How to Drill a hole in Opal

 

How to Drill a hole in Opal or Gemstone

To drill a hole is not as simple as it sounds

We find many people buy opal or gemstone and try to drill a hole and don’t succeed.

This can be very frustrating if the following procedure is not followed.

Two main problem areas

Drill is set on fast speed

Drilling through stone chips other end.

 

Diamond tip drills are suitable for drilling small quantities of stones.

These drill have been tipped with diamonds of different grades and shapes can be round, arrow pointed, long shape or hollow point.

 

120 grit is suitable for drilling holes

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Hollow points are also good if you can find right size

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Drill Speed.

These drills can attach any standard home drill or dremel drill

But if drill set on high speed the diamonds will burn off in a matter of seconds.

This happens frequently as there is incredible heat when diamond drill touches the stone and it needs constant water on the stone when you drill.

Drill must be on slow speed.

If drill doesn’t have slow speed control ,keep depth of drill so it is only slightly touching the stone.

Many diamond tip drills are ruined from heavy hand

Slow speed slow work is best and plenty of water.

Have tube  or hose connected to tap so water flow is constant

Standard home drill attachments that hold drill are suitable but need block to hold stone stable for drilling.

 

Set drill to slowest speed 7,000 to 10,000 rpm,this is slowest setting on dremel drills

 

To start hole tilt the drill and slowly with no force go to vertical if drill hand held.

Keep removing drill bit from hole to clean out excess material and this allows water to wash out hole and keep drill from heating.

Do not use pressure to drill hole

 

Drilling Hole

To drill a hole you can only drill half way through the stone.

Than the stone must be turned around and drilled in from the other end so that the join is in the middle of the stone.

This is not easy to get exact

But if you just drill all way through the stone ,when the drill protrudes at the other end it will chip off edges so unsatisfactory finish.

Some commercial clamps are available that can turn the stone over 180 degrees.

Wooden clamps can be made but it is important that you can turn the stone over and drill in exact hole so it is clean join.

Some cutters glue the opal to bench so it is solid and than drill the hole

Many large cutting factories have Sonic drilling machines and these cut a hole by using a high frequency vibration.

This is good for commercial large operators but are expensive, and I have seen cheap ones that do not satisfactory

 

Making Opal beads

Standard diamond tip wheels can be purchased that are 3-4 inches wide and these are curved so semi shaped bead is formed.

Most are 100 to 140 grit and to start you shape the opal, mainly boulder opal or ironstone opal with colour bars to a rectangular shape.

This long rectangular shape fits against the diamond tip curved wheel by another attachment that can be spinning or manually turned.

The result will be uniform beads with two blocks on each end that can be sliced off with saw blade.

Many cutters do get disappointed when making beads as rough is usually good to start but, most of the colour colours do disappear when making beads.

Many opal beads are worth less than half their value when cut into a bead

So it is important to get opal rough that has colour veins running through them as they normally produce a good finished bead.

Matrix opal is also suitable.

Black opal is rarely used to make beads due to cost of opal rough.

After you try and make some beads you can appreciate why good quality opal beads are so expensive

 

POLISHING TIPS

Rubber tips are also useful when making holes or polishing undulating surfaces

Diamond impregnated rubber tips are ideal for finishing off edges after hole drilled or any undulating surface.

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if you don’t have any rubber tips you can set up 1-2 inch diameter sandpaper on flexible rubber disk and use contact adhesive glue so sandpapers can be changed easily when worn.

No water is required by you must have air suction to take air away and have mask whenever polishing with no water.

Vacuum cleans can be used but must have strong suction and most household vacuums are not strong enough to take dust particles away from your face and mouth.

For final polish you can use lapsa polishing  power made into paste and concave and convex heads are good for difficult tog et at spots especially on undulating boulder opal.

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Opal books are also helpful in giving practical advise for opal cutting and polishing.

Example, Opal and How to work it by Frank Barnet

 

Please visit our forums for more information in regards to cutting opal and feel free to register and ask other forum members questions.

Cutting Opal thread

 

http://forums.opalauctions.com/viewforum.php?f=3&sid=45d30a506e5028215a02c1eeb5e7cd67

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Last Update: 16 Dec 2010