It took about a dozen tests but I’m finally getting good consistent results on shot glasses.
A year ago, I designed a jig to hold 20 shot glasses for engraving (Shot Glass Jig & Template). Within a couple days of getting my Glowforge, I cut a 1-glass version of the jig to make sure it would work as intended. It didn’t. It was close but needed a few tweaks.
With the 1-glass jig perfected, I started seeing what I could do with it. Based on information on these forums, I experimented with a wet paper towel over the glass and, today, with a thin layer of dish soap. With wet paper towels, I was getting inconsistent results likely due to the towel drying out before the engrave finished. I thought for sure that would be a problem with a 20-glass jig. My one test with neither a wet paper towel or soap resulted in a cracked glass. Don’t try this at home.
Today I got five good consistent engraves using dish soap over the glass. Just in time for a trip to the consignment store that has been asking me for shot glasses for over a year. Time for Goldfinger to start paying its way.
Hello, I’ve been working with a rotary on a Trotec (at work), I was hoping the Glowforge (home use) was going to come with a rotary haha! Maybe in a few years. Anyways… how did you get it to work for your shot glasses. I am interested to see your jig. I haven’t received my Glowforge yet, but when I do, skies the limit! … what is the area size that you are able to engrave?
Follow the link in my original post to see the 20-glass jig. The current 1-glass jig is just a subset of that.
Without a rotary attachment, there are limitations on the width you can engrave on a round object. I started out with an intentionally narrow design for that reason. I did a couple wider designs using business logos for the wine & spirits distributor my brother works for and for a friends’ business. I could see a degradation in image quality when the design got much over one inch wide.
Theoretically, you should be able to break the design into strips and adjust the focal length of each strip to get wider. I haven’t tested that yet.
I was making it up as I go based on suggestions I read here on the forums. What I’m finding works in my case is to squirt a drop or two of dish soap onto my finger and then rub it over any part of the glass surface that might get hit with the laser. Somehow, that drastically lessons the chances of unwanted cracks.
The primary purpose of the jig is to try to align the highest point of the surface to be parallel to the bottom of the Glowforge. Because of the almost 2" diameter of the top of the glass, you have to remove the tray.
Because of the tall narrow dimensions of this particular design, it takes significantly less time to complete if you line it up side-to-side rather than front-to-back. That has to do with how the head travels side-to-side and then advances one notch front-to-back and then goes side-to-side again. For this design on one glass, it’s 2 minutes 20 seconds versus 3 minutes 20 seconds.
Here’s a picture of a short glass sitting in the jig just after I engraved it.
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