I default to cobalt drills for most jobs. They are more expensive, but I've never actually dulled one on anything less than a nasty SS.
N. Christopher Perry > On Aug 12, 2016, at 6:59 PM, Dave Cole <[email protected]> wrote: > > One propane torch (a good one) in a wind less area might be able to get > that dark red. > You might need two propane torches to really get it into the red range. > Do you happen to have a weed burner ? That would do it. > I drill quite a bit of hot roll and don't have any issues. > If you need some good drills which are pretty cheap, Ryobi drill bits > are sold at Home Depot and those are pretty good bits for what they charge. > > Dave > >> On 8/12/2016 5:31 PM, Ed wrote: >>> On 08/12/2016 03:39 PM, Gene Heskett wrote: >>>> On Friday 12 August 2016 14:24:19 Gene Heskett wrote: >>>> >>>> Greetings all; >>>> >>>> At what temp do I have to get a piece of hot roll to in order to >>>> soften the ultra hard core of the steel? Is it something this toaster >>>> oven can achieve given enough soak time at about 425F? >> >> >> Add about 1000 degrees F to that for an anneal. >> >> >> >> >> >> >> >>>> Doing the hole, which I haven't tapped yet, for the 4mm gib adjuster >>>> screw last night, I started with a freshly DrillDoc sharpened quality >>>> 3.44mm bit. >> >> Drill Doctors are not a high quality or high accuracy sharpener but they >> are handy. They are known to leave a "heel" behind the cutting edge, >> that might be your problem, give it some more clearance behind the edge. >> I wore one of them completely out and am working on another. >> >> >> >> I had much the same problem building the front clamp. Cold rolled >> would work much easier, but I'd have to buy that online, whereas the >> hot roll is in the bins at TSC. >> >> >> >> Good hot rolled drills easier than CR, bad HR may have hard spots. I drill a >> LOT of both. If you have doubts about the quality cut part way through with >> a hacksaw and bend it, and look for an obvious change in texture >> >> >> >> >>> I found a pdf, from ASM International, 18 pages describing in text and TT >>> maps, what happens to steel as its heated and cooled. But somehow I am >>> failing to make the connection to the temp, time at temp, and cooling >>> rate to get the easiest to machine finished piece. >> >> >> For most low or medium carbon steel heat to 1450F and cool in the >> furnace or if no furnace bury it in Vermiculite insulation to cool to >> under 100F >> >> >> >> >> >>> Thats ASM #05144G. >>> The fact that the TSC stuff carries no label describing its alloying >>> materials and percentages is also "missing" info. >> Unless otherwise marked TSC steel is 1008 to 1018 steel alias A36. >> >> >> >>> I know in the early '50's that making the stuff drillable for cotter keys >>> in the ends of some 5/8" shafting about 15" long was a matter of heating >>> them pretty bright red on the ends, and air cooling, but other than >>> necks of ammo being annealed for reloading longevity, that is about the >>> extent of my knowledge if you throw in what you can do to a puddle of >>> steel with a smith wrench. That is a whole science in and of itself. >>> >>> So, some recommendations, particularly for just the maximum machining >>> ductility, and how best to measure that temp on the cheap, would be much >>> appreciated. >> >> Heat with a torch to IHC tractor red and cool slowly, if you do not >> prefer IHC then try Massey red. >> >> >> Ed. >> >> >> ------------------------------------------------------------------------------ >> What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic >> patterns at an interface-level. Reveals which users, apps, and protocols are >> consuming the most bandwidth. Provides multi-vendor support for NetFlow, >> J-Flow, sFlow and other flows. 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