Laminate Sample #13: Open Molded E-glass / Polyester Resin with Balsa Core
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- čas přidán 18. 02. 2020
- This sample shows how to (kinda) laminate an open molded balsa cored panel with polyester resin.
It is similar to #6 and #8, but this time I'm trying out an end-grain balsa core. It's hard to see how well your core is bonded if there's gel-coat, so this one is just clear resin in one shot. Turns out there were some significant voids/bubbles of trapped air under the core.
This is one of the big problems with coring open molded parts - it's hard to be sure your have the core bedded down completely. Two possible fixes for this are:
1 - use a thickened core bedding putty and place the core down starting on one side and working it in a line so air gets pushed out the "front" for the joint.
2 - use weights (or a vacuum bag!) to press the core down into the first skin. Let the resin gel and then laminate the top skin. For larger parts, this multi-step process is the only option because the gel time of polyester resin is typically pretty quick.
It is a rugged and easy to build laminate and is suitable for projects where light weight is less of a priority but cost, gel-coated surfaces, and molding of complex geometry (in un-cored areas) are important.
Find more about this sample at:
explorecomposites.com/materia... - Jak na to + styl
Excelent content, greetings from Ecuador!
Thanks! I've been slacking off for a few months but will get back to it!
Open balsa soaks up a lot of resin. Better to coat each side with a resin that has a thixotropic additive (micro spheres) to sin the balsa with. Then layup when that gets tacky. There's another channel that did a demo on this... Tech Ingredients: czcams.com/video/tiS8ArzEA58/video.html
Yes - you're totally right - pre-coating is a good option. Thanks for linking to that video - it is a great explanation! Just note that he's using epoxy though which has different viscosity and cure properties than the polyester resin in this video.
Even a filled bedding/bonding adhesive works much better than the straight resin I tried to use. I wanted to show this issue and also not hide the balsa by using a filled adhesive. I think some weights or minimal pressure would have largely solved the problem here but it is something to think about with balsa.
Hi, could you explain what is that black mat(?) that you are working on?
It is a black sheet of G10 plate. Just something I had that was shiny enough to release from.
I am interested to know how tight a radius I can build with Balsa,
If you want to cut solid core into trapezoidal strips, you could go quite tight. With standard contour-scrim balsa, the dimensions of the blocks will limit the extreme contours you can do. With thinner core you may be able to break or manually slice the blocks to better fit tight radii.
You can do all steps like you do same day ?
Yes. The polyester resin cures fast - like under an hour. It is best to bed the balsa down in something more filled though! You could also let the bottom skin cure so the core bedding doesn't slide it around. It can be done in one shot like this, but it is rarely the best idea!
@@ExploreComposites ok understand , thanks for your reply
@@ExploreComposites Sorry broo but you know is the balsa core on a checkmate starflite 1986 is 1/4" ??? I mean in the floor of hull
Where can i buy balsa core
Most places that sell fiberglass supplies will have it in at least a few thicknesses.
Anyone need balsa block and core from indonesia?
Gads that little piece used a gallon
Well, maybe a quart - but yeah it's a lot!