Intro: How to Laser Engrave Small-Mouthed Goblets
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.)
Step 1: Step 1: Showing the Problem...
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...
Step 2: Step 2: Reliably Raising the Rim...
I needed a way to raise the rim…quickly, easily, and RIGHT NOW (hey, Christmas was coming up fast and the original goblets had to be shipped nearly 2,500 miles away).
While pondering potential solutions, I stuffed my hands into the pockets of my sweatshirt with a huff of frustration…
Waitaminute! What's this in my pocket?!?!
A week or so prior, a friend had invited us to the opening showing of a new big-name movie. As we left the theater, we were offered some movie-related goodies. I skipped the poster but absentmindedly accepted one of their wristbands and stuffed it into a pocket of my sweatshirt.
It's just a simple, thick, silicone wristband…but it just might solve my problem…
It took only a minute to slip the band onto the top of the goblet and fiddle a bit with its positioning. Whaddyaknow…it worked! OK, if you look closely at the bubble in the level, the rim is still a wee bit low…if only I would've snagged two of those wristbands after the movie.
The band was initially tried right at the rim, but that didn't offer enough of a boost. By moving it down the bowl a bit, the band makes contact with the innermost portion of the drive wheels which raises it just a wee bit more.
Step 3: Step 3: Focus, Aim, Fire
Follow the normal directions for focusing the laser…though some suggest slightly (very slightly) lowering the glass to slightly (very slightly) defocus the laser to get smoother engraving (better overlap between pixels = smoother engraved surface).
Even with the darker color of the blue goblets, the alignment pointer just doesn't show up very well one the glass. So, I laid a scrap of paper towel on top of the goblet…ahhhhh, much easier to see where the left edge of my drawing should appear.
With the focus and alignment allegedly set, it was time to engrave! I had only one blue goblet with me and of course had a bit too much white space on the left edge of my drawing. That pushed my engraving a bit further down the bowl than I'd like, but it still works since that helps keep the user's bottom lip off the engraved area (the engraving is likely to feel rough to a sensitive lower lip and I don't want the recipient of my gifts giving me a bunch of lip about how it feels).
Step 4: All Done!
Woohoo! Success!! Move the wristband to the next glass (if you're doing more), wipe off the engraved area, fill the bowl with your favorite test beverage, and enjoy the fruits of your labor...