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Question:

Plug welding holes then drill and tap them?

Just wanted to talk about welding I got the fever.Ok so we get these BOP (blow out preventers) and the threads are trash I was thinking how are we going to fix this, dads says plug welding.So he shows me what to do really hard at first, but now after about 50 holes of this stuff I got this looking good or way better at least.Anyhow you guys think plug welding holes is hard when you know they are got to be machine out no bridges gaps etc in the weld.Excited tommorrow to see how my weld turn out when I drill and tap it, so yah I got the fever.

Answer:

It depends on the diameter of the hole and how deep it isI have done that at work a couple times and made it work but here is some problems you might run into 1When you heat metal up to melting point, all the carbon in the surrounding are rushes to the weld making it stronger and harderThis will affect all the surrounding material as well because now you have different carbon levels in your part so in the future cracks may start to appear in the part( could be months or years) 2Machining through welded material sucks ballsjust turn your RPM down 1/3 of what your were previously runningtapping it is even worsetaps break very easilyi don't know how you plan on tapping them but i would do it by handa tap-o-matic would just mess it all up 3depending in the part you are making the surface of the part may have to be machined again to compensate for the part expanding, contracting, warping, etc P.Sin case you didn't know the formula for calculating RPM on a lathe, mill, or drill press is CS X 4 divide by the diameter of the toolThe CS stands for cutting speed which you will have to get a chart that says the cutting speeds for different materialsi happen to remember that the cutting speed for 1020 steel is 100so 100 x 4 400now lets say its a .187 drill bitso you would go 400 divide by .187 giving you 2139and bam you have the maximum rpm for that material.

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