Stamping press main gear failure - photos

[Frank S]

I agree. The opposing side in the last picture has cracks in the same general area and near total failure.

I recently had some failures in a pair of #35 pitch 10 tooth sprockets. These were purchased with a .625" bore .125" keyway the factory had placed the set screw 180° opposite of the keyway, both the keyway and the set screw were located directly timed with the valley of the tooth pattern. I had also ordered some wiht plain stock bore which I was going to bore for bronze bearings as idler sprockets. I told my partner the keyed ones would most likely break before the chain in testing due to the location of the keyways and set screws, which they did the first time we loaded them under stress. So I bored 2 of the stock bore sprockets located my keyways directly under a tooth and located the set screw between 90 and 120° away from the keyway locating it in alignment with a tooth as well this time in testing the master links of the chain was the point of failure, but still lower than what I felt we needed for a FOS for long service life, causing me to have to make some major changes in the design to allow for a double row chain since the smallest 2 strand #35 sprockets were 12 tooth.
Keyway placement and set screws play a huge part in design strength the many don't understand