Rubber stoppers drilling

When drilling a rubber stopper, you will find it prudent to wet the tip of the bit with glycerin or a dilute ammonia solution and drill on a table as indicated above, or in a special stopper drill (Fig. 27). 

Rubber stoppers are also efficient, simple, temporary system closures. Properly drilled, stoppers can support thermometers or funnels. Because new stoppers have no surface cavities or cracks, there is no risk of leaks as with corks. Like corks, stoppers are used to keep things in (or out) of container. Table 1.7 includes a list of rubber stopper sizes. 

When drilling rubber stoppers with a drill press, do not use a rag to hold the frozen rubber stopper. If the rubber grabs the drill bit, the rag could catch rings,... 

Fig. 1.14 An example of forced core drilling of a rubber stopper.

Fig. 7,8. Reversible mercury-calomel electrode with the parts consisting of a 250 ml wide-mouthed reagent bottle, a vented and drilled rubber stopper, a soft glass tube with platinum wire sealed into the end, mercury, a wire to the output of the power supply, saturated KCl, and a glass tube containing 5% polyacrylamide gel made up in 1 M KCl. The tube dips into the buffer reservoir of the electrophoresis apparatus. The anode and cathode should be interchanged after each run. This arrangement will prevent all contamination of the buffer with electrode products even in very long runs (J. C. Finder, Ph.D. Thesis, London University, 1974).

You will need a gallon jug with a 6 1/2, two-hole rubber or cork stopper. (Cork stoppers can be drilled to accommodate glass or copper tubing. Rubber stoppers are better and are sold by any hofcby chemical supply company. But in a pinch cork stoppers will do). 

Drill a hole with the help of auger and insert the access tube in the soil with little disturbance such that no bulge is created in the access tube. Keep the access tube 10-20 cm above the soil and cover with inverted can or close its opening with a rubber cork to prevent entry of trash.In order to prevent water entry into the tube, close the lower end of the access tube with rubber stopper. 

X2.2.3 A convenient holder can be made by drilling two holes, 22 and 8 mm in diameter, respectively, through a No. 11 rubber stopper. The center-to-center distance between holes should be 25 mm. Slit through the rubber stopper between the holes and also between the 8-mm hole and edge of the stopper. When placed in a 2-in. (51-mm) diameter hole in the bath cover, the stopper holds the viscometer in place. Such holders are commercially available. 

If you find that the holes in your preholed stopper are the wrong size or in the wrong location, you can take a solid stopper and custom drill holes which meet your specific requirements. There are several techniques for drilling holes in stoppers, but regardless of the technique used, always start with a solid stopper. Because rubber distorts with pressure, it is more difficult to alter a holed stopper than to drill a new hole. In addition, because elastomers distort and compress, drill hole(s) the same size (rather than slightly smaller) as the tubing you wish to insert. This practice will allow easier insertion of the tube into the hole, yet will still provide a satisfactory leakproof seal. When the stopper is placed into its final location, compression from the container neck will further improve the seal. 

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