|
Hanaldo
|
|
|
Group: Forum Members
Posts: 2.5K,
Visits: 28K
|
Those are very light moulds... A slight curve to the paddle would increase stiffness, and a 'rib' across the back would increase it greatly. The 'standard' paddle design is very suited to composites. You could do it with flat carbon, but it would be significantly heavier for the same stiffness.
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Dravis, Tks for the tips. As seen on the attached pictures, moulds are standard tooling gelcoat, 2 layers 100g chopped strand, 3 layers 200g chopped stand, polyester resin. We'll see what the paddle will look like but I am considering to maybe do a flat paddle. I just wonder how to give the required stiffness when under load. I'll do my homework and find the solution (add many layers of carbon fibre? Laminate layers of carbon fibre interspaced with aramid? Required thickness?). p.s. strange, when I attempt to attach the pictures (around 800kb), i get a popup message that says I exceeded the upload limit size for this message...
|
|
|
|
|
Dravis
|
|
|
Group: Forum Members
Posts: 592,
Visits: 1.9K
|
I have used expanding foam inside hollow CF gun-stocks .. it made no apparent difference in the stiffness of these, but it removes the "hollow" sounds, so makes the user feel a bit better ..  I suppose that in the case of a flat blade, it can help protect a bit against crushing the thinner parts of the hollow blade. Always make sure that you leave at least one opening for the expanding foam to escape from --- the foam can create a very high pressure if the gasses can not escape. And DO keep it in the mould ... the foam could easily deform the part, if its not supported. What kind of mould have you made?
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Dravis," But ... why all the screws? Surely just bonding on the wood (?) gunwale strips on the inside would be strong enough?"
You may be right but I have experienced gunwale delamination from kevlar on one of my racing canoes back in Canada. The boats are made for speed and I have kept the weight to a minimum by laminating thin and narrow candian cedan strips. Using screws might be over-engineering but I feel safer that way (especially if I am a few hours away from my car on a remove river). Another reason is that i have designed the shape of the canoe (no computer modelling of stress and strain) and I can not be certain of the force distribution on the gunwales, better safe than sorry.
Paddle handle and blade split moulds are finished. May attempt a first try at making a handle and blade in carbon fibre tomorrow although I had planned to install seat fittings. Been thinking of possibly injecting expanding foam in the narrow space inside the blade to had stiffness before demoulding ????
|
|
|
|
|
Dravis
|
|
|
Group: Forum Members
Posts: 592,
Visits: 1.9K
|
Looking very good   But ... why all the screws? Surely just bonding on the wood (?) gunwale strips on the inside would be strong enough?
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
OK, it's starting to have the look of something that I would take on the water. Redone the core material and finished the stern starboard gunwale. Wish I would have been better at orienting the carbon strands vertically and horizontally.
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Good news ... and ... bad news. Unmolding went perfectly well. The shell looks great notwithstanding some minor imperfections that can easily be fixed (figure1). Beautiful AND extremely light. Unfortunately, the cheering stopped when I noticed that the core material had delaminated around the middle of the canoe... So I put the shell back into the mold, stripped the diolen sheets and removed the core material. I figure that although I had slit the underside of the core material longitudinally every 1cm or so, and that I applied significant weight to put the material on the shell, this was not enough to curve the core and provide an efficient bond (Figure2). I am now starting to epoxy new core material but in strips of 5cm wide, two to three strips only at a time. Once cured, I will add more strips, and so forth. This is only a minor setback and part of the learning process I guess. Within two weeks, I will install the gunwales and cross bars. Next post should be of the finished seats.
|
|
|
|
|
VVS
|
|
|
Group: Moderators
Posts: 226,
Visits: 334
|
Hope it all works out for you, fingers crossed.
I'm impressed by the size of project, the second picture with you guys along side shows just how much work you've put in. 🍺
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Things are moving along nicely. Layed carbon and diolen cloth. Later today, adding core material and unmolding this weekend... gulp...
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Finally!! See attached picture. Some areas did not release and I struggled to get the pattern out. But eventually it all worked out fine. Should be cruising from here on (famous last words...).
|
|
|
|