Hey all. My blocker has trouble operating correctly with high Rx lenses or with high prism. I'm pretty good at decentering everything by hand (I use rulers and right angles to make a crosshair where the block's center should be.) but it's become tiring. Does anybody know of a better way or a tool that is helpful for this?
I assume you're talking about an automatic blocker? Forgive me if I miss the complexity of the question, but does traditionally spotting the lens on a manual lensometer not get you what you need? Prior to getting my autoblocker everything was manually spotted and centered, and that was the only option regardless of power or prism.
Yes, it is an autoblocker (it detects the three dots as well as progressive markings etc.) but at higher powers the image will get shifted and the block will not place correctly. To get around this I have to manually figure out where the block is supposed to go, dot that, and then figure out how much I need to fudge the measurements on the block correctlyOriginally Posted by DanLiv
Sounds a lot like how we blocked before autoblockers came along.
Indeed, but was there a tool that you used to make life easier?
Also, is everybody's autoblocker but mine blocking everything perfectly without there ever being a need for manual intervnetion?
You should find out why your blocker is not correctly blocking the lenses. In the past we used a marking machine made by American Ootical or AIT and stamped a cross on the lens and then blocked it with several available devices that you could easily see if you were off postion.
A PD stick and lens marker of choice. Took FPD, figured decentration each eye for PD and OC/seg/fitting mark up or down from datum, (measured with a PD stick). Then “knew your beast” of blockers. As example you had to adjust placement of the reference point due to prismatic parallax in the blocker with certain powers/prism amounts…..Ah…good times…
I’ll ask my tech next time our machine is down. If anything there should be an option to tell the machine “hey, this lens has a high Rx or prism so block accordingly”
Every lab should have an old school manual blocker. CAD blockers are great for bread and butter RXs. But for high RX/prism, nothing beats a manual blocker. AIT, Coburn, whatever.
I bend light. That is what I do.
Is there a cut off where you say “ah yes, this should be done manually”?
I use our santinelli blocker in manual mode quite frequently.
If you are creating more than 2 diopters of prism the blocker will start to have accuracy issues. You will notice seg heights off and pd inaccuracy. This is very noticeable with vertical prism in a bifocal or progressive if they are up and down not yoked. One lens will be high the other low. You can compensate if you know the error which you can record from trial and error or if your lab software controls the blocker it should be able to do this automatically.
Agreed. It works perfectly no adjustments or guess work needed.
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