I tried to make some rubber rollers for the Ball Mill yesterday.
In lieu if having any rubber pipe with an inside diameter of 8mm kicking about I tried molding rubber rollers using some Vinamold compound I had to hand and a piece of copper pipe.
All in all a dismal failure, the Vinamold as well as being Smelly/Smokey to work with when it is melted it is pretty viscose.
It couldn't flow down the copper pipe quickly enough as it cooled and the result was stuck all round the inside of the pipe and full of voids.
The roller core pulled out too easily as well (I had used a thin aluminum tube with OD of 8mm to fit the bearings and an ID of 6mm to fasten the roller to the bearings using M6 Studding and Nyloc Nuts.
Having tried this as an experiment, I think it could be successful if a two part mold was used instead of a tube. The mold is better made out of something that is a poorer conductor of heat too, so that the Vinamold doesn't set too quick.
I think I need to return to plan A and find some rubber pipe/hose that suits the job, for now.
Making a two part mold I think is a task for the milling machine when it is complete.