I just finished building a box joint jig using Ed Stiles plans https://www.youtube.com/watch?v=JYxDXHGRRrk

I have a brand new Oshlun box joint blade set.

The jig is great but the joints are way too loose. The slots are exactly 1/4 " but the pins are 15/64. which is 1/64 too small.

Does anyone have any suggestion what is creating this??

And how can I fix it.

Thanks in advance.