Thread: What's a good material for making round knobs?

Originally Posted by Big Shed

Still seems easier to me to cast a round rod, then drill and tap, then turn to a ball using a ball turner.

About the only thing you gain casting in a ping pong ball is the saving of a bit of resin, but at the cost of more work and harder work holding.

If you cast in rod form you can cast in different diameters too.

It's starting to look that way, although drilling a moulded sphere on the drill press couldn't be easier if the drill passes through the hole in the centre of the drill press table. A ball turner will give a much higher quality ball (rounder) too.

Graziano
Thanks for posting the photo of your brass balls...
It has given me the need to make me a knob... but my first problem is what to make it for..
Which knob on which machine is the question.

Russell

Originally Posted by rusel

Graziano
Thanks for posting the photo of your brass balls...
It has given me the need to make me a knob... but my first problem is what to make it for..
Which knob on which machine is the question.

Russell

The first three black ones are now installed on the small cheapo drill press, it actually feels better to use without loose wobbly knobs . I counted eight or nine knobs on the Bantam lathe alone of various sizes, I need two to refit to the reverse levers.

The bronze-brass ones leaves black tarnish deposits on a cloth, it'll need an epoxy dip (epoxy sticks to polyester I understand but not the other way round). I've been thinking about how I've been going about the whole process and I need to take it one step further: use the basic pattern making skills I picked up to make a decent set of ball moulds. I still have some unused table tennis balls I can wax and then embed in a mix of epoxy and sand with a pair of waxed aluminium sheets in the middle to split the mould around. That way I can mould say four at a time complete with a slightly tapered hole ready to drill and tap a thread. This way any moulding seam at the equator sticks out and not in, so it'll sand off cleanly.

One thing the whole exercise has definitely yielded is using the mineral based pigments as colouring: the blacks and red-browns do match older plastic parts I've repaired quite closely which makes sense as they would have used the same cheap plentiful pigments on hand at the time. The end result is tougher than just polyester resin alone.

Russell

If you buy genuine PP Ball they are made from Cellulose, which is highly flammable.

Regards
JohnQ