looking for indexable carbide insert tool holders for turning.

[sawlog]

How snug are you tightening the screws. You don't won't to overtighten the screws but they need to be tight enough the cutting forces won't loosen them.

[jerhalco]

i have found that Mesa tool has great tools for hobby type machines.
Here is a link. http://www.mesatool.com
HTH
Jerry