Make with your mistakes

Along with the ability to write, humans have had to deal with another aspect that goes along with all self expression: making mistakes. To err is human, and so is to erase. From tablets of wax to bits of rough stone or pumice, we’ve used just about everything with a coarse surface to erase our writing mistakes.

The modern-day erasers, or rubbers as they are commonly referred to here in the UK (stop sniggering in America), share their origins with the rubber band, since they are primarily made of the same material. In 1770 an English engineer, Edward Nairne, accidentally discovered the erasing properties of natural rubber and started selling them for this purpose. But Nairne’s eraser wasn’t very successful. It was too sensitive to weather conditions and crumbled when used. Oh, and it smelled awful. The next major development in the history of the eraser came in 1839, with Charles Goodyear’s vulcanisation process that made rubber more durable.

Most common erasers are in block form, or are placed at the end of the pencil for quick and easy use. Pencils with built-in erasers on the other end are largely an American phenomenon, and most pencils sold in Europe are eraser-less. The first patent for attaching an eraser to a pencil was issued in 1858 to Hymen Lipman of Philadelphia. Funnily enough, these little rubbers on pencil ends are not called erasers but plugs, and the small bands of metal that contain the plugs are called ferrules.

Erasers these days come in different shapes, sizes, and colours and are made from various materials, from synthetic rubber to flexible vinyl. Vinyl erasers are durable and have minimal crumbling. During the manufacturing process, a softener, usually vegetable oil, is added to make the erasers more flexible. An abrasive material like pumice is added, along with a dye to give the erasers a particular colour.

Erasers work because of friction. When you rub the eraser on a pencil mark, the abrasives in the eraser scratch the surface fibres of the paper and this friction produces heat, which helps the rubber become sticky enough to hold onto the pencil’s graphite particles. The softeners in the eraser prevent the paper from tearing. As the rubber grabs the graphite particles, small pieces of combined rubber and graphite get left behind on the paper, and that’s the crumble you brush off when you’ve finished erasing.

Eraser flash drive

Project Maker: Ed Lewis
Project URL:


In his attempt to make sure his pen drives weren’t pilfered, Ed Lewis decided to conceal one within a pink eraser. He simply sliced the eraser into two unequal portions, with the smaller one serving as the cap, and used a rotary tool to hollow out both pieces. He then pulled apart the plastic bits of flash drive to reveal its internals that he then snugly fitted inside the larger eraser piece, while the USB male plug went inside the smaller one to complete the conceal.

“The good thing about this project is that I went into it completely blind about how easy it is to work with the eraser rubber,” Ed remarks sarcastically. “It bends and compresses and moves. All of which makes it so frustrating to cut, Dremel, or file down to get a cleaner edge. The rubber gets into the sandpaper or the file. Everything smells awful, and when you’re done the rubbery bits that are left on your workspace just wiggle about when you try and brush them away.” Ed had just used the drive to transfer some files to his Raspberry Pi when we got in touch.

Electric eraser

Project Maker: Adam Bowker
Project Link:


Adam Bowker knows that an electric eraser “sounds really lazy”, but that didn’t stop him from building one. He placed a 1.5–3 V DC motor inside a small box measuring 4 × 2 × 1 inches, along with a 2 × AA battery holder and a 9 V battery snap. He then drilled two holes in the box – one big enough for the motor’s shaft and the other for the mini momentary push-button. Adam then used hot glue to secure the connections from the battery pack to the motor instead of soldering them, which seems the right thing to do for someone lazy enough to build an electric eraser instead of expending kinetic energy to rub off their mistakes. After testing the connections, he poked a small hole in one end of an eraser that he had popped out from a pencil, and secured it to the motor’s shaft with hot glue.

Sumo Robot

Project Maker: David Cook
Project Link:


The robot sumo contest is just the kind of thing that catches the fancy of serial robot designer David Cook. The non-destructive, family-friendly contest pits two autonomous robots that try to push each other out of the ring. The No.2 robot is built on the lessons from the weaknesses of David’s prior sumo robots. Unlike the earlier ones that feature wedges on the front to scoop their opponents, the No.2 robot uses Faber Castell No.2 pencils for attack. “Each pencil rides loosely in the robot’s front comb,” writes David. “Upon colliding with an opponent, the soft eraser tip slides up the competitor until it finds a nook or cranny to grab hold of. All it takes is one pencil to hold back the opposing robot, thus preventing the wedge from coming into play,” he explains. Head to David’s website for detailed instructions on how to build your own rubber-tipped sumo robot.

Monogrammed Stamps

Project Maker: SNLouise
Project Link:


When she received a wedding invitation with a personalised monogrammed stamp, SNLouise was inspired to create her own using items many people will have in their stationery cabinet. She used a US quarter coin to trace a circle on an eraser that she then cut out with an X-Acto knife. You’ll then have to sketch your design and transfer it onto the eraser cut-out. If you’ve printed your design with an inkjet printer, SNLouise suggests you place the design ink-side down onto the eraser and then dampen the paper. The ink from the paper will transfer to the eraser. Once the design is on the paper, she uses a heated soldering iron to trace the design and emboss it on the eraser. Others in the comments and on the internet have used an X-Acto knife to carve the design. Once it’s cooled, use a stamp pad to personalise your invitations.

More features from HackSpace magazine