RepRapMicron

2 Articles

A small plastic object can be seen in front of the tip of a hypodermic needle. The object is made of clear, slightly purple-tinted plastic. It is roughly circular, with edges thicker than the center.

The Latest From RepRapMicron – Nail Gel, First Objects, And More

February 1, 2026 by No comments

We’ve been following [Vik Olliver]’s progress on the μRepRap project with interest for some time now. The project’s goal is to build a 3D printer that can print feature sizes down to about 10 microns – the same feature size used in the Intel 4004 processor. At the recent Open Everything 2026 conference, [Vik] presented an overview of all the progress he’s made in the last year, including printer improvements, material woes, and the first multi-layer prints (presentation slides).

The motion stage has undergone some fundamental improvements recently. The original XY motion table was supported on four flexures which allowed movement in X and Y, but also introduced slight variations in Z – obviously a problem in a system that needs to be accurate down to the microns. The latest version now uses complementary flexures to maintain a constant Z height, and eliminates interference between the X and Y axes. The axis motion drivers were also redesigned with parallel-bar linear reducers inspired by a pantograph, increasing their usable range from two to eight millimeters.

Rather than extruding material, the μRepRap uses an electrochemically-etched needle point to deposit UV-curable gel on the build surface. [Vik] found that a bit of nitric acid in the needle etching solution gave the edges of the probe a bit of a rough texture which let it hold more resin. He started his test prints using normal 3D printer resin, but it turns out that dissolved oxygen inhibits curing – quite a problem for small, air-exposed droplets. Fortuitously, UV nail gel does cure in air, and the next set of tests were printed in nail gel, including the first layered prints (one of which can be seen above, on top of a hypodermic needle). The μRepRap can’t yet print large numbers of layers, but [Vik] did print some hinged parts that could be folded into shape.

There’s much more in the presentation than can be covered here, including some interesting thoughts about the possibility of 3D printing electrochemical memory cells in ionic gel. Near the end of the presentation, [Vik] listed some pieces of related work, including necroprinting and this homemade micro-manipulator.

 

A metal needle tip comes to a point against a white background. A scale bar in the lower left shows a 300 micrometer length.

Etching Atomically Fine Needle Points

October 13, 2025 by 22 Comments

[Vik Olliver] has been extending the lower resolution limits of 3D printers with the RepRapMicron project, which aims to print structures with a feature size of ten micrometers. A molten plastic extruder would be impractical at such small scales, even if a hobbyist could manufacture one small enough, so instead [Vik]’s working on a system that uses a very fine needle point to place tiny droplets of UV resin on a substrate. These points have to be sharper than anything readily available, so his latest experiments have focused on electrochemically etching his own needles.

The needles start with a fine wire, which a 3D-printed bracket holds hanging down into a beaker of electrolyte, where another electrode is located. By applying a few volts across the circuit, with the wire acting as an anode, electrochemical erosion eventually wears through the wire and it drops off, leaving an atomically sharp point. Titanium wire performs best, but Nichrome and stainless steel also work. Copper wire doesn’t work, and by extension, nor does the plated copper wire sometimes sold as “stainless steel” by sketchy online merchants.

The electrolyte was made from either a 5% sodium chloride solution or 1% nitric acid. The salt solution produced a very thin, fine point, but also produced a cloudy suspension of metal hydroxides around the wire, which made it hard to tell when the wire had broken off. The goal of nitric acid was to prevent hydroxide formation; it produced a shorter, blunter tip with a pitted shaft, but it simply etched the tip of the wire to a point, with the rest of the wire never dropping off. Some experimentation revealed that a mixture of the two electrolyte solutions struck a good balance which etched fine points like the pure salt solution, but also avoided cloudy precipitates.

If you’re interested in seeing more of the RepRapMicron, we’ve looked at a previous iteration which scribed a minuscule Jolly Wrencher in marker ink. On a more macro scale, we’ve also seen one 3D printer which used a similar resin deposition scheme.