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Grinding HSS....

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  • #31
    Just a quick question on the valves. How do you know the difference between a sodium valve or a regular one? Just courious. And I have to look at mr.petes you tube again.

    Thanks,
    Chris

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    • #32
      Originally posted by Euph0ny View Post
      Somebody already mentioned Tubal Cain (Mr Pete) and his four toolbit grinding videos on youtube. Here are direct links:
      He likes wooden training tools, too.

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      • #33
        Originally posted by Tamper84 View Post
        At school the instructor says since hss is pretty much out dated, and we wont be covering it. All we use at school is inserts. Anyway, I would like to learn on how to grind them. Besides the south bend book, is there any other resource or how too? I do have some un ground hss out in the shop that I can play with here at the house. Any tips would be greatly appreciated!!

        Thanks,
        Chris
        Thats got to be one of the dullest things i have heard today!, i suppose if he needed a form tool he would commission sandvick to produce an insert and holder, he must have deep pockets!, i would love to see his shop, thousands of dollars in tooling!
        just follow Forrests instructions they are spot on
        mark

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        • #34
          Originally posted by loose nut View Post
          HSS should be stoned (the tool bit not the guy doing it) after grinding to get the best out of it.
          That depends upon the situation. As with everything in life, there are exceptions to the rule.

          Originally posted by J. Randall View Post
          HSS is not that expensive, start with it, and modify it if you need to, till it works to your satisfaction. When you get the basic grind down where it cuts to suit you, then you can start experimenting with chipbreakers, easily ground in with a small grinding disc, even a dremel tool.
          +1. The scarey part about HSS bits like most tooling is that you can buy a few new for the same money as a bucket bought second hand. If the OP keeps his eyes open via ebay, PM classifieds, craigs, auctions, fleas etc, you can find plenty of deals on HSS toolbits to experiment with. I would second simply using HSS and experimenting as you work on other projects.

          To me, offhand grinding HSS is a "must have" skill simply bc of the versatility of it. You can build all of the fixtures you want for a grinder, but eventually you will need to free hand something. Carry that over into sharpening mower blades, chisels, drills etc, and you will find almost endless possible uses for skill in this area. Even with carbide, you still need to understand the fundamentals of cutting tool geometry so that you properly use and regrind it as necessary.
          "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

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          • #35
            AMEN!! Well said!!

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            • #36
              Originally posted by dp View Post
              What have you got when you're done? You have an education and jigs. But if that doesn't float your boat then for God's sake, man, don't do that! I found I could quickly develop the technique for work holding, angles, and visualizing for a wide variety of tool forms faster because HSS is slow to grind, but obviously it isn't for everyone.
              Did not comment on your use of jigs, that is a good idea, stand by my comment on grinding the tool out of mild steel, all you can do is look at it and you still have to grind the real one, the way I look at it you are adding extra time, but my all means as you advised me do it to your own choosing.
              James

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              • #37
                Originally posted by J. Randall View Post
                Did not comment on your use of jigs, that is a good idea, stand by my comment on grinding the tool out of mild steel, all you can do is look at it and you still have to grind the real one, the way I look at it you are adding extra time, but my all means as you advised me do it to your own choosing.
                James
                Just remember this suggestion is for the student grinder, and even the advanced grinder working on a one off or perhaps two or three off form grinds that will need to be refreshed later. That requires practice practice practice to get repeatability. Another case is grinding involute cutters, for example. Not everything you take to the wheel is going to be a lathe cutter.

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                • #38
                  Yup, when I was in school you had to grind your own hss or no turning for you. One guy spent the better part of the first day grinding up one hss bit (3 hour classes). Towards the end of the class I saw him finally making his way over to the lathe. It was quiet for awhile while he set up the lathe to make a pass on some sort of steel we were using to make screw drivers. I heard the lathe turn on, then a little chatter, then BANG, broken hss. lol

                  Anyhow, I wanted to mention that I will use anything I find that will do the job at hand. This router bit was perfect for the velocity stacks I was turning up for a intake manifold.

