Water Jet Cutting
We all accept there is no such thing as perpetual motion and likewise there are some machines that you would never expect to become practical propositions. The water jet cutter is a machine that just sounds impossible, how on earth can you expect to cut things like granite, steel and glass with just a jet of water?
Well - The simple answer is "You can!" and it's proving an extremely successful invention.
The majority of disks used by Oldham Optical are directly cut from sheets of glass with a Water Jet Cutter.
The principle could not be much simpler (see left). A high pressure water pistol is mounted above a table and its movement is controlled with electric motors and a computer. A small amount of sand may be added to the water stream to speed up erosion of the material being cut, but the water does quite well by itself.
A Water Jet Cutter will cut absolutely anything, - including paper, foam plastic, wood, brass, steel, stone, granite and thankfully for Oldham Optical's purposes - Glass.
It does it with the absolute minimum of fuss - Very little mess, noise, no dust, no thermal effects and cutting can be watched in perfect safety from only a few feet away.
Every DIY enthusiast should have one of these things if he/she has the space and can afford it.
We are told they are available second hand for 100K upwards.
The example pictured adjacent is the Water Jet Cutter owned by Spectraglass who are one of the major suppliers of low expansion glass to Oldham Optical.
The water jet is very high pressure and simply wears away the material where it hits.
You might expect it to take a long time to wear away glass, - but it cuts through 1" thick glass at a rate of about 0.5" per second. The example pictured adjacent is the Water Jet Cutter owned by Spectraglass who are one of the major suppliers of low expansion glass to Oldham Optical.The water jet is very high pressure and simply wears away the material where it hits. You might expect it to take a long time to wear away glass, but it cuts through 1" thick glass at a rate of about 0.5" per second.
Of course it does not usually cut one disc at a time, the photograph above was set up for us - The cutter usually cuts up entire sheets of glass at once.
The next photograph shows a sheet of glass from which apparently 54 x 6" mirrors have been cut!
(This was probably a batch of windows for use in pressure vessels)
The scrap glass left after cutting is all in large pieces and is sent back for recycling.
One of the few problems a Water Jet Cutter has to contend with is what sort of a platform do you lay the material on to be cut? The cutter simply slices through the supporting platform after it has finished working its way through the main subject.
Usually the platform is a grid of thin stainless steel.
It can be partially protected by immersing the grid under water by a fraction of an inch. (Look at the top picture where the horizontal lines of the grid can be made out just under the water level.) Often some scrap wood such as hardboard will be placed under the object being cut to give more protection to the grid, but eventually the grid will be worn away and has to be replaced.
The last picture is a close up of the water jet cutter head with the sample of glass. The cutter has nearly finished cutting a smaller disk out of the sheet.
So if you have something really difficult or awkward to cut - you might think about giving Spectraglass a ring!