For the rest of this article I will refer to the arc/bridge light as an arc light, it’s less to type and seems clear enough as a description.

What is an Arc Light?

Generally when one wants to film/photograph something they will either use in-house ceiling/roof lights or set up large video/photography lights. The former generally produces rather unflattering lighting and horrible shadows all over the subject and the latter generally crowds your work space and unless you have a lot of space or can mount them from above doesn’t eliminate shadows. An arc light takes advantage of long strips of high quality and fairly affordable LEDs and allows you to mount them over your workspace, out of the way and in a smooth arc. The LEDs act both as many point lights and a large strip light. This gives a very nice quality of light that helps reduce shadows. If your hand gets between the subject and the lights, there are enough LEDs at almost all other angles to cancel out the shadow thrown.

Why Do I want An Arc Light?

I do a lot of filming/photographing for Youtube and blog posts and almost none of it gets released due to poor lighting. My office isn’t small but it is cramped. While I have professional lighting it can be hard to use when you’re the camera operator, lighting tech and presenter and in a cramped space. It often requires reaching around the camera, between the lights, making it hard to see what’s happening. Using room lights is out of the question because they’re behind me and cause harsh shadows on everything. One option would be to move the desk into the middle of the room and place the lights behind the monitor but this would really cramp the space even more than it already is and make VR a complete non-starter. I feel the best option is an arc light on the desk.

Why Can’t An Existing Design Work?

There are several designs of arc light on Thingiverse, some are thin but solid, some are thick but mostly hollow, so far they’ve all shared two things in common as far as I can tell, once they’re set up they’re sort of there for the long haul. My desk is as cluttered as the rest of my office, there’s a multitude of monitors, a 3D printer and a VR headset, a graphics tablet and a bunch of audio equipment. This means that I’d quite like an arc light that can be adjusted so that it can be quickly and easily moved out of the way of the monitors when not being used for filming/photographs. By having two half bridges it makes it easier to take down without adding too much additional clutter.

However for the sake of completeness my favourite existing designs are:

https://www.thingiverse.com/thing:1703104

As much as I like this design it will take a long time to print on my printer, I can’t even print a single segment on a single bed. It’s also quite chunky which on one hand means it’ll be sturdy and stable but willl take a lot of room on the desk and/or on the floor when not in use. The shape of this design does seem the most viable for turning into an adjustable lamp.

https://www.thingiverse.com/thing:2827629

I do like how compact this design is and I did consider using the shape/design as a reference for the adjustable design however it’s a little hard to take the general shape and make it adjustable. It would require scaling the parts up and reduces the benefits of it being compact.

Thoughts on My Design

My original thought for the design was a long light that could be bent into an arc and then folded flat when not in use. One thought was that it could be mounted to the ceiling and clipped flat against it, pulling down into an arc when in use. As much as I’d have liked to see this implemented it would have required finding at least one joist to mount it and at worst a complicated pulley system to allow moving it in and out of position. Because of this I decided to try going for the more typical arc light design with adjustable segments. I’ll cover further detail in a future post.

Considerations

Time to Create

Much as I love 3D printers and 3D printing, I don’t like spending a lot of time waiting for prints to finish, as I’m sure I’ve said before. I would rather do a hundred 30 minute prints over a week than five 10 hour prints over 3 days. As such I’m looking to make something that can be printed in maybe 2-3 hours per segment for a total print time of maybe 24 hours.

Weight and structural support are big considerations. When the arc light is in its upright position, the bottom will take the entire weight of the light, this is compressive force. When it’s fully in arc position, each joint will take progressively more strain, some of this will be sheering force and some will be tensional force. With these in mind I want segments that are as strong and light as possible whilst still being stable.

Centre of Gravity

Unlike a regular bridge light in which the two halves can rest on each other there are times when the adjustable arcs could be intentionally unsupported. As such, making sure that the weight is distributed as low and far back as possible is key. One way to do this would be to make an arc that’s taller than it is wide.

Strength Vs Weight

One big consideration is making sure that the prints can hold up the weight of the segments above them without weighing so much as to require even more strength.

Printer Size

My printer is a Kossel Mini with a 200mm diameter round print bed, of which only 170mm is really printable. I have managed to push this a little past the limit in one axis but it requires very careful consideration of the width of the part and positioning on the bed so that the head doesn’t collide with the belts on one or more of the towers or the bulldog clips that hold the bed in place. Another consideration is that thermoplastics tend to warp on long pieces and I suspect this is might be worse on a delta printer because of the way the head moves. As such I try to keep prints to less than 150mm on the bed if I can. The print could be printed vertically which also affords closer to 230mm of height, however depending on shape this can result in longer prints for the same volume. It may also require more supports and because the print will be under tension when the joints are at an angle the layer adhesion will have to be stronger to keep the structure intact. As such I’d prefer to to print horizontally, it does increase the likelihood of warping but a good print will likely stand up to more punishment than a vertical print.

Anyway this could be a monster post but I’ll leave it there. I hope you enjoyed the read. If you did consider leaving a comment on Twitter or the Drentsoft Makes Discord server. There will be more posts discussing iterations of the design.