TIPS ON DISPENSING

[chip anderson]

Compression Mounts

Today I finallly decided that I have broken too many expensive lenses trying to do on the spot repairs on compression mounts that had come loose with wear. I learned the following from thier ace benchman.
1) Ream holes with a hand ream to correct fit (very slight resistance when slipped in by hand.
2) Safillo inserts are generally the best. Although Sillhoette's are a little softer and larger (need to be mounted a little snugger as they are affected by heat and cold).
3) Lubricate holes in insert with alcohol spray before inserting metal pegs.
4) Trim inserts to length with razor blade not special snips for this (protecting lens with scotch tape of course). Digg slightlly downward (but not enough to pentrate tape starting razor cut then turn blade for an upward cut.

I hope this saves someone eating some expensive lenses as I have done in the past. Not to mention the embarrisment of going out to the patient and explaining, "Sorry but I broke the lens."

Chip

[Chris Ryser]

Stay away from solvents...................

3) Lubricate holes in insert with alcohol spray before inserting metal pegs.

Additon....................If working on polycarbonate lenses stay away from using solvents which promote crazing.

[rdcoach5]

[quote=cmbrumbaugh;183215]anybody know a quick short hand for calculating the amount of induced prism this decentration creates at given power/cyl's? finally, how many times have you checked someone glasses when they come in the door and you see they are off 5 mm.? you use the correct VOC on the new pair - and either find they are too accomodated to the old pair's induced prism that they can't see as well at first. i've found the bulk adjust soon and some even come back to claim this the best vision they've ever had out of a pair of glasses. sometimes i just split the difference to avoid problems. i know this kicks out a thicker pair of lenses on bottom vs top, but isn't the better vision the best policy.? what do they teach in the vaunted abo classes?




Prentice Rule Simplified. 10 mm by diopter of power. Example -4.50 Diop sph decentered 10 mm total{both lenses} gives 4.5 diop prism base out if too narrow and base in if too wide.Opposite for hyperopes.To estimate power accurately with astigmatic powers , just remember power at 45 degrees from axis is 1/2 of the power at 90 degrees from the axis. Ex. -4.50 +1.50x135. Power at 90 degrees is -4.50 plus half of the cylinder = -3.75, The same is true at 180 degrees.The power is -3.75. At 22.5 degrees off the axis, the power of the astigmatic correction is 1/4 of the cylinder. From this simple memorization you can estimate prism powers about as accurately as the labs can manufacture.
Bob Taylor

[ArtChiQe]

Holy cow. I have only read the first two pages of this thread and now I have so much to tell the office tomorrow. I've been in our optical department for two years with only on the job training. I just wish I found this board sooner. Thank you all so much for sharing your info.

[Fezz]

ArtChiQe-

Welcome aboard. This site is great. Most the folks here are truly a gift to the optical profession. Jump in, ask questions, give opinions, advice, experiences, and thoughts.

Oh, and no matter what anyone else on here may say--

I didn't do it, say it, think it, hear it, imagine it, or make anybody else do it!! Its Johns, Optical24/7, Braheem, and Uncle Festers who are the ones to be VERY WARY of!!!


:D:cheers::D:cheers::D

[chip anderson]

Just a thought, not somehting I have done yet.

Has anyone concidered using slightly tapered drill bits for compression mount holes? Hole slightly larger at the metal prong side to prevent
slipping and prong moving out? Or possibly camfering the outer edge
on the prong side to preven lens chipping/cracking and allow easier starting of prong as well as prevent nylon insert from slipping backwards

Please let me hear any whys or why nots from you.

Chip

[MarySue]

what's up (or down) with VOC's.? does every optician and lab on earth just automatically default to the exact vertical geometric center on SV lenses? shouldn't you place the sweet spot right over top of the vertical center of the eye? i think my lab just weenies out on this - lazy. i know being decentered vertically is not as bad as being off the the PD, but why would you let the best part of the lens be placed 3 -6 mm too low? anybody know a quick short hand for calculating the amount of induced prism this decentration creates at given power/cyl's? finally, how many times have you checked someone glasses when they come in the door and you see they are off 5 mm.? you use the correct VOC on the new pair - and either find they are too accomodated to the old pair's induced prism that they can't see as well at first. i've found the bulk adjust soon and some even come back to claim this the best vision they've ever had out of a pair of glasses. sometimes i just split the difference to avoid problems. i know this kicks out a thicker pair of lenses on bottom vs top, but isn't the better vision the best policy.? what do they teach in the vaunted abo classes?

You should order the lenses if aspheric with the OC specified to the patient's centre of rotation in the frame they or you have chosen.

