Tapered Glass Rotary Distortion

[Ben Satterfield]

I know this topic has been covered several times in the past. I have read a ton of threads and most refer to Dan Hintz posts from several years ago that went into detailed discussion of the issue. I can't find the old posts.

I'm using a Trotec Speedy 400 at a local makerspace. It is currently setup with the wheel / rim drive instead of the cone drive, not sure how much that matters. Using Illustrator but have Corel as well.

For simplicities sake let's assume the glass is 5" tall, 10" circumference at the top, 7" circumference at the bottom.

I understand the need to distort images to laser tapered glasses but apparently I'm not doing it correctly. I'm assuming it is something on the software side. I size my artwork to fit in a rectangle that is 10" wide x 5" tall. I then use envelope distort to distort it into a trapezoid that is 10" wide at the top, 14.28" at the bottom, 5" tall. That works if the artwork is small and is centered. The issue is when the artwork wraps the entire glass, it becomes too distorted toward the edges. Should I be distorting using a different method?

I can upload files or pics if that would help explain the issue.

[Kev Williams]

I know jack squat about how to use the 'envelope' tool, but I DO know an easy way to compensate for cylinder taper using the 'add perspective' tool...

First, don't work in circumference to start with, you want to work in diameter first to get the graphic corrected...

I've drawn up below my procedure for taper adjustments. The cup size I used for this demo is 5" tall, 3" diameter at the top, 2" diameter at the bottom. After drawing the cup shape to actual size, I added a 5x3" bounding box....
the screenshot explains the rest :)
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--once the graphic is corrected, now work in circumference to get the correct plate layout, then size the corrected graphic to fit!

I do shot glasses and wine glasses quite often and this has never failed me ;)