Lenses continue to pop out

[OPTICALWARRIOR]

I Really Appreciate All Who Helped Me With My Problem .

[Speed]

Poorly manufactured.

[geopard]

I had a same problem with accura integrated tracer
I compesated "manually" by adding apox 1mm vertically and adjusting frame to base for thin lenses
Attachment 6750
I agree that its problem with horizontal length and tracer

[snotbagel]

I have this problem with my older non-tracing edger...and I'm sure I know why we're havin a poblem!
The clamping pressure of the chuck is distorting the lens making it shorter in the "a" when clamped, and then it springs out when released. We just never had so many lens shapes like this until the last 3-4 years. I usually shave the pattern a bit at either edge..but I must be the only guy here using a pattern edger.

[QDO1]

1. worn bevel on edger, cutitng a U not V
2. poor trace / former
3. lack of intuition and hand skills *
4. poor quality frame **

* no mater how good your machine is, being able to "cut it big, and finish it by hand" is a basic skill most never seen to bother to learn. There are some shapes, machines will always screw up

** the long bow effect - the top edge of the lens is curved. To get an adequate mount presure around the rest of the lens, the top edge needs to be able to keep its curve, if it strightes itself out under tension, it is a poor design frame

Remember that dummy lenses are always very thin, and usually curved perfectly for the frame in its "unglazed state"

[QDO1]

[QUOTE=CLANDGH;302539]I see a lot of people on here with some very good suggestions. I'm a Master Optician, been doing this for 36 years. The best ways I've found to prevent lenses flexing out of the upper and lower eyewire on rectangles is:

1. If the demo lenses fit well, use the same base curve, this is also a good rule of thumb when working on jobs that will have a clip-on, especially the magnetic kind.
please consider what is best form as well

3. A flat base curve will stay mounted in them better
please consider what is best form as well - this becomes a dispensing decision (or the problem starts with the dispenser), if the Px is +6.00D dont dispense it
4. If installing a "+" lens in them, don't follow the base curve when edging, edge the lenses to the front on the nasal and strap, and to the back on top and bottom, in otherwords, keep the bevel as close to a square straight line as possible.

5. Don't polish the edges. If you do they will slip out more, if you need to polish for the patient, tape the len surfaces, and hand polish only the flat thick areas that will be exposed, the V bevel doesn't show, and doesn't need to be polished.
Dont polish ANY egdes in a V mount, unless absoloutley needed - it just causes internal reflections

[QDO1]

I have this problem with my older non-tracing edger...and I'm sure I know why we're havin a poblem!
The clamping pressure of the chuck is distorting the lens making it shorter in the "a" when clamped, and then it springs out when released. We just never had so many lens shapes like this until the last 3-4 years. I usually shave the pattern a bit at either edge..but I must be the only guy here using a pattern edger.

Does it do this with a smaller chuck?

[snotbagel]

I haven't really tried to solve this issue with chucks..and you'd have to compensate for both front and back curves. A flexi-chuck should reduce the error, though. It's probably way too much time and money to stack pads three thick to reduce the warping, and then you'd have slippage (torque) problems. Never had this problem with glass lenses in half eyes!