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lattice frame fuse

Building info wanted

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Bill Reed25/06/2019 14:23:41
80 forum posts
2 photos

Being a new builder I do not know the correct way to build frame work.

On the tail surfaces I was able to lay parts out in a way that I did not have to slide pieces in so no glue was "pushed" off.

On the fuse this is not possible had to lay the longerons down first. the verticals had a bit of play from moving the longerons BUT the diagonals had to be pushed in and to me looked like all the glue came off,so much so I wonder about strength, should I be using CA over PVA?

Peter Miller25/06/2019 14:47:00
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10316 forum posts
1231 photos
10 articles

In fact you will almost certainly have enough glue in the joint. Joints with gaps are weak even when using Aliphatic resin glue.

A dab of glue on the end of the upright or diagonal and a smear on the longeron works fine.

If you want the ultimate the technique that we used to use with balsa cement is called precementing. WE used to apply the glue to both parts and leave it to dry before applying a second coat and making the joint.

Of course balsa cement dried a lot faster that PVA or Aliphatic glues. THis meant that balsa cement didn't soak into the grain as much which modern glues do thus making a stronger joint

Percy Verance25/06/2019 19:41:09
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8108 forum posts
155 photos

No Bill don't use CA on those longeron to diagonal joints. The resulting joint, although strong will be brittle. Vibration from an ic engine or perhaps a rough landing, could pop a few of those joints. I'd personally use Aliphatic Bill. Aliphatic dries harder than PVA and sands far better Bill. It's also allegedly gives a superior bond. Just be sure to cover the plan with clear plastic sheet, as some glue will inevitably squeeze out from the joints. 

As Peter points out, accuracy with the joints is key here.

Some builders might cut all the uprights and diagonals and pin them to the board before gluing the ends and adding the longerons, but again accuracy will pay dividends. Either way works well enough Bill.

 

 

Edited By Percy Verance on 25/06/2019 19:49:13

Trevor25/06/2019 19:46:49
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392 forum posts
57 photos

Too late for you this time but you can avoid most of that issue with the diagonals by fitting them as you go rather than waiting until all the verticals are in place.

Trevor

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