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cpm10v
03-02-2005, 03:47 PM
Anyone have advice regarding the best way to go about plugging holes in hardened steel? The piece in question is D2 @ 59Rc. A dowel hole was machined .010 off in the Y-axis and I'd like to plug it and circle mill the dowel hole back into the correct location. I have all the facilities to do this, just don't know the best way to go about it. Was thinking of turning down some D2 to 5/16 (dowel hole size), hardening it, pressing it into the dowel hole, chamfering the top of the plug and dowel hole to create a "valley," TIG-weld valley full with D2 rod, cool, grind flush and remachine. Any other ideas? Sorry if this is off topic.
Greg

precisionworks
03-02-2005, 04:49 PM
Greg,

Sounds like that will work. As you probably know, less weld is better than more since the welded area (HAZ) will get REALLY hard. Even solid carbide tooling doesn't perform well above 45HRC, so you may have to use one of the specialty mill cutters, or use a diamond-coated grinding pin.

roninB4
03-02-2005, 06:57 PM
Depends on what the piece is for and the function of the dowel (besides location). If cosmetic is important then you have the right idea. If not, just wire EDM an oversize hole and press the hardened plug w/ a shoulder on the back side using an interferance fit. Only a very thin line will show when ground flush with the face. I guess the next size dowel is out of the question so I won't suggest that. I don't really care for welding as any stress to the dowel can fracture the welded area and you now have an even bigger blemish. We have done the wire-n-plug method on stamping dies with good results and you had to look real close to see where it had been plugged.

cpm10v
03-03-2005, 07:52 AM
Thanks for the replies. I could theoretically open it up to a 3/8 dowel but that would mean that I'd have to alter a bunch of cut-off punches that locate off that dowel that are already made to a 5/16 dowel. The dowels only function is to locate a cut-off punch. Something else, the dowel hole is blind, ~ 5/8" dp. because the section is 4" thick. The piece in question is a wipe-form block that also has a cut-off punch bolted to it. How much of a press fit would you all recommend?
Thanks,
Greg

precisionworks
03-03-2005, 10:29 AM
The ASME standard (Y14.5M 1994) for a Class V (permanently assembled) fit is for 0.0003" minimum interference, 0.0016" maximum interference. This is for a nominal basic diameter of 0.3120".

A standard 5/16" dowel pin will measure 0.3127", so a hole size of maximum 0.3124" to minimum 0.3111" is needed.