Years ago I used old hacksaw blades for testing abrasives, but the new ones at the hardware store are all bi-metal where (I believe) only the tips of the teeth are hard, and the rest of the blade is soft. Files would be too hard and are a difficult shape to work with, and box knife blades are a bit soft. Are there any good substitutes?
Cheap source of hard steel? (for abrasive testing)
- Thread starter Mr.Wizard
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Nothing exotic, just sintered alumina that I wish to classify based on approximate workpiece roughness and cutting speed.
I would like something above 60 HRC? For soft and medium hardness samples I have dollar-store paring knives and carbon steel box cutter blades, but I am missing a high-hardness stock since I threw out my old hack saw blades, not realizing they were unusual now.
Since posting I found a listing for a set of Bosch "basic metal" HSS jigsaw blades that are probably like the old stuff I had, but they are a little narrower than I would prefer to work with. I also found HSS planer blades but they are rather expensive at $14 for two 3.25" blades.
I would like something above 60 HRC? For soft and medium hardness samples I have dollar-store paring knives and carbon steel box cutter blades, but I am missing a high-hardness stock since I threw out my old hack saw blades, not realizing they were unusual now.
Since posting I found a listing for a set of Bosch "basic metal" HSS jigsaw blades that are probably like the old stuff I had, but they are a little narrower than I would prefer to work with. I also found HSS planer blades but they are rather expensive at $14 for two 3.25" blades.
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I think a file is far from too hard but how far off is the shape? Anther option but perhaps too expensive is HSS cut off blades for lathes. You can get some real good and hard steels in that format but probably $15-$40 each depending on steel, size and supplier. With good cut off blades there is no mystery about heat treat quality or what the steel is.
Thanks for the ideas; I'll look at that. Are files untempered? How differently from tempered blade steel will that behave? Ideally I would like something similar to the M2 in some old Benchmade knives, or Hitachi Blue Paper steel, but I cannot afford either of those for testing.
Cut-off/parting tools are fully hardened.
Here's some stuff about high speed steels (hss).
I have knives made from m2, m35, m42, and t42 steels. All except the m2 ones were made from cut-off/parting tools. They are very hard and make excellent knife blades.
Here's some stuff about high speed steels (hss).
I have knives made from m2, m35, m42, and t42 steels. All except the m2 ones were made from cut-off/parting tools. They are very hard and make excellent knife blades.
That is it, they are through-hardened. Cheap Chinese like you found is going to be a crapshoot for quality, as in don't be surprised if it isn't top-notch. Probably good enough for testing stones, but not for it's intended purpose. They come in many sizes and two shapes. One shape tapers on both sides like a knife, sort of, and the other style is in your photo. Look at the raised area along the backside, this is for relief when cutting metal. The backside in the photo is the top of the tool, the front of the photo is the bottom of the tool and is narrower.
Good files are mid to higher 50s, I think, but that does depend on how good the file is.
Good files are mid to higher 50s, I think, but that does depend on how good the file is.
I am having trouble finding information about files, steel and hardness, but I found several statements that a lot of files are now case-hardened low-carbon steel, rather than through-hardened high-carbon steel. If this is true I think HSS saw or parting blades are a safer bet, even cheap Chinese ones?
I'm just looking at it from the standpoint of knowing exactly what you have, and it's just a one time purchase.
Machine shops in your area, or someone who works industrial maintenance might be a source for scraps.
If you do get a full hard hss hacksaw, be aware the ends might be partially annealed at the holes.
How bout a drill bits? Plenty of those get used up and thrown away. I think the most common alloy for US made is m2.
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I've not tested them myself, but this post
https://www.bladeforums.com/threads...pling-of-production-and-custom-knives.972988/
claims black OLFA LBB blades are low 60s.
https://www.bladeforums.com/threads...pling-of-production-and-custom-knives.972988/
claims black OLFA LBB blades are low 60s.
Drill bits are not that hard, especially the shanks. I have lathed and milled them enough to know. A broken tap shank would be better, and of no use to anyone else. In the spirit of you get what you pay for a parting tool blade would be the best option I can think of. A really good range of steels to choose from and good heat treating, if you get higher end. Western Tool and MSC are two places to shop for parting blades. Here is the page on McMaster-Carr, but the prices are kinda high. I think Western is your best for price.
I know what you mean about not trashing a knife to test stones. I have a CRKT tanto in 440c I found on a trail that I used for that purpose but it still bothered me to just grind away on it, even though it's not a blade style I would ever use. Kudos to BBB for giving me some CPM 4V and 15V rectangular blanks to grind on when testing stones.
I know what you mean about not trashing a knife to test stones. I have a CRKT tanto in 440c I found on a trail that I used for that purpose but it still bothered me to just grind away on it, even though it's not a blade style I would ever use. Kudos to BBB for giving me some CPM 4V and 15V rectangular blanks to grind on when testing stones.
You really need to get some better quality drill bits and files .....
On all shock absorber surface on rod is hard chrome ...and between 70/73hrc
I never buy budget drill bits and the only ones that are hard are carbide, which make much more accurate holes. The idea that a file will be 65 hrc is a bit absurd. I thought that high-quality HSS tool blanks were around 64 hrc so that would put good files a bit lower. I am just guessing on the files as I have never lathed or milled them but I have lathed both drill and tap shanks and milled Weldon flats on drills, taps are much harder. I have also lathed dowl pins and they are very hard too.
I am not sure how useful hard chrome would be as it grinds much differently than any steel.
Uh, no. Good quality drills and files should be at least bare minimum 60Rc. I would consider even that to be sub-optimal. The shank of a drill is purposely made soft via such methods as induction hardening so that only the business end is hardened - for most drills this will be in the neighborhood of 63-65 HRc. Files should be closer to 65. How long have you been doing this work? Your inexperience is showing.
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How hard do you think a Cleveland HSS tool blank should be? I just never paid too much attention to the Hrc of these items. From use, I can tell you the comparative hardness of these items but I have never had access to a hardness tester. Being small shop and self-taught at machining my experience is different, I never did any schooling on machining or tool making.