1.74 exploding when drilled?

**tdj** · 12-09-2012, 11:48 AM

I had a lab rat friend tell me a few years ago that 1.74 is prone to exploding when drilled. Is this true? I've never put it in a drill mount because of that, but I've heard mention of people using it in a drill. True or no?

**regional_manager** · 12-09-2012, 12:31 PM

http://www.opticianonline.net/assets...px?ItemID=5152

I wouldn't drill it.

**Robert_S** · 12-09-2012, 01:52 PM

1.7 would be a good substitute. I would agree that 1.74 isn't really suitable for rimless, although Hoya claim that theirs has higher tensile strength than their competitors' 1.74. I'm not saying that's true, it's just what they told me, but you may want to look at getting the job from Hoya if it has to be 1.74.

We have used 1.74 from both Zeiss and Hoya in rimless mounts without any issues before.

**scriptfiller** · 12-10-2012, 01:02 PM

I have had no problems glazing 1.74 into drilled rimless mountings. I have a manual Santinelli Less-Stress drill, and find the middle speed to work best.

**Java99** · 12-10-2012, 01:06 PM

My drill pair is a 1.74, no issues.

**sharpstick777** · 12-10-2012, 05:31 PM

There are differences in 1.74, Essilors is brittle but Seiko's seems to hold up OK. We stopped drilling any Essilor 1.74s after too many cracked lenses. Still do Seiko's.

I still recommend 1.67 for drills though. Its pretty though.

**oxmoon** · 12-10-2012, 06:37 PM

Originally Posted by sharpstick777

There are differences in 1.74, Essilors is brittle but Seiko's seems to hold up OK. We stopped drilling any Essilor 1.74s after too many cracked lenses. Still do Seiko's.

I still recommend 1.67 for drills though. Its pretty though.

Zeiss has stopped drilling 1.74 because of cracking, but we get many from Essilor that look great and hold up very well.

**KKirkpatrick** · 12-10-2012, 08:27 PM

Yes..Considering it has been edged, drilled, chamfered on the front and back of every hole drilled, proper fittings, and adjusted carefully.
I have two pair of Silhouette rimless, drilled Seiko 1.74 in both pair. I've had these for over a year. The O.D. next door to me also wears a Silhouette rimless with the Advanced HD 1.74 from US Optical. I have also used 1.67 many times. Equipment could have some involvement in lens issues, I use a Tabco smart drill.

**AngeHamm** · 12-11-2012, 11:22 AM

I have a pair of Zeiss 1.74 lenses drilled. No problems.

**Tangleoak** · 12-20-2012, 12:49 PM

1.67 or trivex are best for drill mounts; 1.74 is too brittle for most. Silhouette's compression mounting is more forgiving than most other 3 piece drill mounts though.