engineer

tim   .

                                                      


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.   hunkin

                                                         


cartoonist

 

CHAIN

THE COMMENTS

I enjoy reading all the comments but apologize that there are so many I canít answer individually. Iím delighted that my new videos have been so enthusiastically received, which is reflected in the majority of the comments. The videos arenít perfect though so below each video Iíve compiled the comments about things I omitted or people thought were misleading. A few comments added wonderful additional information so Iíve included them as well. 

Several people defended the use of Ďspring clipsí to join chain. I should have said my problems with the clips are just with small 6mm and 8mm sizes I mostly use - for bike chain and larger sizes the spring clips work fine. Two people described their technique for fitting the clips, using long nose pliers between the clip and a pin, which helps prevent the clip springing off.

It was also a bit misleading to say that chain Ďstretchesí with wear. It does get longer but this is due to the wear in the bushes and pins making them a looser fit rather than the steel actually stretching.

Several enthusiasts wrote about ínon-greasyí bike lubricants. I hadnít come across them, but obviously a step forward.

Di Zolytan wrote that bike chain efficiency reduces noticeably with small sprockets, under 16 teeth. 8 teeth is the generally accepted minimum number of teeth for a roller chain sprocket, though I did once get a 6 tooth sprocket working on my gravity escapement clock where I needed large reduction ratios.

Juncus Bufonius reminded me about the ancient Romans use of chains of bronze water buckets.

Two people wrote to say that the tiny fusee chain was traditionally made by children working in appalling conditions!

Flurng desribes an ingenious use of chain I didnít know about to regulate the depth of deep sea bathyscapes. Heavy chain dangles below the craft to weigh it down. Once the chain touches the sea bed any further increase in depth reduce the weight of chain pulling down the craft. This also reminded me of watching a large ship being launched. I was down near the rudder and as the hull started to slide into the water there was an extraordinary noise. I hadnít noticed the hundreds of tons of huge chain which were being dragged into water along with the hull to act as a brake.

Flurng added this wonderful addition as well: One of the most novel and unique implementation of chains that I've seen was on the Wright Brothers' Wright Flyer craft - on that aircraft, the twin propellers were driven from the same pulley, yet the two blades were counter-rotatating (one clockwise, one counter-clockwise). They achieved this by criss-crossing the left propeller drive chain, so that it moved in a "figure 8" manner. The design included "guide tubes" for the chain, to prevent it from snagging on itself as it crossed over in the mid-point! Truly ingenious!

I should of course have included chainsaw chain, particularly the difficulty of keeping the teeth sharp. I donít often use my chainsaw and have never found a good solution so I just keep a few new spare chains. My friend Andy who uses them more often swears by an angle grinder with a 3mm cutting disc, just touching each tooth gently.

Its hard to know where to draw the line, the video could easily have been twice as long. Iím particularly obsessed by jewellry chain making machines. A bit like hand sewing machines, a roll of thin wire goes in one end and perfectly formed chain comes out the other. A friend has one which I find endlessly fascinating and beautiful to watch.

 

 

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