Drinkware Adaptor (Tapered and Mugs) and Image Adjustment for Laser Rotary

Have you ever had problems engraving a tapered cup? Do your images come out distorted? Do you want to engrave a mug with a handle? Then, this instructable is for you!

This is a two-part instructable for laser engraving items on rotary attachments. The first half will describe the steps to build a set of wheels to keep tapered items level on a rotary, or allow mugs with handles to rotate unimpeded. The second half will detail the process to calculate and adjust an image for engraving on a rotary device. If you already have a method to rotate your item and just want these calculations, skip to Step 7.

Rotary Adaptor Supplies

• Material of choice (wood, acrylic, etc)
• Paint or stain to enhance the engravings (optional)
• #8-32 machine screws (various sizes)
• #8 washers and nuts
• #8-32 brass expansion nuts (various sizes)
• Rubber stoppers - preferably with a hole (various sizes)
• Drill bits (if you need to makes holes in the rubber stoppers)
• Rubber bands, wide (optional)

A few links to some of these items:

• #8-32 x 15/32 in. Brass Expansion Nut
• 10x #000 Neoprene Stoppers, 1 Hole
• 10x #00 Neoprene Stoppers, 1 Hole
• 2x 0.375-in Black Neoprene Hole Plug
• 36x #8 Stainless Steel Standard Flat Washer
• 22x #8 x 32 Zinc-plated Steel Hex Nut

Image Adjustment Supplies

• Adobe Acrobat Reader (Free)
• Inkscape (Free)
• Lightburn (or your laser program of choice)

This part is dependent on your needs. The easiest method to determine what size you need is to measure the widest part of your item's opening or base - whichever is larger, and add twice the width of your handle (if engraving a mug). This will allow the item to rotate evenly without hitting the rotary device. I've included multiple sets of SVGs for 100mm and 150mm guides. For sizing consideration, here are a few options:

• If your size requirement is less than 100mm, use the 100mm guide. (For regular tapered tumblers, bottles, etc.)
• If your size requirement is between 100mm and 150mm, use the 150mm guide. (For large tapered tumblers, bottles, regular mugs with handles, etc.)
• If your size requirement is greater than 150mm, start with either the 100mm or 150mm guide that has alignment lines larger than your item's opening or base and add a circle 10mm larger than the requirement and center it on the guide. Set this circle to cut, and remove the cut radius for the selected guide. (For large mugs with handles)

Example: I measured a large mug that is 105mm wide with a 40mm handle. I require a 185mm guide. I load the 150mm guide, create a circle 195mm wide and center it on the 150mm guide, and delete the 150mm cut line. Please keep in mind to watch what direction the image will rotate the handle, and that it doesn't strike your laser head.

Each size guide has two hole alignments, and each set requires both the engraving and cut files for the guide. The includes sets are:

• 100mm guide with holes and alignment lines on the 10s (10, 20, 30, 40, etc.)
• 100mm guide with holes and alignment lines on the 5s (15, 25, 35, 45, etc.)
• 150mm guide with holes and alignment lines on the 10s (10, 20, 30, 40, etc.)
• 150mm guide with holes and alignment lines on the 5s (15, 25, 35, 45, etc.)

Note: I recommend cutting at least one of each of your chosen width. This gives you the option between the two guides to get within 5mm of the correct diameter for the base of your item - especially if using expansion nuts.

Load the files for your chosen size in your laser program. Select both the engraving circle and the cutting circle, and center them on each other. Load your material in your machine and begin engraving/cutting as appropriate for your material in the following order:

• Engrave all markings
• Cut the guide holes
• Cut out the wheel

Originally, I used plywood, and didn't need to do anything to enhance the engravings. However, when I used acrylic, I applied white paint and wiped it off to make the engravings easier to see.

I use #8-32 machine screws, #8 washers and #8 nuts to secure my grips. The washers protect the screws from damaging the outside of the wheel. The nuts allow me to use longer screws on the rubber stoppers to compress them to widen their grips as needed. I keep a range of grips from expansion nuts to rubber stoppers with holes to allow me a wide range of options for gripping different shaped items.

If you can't find rubber stoppers with holes, you can use a drill with varying sizes of drill bits to drill a hole in the center of a solid stopper. Begin with the smallest bit, to ensure you guide the bit through the middle. Don't worry if you're a little off, as you can correct this as you get closer to your final size. I checked the fit with a screw each time I finished with one bit, eventually finishing with 3/16" bit, as I wanted a tight fit. (This will make a mess!)

