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Thanks BrianTee , this is interesting indeed. The reason for me is that I have used this process in making my own cold chisels.I went to a "vintage days" and bought a chisel from a blacksmith who was displaying his wares. He bragged up his chisels saying they would go head to head with SnapOn. So I get this chisel home and am excited to try it out. I clamped a quarter inch grade 5 bolt in the vise and gave 'er a smack. My 15 dollar chisel mushroomed instantly because it was too soft. Well I figured I might as well give it a go and make my own. I had some valves from a motor lying around so I used one to make a chisel. It worked great. I have also used struts from a car. It did give me satisfaction that I could make a better chisel than that blacksmith.I still can't afford to go head to head with a SnapOn though!
 

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That's an interesting video. It confirms a conclusion I have come to with one of our hobbies.

Because this connecting rod has roller bearings in both ends it has to be fairly hard. I was slightly concerned that the hardening and tempering process was off base because this engine can no longer take what we have done to it and it keeps cutting its self in half.

By comparing the break on the rod beam to the examples in the video, it appears the metallurgy is pretty good. The real problem here is the length of the connecting rod the designers chose is a way too short, as compared to the length of the stroke, which makes the the rod axis angles far to large, when you modify the engine to make high torque, at high RPM, and not having the torque peak start to drop off at the modest 8500 RPM, as it was designed for in this case.



As you can see this engine uses a slipper piston and is a very over square engine with a short stroke to keep the piston travel speed low at very high RPM, but they ruined it with the short rod. The wrist pin is also up to the oil ring, so there isn't a reasonable way to use a longer rod and a redesigned piston. I think we'll give up on the red ones and change colors.



Ag engine designers need to watch out for this. Engines that produce high torque all of the way up to peak RPM need to have very robust bottom ends with long rods in relation to the length of the stroke, or life will be shortened and usually end catastrophically.
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