Hi Barn, thanks for posting this info in response to my earlier post. Luckily my two patches are nothing close to a snapped board.
Excellent posts....Thanks for putting the effort in with photos and diagrams.
Where's the best place to shop for the repair materials mentioned?
Barn, the method you described is super cool and better than the one from Boardlady. A PhD student would modify it a bit to avoid using any metal tools and have more control...
Then it's perfect and i'll use it for my future repairs... :)
Here is what I would do to make it simpler and more streamlined...
Modification on how you prepare the bottom layer:
I would take a strip(s) of glass/carbon of the right size and lay it on a piece of glass/flat plastic bag/an instant wrap, and cover it with epoxy and let it dry. You will get a nice thin, sharp, flexy, manageable piece of material afterwards which you can cover with more epoxy and squeeze pretty easy under your shell and over the EPS foam. You can even play with injectable polyurethane foam if you wish it to be squeezed more from the bottom up. You can even flip the board and add hang some light weights to insure it presses nicely against the bottom layer..
After this procedure everything is simple.. add divinicell, cover with more glass/carbon..
WARNING! WARNING! WARNING! to anyone attempting to do a board repair like this.
This is not the strongest way, yes it might hold up for a while but it will break earlier than a better repair.
just doing a straight line of glass across the board creates a stiff breaking point.
It's a bit like scoring a straight line along a piece of glass before you snap it.
the top glass should be curved or a diamond shape to spread/feather out the stiffness/load.
I fully concur with Mark Australia
Interesting thread. I tend to agree that poking glass under the bottom layer seems a bit agricultural but it would be interesting to see what sort of shape that bond was actually in once it was set and if there was any real strength in it. That aside, if my memory of composite construction serves me correctly I believe that the bottom layer of glass would actually be in compression after landing a jump and the top layer would be in tension. As such the strength of the bottom layer of glass would not contribute very much in comparison to the top layer.
Yep, you're right, the area of the deck between mast track and footstraps is under tension when a jump is landed.
But I've seen this area fail, because rider puts front foot forward while slogging, in that case the underneath layer is in tension. I agree with Barn, in structural areas, it's best to reproduce the original sandwich as much as possible. A sufficient overlap of top and bottom fibers ensures the same tensile strength.
But I guess it could be argued that the overlapped area is stiffer.
Like Barn I'm not convinced this is a problem. Relative to the stressed area, the overlap is very short. I can't see it increasing the stress at the transition significantly.