Note: If you have issues with your wheels slipping due to the material or the grip of the rotary bars, you can add a wide rubber band around the wheels.

Once you have your wheels and hardware ready, it time to put them to use.

First, "measure" the base of your item. I find this is the more challenging attachment point, because it is typically attached on the outside. If you have a longer item and aren't worried about the size of the engravable area, you can use the rubber stoppers. Otherwise, you can use the expansion nuts, but be careful with the size of these nuts. (Mine are small.) Place the screws through washers in a circle about 10mm wider than this "measurement". Hand tighten the expansion nuts or slide on the rubber stoppers, then attach the item by carefully pushing the item into the middle of the grips.

In the example photos, the base measured about 55mm wide, so I placed the expansion nuts at 65mm. This was sufficient to maintain grip without tightening the nut, but I have tightened the nuts on other items. (It provides another 2-3mm of width on the grip.)

Second, "measure" the top of your item. Place screws through washers in holes 10-20mm inside of that "measurement". Attach the rubber stoppers by pushing them (or screwing them if you have a very tight fit) onto the screws. If desired, you can use a nut to provide a slightly wider fit. Attach the item by carefully pushing the item's opening around the grips.

Third, make sure both ends are even. A gap may be visible and is acceptable, as long as the item is secure. A good test is to roll the item to check how even it is.

Note: Take care to ensure none of the washers or grips extend past the side of the wheel. This may interfere with the smooth rolling of your rotary device.

At this point, you need to prepare your rotary and the item to ensure the engraving surface is level with your laser. By using a level, you can ensure your spoilboard and laser are level to the ground. Once this is complete, angle your rotary in order to make the top of your item level to the ground. Once this is done, you're almost ready to begin your engraving...

Unfortunately, round/even items will engrave narrower images and tapered items will engrave conical shaped images. This distortion is due to the difference in rotational distance between the wheel (normal) and the item (slower), as well as the angle of the item's centerline on tapered items.

In these photos you can see how the example image is narrower and even smaller toward the bottom. The final photo is with an image correction. (There is still a slight curve in the top and bottom due to the angle of the item, but the width is corrected.) I won't bore you with all of the calculations, so instead I've created a PDF that does the calculations for you.

In order to use the Rotary Calculations file, you need:

• Width of the wheel (If you are not using guide wheels, or have an adapter the same size as your top on the bottom end, enter the width of the top of your item.)
• Width of the top and bottom of the item
• Height of the item
• Width and height of the image
• Height on the item of the center of the image

Enter all of these items into the Rotary Calculations, and follow the instructions:

• If the item has equal sized ends with straight sides, increase the width while maintaining the height to the adjusted image dimensions.
• Otherwise, export the image as an SVG, open the file in Inkscape and group all of the vectors.
• Click Path → Path Effects…, click the + symbol (Add path effect) in the Path Effects dock, and select Perspective/Envelope.
• Ensure the Type selected is Perspective, change the Handles to the calculated adjustments, and save the image.

Note: This process tends to break some of the nodes on the vectors. If you have one's set to fill, the instructions will help you in Lightburn. If you are using another program, please look for a function that allows you to close the paths.

Your image is now ready to engrave!

There are various ways to level your rotary device depending on which model you have. I own the xTool Rotary Attachment, which has two very convenient long rectangular openings on the bottom. By measuring the rotary device and the openings, I built a rotary leveler that incorporated the rails to consistently allow me to attach the rotary device to the leveler perpendicular to the hinges that angle the mount. (Also added a centerline for the widest setting on my rotary.) I adjust the angle of the leveler by using bolts with a nut to keep the leveler at the appropriate height.

Unfortunately, I can't address all of the rotary devices out there, but most appear to have parallel sides. If you have one of these devices, you can mount a simple rail on the "downhill" side of the angle parallel to the hinge to similarly keep it in place.

If you are trying to engrave on a stemless glass, this method requires a minor adjustment. Since the bottom of most stemless glasses are rounded, the grips for the guide above will probably not allow a secure attachment. As a result, you'll need to create a new set of guide wheels. These will be dependent on the widest part of the glass as shown in the diagram. By following the example in Step 1 for a custom size, create a guide wheel that is the same diameter of the widest part of the stemless glass. The example glass I used was 75mm wide, and the SVG files are included below. These files include a larger hole in the very center. This hole is intended for a large bolt and as many nuts/washers you'd like to include for added weight to stabilize the whole setup on your rotary. This will allow two points of contact with the same diameter - the widest part of the glass and the guide wheel.