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Thread: Maybe a case against Robust tool rests?

  1. #31
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    Quote Originally Posted by Brice Rogers View Post
    I'm impressed that you were able to measure Rockwell hardness. ...
    I have often considered buying a rockwell or brinell hardness tester since I first used them in the metallography lab. Maybe someday I can find a used one.

    JKJ

  2. #32
    Quote Originally Posted by Brice Rogers View Post
    I'm impressed that you were able to measure Rockwell hardness.

    Were you using an indentation method or a file method? Just curious.

    Also, I found it very interesting the you confirmed my suspicion that the weld areas would be softer. I was wondering about that. It would be possible to re-heat treat the entire tool rest but it would be kind of a nuisance and would either need to be done in an inert oven or scale would need to be dealt with.

    I bought a 3' length of A2 drill rod from McMaster Carr and was surprised that it came fully annealed (very soft). So, I'll need to heat treat it first. I am contemplating tack welding in just on the ends and then adding a fillet of epoxy or JB-weld. That way it is more likely to stay in place if I drop it.

    Thanks for this interesting feedback.
    Don't be too impressed. As mentioned before I'm no expert at this. I used the Tsubosan files to measure hardness. I don't think they're meant to be all that precise but you get a good indication or range of hardness. The top bar on the Robust and Advanced rests were noticeably softer near the welds. I also tested some of my turning tools and all of them with the exception of some very old ones didn't receive a mark with my 65 HRC file, the hardest of my set. I don't know what practical value was served in this exercise but it satisfied my curiosity.

  3. #33
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    Quote Originally Posted by Steve Mathews View Post
    Don't be too impressed. As mentioned before I'm no expert at this. I used the Tsubosan files to measure hardness. I don't think they're meant to be all that precise but you get a good indication or range of hardness. The top bar on the Robust and Advanced rests were noticeably softer near the welds. I also tested some of my turning tools and all of them with the exception of some very old ones didn't receive a mark with my 65 HRC file, the hardest of my set. I don't know what practical value was served in this exercise but it satisfied my curiosity.
    I never heard of those. Found a set on ebay: "TSUBOSAN Japan Hardness Tester Checker File Set Ma00600 908", $58

    JKJ

  4. #34
    Quote Originally Posted by John K Jordan View Post
    I never heard of those. Found a set on ebay: "TSUBOSAN Japan Hardness Tester Checker File Set Ma00600 908", $58

    JKJ
    That's the cheapest price I've seen for the set. I finally broke down and bought one after seeing the machinist community use them. They're probably only a step above an ordinary file test but at least it gives some rough HRC numbers. They helped when in my first attempt at hardening/tempering a piece of tool steel for a forming tool.

  5. #35
    There are 3 types of drill rod, A for air, O for the oil, and W for the water cooled. Of the 3, the A is by far the hardest bought in raw form. In testing, I had one rod hardened on the tool rest bar, and the other the rod was hardened first, and then welded to the tool rest bar, and my welder got one end of the hardened bar 'red hot'. There was no difference in the file and hack saw test. I don't know anything about metals other than being able to grind them.... The hardening may be able to be done by a competent blacksmith. I would expect the rod not to be hardened before you get it because that would make it a lot more difficult to machine to your specs, especially if you want to bend it. Can't remember if I said this before, but on my Vicmarc tool rest, there is a bar on it, but it isn't hardened. I think the epoxy fill may make the tool rests look a little nicer, but isn't necessary. Not sure if a tack weld would be good enough to hold a piece of drill rod on if, okay, when you drop it, and of course, it will land on the end.... A short weld bead will suffice. If you have your drill rod hardened professionally, they charge by the pound.

    robo hippy

  6. #36
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    Thanks Reed for the feedback. I have a small kiln/heat treat oven, so I'll probably heat treat it myself based on a published temperature/time schedule. But interesting that they charge by the pound. I suspect that a 1/4" or 5/16" drill rod 7" long probably only weight a fraction of a pound.

  7. #37
    Well for doing one or three, if you have the knowledge, doing at home makes sense. Brent does weld his to the support arm first and then heat treats them. I would guess he has his own heat processing set up rather than getting it done commercially. Doing any quantity would require a fair cost, and the rod is a lot lighter than the whole arm.

    robo hippy

  8. #38
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    Reed, I think that when the pros heat treat that they do it in an inert atmosphere. I don't have that capability. When I heat steel up to around 1600 or so degrees, I get scale (iron oxide). So, my own ability to weld on the drill rod and then heat treat the entire assembly (post and all) is compromised. I suppose though that I could always try it. It is likely to be functional although a little ugly.

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