Hello everyone, There was no subforum for drilling equipment, so I'm asking here. If there is a better location, please advise. I manufacture quite a bit of large rock drills, rock augers, edges, Bauer pockets etc and am curious as to why the majority of the Kelly boxes on such rigs are cast steel rather than fabricated. Clearly, fabricated boxes can be made cheaper in quantity, but is there any reason not to fabricate the boxes (full weldment)? Does anyone have experience with welded Kelly boxes? Thank you
Could the reason be: the material for the weldment becomes in a sense limited in respect to the final desired mechanical properties either by chemistry or cost or uncertainties of mechanics ....compared to a casting which can be cast (eg uniform grains) w say "x" grain structure, then heat treated to obtain final "y" grain structure. ~~~~~~ I don't really know much about these drill rigs because when we hire these rigs, the operators can't hear very well so they don't converse much which I believe is due to the extreme banging of the drill as it reenters the hole but they say "one gets used to it".
Actually I really doubt you could fabricate what I think you're talking about cheaper than casting it in one piece. I would also assume most outfits that build drill rigs probably buy that unit from a manufacturer that specializes in making them and they do batch runs of the castings.
This confirms my suspicions. By the time the box is fabricated, there would be about 200lbs+ of weld in it plus the labour to gouge and bevel 2" steel plate. For a given coupling strength it makes sense to simply purchase the casting as a unit.