@a smile, for reasons I don't fully understand, I have found that measuring the key results in a fairly consistent measurement varying only slightly depending on which pair of faces is used.
However, measuring the corresponding female socket on the chuck is highly variable. Perhaps it is wear related or poor quality, or or or. In most cases, my chuck keys are a loose to very loose fit to the sockets. In all cases on my chucks, fiddling with the Calipers can change the readings more than I think is reasonable.
Hi Daddy SUS, I've seen a lot of responses on this thread from people worried that too much torque will damage the chuck? I am not a professional mechanical practitioner, my early use of chuck is 160mm, using 10*10 keys, now using 200mm, 250mm/300mm chuck, key 11mm,12mm. I don't think I have enough strength to damage the chuck with the current key, even if it is used continuously for a long time, it is difficult to damage the chuck, unless you increase the length of the steel pipe and add a lot of torque like many savage turns. Therefore, according to my actual use effect, the length of the 10*10mm key extension rod is 240mm, the length of the 11*11, 12*12 extension rod is 240mm, 260mm, and the maximum length is 280mm. I think it is very difficult to damage the chuck even if you use 280mm afterforce bar on 10mm key, I would be more worried about the key being damaged. Therefore, please rest assured to use the appropriate key, the only premise is "please do not use inferior chuck, especially made in China".
Probably because of the habit I developed in the forums in China a long time ago, I don't think the forums are a suitable place to sell. After all, the purchasing power of forum members is much lower than that of enterprises. Very few DIYER would use expensive tools, and even if he was wealthy, I think he would have calculated expensive expenses carefully. There is also a more personal reason, I think once the money relationship with friends in the forum, it will destroy the peaceful and friendly atmosphere between friends, but I don't mind friends buying from my Amazon store, and I hope he will give the actual use of the evaluation (good or bad) I welcome. I like it here because there is a large group of people with the same hobby as me, and I can relax and exchange experiences and feelings with each other.
I am currently changing the design scheme of the key, and I hope to have better works that can make everyone have a better use experience. For me, constantly improving the level of tool design and production is the main reason why I am here, and also the source of happiness.
So, if I settle on a new design, that's roughly how many of the existing products from these three models will be made. May I request that you test the square dimensions of the inner holes of each chuck? Are you sure these sizes are not using metric keys that are close to the imperial size?