Nylon muscle fibre 'almost' tests and more medieval-ness...

Medieval Reenactment shenanigans...

So the weekend of the 13th and 14th of August was spent at Cardiff Castle for their Grand Melee event. Much fun was had. I was a 14th century medieval person and I gave myself mild-sunstroke by working on the archery range all Saturday :p
It took most of the following week to recover properly. But I still had fun at the event meeting friends I've known for years, but not seen that often.

It was also the first event where I wore my new medieval underwear, which consisted of wrapping a rectangle of linen round my waist and pulling the back-piece of cloth up between my legs to the front. Essentially a nappy.
While it didn't take long getting used to wearing it, the bit that was brought up round the front kept slipping out of the belt cord.
It did actually fall loose while I was carrying something! Luckily my tunic covered everything. All you could see was a piece of linen hanging down at the front.
I was wearing modern underwear underneath as a precaution for such an eventuality.

My plans to solve this are to put some toggle-like buttons on that part of the linen. So that when it is tucked round the belt cord it can secure itself in place.

I didn't take any photos of said underwear failure and hopefully no one else did. :/

Muscle fibre project...

Now last week and the week before, due to scheduling my time, I made a decent amount of progress with this project. Typically though, the amount of progress made also brought the same amount of fail.

Pegboard evolutionary stages

First off; I finally settled on a design of pegboard that would reliably hold the coiled nylon muscle fibres in place.
It eventually turned into some multilevelled slot-together thing, where the pegs slide into holes in both upper and lower layers in order to stop them being twisting about by the nylon coil.





This is where things start to go off plan. I opened up the packet holding the Nickel Chromium wire (some would think I should have done this as soon as getting it) and discovered that it is quite a stiff wire. I had thought it would be a nice flexible sort. "Hmm, oh well, it'll make it more springy" I thought optimistically.

NiChrome ready for soldering.

My plan for the wire was to solder the ends; solder the tops of the crimps holding the nylon coil and then join them together. Although I would solder one end of the wire down first, then coil the wire around the nylon and then solder the other end of the wire down.

However, science happened and the solder did not adhere to the Nickel Chromium wire. A quick search on the web reveals that the best method is to crimp the ends and then attach the crimps.

NiChrome wire crimped and soldered.

So I did this. Crimps attached, then soldered.
A fair enough compromise I thought.
It alters things a bit, considering that I wanted the crimps on the ends of the nylon coil to be the attachment and electrical connection points for the whole muscle fibre.

Splodge. :(

The next fail in was in trying to add solder to the crimps holding the nylon coil.
The insulation tape melted and released the nylon (melting the nylon a little too) and so messed up the whole thing.
Luckily I had another piece of ready-crimped nylon ready to twist as a replacement.
Although I did use this opportunity to test-repair the splodged one.

Twisty twisty twist...

Once the new nylon coil was made, I clamped it in place and twisted the Nickel Chromium wire round it. "Meh, that'll do" was my initial response.
In hindsight I should have used a metal rod to act as a mandrel in order to wind the wire round, spring like. But instead I got a messy twist.

Moving on...

Fitted and under tension.

After some fiddly fitting of the nylon coil and the twisted wire into the test rig everything was ready for my first test.

According to my calculations (famous last words!) a simple 9 volt battery should supply enough juice to heat up the 5cm length of Nickel Chromium wire from 22 degrees C to 100 degrees C.
No resistor required. Awesomes.

Unfortunately;

SCIENCE!

• My interpretation that a 0.001 ohm resistor meaning I didn't need one, was wrong. It simply meant that 9 volts would not be enough. I should have used the concept of a 1 ohm resistor and the energy requirement, in order to work out the voltage needed.
• My 9V battery expired in 2014 :/ All the electric thingies had escaped. :(
• I had not tested the electrical connections on the Nickel Chromium crimps to see if they where good. (Note : When testing said resistivity of Nickel Chromium as a way of checking good crimp connectivity, don't do it while it's clamped into an all metal frame)

As you can see, progress and fail of fairly equal proportions. With no actual results to show. I think this is also what made me reluctant to do a blog post last Monday. Too much fail on the brain. :/

Lessons I have learned :

1. Checking and understand the properties of materials I'm going to use before I use them.
2. Make sure all equations & answers make sense.
3. Ensure equipment, that have best-before dates, are before said date!
4. Have more patience!

So hopefully I'll organise myself a bit more this week and perform another experiment. I'm eager to start the next stage of building robot frames and developing the electronics to go with it. I've got an ardunio board and a raspberry Pi board waiting to be used.

Alternative artificial muscle project...

Mag-muscle concept

EM segments printed out

Due to the fail on the current muscle fibre project, my brain started reminding me of a past idea. Which was to use small electro-magnets in a line to act as a muscle.

I drew and quick plan on Friday and printed a few off this morning. All I have to do is get some 5mm diameter metal rod to wrap EM wire round and I can play. :)

Although I still have to work out the correct amount of windings required, the voltage needed...which means putting together a board with the required transformers for the voltage, blah, blah, blah...
It'll be voltage heavy however I do it.

Last few things...

Right, I'd better wrap up this blog for today. I attended the Newport ship open day in Newport, Wales on Saturday 20th. This was as a medieval person again along with my reenactment group.

Each of us attending did various craft things and displaying of swords & armour to members of the public visiting.

The event itself is to highlight the work done on the recovery of a 15th century medieval ship found along the Usk riverbank. More details on their website.

As part of the restoration they've been laser scanning the timbers and 3D printing a scale model of the boat. I'll add some photos eventually.

It was a nice day out, very enjoyable. May we have many more events there.

I had a chance to play on a HTC Vive this past weekend. It was awesome. My first experience with VR. I'm going to try and design some custom 3D models and skins for the controllers and home room areas eventually. :D