Digital Sag Gauge

[DocInChina]

I am looking to purchase a digital sag gauge. Any recommendations?

[DragonLensmanWV]

PSI has a couple, one with a table stand, one without.

[Jacqui]

I got mine from Optek. It reads out not only sag, but also radius and true curve.

[DocInChina]

We decided to tool our own Steel Sphere Bell Gauge and make our own center thickness stand for blocked SF lenses. We were able to purchase the 0.001mm and 0.01m digital indicators. I thought I would share the photos.

Doc

[Jacqui]

Should start selling them, Doc. :D

[LENNY]

Cool!

[fjpod]

You should see my homemade surfacing thickness gauge. I took a 10 dollar digital thickness gauge, and glued on some longer bigger feelers made out of a pattern blank. One with a point and one flat to put the block against. Works like a charm.

[LENNY]

Pic please!

[sharpstick777]

I got mine from Optek. It reads out not only sag, but also radius and true curve.

Jacqui, I know this is an old thread, but I couldn't find the item on their website, do you have a model number or pic? Thanks

[MikeAurelius]

You can pick up digital gauges pretty much anywhere, expect to spend maybe $50-$75.

Have a machinist make you a bell to fit the gauge, with a 50 mm inner diameter, with high tolerance +/- 0.005 mm, in either brass or steel (recommended). Inner (contact with the lens) edge **MUST* be free of burrs and gouges. To read minus, a 50 mm outer diameter ring is required, with the same tolerances.

The only thing is going to be finding a setup test lens that has a known, marked curve and saggita. They should absolutely be glass. Any other material is going to wear and you will end up off curve.

I can make the setup test lens, with both plus and minus curve marked in radius, 1.53 diopter, and saggita if anyone is interested. They run $30.00 each. Curves are traceable back to 1/4 wave master test plates.

[sharpstick777]

Thanks Mike, what interested me was the Optek one can also do True Base Curve, can you modify your design to measure True Base as well? is there another gauge that measure true base accurately and digitally? Thanks

You can pick up digital gauges pretty much anywhere, expect to spend maybe $50-$75.

Have a machinist make you a bell to fit the gauge, with a 50 mm inner diameter, with high tolerance +/- 0.005 mm, in either brass or steel (recommended). Inner (contact with the lens) edge **MUST* be free of burrs and gouges. To read minus, a 50 mm outer diameter ring is required, with the same tolerances.

The only thing is going to be finding a setup test lens that has a known, marked curve and saggita. They should absolutely be glass. Any other material is going to wear and you will end up off curve.

I can make the setup test lens, with both plus and minus curve marked in radius, 1.53 diopter, and saggita if anyone is interested. They run $30.00 each. Curves are traceable back to 1/4 wave master test plates.

[MikeAurelius]

I believe they were 'programmable' gauges, if I could find out which model, I'm pretty sure it would be fairly easy to program.

I will take a look around in the a.m.

[MikeAurelius]

Just checked several sources, Mitutoyo and Starrett, neither one makes a programmable indicator. Starrett used to, but discontinued it about 4-5 years ago.

You will have to go with direct sag reading, sorry!

[PrecisionTool]

Hello,
We make them and can provide sag charts as well. http://precisiontooltech.com/catalog...x.html?page=18

Thank you,
Jared

[sharpstick777]

Hello,
We make them and can provide sag charts as well. http://precisiontooltech.com/catalog...x.html?page=18

Thank you,
Jared

Jared, Thanks so much. On page 4 and 5 you offer 2 table top models, that appear to measure True Base, 25mm and 40mm chord. I am assuming the 40mm offers some wider accuracy, but it doesn't mention whether in can measure unblocked/lose or Schneider blocked lenses.

< my primary goal is to measure true base on semi-finshed spherical lenses

Can you pm me prices for both?

[WFruit]

You can also use this: http://www.opticampus.com/tools/surface.php to convert from Sag to True Curve (without, you know, having to do any actual math). I've got the nice Mitutoyo model on my desk, with 40mm and 50mm chords, which measures semi-finished lenses quite nicely.

[Michael Walach]

Just checked several sources, Mitutoyo and Starrett, neither one makes a programmable indicator. Starrett used to, but discontinued it about 4-5 years ago.

You will have to go with direct sag reading, sorry!

You can get a MITUTOYO digital indicator gauge, MITUTOYO serial interface to your computer and get the digital input in your Excel spread sheet. Then just put it through any algorithm you might require. For highest accuracy I recommend using 3 steel balls contact points rather tan knife edge bell. I have made some for spherical surfaces as well as 2 contact point balls for toric surfaces; works like a dream, contact me if I can be of help.

[jherman]

nice post

You can get a MITUTOYO digital indicator gauge, MITUTOYO serial interface to your computer and get the digital input in your Excel spread sheet. Then just put it through any algorithm you might require. For highest accuracy I recommend using 3 steel balls contact points rather tan knife edge bell. I have made some for spherical surfaces as well as 2 contact point balls for toric surfaces; works like a dream, contact me if I can be of help.