Help! Tips for Cutting Double Bevels for Wing Foldovers

[Scrivner]

I'm new at doing the foamboard thing and I'm hoping the group might have some tips or tricks to share on cutting bevels. More specifically...

I'm having trouble with doing the double bevels for the part of the wings that fold under. I can't seem to get a shallow enough cut (it bends around but still needs about 45 more degrees of bend to lay flat). Also I keep cutting into the paper at the leading edge.

If anyone has any tips I would really appreciate it! Thanks in advance for any advice!

*I'm kinda new so sorry if this isn't the appropriate place to post this. If not, please let me know which forum category is more appropriate. Thx.

 

[BlockerAviation]

Here's a really cool way to get good bevels.
First score the center of where you want the bevel.

Then mark where you want the bevel to end, make a mark and cut through just the paper.

Finally, remove the paper, fold over the piece and sand the exposed foam. The result is a perfect bevel almost every time!

I don't know where I found this trick but I do know it's really simple and makes great results!

 

[Scrivner]

Nice! @BlockerAviation, thanks for the tip!

 

[BlockerAviation]

Nice! @BlockerAviation, thanks for the tip!

No problem! Bevels have always been my weakness until I found this little trick.

 

[maxboo]

In case you are using a knife: always use the best knife available for bevels.

I always have at least two paperknives on my desk: a new/sharp and a old one. I save the sharp one for the important cuts. After a while the it gets degraded and replaced by a new.

 

[Dean is the name]

You can also use a sharpie (or something that size) and crush the foam and paper. I did that on my scratch build mini guinea and it worked great!
And also, you don't have to bevel the hole thing, just where it folds.

 

[MCNC]

Before you discard any foam board scraps, cut a double bevel in them. Try different angles of attack with your blade. If you have a stone, hone the blade often.

 

[JasonK]

This might not help directly, but i printed this out and use it, I get consistent bevels all the time.
https://www.thingiverse.com/thing:1358344

if you don't have access to a 3D printer, you could build a jig out of some wood or other material and get the same result.

 

[Scrivner]

Thanks, all! I did practice on some scraps last night and I did get better at it. I do ok with the 45 degree bevels for the control surfaces but I have a lot of trouble with the shallow angle bevels needed for the wing fold-overs.

@Dean is the name, thanks for the suggestion. Could you clarify your technique? I'm not clear on the details.

@JasonK, that tool looks great! I don't have a 3D printer but my brother-in-law just got one a few weeks ago and I'm sure he would love an excuse to play with it more. Maybe I can design a tool that will cut the wing bevels.

 

[JasonK]

@JasonK, that tool looks great! I don't have a 3D printer but my brother-in-law just got one a few weeks ago and I'm sure he would love an excuse to play with it more. Maybe I can design a tool that will cut the wing bevels.

I do all the FT plan bevel cuts with that device.

 

[Scrivner]

I do all the FT plan bevel cuts with that device.

Oh - ok! It didn't look like it would cut shallow enough angles for the wings. I've already got my request in to my bro-in-law to print one up for me so I'll give it a try when my order comes in.

 

[JasonK]

it cuts exactly 45deg cuts when setup correctly

 

[Bricks]

First on the leading edge where the fold is going to be put packing tape on the outside of the fold before cutting. I am not to bad at the 45 degree cut but to touch it up i glued two pieces of light ply together at a 45 angle and glued sand paper to that and finish the 45 using the sanding block.

 

[Dean is the name]

This is the Flitetest video they made about the no knife bevel. In the video they also say that you can use sandpaper.

 

[Scrivner]

@Dean is the name - thanks for posting that video! That is a huge help for me.

It looks like the wing fold-over technique I've been using has been wrong. I've been trying to cut the bevels shallow enough for the fold to lay flat while putting very little stress on the upper part of the wing. But the video shows that you're supposed to let the score marks along the length of the wing absorb the stress and bend to make the upper wing camber. I think my biggest problem is that I've been making my score marks incorrectly as they don't have enough flex to allow the fold to lay flat. Also, I now see what you mean about using the sharpie to crush the foam. Makes sense now.