There are some fantastic text books to help, but a good course designed to teach you the theory and practical application for dispensing optics is something you might want to pursue. I know that J Sargeant Reynolds in Richmond Virginia has such a course if you're keen

Otherwise some good practical books can be found online - one of the user friendly manuals is by David Wilson and that link is: http://www.abdo.org.uk/books/bkmore.asp?bk=BK019

Also - Mo Jalie has practical text books available as well - a page display for measuring the centre of rotation can be found at:

http://books.google.com/books?id=Zl45vQkISCwC&pg=PA40&lpg=PA40&dq=centre+of+rotation+measurement+spectacle&source=web&ots=gRn-5F6HkP&sig=UckqlwFVtl1U5pt9sW1xSEMDXes

Cheers!

[DragonLensmanWV]

Has anyone concidered using slightly tapered drill bits for compression mount holes? Hole slightly larger at the metal prong side to prevent
slipping and prong moving out? Or possibly camfering the outer edge
on the prong side to preven lens chipping/cracking and allow easier starting of prong as well as prevent nylon insert from slipping backwards

Please let me hear any whys or why nots from you.

Chip

What I do is drill the holes at 1.2 mm, then use a tapered ream from the front to enlarge the holes. I have a mark on the ream that tells me when to stop. This will let the pins set fully into the pegs, allowing a slight bit more room for the solder at the base of the pins to flush mount.

I don't do that for the Kishimoto drill mounts as the pins are integral, not soldered.

[Chris Ryser]

Is it dumb to strip AR coatings?...............

Sounds like trouble. Stripping AR and tinting is a dumb gamble. Who knows what coating, and or what material. Probably an Old Lenscrafters featherwait, or poly with a bad AR.

I have advertised AR strippers the first time in 1985 and sold thousands of them every year since then.

Therefore there must also be also thousands of dumb opticians and optometrist's as well as labs that are stripping AR coatings.

If you keep strictly to CR39 and strip no AR from poly and high index lenses, you will encounter no problems at all. It takes 5 to 10 seconds to strip the AR, and thats it.

If you have scratches on the lens you go on stripping for about 2 hours and the hard coat will be gone and so will be the scratches and you have a totally new and clean lens.

What is dumb about that?

Actually you are doing the patient a real favor, of having lenses that do not bother him or her. As glasses will have to be changed for a new Rx you will have a happy customer coming back yo you for the new Rx.

What is dumb about that ?

I assume that if you can not get out of stripping a lens you will send it to a lab to do it. They will charge you for the 5 second job. You will loose a couple of days turnaround besides having to pay for it.

[DragonLensmanWV]

One little tip I use that I'll pass on. Concerning stuck screws:
how many times have you tried to use a slot file to make a new slot in a screw that's in a frame with little room?

What I do with my slot file is to break off the tip at a 45 degree (or more depending how it breaks) angle. That will give you a smaller tip of the file to work in smaller areas with more clearance.

[Fleming]

In response to the question of "how do you clean the groove on a grooved poly lens" here is my reply. Some of my most useful tools are free. Try a tooth pick (just follow the groove with the tip and use your fingernail to do the rest) finishing up with a medium to hard tooth brush .. job done.

[harry a saake]

nosepads

when turning nosepads out to make them fit flatter, on flatter type nasal areas, they will also widen at the same time, causing the frame to sit lower, therefore you may have to push the pads back in towards the nose slightly, you may have to repeat the process a couple times. I usually start when i see this situation by pushing the pads in more then usual and then turn them out with the pliers.

[harry a saake]

screws

another inherent problem is nose pad screws that back out, try putting a small dab of fingernail polish on the screw head, just before you tighten it all the way down, so some of the polish will get under the screw head.

If you ever have to loosen it just heat it slightly

[chip anderson]

Frozen Screws

I haven't tried this yet, but the DIY Network said today, that whenever you have frozen screw, drop some H2O2 on it and wait a minite or two.

Of course I would really know who makes the Grabitt for Sears and see if they could make this in opthalmic sizes.

Chip

[harry a saake]

4 point stance

One of the most misleading tasks i see opticians do is the 4 point stance, which often means nothing, or at least the glasses are not in alignment, but appear to be.

If the front of the frame is not aligned straight across, as should be, often a tech or optician will compensate by bending one temple or the other up or down, thus giving the appearance of a perfectly aligned frame.

It is quite common to see frames that have one side bent in more then the other, and this should be the first check one should make.

One way that this commonly happens is when doing face form and the optician inadvertently bends the frame around and in at the same time, one side more then the other.

So check all frames to see that they are straight across the front, all screws are tight, and then check for 4 point stance, you will be amazed how many times by straightening out the front of the frame, you will not have to bend on the temples, which is usually a good option