My wife wanted some goblets laser engraved as last-minute Christmas gifts. Usually, laser engraving round glass objects is a piece of cake...but goblets tend to have small mouths, wider bottoms of the drink-holding section, and short stems. The short stem and tiny mouth conspire against the height adjuster on the rotary attachment.
This short Instructable will show how I solved that problem using a simple, low-tech (and very low-cost) trick. I made her gifts at TechShop: http://www.techshop.ws
(I neglected to get photos while engraving the gift goblets, so I tracked down another goblet and repeated the process. The clear goblets were the last-minute gifts. The blue goblet was originally engraved to get photos for this Instructable but later became a gift as well.)
There's a clip on the left side of the rotary attachment that helps keep a glass in place while it's being engraved. The clip only works if the mouth of the glass is facing the left side of the rotary attachment.
That means the base of the goblet normally rides on the height-adjustable wheels. The base of the goblets I used are the same size as the mouth or slightly larger. For glasses like these, the base needs to be lowered not raised, in order for the engraving section to be leveled.
When working with long-stemmed glasses, the adjust height-adjusting wheels can be slid under the bottom of the bowl or even under the stem. But, the stem on goblets can be so short that the goblet's base catches on the height-adjusting section, preventing proper leveling of the bowl.
I needed a way to raise the lip of the goblet while keeping it on the left hand side of the rotary attachment so the clip would keep the goblet positioned properly during engraving...