Chris Williams

And here I was expecting duck tails...

Hey! I resemble that remark! It is usually when I am closer to either tail of the curve where I get most of the strange looks, though.

I think that a door between the bathroom and garage would be useful, and shouldn't be a zoning problem.

I am not sure that a thermite reaction would have leveled a building, as it is highly exothermic but not particularly explosive. However, a dust explosion certainly would have (just look up thermobaric explosives). I once experienced a very small one while working as a gopher at a local machine shop the summer after high school. While sanding stainless steel tubes with a belt sander on a lathe, I used compressed air to blow off previously accumulated (unknown composition) metal dust on the lathe just as I hit the power switch. The spark ignited some of the dust and left me with a little burn on my hand and arm and much improved wisdom. Dad was a work lead at a feed plant, and got thrown 30+ feet when the dust in a grain elevator lit off. Any flammable powder mixed with air can cause a devastating explosion. Coincidentally, almost anything that we grind fits in this description. Be safe, and keep a clean work area (in addition to the advice above from others). Just don't clear dust with compressed air!

www.specialmetals.com/documents/Inconel%20alloy%20718.pdf "Working Instructions" starting on page 24 give atmosphere requirements under "heating and pickling." "Hot Forming" on page 25 gives temperatures, reductions, relative pressures required for deformation compared to mild steel 302SS,and other Inconel alloys, and heat treat/property information.

Can anyone with an understanding of the light spectra produced by a gas forge comment on the safety of using sunglasses around an IR source? I have read elsewhere on this site that sunglasses both don't block IR, and that they actually enable you to open your eyes more and get higher IR exposure, making them doubly dangerous. However, I noticed that noone here appeared to be concerned about the comment above, even though some of the above commenters are demonstrated experts in gas forges. Can someone that knows the safe thing to do here please clarify when something like shade 3 or shade 5 glasses is appropriate ppe, and when (if) sunglasses are ever ok around a forge?

I hope that I am not over simplifying this, but the spring in the picture looks like the last coil on the end is just bent outwards 45 degrees and then maybe closed a little. I would second BGD's comment on bending it cold after cutting to length.

I think that it could be a precursor to modern autopolishers. The new ones rotate the sample(s) above the polishing media (anything from 80-120 grit paper through ~0.03 micron slurry and anything in between, with sample cleaning and abrasive changes between steps), holding them flat and level while also preventing uneven wear on paper or slurry buildup. The sample holder rotation (and possibly also the arm motion here) would also change the angular relationship (think time on a clock face) of the sample relative to the direction of travel of the grinding / polishing media, which saves a step in making sure that you have progressed through the scratches caused by the previous, more course grit. http://www.struers.com/default.asp?doc_id=364 I agree with gote and others that the sample holder is missing. I said all that to basically say that I also think that Frosty is correct, and point out that the item is very familiar feeling to me despite its age and my rather niche application for lapidary type equipment.

If I were using it, I would apply adhesive backed sandpaper directly to the plate. It looks flat enough. The paper is easy to change out without contamination, but make sure that you don't have anything under the paper (like that black stuff near the top of the last pic), or that high point will catch whatever you are sharpening.

Do you know what alloy of Cobalt (or if it is a pure electrolytically deposited sanple)? I would expect that its hot working charactistics could vary significantly based on what you actually have. I found the following document that covers forging of some Cobalt based superalloys, but it may or may not be suitable for your material. http://www.haynesintl.com/pdf/h3159.pdf

The charts are under "hardness testing resources, " and the direct link is http://www.buehler.com/Posters/Hardness%20Conversion-ASTM.pdf This table also includes minimum acceptable stock thickness based on hardness, which will give you a good idea of when you would be getting a false measurement. Like Dave Budd said, a witness coupon made from the same stock as the part (but with flat, parallel faces) will help when you have something with a difficult geometry and can't put a flat on. Make sure that the witness coupons have the same thickness as the part and are heated and quenched at the same time as the part so that you don't have any variance from quench rate differences or a maximum through hardenability. The angled shim idea can be made to work in extreme cases, but is not good practice. If you have guaranteed the test to ASTM E18, or the heat treatment to some other spec (which should specify inspection criteria), avoid doing anything "creative." Like Dave already said, the shim and part will tend to slip relative to each other.

Oh, for anyone not already familiar with hardness testing: grind or file parallel flats if you need accurate tests on something with too tight of a radius. If you can't grind a flat large enough for the anvil on the hardness tester, make a small flat on the test side and use a V block anvil. The flat needs to be at least large enough for 5 indentation diameters (2.5 diameters from the center of the indentation to the nearest edge in any direction).

I use an old Wilson table for cylindrical correction values. The information in the table comes from ASTM, but that spec costs money for access. I assume that you already have the spec if you are promising certified hardness values. The Wilson chart is freely supplied. From searching for the official website, I think that Buehler may own Wilson now. http://www.buehler.com/hardness-testing.php

I actually saw a few snowflakes falling yesterday while making a good start on a hardy. It was low 40s with 30-40 mph gusts. Weather man said that it would be the coldest feeling day of winter.

Thomas, I would have thought that the skin was titanium, but the Russians apparently weren't good at welding it back then. I wonder how fast the foxbat would have been had it been lighter? I didn't know about that. I will probably choose stock to minimize weight, but that 1" material would probably last at least a couple of months in this humidity. I specifically pursued metallurgical engineering due to a love of fire, but I was mostly exposed to casting in school. I didn't have interest in forging, as I thought smithing was completely obsolete due to my lack of exposure. I have since been disabused of my misperception, thankfully, and finally experienced one too many broken junk Chinese "forged" tools from the nearest chain home improvement store. I will happily spend more time, effort, and money to do something the way I want it myself rather than buy garbage. Playing with fire and hitting things is just gravy. I have certainly learned more about processing materials by analyzing problems and mistakes than by reading or watching how something should be done. What not to do is sometimes more important than what to do.

Hello from Orange Park, Florida. I am setting up a backyard shop, as I am fairly well addicted to forging after having an opportunity to play with a brake drum forge and an anvil made from an 80# clevis. I have been reading here, from several books, and the abana tutorials while scrounging equipment and stock, but know better than to think that I know what I am doing yet. As for my day job, I perform metallurgical failure analysis and production shop support for overhaul and repair of Navy aircraft. Most of my materials knowledge is in aerospace alloys, so I will have to learn more about ferrous metallurgy. I received my first commission this past weekend, when my wife requested wire frame animals with Christmas lights on them. I don't even really need heat for these, but that won't stop me.