3D Printed Finials for PVC Fences

Frankie's Girl said:

Those all look great! What a super use of a 3D printer.

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Thank you.

There's just one problem with using a printer for these: they take hours to print, and you need nine of them per 8-10' section of fence. Since the main section of my yard needs at least 9 sections of fence, that'd mean printing 81 finials. Not counting any extras.

At the current rate, it's almost two weeks of non-stop printing, or a little under one finial per day from now to Halloween. I've considered making printable molds so they can be cast in something like silicone or even Great Stuff to speed up the process, but I haven't had a chance to experiment yet.


I'm still working on additional designs. This is the work-in-progress pic of my bat finial that I posted in the other thread:


My plan for my fence (based on the Instructable) is to cap the small pickets with the Tetra design, to put lanterns on the corner posts, and to put something like the bat finial on the remaining 2" posts between sections of fence.

Then I plan to use red reflective tape in the eyes of the bats so that the headlights from passing cars will hopefully catch them.

annamarykahn said:

i don't know anything about 3d printing ... what am i getting myself into? lol ...

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It's a rabbit hole, to be sure, but fun and very handy.

but couldn't you make a print job, that probably isn't the correct term, to print multiple finials? wouldn't that speed things up some? but the throughput gains may not be that gr8

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It might speed things up slightly, but the savings will be on the order of minutes per batch.

For example, according to Cura, my Tetra finial printed once at 0.3 mm layer height takes 151 minutes (2 hours and 31 minutes). If I place three of them on the build plate, it will take 443 minutes (7 hours and 23 minutes), give or take a few minutes depending on how far apart they are spaced (which matters because the print head takes time to move between them, and it does that every single layer).

Three finials at 151 minutes each equals 453 minutes to print them consecutively (plus however long it takes me to remove each one and start the next print). I would save at least 10 minutes by printing three at once. Every little bit helps, and saving 10 minutes per batch over 27 batches would gain you 270 minutes total. I don't run my printer unattended because that's a fire risk, so assuming I have over seven hours to sit around the house while the job runs, that would be fine.

Unfortunately, the problem is that you run a significantly greater risk of print failure whenever you do multiple parts.

Tall, narrow parts like these already run a fairly high risk of failing because they don't have a large footprint to keep them stuck to the bed, and because they have a large amount of inertia trying to resist the Y-carriage's back and forth motion (i.e. the finial WANTS to throw off the shackles of slavery and be free). To make matters worse, the risk of a tall part failing is often concentrated toward the end of the print job, when the print is at its tallest.


With one finial, if it detaches from the print bed 90% of the way through the job, then you wasted 135 minutes and enough material for that one part.

With three finials, every one of them has the same risk of detaching as the single finial, so the combined risk of something happening is higher. If any one of the set detaches, it can (and likely will) wipe out the other two in the process, and if it doesn't, the nozzle very well might, since it is now extruding into thin air instead of onto the missing part. Say the failure again happens at 90% completion. Now you have wasted almost 400 minutes and three times as much material.


It's not something I would recommend to a newbie. Mind you, once you have been doing this for a month or two and have learned how to reliably get successful prints, you can take steps to improve your chances (i.e. clean build plate frequently, make sure printer is level and calibrated properly, etc.) and can probably pull it off more often than not.

This is the 13th post in this thread, so I am required by law to post spooky pics. Here is a new model for the Bat Head that I experimented with last night in Sculptris while listening to the newest Hauntcast. Its a bit rough, but I'm not really used to sculpting and it was started literally than 5 minutes after installing this software for the first time.





I think the ragged look is spooky, though. Imagine driving past and seeing a couple of those with gleaming red eyes atop posts between the fence sections (see upthread where I mentioned my plan to put reflectors in the eyes). Similar to this:




(Sculptris is Pixologic's free 3d sculpting program, kind of similar to ZBrush. I already had the ability to do 3D sculpting through Blender, but this is a great deal easier to just jump straight in with.)

Here is a sneak peak of another new design in progress...



Edit: forgot to mention, it's Cthulhu. Specifically, it's meant to be the stone statuette described in The Call of Cthulhu.

The other Mythos finial I'm intending to make is an Elder Thing from At the Mountains of Madness (which was a banister motif in Dreams in the Witch House)