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Repairing a 3D Angel "Jigsaw"


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Posted by alex nicol on 02/11/2019 16:35:15:

"...the method I've used is to build a jig to hold/support the structure and cyano all the original parts in place ( no matter how small) once this is done it should be strong enough to handle unsupported.

Next step it to apply lightweight glass cloth on the outside of the fus over the glued parts. Warm the epoxy in the microwave before mixing to reduce the viscosity apply cloth and epoxy then cover with acetate sheet and squeegee any excess epoxy off and leave for 24 hrs to dry. once dry remove the acetate sheet. Done properly it'll leave you a very strong lightweight repair with a smooth glass like finish."

These are good tips, thank you Mr. Nicol.

The OP has made excellent progress; it's quite inspiring really, to see what can be done with a wrecked model. I've several basket cases that could benefit from techniques so thoughtfully demonstrated here.

 

Edited By mrwood on 03/03/2020 03:22:07

Edited By mrwood on 03/03/2020 03:22:34

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  • 3 months later...

Finally got back to this project.

I finished the fuse sides, recovered first with lam film, then reapplied the old removed covering.

img_20200620_214725.jpg

Now working on the canopy which was wrecked.

Need to develop some techniques for repairing acetate.

I have another moderately damaged one that I repaired first with fretted ply, fibreglass cloth and cyano (Locktite 401)

img_20200626_174250.jpg

Planking the front which was all moulded acetate.

img_20200627_212656.jpg

Now fixing in a piece of acetate with cyano. Sticks are temporary supports.

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The spare wings in blue red white.

One needs repair.

Inserting carbon strips and half ribs prior to sheeting. Oracover peels back and re-sticks quite well with heat. img_20200623_163009.jpg

img_20200625_094323.jpg

The Ali tube is the forward wing locator and needed careful placement. Ply rings reinforce the ribs where it goes through.

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The spare wings in blue red white.

One needs repair.

Inserting carbon strips and half ribs prior to sheeting. Oracover peels back and re-sticks quite well with heat. img_20200623_163009.jpg

img_20200625_094323.jpg

The Ali tube is the forward wing locator and needed careful placement. Ply rings reinforce the ribs where it goes through.

img_20200624_141853.jpg

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The fretted plywood grain directions are good on the longitudinals but weak on the diagonals due to the grain direction.

The lightweight artf laser cut ply structure would be strong enough in practice If there were no heavy motor and battery which results in lots of kinetic energy to be dispersed in a hard arrival.

In fairness, full size aircraft don't do well in crashes either!

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I found canopy glue was the best thing for patching in new acetate/petg or whatever they're blown from. If you can find a similarly tinted pop bottle to cut a patch from the repair would fade into the background - if you're short-sighted and squint a bit cool!

My late friend Dave had a collection of Angel wings, all different colour schemes. I dread to think how many he got through over the years but if he ever damaged a wing he was pretty sure to have a suitable replacement under the benchangel

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speaking of rebuilding,--I have a simple question. For years, when building from plans, I have been using a COPING SAW to cut around corners. At least this is what it is called in the U.S.--This hand held saw uses those thin 7 inch or so blades and I have gotten along fine with it. I noticed a bargain motor driven unit called either a scroll or fret saw. We all collect tools and I was wondering if it is used only occasionally or is an important go to tool always in use? Odd question I know, but is this really a "need to have" tool ?Bob in Kansas USA

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Robert,

I have used a Dremel scroll saw for years, mostly for stripping balsa but more recently I obtained a second-hand table-top band saw which I use for almost everything and with the right blade it also cuts metal. The Dremel saw was around £100 about 20 years ago but you can get a band saw for less than that these days. The only disadvantage with the band saw when cutting out shapes is that you can't feed the blade through the workpiece to cut holes. You can't do your self an serious injury with a scroll saw whereas a band saw it's quite a different matter.

A.

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Locktite 401 cyano gives an acetate bond that can't be pulled apart when cured and is completely transparent. The only difficulty is in maintaining close contact between the parts during curing. I have had success in welding patches inside the canopy to bridge splits. The result is much stronger than the original. The patches are tidy enough for me.

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On the subject of powered fret saws, I too had a 2nd hand one but sold it again as it took up too much space. Likewise the band saw. I only ever use a hand fretsaw now and I find you can cut thin ply just as quickly if you use sharp blades, which are very cheap. The hand saw gives a finer cut and it is easier to follow a line accurately. Take your time and it becomes kind of therapeutic.

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The structure of the Angel and similar models is certainly not built to withstand crashes, but is designed to be factory assembled and is very light. Before lockdown I took my Angel and Ballerina to the field, and pondered the differences, given they are almost the sams size, and both are powered by a 3s 4000 setup. The Angel has much better vertical performance, and lands at a much lower speed, due to its weight. Of course, it will also perform aerobatics very well, that's what it's designed for. This isn't a dig at Peter's Ballerina, which is a brilliant sport model, and, crucially, one which most of us can build easily. If a full set of drawings were available for the Angel, building it would be a massive challenge.

For me, it's horses for courses. Depending on the end result I want, and taking account of my limitations, I build some from plans, some from kits, buy the odd wooden artf and have several foam warbirds. The choices we have available nowadays is one of the joys of the modern hobby.

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  • 11 months later...

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