Bifocal Issues on 7Ex

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08-11-2017, 05:51 PM
jonathan barber

Bifocal Issues on 7Ex

This may seem like a simple issue, but I can't seem to get much help anywhere. The majority of my flat top lenses (bifocals and trifocals) are coming out crooked. I've tried calibrating the axis on both the blocker and edger to no avail. Any help would be great!:help:
08-11-2017, 06:22 PM
lensmanmd

Quote:

Originally Posted by jonathan barber

This may seem like a simple issue, but I can't seem to get much help anywhere. The majority of my flat top lenses (bifocals and trifocals) are coming out crooked. I've tried calibrating the axis on both the blocker and edger to no avail. Any help would be great!:help:

Gonna need some more info. How far off axis? Same amount on both eyes? Beveled, grooved, rimless? With/without polish? Stored shapes or new traces? Many variables. I think I might have a solution for you, but I will need as many specifics as possible.
08-11-2017, 07:14 PM
jonathan barber

Quote:

Originally Posted by lensmanmd

Gonna need some more info. How far off axis? Same amount on both eyes? Beveled, grooved, rimless? With/without polish? Stored shapes or new traces? Many variables. I think I might have a solution for you, but I will need as many specifics as possible.

Usually about 10 degrees or so to the right OU. Both grooved and beveled lenses, although it seems more exaggerated on the grooved lenses sometimes. I almost always use a new trace for a frame. Most SV lenses and PAL's seem not to be turning the way the straight top lenses are. Lens material and treatments do not seem to make a difference.
08-11-2017, 07:23 PM
lensmanmd

Ok then. I was thinking more like 2-3 degrees. Just enough not to notice on SV or PALs. 10 degrees will show on all lenses. When was the last time you calibrated the axis on your tracer? My money is on the tracer axis.
08-14-2017, 09:15 AM
Don Gilman

Quote:

Originally Posted by jonathan barber

This may seem like a simple issue, but I can't seem to get much help anywhere. The majority of my flat top lenses (bifocals and trifocals) are coming out crooked. I've tried calibrating the axis on both the blocker and edger to no avail. Any help would be great!:help:

Possibly slippage due to the seg ledge if only on Flat tops??
08-17-2017, 05:20 PM
Tallboy

It has to be slippage if the SV and PALs are okay. Are the blocks looking like they are turned in relation to the ledge? Or is the entire shape just cut off wrong so it looks "turned".

If it is actually turning, try taking high end lens tape and cutting in half, put one part above the ledge and one part below the ledge, leaving a gap in the middle, this will give a better secure pad adhesion. Works for me. Did this just start recently or it has been a problem for a long time?
08-21-2017, 06:17 PM
jonathan barber

Quote:

Originally Posted by lensmanmd

Ok then. I was thinking more like 2-3 degrees. Just enough not to notice on SV or PALs. 10 degrees will show on all lenses. When was the last time you calibrated the axis on your tracer? My money is on the tracer axis.

Hadn't been able to be on for a while, but just wanted to let you know I haven't had any issues since I recalibrated the tracer axis! Thanks!
08-21-2017, 06:18 PM
jonathan barber

Quote:

Originally Posted by Tallboy

It has to be slippage if the SV and PALs are okay. Are the blocks looking like they are turned in relation to the ledge? Or is the entire shape just cut off wrong so it looks "turned".

If it is actually turning, try taking high end lens tape and cutting in half, put one part above the ledge and one part below the ledge, leaving a gap in the middle, this will give a better secure pad adhesion. Works for me. Did this just start recently or it has been a problem for a long time?

I had honestly considered this possibility, but I just wasn't sure how feasible that would be. This is honestly the first office where I can ever remember having this issue when edging.
08-21-2017, 08:29 PM
lensmanmd

Quote:

Originally Posted by jonathan barber

Hadn't been able to be on for a while, but just wanted to let you know I haven't had any issues since I recalibrated the tracer axis! Thanks!

Glad I could help.