Looking for advanced/automated building techniques

[ThrottleTherapy]

Hello everyone!

I'm new here and it's my first year flying planes! 🎉
I may have been bitten because I already own 10 fixed-wing aircraft (5 over 1m wingspan)!

Our club is organizing to have air combat and I want to build my own flite-test foam board planes to participate.

So... I do commercial large-scale vinyl printing, CNC cutting as well as web development. I own and operate all of it.
I'm seeing A LOT of information for building the planes on FT website and forum, however a lot of that info is geared toward making it easy with home tools and materials (patching the plans together, gluing paper decals, using dollar store materials, etc.).

Does anyone have pointers on building with a little more tooling and automation?

I'm waiting on a large drag knife for the CNC but I might build a needle-cutter if that's a good solution for cutting the foam board. I have a diode laser cutter but it doesn't seem to like the foam-board.

My plan is to pickup one of the decal plans from this post or make my own, print it on vinyl and use the lamination machine to apply it on dollar store foam board. I should then be able to lay it on the CNC router and have it cutout the through cuts, I don't trust it for the score and other types of cuts without a vacuum table.

I'm not trying to make this commercially, I'm just having a hard time not using the equipment when I know it could yield such high quality results.

Anyway, that was my presentation haha!

 

[Flying Monkey fab]

Well, far and away the best cutting of of DTFB is with a CO2 laser but once vinyl gets involved that is off the table as it produces clorene gas! LED lasers don’t work as they are of the wrong wavelength so the paper cuts but the foam doesn’t.
I have not seen anyone use a drag knife but it peeks my intrest. I can’t tell you much more about workflow as I have no idea what you are working with for software and hardware besides what you told us. Will your CNC do 20x30?

 

[ThrottleTherapy]

Well, far and away the best cutting of of DTFB is with a CO2 laser but once vinyl gets involved that is off the table as it produces clorene gas! LED lasers don’t work as they are of the wrong wavelength so the paper cuts but the foam doesn’t.
I have not seen anyone use a drag knife but it peeks my intrest. I can’t tell you much more about workflow as I have no idea what you are working with for software and hardware besides what you told us. Will your CNC do 20x30?

My CNC router will do 4x8' sheets so yes it will easily do 20x30 foam boards
I'm working with Aspire and Mach3 on the software side.
I've just received the drag knife kit in the mail today! Will let you know once I have figured it out
I have high hopes it will cut the vinyl and foam board in one pass, I'm just worried about sharp corners getting rounded.

 

[Flying Monkey fab]

I'm just worried about sharp corners getting rounded

Working with Vetric SW makes that a nonproblem as there is a wiget for working with a drag knife where it will make a loop when making tight turns. If you don’t have it installed go to the widgets on the Vetrics sight and search drag knife.

 

[Flying Monkey fab]

If you can’t get the drag knife to work for you (I hope you can because , well, that would be cool) is make a template out of 1/8” material using the CNC. That would not be as good as the drag knife but better than no automation at all.

 

[ThrottleTherapy]

If you can’t get the drag knife to work for you (I hope you can because , well, that would be cool) is make a template out of 1/8” material using the CNC. That would not be as good as the drag knife but better than no automation at all.

That's a very good idea thank you, it might be useful to have a template in the field for quick repairs!

 

[Foamforce]

You mentioned a needle cutter already and I can vouch for how well that works. I built one of the TimSav needle cutters and I get great quality cuts. It took me a fair while to get everything tuned and reliable, although it turns out that a big issue of mine was due to a failing USB port on my laptop.

The advantage of the laser cutter is that it cuts a sharper line on the paper, while the edge of the needle cut foam board is a little fuzzy. In practice, the difference on a built airplane is barely noticeable. The laser cutter is also quieter while the needle cutter is fairly loud.

The advantage of the needle cutter is that the edge of the foam isn’t melted and concave, so edges glue together better. The joints don’t need as much glue, are probably stronger, and are easier to get square. Also, the needle cutter is safer (no fire hazard).

If you’re already familiar with CNC, then it should be pretty familiar to use, since it uses GRBL without the third dimension.

 

[LitterBug]

I use a 10W diode laser cutter. I mostly use it to mark the foamboard then use a knife to cut everything out. It marks the paper and makes a nice dip in the foam which helps guide the knife. Also have a nice straight edge for the long straight cuts. I have had some success cutting foamboard all the way through with it if conditions are perfect, with speed, number of passes, air assist level, height adjustment, and flat foam, but it takes a lot of fiddling and that time may be better used just completing the cuts with a knife. Good ventilation is a must too.

Black paper foamBoard works better than white.

LB

 

[ThrottleTherapy]

Thank you all for the suggestions. I have built my first plane ever this weekend! I made a Bloody Baron
I haven't got to using the drag knife yet, I wanted to build one to get a feel for what the work is like.
So, I print the plans combined with the bloody baron skin found here and listened to the build video while it was printing.
Here is the result :

I printed it full-size on vinyl (same kind used for cars but not wraps). Turned out to be 2 sheets of 20x30 and 2 extra prints.
2 x 20x30 main plan
1 x Back of elevator and rudder
1 x Firewall and control horns

I applied the vinyl on the flat foamboard before cutting with an Xacto knife.
On the picture it's still missing the push rods but I have solved that, just haven't taken a new picture since.

Things I learned :
- Watch the build video BEFORE preparing and printing the plans. (You can see cut lines on sides that I didn't want to cut like the leading edge)
- Use a fresh Xacto blade, just a bit dull tends to pull on the foam inside.
- Well applied hot glue can be quite robust!
- The build video is 9 years old and features a different piece for the elevator (used to be 2 pieces now its 1). I'm not blaming the video but that is the only problem that I had while building, I applied too much glue on the elevator near the power pod slots and glued in my power pod...Pulled on it, ripped the tabs into the slots... Oh well!

Maiden coming next weekend! Will post updates