Archive for May, 2012

Personal magnetism

Posted in Uncategorized on May 16, 2012 by Spark

I’m magnetic!

Lifting a paperclip with my finger

Last week Nessie and I flew down to Pittsburgh for a day to have renowned body modification artist Steve Haworth surgically implant tiny neodymium magnets in our fingertips.  They give us a new sense – we can feel magnetic fields.

The magnets let us know how ferrous a metal is (useful when welding with scrap metal).  We can feel the field given off by a transformer or a motor and gauge the amount of power it’s using.  Microwave transformers are particularly strong – I can feel them a good six inches away.  If there’s a strong enough current moving through a wire, we can feel that too.  We can also lift small metal objects.  Nessie’s magnet is closer to the skin, so she can lift things like bottle caps.  The heaviest thing I can lift is a small paperclip.

Nessie lifting a bottle cap with magic

As someone who loves playing with electricity, this new way of experiencing the world around me is profound.  It takes an invisible force that is all around us and makes it tangible.  It’s one thing to know that a spot welder uses a couple hundred amps to melt two pieces of metal together.  It’s another thing entirely to actually feel the visceral thump of power when you press the switch.

The texture of magnetism

Magnets, ferrous metals, and DC magnetic fields like the one given off by the current in a spot welder feel like pressure in my fingertip.  I haven’t been able to distinguish pushing from pulling yet, but as the sensitivity increases and I practice more I should be able to.  The tug of a weakly ferrous metal like stainless steel is difficult to detect.  I have to move my finger back and forth across the edge of the metal, hovering just over the surface, feeling for a faint tug when I move across the metal.  My cast iron vice is ferrous enough that I can feel it just by moving my finger near the surface.

AC magnetic fields like those given off by transformers and motors create a buzzing sensation.  I’ve heard reports of people with these magnets being able to feel the current in an extension cord, but neither of us can yet.

The sensitivity increases for around a year after getting the implant.  Initially the incision needs to heal.  Even after it’s fully healed, the sensitivity continues to increase as the brain remaps the signals coming from the fingertip.

My Magnetic History

I’ve actually attempted to have this implant done twice before.  The first time was in March of 2011, when Steve Haworth was in NYC for a convention. I had the magnet put in my right pinky finger since it’s the only finger I don’t use to play guitar.  After about three weeks it started to reject, slowly pushing its way out of my fingertip like a splinter.  It took about 4 days to work its way out.  These types of rejections are very rare but are a risk with any subcutaneous implant.

Steve didn’t come back to the east coast until July 2011.  He offered to try again for free since it hadn’t worked the first time.  I headed down to NYC again.  This time I put the magnet in my right ring finger.  Steve recommends the ring finger since it is the least exposed.  We thought that the fact that my pinky was so skinny may have been a factor in its rejecting the first magnet.  I babied my finger for two weeks, not even going near anything magnetic until the cut was fully healed.  When I finally went to try it, there was nothing.  The magnet had disappeared.  I even went to have my hand x-rayed to be sure – it was definitely gone.  I know he put it in because he hung the suture needle from my fingertip when he was done.  I was mystified.  I still have no idea what happened.  My best guess is that I banged my finger on something when the cut was still open and the magnet flew out without me noticing.

I’m really hoping it works out this time.  I’ve missed my magnet every single day since it rejected the first time.  It feels like a sense I should have had my whole life.

Further Reading

Curious about magnetic implants?  Check out these links:

Steve HaworthA Sixth Sense for a Wired WorldMagnetic Implant – BMEzine EncyclopediaJaa’s Blog – Entries tagged as smii


Hexapod on

Posted in Robotics, Things with tags , , , on May 3, 2012 by Spark

The hexapod robot is making the news!  We’ve shown up on, hackaday, slashdot, BoingBoing and a few others.


Gui rendered a concept model that gives a good idea of what the robot is going to look like:


Stompy, the hexapod robot


Right now, I’m working on the PID controller for the joint actuators.  I’ve got a bare-bones PID algorithm working and I’m going to add a few more features to make it a little more robust.

Trebuchet Competition

Posted in Things with tags , , , on May 2, 2012 by Spark

Last week I entered the Trebuchet Competition at Artisan’s Asylum!  Nick Anastasia, Alex Phillips and I made up team Percussive Maintenance.  We spent a week from Sunday April 22 to Sunday April 29 designing and building our trebuchet, the Small Adjustment Tool.  Artisan’s Asylum provided a pile of lumber and assorted hardware, and we had a week to come up with a trebuchet that would throw water balloons with a maximum counterweight of 100lbs at targets set up on Cambridge Commons.



There were a couple other floating arm trebuchets, but ours was the only arm-slides-over-cam style.  We were looking great in testing with a range of at least 150′ and good consistency between shots.

At the competition, we had a couple shots to calibrate our trebuchet, then ten shots to hit the first target twice.  The targets were plywood castles, set up at 50′ for the first round.  Our first calibration shot went a little long, so we pulled some weight off and tried again.  The next two shots were dead on target.  Figuring we were all set, we went ahead with our ten shots for the qualifying round – and not one hit the target!  They were going all over the place, landing anywhere from 10 feet to 100 feet in front of us.  The only thing we can think of is that the wind and unevenly filled water balloons combined to add a lot of variability.

Even though we lost in the first round, we had a great time and built a really cool trebuchet.  Overall, I’d call it a win!

Check out Kieth Simmons’ photos of the competition here