Working with Rubber

[19brendan81]

Hey can anyone comment on the machineability of that red rubber stuff commonly found as a stopper for various test tubes and flasks etc?

I have found some stoppers that are the right dimensions for some of my home brewing equipment, but I will need to drill a hold through the middle of them to suit my needs. Is this doable in my lathe or drill press?

Cheers,

Brendan

[Dave J]

In my experience the hole will close over after you with draw the drill bit. If you have the lathe I would try a piece of small tube, slightly smaller than what you need, sharpened like a punch then use that as the drill bit in the lathe. It should cut the piece completely out.
A piece of brake line off a car or fuel line would do.
Dave

[19brendan81]

"A piece of brake line off a car or fuel line would do."

This is precisely what I want to fit in my hole! And I want it to be a sealed, interference fit. Do you know the diamter of brake/fuel line?

[RayG]

Forget trying to drill rubber,

You need a set of stopper hole cutters, years ago when I worked in a chemistry lab we had sets of sharpened tubes, they were sized to nest inside each other with a handle on the top of each one, nickel plated brass if I remember correctly.

I don't remember what they were called.

A piece of brass tubing with an edge sharpened on the inside of the tubing would do the same job, and you just push the sharpened brass tube through the rubber stopper with a twisting action.

Regards
Ray

[19brendan81]

Excellent. Thanks Ray, sounds like i will be able to get a custom hole through the stoppers, which is good news.

Do you think I would be better off holding the stopper in my headstock and chucking the tool in my jacobs chuck, or vice versa?

[RayG]

Hi Brendan,

They are called cork borers, (that's a wonderful thing google)

http://www.backsaw.net/pics/b_l_cork_bore2_08.jpg

I wouldn't bother buying a set if you only need to do a few holes, just as easy to make one from a bit of tubing.

You could try doing it in the lathe, I expect it would be better to hold the rubber stopper in the lathe chuck and the tube in the tailstock chuck. Go slow or it might get too hot and burn.

After all that, we finally got to what Dave suggested first off....:rolleyes:

Regards
Ray

[19brendan81]

Very cool. thanks for your help. Ill let you know how I go.

Brendan

[Dave J]

When I first read that heading, I thought this young fella needs help to stay safe.:rofl:
Dave

[19brendan81]

My lathe only has a 10 inch swing, thats not enough for me to be making myself the sort of DIY rubbers that your referring to Dave ; )