I haven't had time to try any of this yet but I bet I'll be a master wing-maker pretty soon using the techniques everyone has provided in this thread. Thanks again all!

 

[Walden]

Thanks, all! I did practice on some scraps last night and I did get better at it. I do ok with the 45 degree bevels for the control surfaces but I have a lot of trouble with the shallow angle bevels needed for the wing fold-overs.

@Dean is the name, thanks for the suggestion. Could you clarify your technique? I'm not clear on the details.

@JasonK, that tool looks great! I don't have a 3D printer but my brother-in-law just got one a few weeks ago and I'm sure he would love an excuse to play with it more. Maybe I can design a tool that will cut the wing bevels.

Maybe it's my woodcarving and metal fab background, because beveling foam board has always been second nature to me. I am not afraid to put shallow bevels anywhere and everywhere on my designs. Besides using a sharper blade and the tangent method for bevels (see BlockerAviation's post), the other often repeated wisdom I would recommend is don't be afraid to make multiple passes with your blade. For example, to make a standard 2cm bevel I'll do the following:
1. Mark, score, and peal the paper off as per the tangent method
2. Make a ~45deg bevel focused on being aligned to the bottom edge
3. Make a very shallow cut aligned to the top edge (sharpest razor, large draw angle)
4. Make a third pass slicing off what little foam which remains in the middle. The focus for this cut is simply to leave a final flat slope. Finish off with sandpaper if needed.
The beauty of cutting the bevels like this is the edges of your bevels will be straighter/more accurate (less holes) because you are only focusing on one side at a time.

 

[Walden]

Maybe it's my woodcarving and metal fab background, because beveling foam board has always been second nature to me. I am not afraid to put shallow bevels anywhere and everywhere on my designs. Besides using a sharper blade and the tangent method for bevels (see BlockerAviation's post), the other often repeated wisdom I would recommend is don't be afraid to make multiple passes with your blade. For example, to make a standard 2cm bevel I'll do the following:
1. Mark, score, and peal the paper off as per the tangent method
2. Make a ~45deg bevel focused on being aligned to the bottom edge
3. Make a very shallow cut aligned to the top edge (sharpest razor, large draw angle)
4. Make a third pass slicing off what little foam which remains in the middle. The focus for this cut is simply to leave a final flat slope. Finish off with sandpaper if needed.
The beauty of cutting the bevels like this is the edges of your bevels will be straighter/more accurate (less holes) because you are only focusing on one side at a time.

PS: Second nature specifically because this was the best way I found for grinding bevels in plates and pipe for welding, and also 20mm has been a standard bevel size for my designs due to I know that 20mm is about how wide I can reliably cut a bevel with a sharp utility knife blade without needing sandpaper.

 

[Hai-Lee]

I have done many hundreds of FB builds by now.
Wing folds and hinges have caused me some drama especially in the early days.
I now use a balsa stripper to score the paper and then remove most of the unwanted material with a knife and sand the hinge or fold line to give the perfect angle.

To increase the line of a hinge I use the following hinge structure or design; https://forum.flitetest.com/index.php?threads/standard-foamboard-hinge-weakness.57666/

Of course I always seal a hinge line with with wood workers glue to increase wat6er proofing and to allow painting.

Prior to any bevelling I always support the hinge or fold line paper with clear packing tape so that the paper does not tear under pressure.

For fols lines I score with a knife and then score again with a BBQ skewer to give a little pressure relief along the fold line ot make it more accurate in profile.

Just what works for me!

Have fun!

 

[kilroy07]

For regular hinges/bevels I prefer to iron them now; https://forum.flitetest.com/index.php?threads/ragged-foamboard-edges-iron-them.58075/

For a leading edge bevel I use the tool @JasonK linked above (if you don't have access to a 3D printer, PM me, we'll get you taken care of.)
I use it on both sides, THEN (and here's the tip) mash it down with the end of a sharpie pen (the "regular" sized one, and not the cap end). That mashes down the foam and makes nice smooth curves and seems to stress the paper less.

 

[JetCrafts]

use a scale