It's Christmas Time!

This year, I'm publishing a lot of Christmas ornaments. I've worked on them almost all year. The plan is to publish a new ornament every day - STARTING TODAY!

There are 4 basic shapes:

• Bulb – a traditional Christmas ball elongated with a stem on top
• Stretch – a small bulb with long stems on the top and bottom
• Finial – an ornament with two bulbs arranged vertically and stems on top and bottom
• Topper – an ornament for the top of the tree

I've created many different 3D designs that I've applied to the various shapes. Some will only be available in the 3 types of hanging ornaments (bulb, stretch, finial). Others will also include the topper.

Colors

The ornaments all look great in just about any type of filament – single color, two color, rainbow, transparent, even glow in the dark! Three filament color should work well for bulb and stretch designs (they're printed as one piece) and toppers (printed as two pieces, but both halves are printed right side up). Finials are designed to be printed as two pieces – the top half printed right side up and the bottom half printed upside down. If you rotate the bottom half 180 on the Z axis, you can get a 2 color filament to line up at the seam. However, if you use a 3 color filament, you'll only get the colors to line up on one side. If you want to use rainbow filament for a finial, print both pieces together and the colors will change from the middle out. They look great that way!

Gluing Two Piece Ornaments

The best way to glue the two pieces of the toppers and finials is by placing a roll of filament in an inexpensive Lazy Susan and then setting the larger half of the ornament in the center hole of the filament roll. this makes it a lot easier to align the pieces. Best of all, once the pieces are aligned, you can just walk away and let the glue cure.

I recommend against sanding either half of the ornament before gluing them. Sanding seems to significantly accelerate glue curing, leaving little time to align the pieces.

Printing

Honestly, if you're using PrusaSlicer or a slicer that can read PrusaSlicer files, just use my 3MF files and adjust to work with your printer and filament. I did a lot of work to get the prints so they print cleanly, are extremely light and they positively glow when you print them in transparent filament.

Filament Settings: I varied my hot end and bed temps a bit across my files. Bed was always either 60 or 65 degrees. I set the hot end temp to 205 – 215 for the first layer and 190-195 for most prints on the second+ layers. I increased flow for silky filaments (1.015 – 1.025) and decreased it for transparent filaments (.99).

Cooling: Printing the long stems is a challenge. I solved it by modifying PrusaSlicer's “Slow down if layer print time is below” from 10 seconds to 2 (so it doesn't slow down much). Faster print speed seems to reduce the heat transfer from the current layer to the previous layers. The setting is located in Filaments – Cooling.

Perimeters: 1 everywhere except the top loop and a few millimeters above and below the seam on a finial, where I added a second perimeter for strength. I removed the extra perimeter at the seam when I printed finials in transparent filament because transparent filaments are a lot stronger and it lets in more light this way.

Perimeter generator: Classic

External Perimeters First: Yes

Seams: Aligned (except for transparent filament, which worked best with Random)

Solid Layers Top and Bottom: I usually used 3 (sometimes 2 or 4), but I changed it in places using tiny shape modifiers and height range modifiers. Sometimes, I used height range modifiers to reduce Top or Bottom thickness to make the print more transparent. I always increased the top/bottom on the loops to make them stronger and print more accurately.

Minimum shell Thickness: 0.3mm, but I varied it when necessary.

Speed: I slowed the print speed down and got a better result. I reduced small perimeter speed by 20% (to 20mm/sec) and external perimeter speed by 50% (to 12mm/sec). I use a Prusa MK3S+, which is not a high speed printer. I don['t know what speed will work best on a MK4S, XL, Bambu, or other high speed printer.

Infill: I used tiny shape modifiers and height range modifiers to add infill and create tiny shelves in the few places that otherwise need infill. This speeds up the print, makes it much lighter, and much more transparent.

Supports: All of these designs need supports of some kind to keep them adhered to the bed.

Bulbs also need supports for extreme overhangs.

I frequently use “Enforce supports for the first n layers”. With that, PrusaSlicer will add supports on the layers specified regardless of the overhang angle EVEN IF YOU TELL IT NOT TO GENERATE SUPPORTS AT ALL. I have also been known to add that on a per-object basis. If you use my 3MF files, you try to decrease or remove the supports and nothing changes, that's why.

I created custom supports for the stretch designs. They eliminate the need for slicer-generated supports (which would be very hard to do) or cutting the ornament in two pieces (and having an unsightly seam).

I made the stretch supports separate STLs to give them per-object print settings, which I used to increase the print speed of the supports and add infill. It also allows you to fine tune the gap between the supports and the ornament by applying “XY Size Compensation” to the supports (right-click the supports, scroll down to Add Settings – Advanced, and XY Size Compensation is the last option). A positive number will expand the outer perimeter by the value specified, which effectively decreases the gap between the supports and the model by the same amount. A negative number decreases the gap between the supports and the ornament.

The stretch ornament supports and ornaments are lined up perfectly relative to one another in my 3MF files. If you don't use my 3MF files, you'll need to carefully align the supports with the ornaments because many of the designs have an odd number of sides so the center of the pattern isn't the center of the STL. Just giving the ornament and supports the same X and Y coordinates isn't enough for many of them.

The loops don't need supports. They printed a little better with supports, but removing the supports can also be a challenge. Sometimes, I added supports for the loops and sometimes I didn't. When I did, I used paint-on supports. For most of the stretch ornaments, I couldn't use add supports to the loops because combining slicer generated support with my custom supports generated G-code errors.

I decreased the Z distance between the supports and the model from 0.2mm to 0.1mm. This solved a problem I had early on with ornaments being pulled out of the supports as they printed. The supports still release cleanly.