Week 9 Lab Data: Bronze Age Saws

Introduction:

This week we looked at saw markings from Bronze Age Greece. Our experiments involved testing out full scale, working models of pendulum saws, evidence of which is found in masonry remains primarily in Mycenae, during the height palatial period (1370-1190 BC). The questions that this data is concerned with involve the effectiveness/efficiency of the pendulum saw. And, comparing the workability of a fulcrum based, vertical, and horizontal saw designs. Our group assessed the vertical saw design, which is modeled in the images below. 

Setup:

Our groups used a saw that cut up and down as shown in Fig. 1. We attached a stone with two ratchet straps that we cut with the saw. This worked well but we ended up cutting through both ratchet straps.

Also, we attached a bucket of sand to the post hanging down to help with “mechanical advantage” but it didn’t seem to work that well (Fig. 2). At the front of the saw a wooden frame moved the saw blade up and down but proved to be ineffective as the lab went on and we put it in its upright position. In the upright position the frame did not touch the base of the saw which together with the bucket of sand strained the beam holding the saw leading to the beam and base splitting in several places. If we were to do this again our groups would like to remove the movable front frame and have a shorter distance from the saw blade to the fulcrum. 

Another issue was that compared to the other groups our saw involved a lot more effort. We think this was due to the poor design because we had to have a person on the front pushing the blade up and then someone in the back pushing the blade back down. This resulted in two people squatting up and down and made for an entertaining video:

Data:

Time (h:m)	Cut Depth (cm)
1:25	0.3
1:39	0.4
1:59	0.7
2:19	0.9
2:27	0.9

Fig. 3 depth of cut based on amount of time worked

For the first hour and twenty five minutes we cut 0.3 cm and then we timed ourselves for fifteen minutes and got another 0.1 cm. Afterwards we decided to do a hard push instead of our leisurely pace and got 0.3 cm in fifteen minutes. Then we pushed for another fifteen and got another 0.2 cm. After these pushes the bronze saw blade was hot to the touch. If we averaged our work rate it would be 1 cm per hour. Our stone was 5 cm thick so to cut through the whole stone it would take 5 hours. However, our initial depth data was affected by the grey sludge that was a byproduct of cutting the stone.

After cleaning the stone we measured the depth of the whole cut and concluded that the actual cut was actually 1.761 cm deep making our calculation 0.8 cm off. With this new depth our revised work rate is 0.7188 cm/hr over the course of the full two hours. But our pace sped up after the first hour and a half so this work rate is less than what it likely was. In order to get a good idea of the work rate there must be more experimentation. 

Fig 7. All data points for the depth of cut

Experiential:

We interviewed a few passing spectators including students, alumni, professors, and wedding planners. All of them were intrigued by the saws and wanted to know what we were doing. No one said they were grand but a few said that if they needed to make an outdoor patio and it was between these saws or a handsaw they would pick these saws. Also, one person said he thought we were mining for ore. The wedding planner said it was the most interesting thing he’d seen done in front of Anderson in his time at Carleton. A geology professor said it was interesting and not what he was expecting.