Lens breakage/drill mounts

[vinmcmahon]

What can be done, (aside from using polycarbonates) to decrease lens breakage when assembling drill mount frames with pressure fit bushings? ie: Silhouette?

[Jeff Trail]

Even though I am a wholesaler I get called often into the retail side and try to help out accounts with problems. One of the first problems I noticed most often is the bits, they were using old dull bits and some of the accounts were using the SAME bits drilling lens, screws and everything else :)
I can tell you how I do it, especially the pressure mounts is I have a set of bits that fit the mounts I keep in a tray that is labeled.. I also, if it is poly, drill a pilot hole that is half the diameter..especially in higher RX's where I am going through a lot of material and "heat" becomes the enemy.
I change bits fairly often and do NOT try to make it last till it is just a rounded off nub, and if a bit does break I do NOT just slide it out a little further and keep using it, that tapered end is there for a reason :) .. Some think my way maybe a little expensive, but the thing to remeber is the bits we can use on the lens is NOT the same we need to use on the frames.. you can pick them up for hardly nothing.. my bits usually run around .80 to a $1.10 a pc. for the ones I use on lens and I'll get hmm probably 45 or so drills out of that bit before deciding to change over (probably could get 3 times that amount if I wanted) I just weigh the cost of the lens (the blank,the labor etc.,) and it is far cheaper to replace a $1 bit than have to eat a lens
If you are in retail you know what drill frames you have on the wall and take them apart and find the CORRECT drill bit sizes to do the job, place them to the side and use them ONLY for lens..
I also found "wood" bits seem to cause less stress than "metal" bits (material the bits were designed to drill) and using a variable speed drill helps as well, let the bit work its way through and not "force" it through and use clean sharp bits and you will see the backside chipping and cracking disappear.
Well it works for me anyway. I just look at the big picture, I have a $350 drill frame with $200 PAL's going into it so what is the price of popping in a new bit compared to all that?
I also stock plenty of washers (both metal and plastic) and even IF they did not come with them I put them on between nut and lens surface, and more often than not I'll place a plastic sleeve in the majority of my drill mounts that take a bolt just to ensure less stress from bolts to lens material.
I'm sure you will get plenty of other idea's from everyone else here..

Jeff "cut me, do I not bleed resin" Trail