Drilling hardened rod

dbq49

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Nov 16, 2013
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Yes this is an age old issue. Here goes- Broken off hardened steel rod on a dozer throttle 1/4" rod , 3/8" deep I think. Drills don't drill hardened steel. CAN I heat the stub to soften the rod and then drill it out. I am not sure it can be removed from the dozer at this time. Any help, Please!
 
If you heat it up past the Curie temperature (usually dull red) and let it cool slowly (covered in ceramic wool helps), you might have some luck softening it. You can test it with a file afterwards to see if it works.



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Yes. It is unlikely that the material will air-harden, so simply heat to red and allow to cool. No special care or treatment required, just don't quench it with water.
 
How hard is the question, if it is very hard a carbide drill or end mill will do it but I would not try this with anything other then a stout milling machine.

I often reduce the shanks of taps with carbide tooling, your part is unlikely to be full hard HSS but you never know until you try. Straight flute carbide die sinking drills are excellent for this sort of work. They are very fragile so do not use them in a low cost drill press or mill as you will break them easily.

https://www.mscdirect.com/browse/tn...earchterm=die+sinking+drills&navid=4287923630
 
Doesn't it seem unlikely that a throttle linkage rod would be hard (un-drill-able)?
Is something else going on here?
 
It was on a governor throttle. Broken and destroyed 8 bits trying to get a pilot hole created.
 
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