small actor on giant table

NERF – Neural Radiance Fields

Making narrative film just keeps getting easier. What once took a studio is now within reach of the dedicated hobbyist. And Neural Radiance Fields are making it a dramatic step easier. The guys from [Corridor Crew] give an early peek.

Filming and editing have reached the cell phone and laptop stage of easy. But sets, costumes, actors, lighting, and so on haven’t gotten substantially cheaper, and making your own short film is still a major project.

Enter 3D graphics. With a good gaming laptop, anybody can make a photorealistic scene in Blender and place live action actors in it. But it takes both a lot of skill and work. And often, the scene you’re making is available as  a real place, but you can’t get permission to film or haul actors, props, crew, and so on to the set.

A new technology, NERF, for “NEural Radiance Fields”, has decreased the headaches a lot.  Instead of making a 3D model of the scene and using that to predict what reaches the camera, the software starts with video of the scene and machine learns a “radiance field” – a model of how light is reflected by the scene. Continue reading “NERF – Neural Radiance Fields”

3d printed escalator, from side, showing mechanism

Tiny 3D Printed HO Scale Escalator That Works

[Luke Towan] has a cool HO scale Escalator mostly made of 3D printed parts, with some laser cut acrylic, for a station on his HO model railroad.

Escalators are mesmerizing to watch – there’s something magical about the stairs unfolding at the bottom and folding up at the top. But they’re very hard to model.

[Luke Towan] has done it – his 3D printed version closely resembles the real thing mechanically. Pins are carried around, cantilevered out from a 3D printed chain. A stair swivels on each pin – at the bottom each stair’s free end rests on a ‘bottom’ far enough down for the stairs to be level, while on the incline the ‘bottom’ is just below the pins. It’s a tricky build.

If you like pushing the envelope of what 3D printing can do this is an interesting project, even if you’re not planning to build an escalator. There are lots of tips for making small mechanisms with 3D printing, and for making small mechanisms that work reliably without stuttering.

He’s not the first to build an escalator. Back in 2015 we covered this wooden escalator for slinkies,  and just recently this 3D printed version from [AlexY].

I See By Your Tattoo That You Are A Hacker

We spotted [Segfault]’s new tattoo on a fast failing bird app a few days ago. We thought it was nice looking piece of skin art, but without a write up couldn’t cover it. The bearer of the tattoo pointed us to this blog post about the tattoo, and now we really like it.

It’s fun on it’s own, but when you start staring at it you realize it’s full of hidden jokes and meanings. If you like puzzles, go hunting for them before you read the blog post. We also liked the reminiscence about [Segfault]’s early electronics experimentation days, and how the 555 timer IC figured prominently in them.

We’ve not covered a lot of tattoos here at Hackaday.  Mostly we cover the technology behind skin fused or embedded hacks. But occasionally some tattoo art catches our eye, as it did in this interesting barcode tattoo.

Jansen's linkage, paper model of a bar linkage

Making Paper Strandbeesten

We love the artistry of paper mechanisms.  Simple tools and techniques creating humor, beauty, and amazement.

[Federico Tobon] from [Wolfcat Workshop] makes amazing automata, crosses between cut paper art, origami, and traditional carved wood automata.  He’s put out a useful new video on making linkages in paper parts.

In this short video, [Federico] shows us how to make a paper version of the leg mechanism for [Theo Jansen]’s classic Strandbeest, which we’ve covered in many variations.

Rotating joints in paper automata are sometimes done with a mechanical fastener like a post screw, but it violates the simplicity of the affair and often looks clunky.  [Federico] uses a simple self fastener. A 5 mm hole in one part mates with two “flaps” in the other part. He’s made a separate video covering how to make the fastenings. He’s using a paper crafter’s Cricut-type machine to cut the parts.  Pretty cool.

We’ve covered lots of other cool stuf from [Wolfcat Workshop]. If you want more of his automata eye candy, check out Simple Automata Extravaganza.

Custom Lathe Tool Cuts Complex Oil Grooves

Oil grooves are used to lubricate the inside of a bearing, and can come in many forms — from a single hole that takes a few drops of oil, to helical patterns that distribute it over the entire internal surface. The ideal arrangement is a looping figure eight pattern similar to an oscilloscope Lissajous figure, but cutting these is a nightmare. That is, unless you’ve got the proper tool.

We figure [Machine Mechanic] must need to cut a lot of them, as they spent quite a bit of time perfecting this custom lathe attachment to automate the process. Through an assortment of clever linkages and a rod-turned-crank that was welded together in-situ, the device converts the rotational motion of the lathe into a reciprocating action that moves the cutting tool in and out of the bearing. Incidentally the business end of this gadget started life out as a bolt, before it was turned down and had a piece of tool steel brazed onto the end.

With a little adjustment, it seems like this device could also be used to carve decorative patterns on the outside of the workpiece. But even if this is the only trick it can pull off, we’re still impressed. This is a clever hack for a very specialized machine shop operation that most would assume you’d need a four-axis CNC to pull off.

Lathes seem at first like rather single purpose machines, we’re always pleased to discover strange and wonderful things being done with them, like this seemingly impossible-to-turn piece, and this combo wire EDM and lathe.

Continue reading “Custom Lathe Tool Cuts Complex Oil Grooves”

strut mounted on lathe

Turning Irregular Shapes

In case you’re not closely following Egyptian Machinist YouTube, you may have missed [Hydraulic House]. It’s gotten even harder to find him since he started posting under[بيت الهيدروليك]. Don’t let the Arabic put you off, he delivers it all in pantomime.

