Cuttle bone can splinter and damage the throat & crop.
I reccomend the use of calcium enriched mineral block.

I've never heard that before. Dakota has them available to him, but Ollie doesn't. I've heard so many times not to supplement greys with Calcium unless prescribed by an avian vet- so I just stay away from it!

the backbone of it correct? not the powdery part?

Arty, I have never had yet one of my fids go for those calcium blocks. I've tried just about every one on the market. Any suggestions?

Same here. Quito and Tausi both have untouched calcium perches, and I've tried the mineral blocks with both fids as well. Nada. They could care less about them.

i sometimes grind it up and add it to the food, but valo and bella don't care for the cuttlebones either

We used to use Cuttle bone, it took time for the birds to adjust to mineral blocks, Our keets and tiels knaw the mineral blocks down to nothing in no time.
We also use the mineral perches.
It just takes time for the adjustment.
Our vet came to our bird club for a seminar and she spoke of injuries from cuttle bone, then I also heard it again from John (Beaks), I don't recall her saying what part of the cuttle bone is unsafe.
I also used to take what was left of the bone and chop it up fine and offer it as grit.
I also take our egg shells from breakfast and nuke them for a minute, chop them up into almost powder form and give to the birds, high calcium and they enjoy the stuff.

Wow I learn new things everyday...I love this site

Thats a new one on me. Everyone uses them here.

Cuttle bone is used heavily in the Avian world, I am simply saying there are risks as they do splinter.