Skip to content

Disinfection of PPE such as N95 respirator masks

An article from Consolidated Sterilizer Systems starts with: "With the global Covid-19 pandemic everywhere in the news, many healthcare professionals and concerned citizens are grappling with the shortage of respirator masks, vital tools for ensuring that healthcare workers are not infected by the people they’re trying to help."

The article suggests that microwave steam based disinfection has been effective at disinfecting, specifically removing H1N1, from non-metal N95 respirator masks. Here is a 3D grid that can be placed into a glass tupperware container filled with some water and then put into a microwave. Don't put anything with metal into the microwave. Alternatively, you can use this grid in the oven as well; see the description in the article.

This grid is 4.4" square and 1.25" tall. It's easy for me to produce any other dimensions.

The log reduction for microwave steam is around ~5, i.e. 100,000 times less viable virus. The article does not give a protocol. I put the filter in the microwave for 3 minutes which was sufficient to boil the water for 2 minutes. For oven steam, the protocol requires 3 hours under warm water steam and let to a slightly smaller log reduction of ~4.8, i.e. 63,000 times less viable virus. This requires an oven that has good temperature control.

Disclaimer: It is unclear if this is effective for disinfection. Even with high-temperature filament, it is unclear if a 3d printed grid is appropriate for this application.
Categories: Hacking

How to forge a sword: From start to finish!

Did you ever wonder how swords were made? My recent video series shows all the steps involved in making a sword. I start from scratch by heating and forging a piece of high-carbon steel into the form of a sword and finish by showing sharpening the sword and cutting exercises. The techniques are very similar to how swords were made for thousands of years. The video documentation is split up into four different parts - you can also go directly to the complete play list on how to forge a sword

In the first video, I take a flat piece of 1075 steel, heat it in the forge and forge in the tang and the tip of the sword. I then forge the bevels and the fuller. After checking that everything is straight and that I have achieved the right dimensions, I normalize the sword to relieve stress created by hammering it. The video shows how to make the sword blade hard by heat treating it - that is quenching it and then tempering the blade.

The second video shows to make the lower and upper guard as well as the pommel. I show how to establish the basic shape and spent a lot of time grinding the blade on a belt sander. This creates the correct geometry and reduces the weight significantly. It is important for the complete sword to be as light as possible since that makes it less strenuous to swing.

Now, I finish shaping the guards and pommel and use a laborious process to fit them perfectly to the shape of the tang. I also take a piece of wood and fit the tang by burning it through the wood. At the end of this video, all the pieces can be roughly assembled.

The final video shows how I create decoration with gold wire using a Koftgari-like process. The wooden core is wrapped with hemp cord and leather and finally everything is put together. I hot peen the tang over the pommel to create a strong mechanical connection. Finally, the sword is sharpened and put to use.

After watching these videos, you should have a very good understanding how the sword is made. The whole process took about 100 hours. The videos condensed this into about 40 minutes. Enjoy!!!
Categories: Hacking
Defined tags for this entry: , , ,

A Day at the Forge: A Study in Sound

A lot of people ask me about putting more emphasis on the "authentic" sounds that accompany working at the forge. My usual answer is that it can be damn loud. So, loud that it's difficult to talk with each other, especially when running a forced-air burner. The other day, I decided to take my day at the forge to demonstrate these sounds. You will hear the noise atmosphere from neighboring shops, the fan of the coal forge and the very loud forced-air burner. Enjoy.

The background music is "Passing Time" by Kevin MacLeod from Youtube's Audio Library. The video was shot in low light on a Blackmagic Camera using a Canon 17-55m f/2.8 lens. Audio recorded with an Audio-Technica BP4029 shotgun microphone on a Tascam DR-100 MkII. Editing and grading in Final Cut Pro X. Video and Music synchronization via PluralEyes.
Categories: Hacking
Defined tags for this entry: , ,

Forge Diaries: Episode 2

Here is Episode 2 of Forge Diaries. We will find out if the fire steel can be used to light a fire. There is also a tiny glimpse at the Serpent in the Sword project:

Ps: Just to remember: Forge diaries are rough and unpolished videos that allow me to post more frequent updates of some of the work I do at the forge. So, don't expect too much!
Categories: Forge Diaries, Hacking

A new video series: Forge Diaries

Forge diaries are rough and unpolished videos that allow me to post more frequent updates of some of the work I do at the forge. Similar to the videos, the work at the forge is unpolished, too. You will see frequent failures, experiments and the occasional tips and tricks.

The first epsiode starts with an explosion, literally, but then cover a few other items. Find out more at:

Categories: Forge Diaries, Hacking

Making Wootz Steel

Our experiments in creating crucible steel with a composition similar to ancient Wootz steel are continuing. In this video, we show the process of making a Wootz ingot and our first successful forging of the ingot into a bar. Our crucibles are charged with wrought iron from wagon tires, pulverized charcoal, some O1 tool steel, calcium carbonate and glass. Watch the video for all the details.
Categories: Hacking