A recent drop is “How To Turn Irregular Shapes On The Lathe“.  We’re not sure, but think the part he’s working on is the front suspension of a  3 wheeled auto-rickshaw. The first metal at the center is over 30cm from the bottom. No problem, he just makes a long driven dead center from a bit of scrap material and goes on with his business.

By no means is this the only cool video.  We liked his video on a remote pumped hydraulic jack  and one on making your own hydraulic valves.

If you’re into machinist-y things, don’t miss him. Every video is full of pretty nifty tricks, sometimes made with a zany disregard of some basics like “maybe better to have done the welding before mounting in the lathe”, turning with a cutoff tool (I think), and occasionally letting go of the chuck key. It’s definitely ‘oh, get on with it’ machine shop work.

We love videos from professionals in the developing world making with relatively simple tools. Often hobby hackers are in the same position, milling with a lathe and some patience instead of a giant Okuma. Not long ago we posted this article about making helical parts , with the same ‘imagination and skill beats more machinery any day’ vibe.

Continue reading “Turning Irregular Shapes”

types of gates

Handling Bulk Material: The Spice Must Flow!

Your [Bornhack] plans include leaving lemons in patterns as an info display. Your squirrel feeder needs to only dispense nuts when the squirrels deserve it. As promised last week, an intro to gating, feeding, and moving bulk material.


Bulk material flow needs control. Starting is easy, it’s stopping that’s hard.

Dump Gate, Slide Gate, Clamshell Gate

If your need is just to dump out the entire contents of the bin, a dump gate works – a trapdoor with a latch. If you need to stop before emptying the bin, you can use a slide valve – a flat piece of material in a box that slides in and out. Friction from material bearing down on them causes large open/close forces. Material can  jam between the flap and the housing when closing.

A variation is the clam shell gate — a section of a cylinder on arms that swings aside, like a crane’s grab. They tend to leak, but with the material’s weight against the hinge pin, they are easier to close with a high force against them.

The upward bell gate, helps with in-bin flow pattern and seals well. Open by pulling from above or pushing from below, through the outlet. The material moving around the gate acts to improve the flow, and because the material at the lip is on an inclined surface, they tend to seal better. If it still has a leakage problem, a flexible lip can cure it.

A cone, suspended on a cable below the outlet of the hopper is a downward bell. Lowering the cable lets material flow between the outlet rim and the bell. When the cable is raised, if a lump sticks at one place the bell moves aside. The sealing surfaces are angles, so material rolls off. The bin is shallower and there’s no outlet pipe. This design ensures clearance so large particles don’t wedge against the wall as the bell closes.

Upward Bell, Downward Bell, Double Bell

Any of these gates would close just fine if not for the material in the bin. Double gates exploit this. The main bin has a normal gate and outlet. The outlet is below the lip of the much smaller, lower control bin. If the control bin fills, the main bin stops. The control bin has a gate larger than the main bin. Closing the main gate as far as it will go reduces flow through the control gate to a trickle. The control gate can now be fully closed, which fills the control bin and blocks the main outlet.

You might not want to share environments between bins. Maybe one has pressure, nasty chemicals, or hot gases. In that case, a rotary airlock gate is a paddle wheel apparatus in a close fitting housing. Material is metered out as it turns. A double gate also works (blast furnaces use double bells). If you need to meter a set amount, a sliding cavity like a grocery store bulk bin works. So does a rotary airlock.

Locomotive sander systems spread sand on the rails to increase traction.  The sand is gated with a “sand trap”. A pipe supplies sand to a ‘valve’ with a sharp upward U bend. Of course this blocks. A compressed air line from a valve in the cab feeds into the upward end of the U bend. As long as air flows, the blockage is constantly cleared and sand flows. It’s collected and sent to the wheels.


If you need a constant flow, independent of how much is in the bin, you need a feeder.

The rotary air lock can be a simple feeder. A conveyor feeder is a belt at the bottom of the bin. One side has a slight gap between bin and belt. Material covers the belt as high as the gap. A screw feeder is a helical screw at the bottom of the hopper, taking material off to the side. The screw needs a varying pitch, starting out slow and increasing, to let it fill gradually from all along the hopper. A vibratory feeder is a chute designed to arch, with a vibrator to make it flow anyway.

Any of these can have a poor pattern of feeding, taking from one place along it’s inlet. Fins and inserts in the bin can help – a doctor blade to regulate how deep the first couple inches of belt feed, or an anti-rathole type insert to keep mass flow going.


Unlike a feeder, a conveyor depends on whatever is feeding it to control the feed rate.  Feeders are for controlling feed rate. Conveyors for moving stuff. A feeder will change it’s output when it’s speed changes. A conveyor may change  how much is in each section (the ‘loading’) but the output is speed independent.

Screw conveyors should have a fixed pitch, and can be angled up to 45 degrees. Belts can be inclined up to the angle of repose of the material. These are best made with a slight ‘V’ in the belt so the material doesn’t roll off. Boards on the side also work, but introduce friction into the system as the material slides against them.

Don’t overlook skips —  a bucket pulled up an incline. The front wheels run on tracks slightly narrower than the back wheels. Dip the inside tracks down at the end to dump.

Moving floors made of long strips will move a pile of material if actuated in the proper sequence. Picture the order as ‘123123123123’: shove 1 backwards suddenly, and the material above it will stay with the mass, do 2 and 3, then slowly move all forward. They also move solid objects, so many trucks have such floors.

Finally, you can always fluidize the material and blow it about with air or water, then remove the fluid at the other end.  Think old time logging, with logs floated down the river.

Have fun hacking. We hope we’ve given you some options for dealing with walnuts.