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side wall delamination

Posted: Sat Mar 23, 2019 3:14 pm
by ember
Today I was profiling my cores and when I got to the end the side walls delaminated from the wood I used epoxy (from snowboardmaterials) and sanded and flamed the side walls. Any ideas on what I did wrong or what I can do next time so this doesn't happen again.


Re: side wall delamination

Posted: Sat Mar 23, 2019 4:41 pm
by MontuckyMadman
Ur prolly gonna have to give more details.
How did u profile?
Planer crib?
Did u leave it longer for snipe?
Router jig?
Did u glue it down?
Overhead sander?

Maybe u wanna use pu glue?
Maybe u wanna prebond ur sidewall to wood and rip and stick to core?
Maybe u should read the forum?

Re: side wall delamination

Posted: Sat Mar 23, 2019 5:45 pm
by ember
MontuckyMadman wrote:
Sat Mar 23, 2019 4:41 pm
Ur prolly gonna have to give more details.
How did u profile?
Planer crib?
Did u leave it longer for snipe?
Router jig?
Did u glue it down?
Overhead sander?

Maybe u wanna use pu glue?
Maybe u wanna prebond ur sidewall to wood and rip and stick to core?
Maybe u should read the forum?
I profiled the core with a router jig
I clamped down 2/3 of the core while I profiled it
Like I said did prebond the side wall to the core unless you mean something else

To elaborate a bit more I was profiling the core with a router and got to the end and the prebonded side wall came off of the wood core, I used epoxy from snowboardmaterials to bond the side walls to the wood could I just reatach the side wall to the core with pu glue or something or do I have to start over

I'm new to this so idk if that is enough detail or if I'm even doing it right, I read through this forum and all of the happy monkey wiki

Re: side wall delamination

Posted: Sat Mar 23, 2019 6:23 pm
by Head Monkey
If it's come loose a few inches at the end it's not a big deal. It happens to me now and then. Just carefully work a little glue in there and put some tape on it overnight, then be careful with it until it's time to layup. The sidewall just needs to be held in place until you laminate the board; the bond to the wood core just needs to be sufficient for that and no more.

Re: side wall delamination

Posted: Sat Mar 23, 2019 7:26 pm
by BAR
I'm new as well so i might not be the best resource. I had a similar problem using a router jig on my core. Recently i have been thinking about this problem and i have a theory about this.

If you watch a cnc router profile a core it cuts the center and then runs in a slowly increasing perimeter cut always in a clockwise direction. This means that the cutting action of the bit is always inward meaning that the router bits cutting action is always pushing into the glued joint rather than pulling the joint apart. This means the glued sidewall has substantially less destructive forces it has to deal with if you cut in this rotary path. Maybe that's the most obvious thing in the world but i certainly didn't do that on my first core and i had the same problem.

See this video I think its Head Monkey's video.

Re: side wall delamination

Posted: Sat Mar 23, 2019 9:36 pm
by Head Monkey
Here's a pic I took 10 min ago for you man. This came off my CNC machine fine, but somewhere along the way I knocked it in the shop and part of it popped off. It's a thin zone, and it's delicate, so yea, it happens. I'll give the last 1" or so a little hit with some 80grit, spread some glue, and tape it back on sometime and it'll be just fine. This will still be a tight fit. If it was separating away from the wood, or if the joint was failing in the middle, then I'd be worried. But this... nah.
IMG_20190323_221855.jpg
IMG_20190323_221855.jpg (260.26 KiB) Viewed 624 times
The cutter you use in your router can be a factor. You should use a straight edged bit, not something like an up-cut spiral.

The cutting speed and direction can matter a bit too. But again, it's just a delicate spot.

BAR, the reason you see me going in the direction I do in that video is because I'm "conventional cutting", as opposed to "climb cutting". This helps reduce the backlash in my machine, but is the only advantage. Edit: well, I should say, it's the only advantage traditionally, and also likely in my case since the sidewall material is supported on both sides. If you're sidewall is unsupported on the outside, then I agree with BAR's suggestion above.

Google "climb vs conventional cutting" to see a bunch of explanations of this.

Re: side wall delamination

Posted: Sun Mar 24, 2019 12:48 am
by chrismp
Using a downcut router bit can help with that problem too.