Grinding Colorant?

I was planning on trying the coffee grinder route, then sprinkle it on the pellets during the drying process to get it to stick, i dry my pla in a toaster oven at around 150-175f.
have some smaller masterbatches that static stick to the hopper that this worked with.

so far i've only tried extruding a small patch of highly concentrated colorant/pellets and chopping that up to mix at a much closer ratio. worked great for an even color but don't have a good way to pelletize filament atm.

You were probably using a blade grinder, a burr grinder would be more appropriate.

I'm thinking it's easier to just buy pre-coloured CMYK Pellets so there's no need for masterbatch.

The low ratios of masterbatch make filastruding tricky because only a bit goes in to the melt chamber... so a little bit extra masterbatch can drastically change the colour.

But If the pellets itself are precoloured the safety  tolerance is so much higher.

our next order may be for CMYK pre-coloured pellets. so the mixture is more stable.

Where. I want to try.
Its hard to perfectly mix colorant with pellets. Sometimes you get slightly more in one place and less in another resulting in uneven color.
I moved auger closer to the nozzle, about half inch away allowing more mixing to take place and it helped dramatically but still not 100% even.