here is the answer: this method allows to make perfect holder with precision about 0.1mm or better. without using any tools.
(this is my first instructable, i will edit it later)
Step 1: Stuff Which You Need
1. Some small motor.
2. Epoxy resin or acrylic oxide(cures faster)
3. Syringe (size depends on motor axis and drill diameter)
4. drill bit which you want to attach to motor
Tools you will need:
something flat and sharp ( knife, screwdriver or anything else )
Step 2: Lets Start
there are few ways, you can either glue something or do in my way:
Mix some epoxy resin or acrylic oxide and put it in to syringe.
try to avoid bubbles.
now insert motor axis deep into syringe and wait until epoxy hardens( with acrylic oxide you only need to wait few minutes )
here all funs will start:
now we have piece of plastic attached to motor.
just power on your motor and use knife to cut away unnecessary part of syringe and shape that piece of plastic into nice and symmetric cone.
you may need to remove all syringe if it wobbles to much, then you can shape plastic freely.
finaly some hard job is coming. now we need to drill perfect hole in the end of cone.
so take your drill bit and use it.
Drill will find perfect center automatically. All you need it to keep drill bit straight somehow.
Drill bit holder is ready for use.
Step 3: FInish
best way to attach drill bit is to use super glue. it is not permanent fixation and since super glue does not bond to metal very well
Since all this is quote easy and cheap, it is easer to make separate holder for each drill bit.
precision is very high and surpasses cheap dremels or drills.
currently I have no better way to achieve same precision