3D-printed caps for protruding bolts

When I attached our children’s swing to the ground there was still a significant piece of sharp-ish threaded metal sticking out above the bolt head and I was worried about them falling on it. Grinding the end off might still leave some sharp parts, so I thought it safer to print plastic covers for them.

I designed the caps using OpenSCAD, using the ScrewsMetric library for the bolt-shaped inset.

You can see the source code for the design in this GitHub gist:

include <ScrewsMetric/ScrewsMetric.scad>;

$fn = 30;
GHOST = false;
outer_size = 40;

difference() {
    sphere(d = outer_size);
    translate([-outer_size/2,-outer_size/2,0]) cube(outer_size);
    translate([-outer_size/2,11,-outer_size+1]) cube(outer_size); // cut
    rotate([0,0,30]) translate([0,0,0.002]) BoltNormalWithSurface(hexHeadBolt, M12, 15+0.002);
}

The biggest challenge was to find an acceptable compromise in shape and size:
– tall enough to cover the top of the bolt
– narrow enough base to fit next to the swing’s leg
– should be printable without overhangs and no need for supports

The final design I went with is a bit different from in the photo above because that one didn’t fit. I kept the size the same and chopped off one side of the dome to leave space for the swing’s leg.

You can download the generated STL files for printing from the Thingiverse website.

It printed really well and I stuck the pieces in place with some leftover silicone.

3D modelling replacement knobs for back massager

small wooden knob

small wooden knob

There’s this fantastic device we have at home that I’m fairly sure is for giving back rubs, or maybe massages in general, like on your legs or something. I’ve tried it a few times but mostly the kids play with it. However it bothers me that there’s holes in it where the little knobs are supposed to be, so it doesn’t roll properly. I think the kids pulled them out, but maybe they were just never glued in properly.

holes from missing knobs in massager

holes from missing knobs in massager

Anyway, I doubt I could go in a shop and say “please give me tiny wooden knobs to this size” so I decided to attempt to print some. I’ve done some basic 3D modelling work before so with a bit of work and the right measurements, this should be doable, and it’s an interesting shape.

sketch with measurements for wooden knobs

sketch with measurements for wooden knobs

Here’s a hand-drawn sketch I did quickly after measuring the wooden knob with a pair of callipers. It immediately became apparent that this was not going to be as simple as I thought because shaft part isn’t straight, but more like a chopped-off cone, and the head part isn’t round on every axis, it’s an ellipsoid. I Googled that word 😅 just to write it in this blog post, it’s the 3D version of an oval. Continue reading

Social content

Aside

I’m imagining how much more full of interesting content, like photos or stories or ideas, this blog could be. What if every time I had posted something to a closed system, like Facebook, I had published that here instead?

Sawing wood in the forest

photo

This week we went wood chopping in the forest not far from the village. My family in-law use a boiler powered by a wood furnace to heat their house. That’s why it’s important to collect enough wood in advance, so that it can dry out enough to be used for firewood in years to come. They own part of some land covered in trees and with the foresters permission they collect some every year.

A small group of us drove out in the morning and cut down trees in teams of two: One person saws down the tree and cuts it up into metre-long logs, while the other person carries the logs out to the road and collects them into piles. The others have experience using chainsaws, so I’m on collecting duty.

photo

It took us until about lunch time to collect as much as we planned. Lunch in the woods means ham and sausage. After that it was time to stack the logs on the tractor trailer. It’s pretty clever how some tall, thin trees were selected as supports to extend the sides of the trailer and stop the huge pile of wood from toppling. The amount you can see on the trailer in the photo is probably almost half of what we collected that day.

Back at home the wood gets split and then stacked for drying and, in fact, a few years ago I wrote about the wood splitting part. The next day I had quite a muscle ache from stacking all that wood.

First time in Hacktoberfest

This year was my first time participating in the online Hacktoberfest event.

I often use code from GitHub and occasionally publish my own projects there but I realised I rarely contribute to other people’s code. Hearing people talking about the event on the Ladybug Podcast, I was inspired to make a small pull request. The boost I got from something so insignificant being merged lead me to look through my favourite projects’ issue lists to see if there was a bug I could fix or a missing feature I could implement.

Continue reading