in low cost printers but I have read that you can machine nylon parts, I have not tried

 

to do this yet. I will make a part in the new year and put it in the lathe and see the results, stay tuned.

 

But don't forget that you could make a composite aluminium/steel and nylon part using the advantages of both, Nylon can be cemented or welded to other nylon parts to make a part much larger than the bed size. I believe that this is one of the most exciting technologies to come to home aircraft building.

 

 

[Peter Anson]

3D printing is still very limited at the bottom end, which is what most of us can afford. I make these NACA intake vents for Sonexes from PLA. The screw is printed in nylon because I needed a flexible part, but that's also the problem with nylon - low elastic modulus. These vents take about 8 hours printer time and with my el-cheapo printer, failure rate is pretty high. For more information on these go to http://www.ansoneng.com/sample-page/products-summary/fresh_air_intake/. (Note that it is a commercial site.) Nylon printed parts would probably be OK for many low-strength structural parts such as bearing blocks and cable guides, but those sorts of parts are often commercially available or easily and more accurately machined. I think one area where cheaply printed parts could be useful is for making cast aluminium parts in a process similar to lost wax casting. There are a couple of you-tube videos showing the process. (search lost PLA casting)

 

 

 

At present, a more useful process for home-building aircraft is CNC routing. I had a large number of parts made for my (scratch built) Sonex by a commercial company and they were perfect; so accurate I couldn't measure any error and with a better edge finish than laser cut parts.

 

Peter

 

 

[old man emu]

Early in my experience with 3D printers, I came to the conclusion that 3D printing is best suited to prototyping components to test for assembly problems and accuracy of the CAD drawings. Once the part has been proved with a 3D printed version, the CAD drawing can be run through G-code generating software so the part can be made from the most suitable material by CNC machining.

 

OME

 

 

[zodiacpilot]

FYI I believe Airbus 380 engine pods are 3D printed titanium!! And some fuse parts.

 

Cheers.