Mike

I thought people might get a kick out of seeing a commonly occuring router duplicator that woodworkers will never use. This machine is called a Horizon II and it takes round eyeglass blank stock which has the proper amount of curve to correct your vision and shapes it to fit into your eyeglass frames. The way this is done varies depending on how new the shops equipment is but most still use a simple machine like this one. A plastic pattern of the finished lense size is loaded on the left chuck and the lens is attached to a special block with heated optical wax and placed on the right chuck. When the machine is activated a special Bosch router motor (Identical to the 905? except for two locating holes in the case) powers up and is slid forward to the cutting position. The bit used is a 3/8" shank carbide ball cutter with 11 cutting edges. The carriage which holds the chucks slides forward to contact the cutter and a motor causes both chucks to rotate for a large rough cut and a smaller finish cut. This part of the operation is very much like a key duplcating machine. The ball shape of the cutter allows a nice smooth radius to be ground with no sharp edges. Once the proper shape is formed the lense moves on down the line to assembly. Watching this duplicator at work is interesting, just thought I would share it with you.

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Mike

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Joe Lyddon

Just like a fancy key making jig... right?

That's pretty cool...

But, aren't the number of Prescriptions somewhat infinite?
Where does the Master piece come from?

Mike

Joe, this machine does not effect the prescription directly, this cuts the shape of the lens to fit into the frames. When you try on frames the attendant used a small measuring tool to determine the location of your pupils in relationship to the frames. This gives you the focal points. The machine the Dr used with all the lenses gives the amount of diopter or curve to the lense. Lenses start out as oversized round blanks with "X" amount of curve. A 0 diopter is flat while a 10 diopter looks like a cereal bowl. Lenses are premade in 1/4 diopter steps. Lets say you need 1.86 diopter to correct your vision. You can grab a 1.75 off the rack and it will almost be right. the lense is then finely machined on a special CNC lathe to correct it to 1.86, or to transition to a 2nd diopter for reading. Bifocal lenses (with lines) are preformed and can be machined the same way to fine tune them. Then the lenses go into a polishing machine with a white liquid polish, water and are polished by daisy shaped abrasive pads mounted on aluminum blocks of the proper shape. Next comes an optional special coating to protect the lense which is cured under a very powerful UV light. Now the lense is shaped to fit inside the frames, then inserted into the frames and a final check to be sure the focal point and prescription are on the money. All in all many machines that are computer controlled and a few skilled people. I preferred working on these machines as opposed to industrial equipment since you can change a motor with one hand instead of using a crane.

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Joe Lyddon

Thank you Mike...

That's very interesting...

I've been using those special 'blended' lenses instead of trifocals, etc.... forgot the brand name... takes a little practice to get used to wearing them. but afterward, they're COOL!!

My bigest problem is when I'm looking at something low... and I have to look thru the bottom part of the lenses... it about breaks my neck!! I've found it's easier to just take the glasses off! (near sighted)...

I guess you have (are) maintained that type of equipment?

challagan

I have the same problem Joe....it's called getting old It's a PIA, take them off to see the real small print ... put them back on to read something else...

Corey

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challagan

Next time I get a new pair of glasses I think I will ask for a nice Roman Ogee on my lenses

Corey

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My Shop Website - Woodshop 51503
http://woodshop51503.tripod.com/

harrysin

Good article Mike,although you mentioned it in passing,I don't think that Joe realised that frames arrive with dummy lenses fitted and that it is these dummies that are copied so that the pre-made lens will be a perfect fit into the frame.The photos. sure look like the machines that I have seen operating here in Australia.Harry

Mike

Yes Joe, I worked in the machine repair department for one of the nations largest optical firms. If a dancing man talking about "Sexy Specs" means anything to you then you will know the company name. (I have a very cool pair of glasses with the Cosmic tint and he calls me CosmicMan)
Harry, you are correct about many frames coming with sizing lenses but for those that don't there is the Triumph Tracer. This is a CMM (Computer Measuring Machine) that has an arm that traces around the inside of the frame and translates the information into the computer for more advanced machines that cut the lense shape directly from the numbers, such as the Horizon III seen below.

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Mike

harrysin

Mike, I'm being sincere when I say that Wikipedia is all but redundant with you around, there is hardly a day that I don't learn something interesting from you either on the Forum or by Skype.Keep it up and I look forward to our next chat. Harry