prevent core shift during layup

[ggardner90]

It is my first time attempting to put inserts into a core. i am curious how you guys are able to prevent the core from shifting at all during the layup. i have been using a home made casset jb welding aluminum bars to the aluminum sheet on the mold. this works fine but there is about .5-1mm of shift that can occur durring pressing. it has never been a problem yet because i comensate with slightly wider sidewalls. but since there are inserts and any shift would make the threads off of center i just want to see how others are doing it

Thanks

[Idris]

Glue 2 of your inserts to your base, cut the appropriate holes in your lower fibreglass/carbon layer to let the insert through. Your inserts now guarantee your alignment.

[twizzstyle]

Do a search on locator pins or dowels.

I drill two holes, one just in front of the bindings, and one just behind, doesn't need to be accurate at all. I place the core on the base exactly where it needs to go, and then superglue two short pieces of dowel to the base between the holes. After a few minutes you can lift the core off, the dowels/pins stay on the base, and that keeps the core in place during layup. You do have to cut holes in your bottom composite layers, just like you do with Idris's method.

[ggardner90]

i never thought of the gluing the inserts to the base. that is awesome and solves the problem thanks. so much

[gozaimaas]

If the insert is the correct height

[vinman]

Definitely make sure you sand the locator pins down at least to flush with you core. I tend to make Sure they are countersunk by a mm or so. If you leave them too long they will press into your base and royally screw things up.

You can fix this by drilling the defect out and into the pin and having the shop fill it with a hot ptex gun before grinding your bases. Better off not to have it happen in the first place though....

[twizzstyle]

Yeah good call Vinman, I always just rough cut my dowels by eye, and they end up just slightly shorter than the core. I helped a buddy make a pair a few months ago, and the dowels were a little too long. I said "no biggy, the fiberglass will account for that" and it didn't. Luckily the base dimples weren't so bad that they couldn't be ground off, but it could have been much worse.

When I do my inserts they are countersunk into the core so that they are flush with the top of the core, so gluing the inserts to the base wouldn't work for me.

[ben_mtl]

I believe I already posted that somewhere..
here is how I do :
- I glue 2 slim pieces of wood between my 2 cores
- drill small holes in those extra parts
- I glue 2 dowels (double sided tape) on my bottom mold so those pins match the position of the holes in the "links" and everything is aligned properly (bases are spray glued to the bottom mold prior to that)

When it's time to put the cores in the layup, I just have to make sur I "plug" the cores into the locating pins and nothing can move !

Here's a pic of my setup before it's placed on the bottom mold : you can see the "links" with holes between the cores, and you can also see the "locating pin"s that will be fixed on the bottom mold.
It's not fast, but nothing moves and the postionning system gets removed with the flashing !