Guest Post - Lorraine W

 One of my students decided to get some hard data for herself so she could better gauge her beating.  She kindly agreed to write up what she did.  Here is part 1.

How hard am I beating ?

 I was weaving today and I noticed as I looked at my web, that there was this periodic line across the width of my cloth. I thought to myself this line is occurring with a regularity that resembles the frequency of my warp advancement. Is it possible that I am beating too hard at the start, after each time I advance the warp? I left the loom and I said to myself, there has to be a way that this can be measured so I can teach my body what the acceptable beat is for this project. What I was looking for was to establish a  biofeedback loop, so I could learn fast from real data.

 Sitting at my desk, I began  to consider the first principles. The force of the beater hitting the fell of the cloth may be resulting in this variable density that I am observing, or at least it is one of the parameters. I began  scribbling, F=ma (force= mass x acceleration). I know that the mass of the beater is fixed and constant . The exact beater mass value is not relevant, since on each beat the mass will be the same, so all I need to do is measure the acceleration of the beater as I move it towards the fell line. If I can get that measurement in a reoccurring manner and record it, I can use the data to help me confidently refine my beat to the desired range, for that project and all others in the future.

 As an engineer I know that there are measuring devices for everything, so I started to look for an accelerometer that I could strap to my loom. I wanted it to be inexpensive, since I was only going to use it for a short period of time to increase my mindfulness. I then had another idea, what about my Garmin watch that I use for running , that has an accelerometer. If my watch has it then perhaps there is an app that I can load on my smart phone. Of course there was an app, many in fact and I chose one called G Accelerometer and the price was right, it was free.

 

After uploading the app , I went into the settings and zeroed the gravity component ,we don’t really need it since I am only interested in the horizontal displacement of the beater. If you leave the gravity component on it is ok, but not necessary. I strapped my phone with the accelerometer app on to my beater and I began to weave. The picture below shows the simplicity of the setup.

 

 What I found was that I had a very sporadic beat after each advancement of the warp, the value of which ranged by an order of magnitude. This graph below was plotted using the numbers that were exported from the app. The absolute magnitude is not of importance, I was looking for feedback on my beating pattern and trends. The Y axis is measured in Gravity units (Gs) and the X axis is seconds. You may recall that one G is 9.8 meters/ sec ² or 386 inches/sec ². If I eyeball this graph and take out the extreme high beat values, I can see a trend line around 0.05 Gs or 19 inches/ sec ²

 

 

 

I repeated this process several more times and I plotted my progress throughout the following days and I eventually got a much improved beat consistency at a lower beat, that gave me the picks per inch I was looking for.  In the graph below, recorded for a longer period of time, you can see  a trend line around 0.015Gs, which is approximately  6 inches/sec ². There are still variances and there always will be, since I am not a machine, however I have learned that a simple app can give timely feedback into our body movements that can be used to improve weaving .  I hope you will give this a try for yourselves, it may be interesting to see how many Gs you are putting on any given project.