                  Andy

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                  • #39
                    Originally posted by Chuck K View Post
                    The biggest loss I see from not learning how to grind your tools is the understanding of the effects of the geometry of the tool. That
                    Now that is an excellent point.

                    Once the tiny effort is made to understand 1) tool geometry, 2) how speed affects tool life and 3) how cutting force and rigidity work, the return on investment is amazing as these things are the basics of every machining operation. Everything just makes more sense and what's going on in most situations becomes almost intuitive

                    I started at 12 with a Unimat. As it was the only way to get a cutting tool, every machinist did so, all the books I collected made nothing more of it than any other shop function....and didn't occur that I might not be smart enough, I (like everyone else) just did it. Much the same as no one starved to death before instant breakfasts. Today it sometimes takes on the air of the difficult with beginners sometimes avoiding it. If for no other reason than Chuck's point, it should be where they start.

                    I think it's just like tying your shoelaces. It's no more difficult and that too once seemed formidable.

                    Good on you Chris, you'll be a better machinist for learning tool geometry.
                    in Toronto Ontario - where are you?

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                    • #40
                      It is the difference between giving someone a fish,
                      and giving them a fishing pole. Learn to grind HSS.

                      --Doozer
                      DZER

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                      • #41
                        Originally posted by dp View Post
                        Just remember this suggestion is for the student grinder, and even the advanced grinder working on a one off or perhaps two or three off form grinds that will need to be refreshed later. That requires practice practice practice to get repeatability. Another case is grinding involute cutters, for example. Not everything you take to the wheel is going to be a lathe cutter.
                        Totally agree, practice is what will get you there, no matter what form of tool you are grinding.
                        James

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                        • #42
                          Why do you suppose there are companies still today, who make high speed steel inserts?

                          Because sometimes, hss is better for the application. Under some circumstances, you can get a better finish, etc.

                          Please carry on,

                          doug

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                          • #43
                            I've wondered also about how to identify a sodium filled valve, without grinding into it. I have some stellite valves that I've used for making custom cutters. Seems to work as well as some of the hss cutters, maybe better. With this kind of thing it takes time to prepare a cutter, since there's often a lot of slow grinding to do.
                            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                            • #44
                              HSS does not mind being ground hot, so some color change in the bit will not damage the steel. It is designed to cut at 1000F without loosing its hardness, not that you would want to grind it
                              at any where near that temp. There is a school of thought, bolstered by a reviewer on the old rec.crafts.metalworking site that spiralled into oblivion >10 yrs ago, that dipping really hot HSS into
                              water to cool it can induce microfractures at the thin edges, a POV supported by metallurgists at Carpenter Steel, a tool steel specialty company. YMMV, but be not concerned by a little
                              heat induced coloring near the tip. Another consideration is that smaller bits are a lot easier to shape, ie 1/4 to 3/8" is easy compared to 1/2" or above, especially for threading cutters.
                              It helps to have a threading gauge and a set of ID/OD radiuses for shaping tool bits for same. A good sharp cutting wheel of high quality ALOx, reduces cutting heat significantly and can make
                              short work of shaping a bit. A bad or inappropriate wheel will cut slowly and burn your gloved fingers. A tool holder is a nice thing to have along with an easily calibrated angled tool rest.
                              Steve

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                              • #45
                                Originally posted by sch View Post
                                There is a school of thought, bolstered by a reviewer on the old rec.crafts.metalworking site that spiralled into oblivion >10 yrs ago, that dipping really hot HSS into
                                water to cool it can induce microfractures at the thin edges, a POV supported by metallurgists at Carpenter Steel, a tool steel specialty company. .
                                I remember that, and while he didn't seem to have a lot of support it also seemed an informed and well reasoned view, and he carried on despite the mob reaction it generated.

                                .....perhaps we would be better to hold the bit with vise grips and let it turn blue...and maybe dunk the other end to draw off heat but not shock the business end

                                I've not embraced the well reason view into practice because 1) its so much easier to sharpen the bit hand held and you need to cool it to hold onto it and 2) if I was inducing micro cracks I can't say I've noticed it in performance. hss bits last a long time in my experience...then again I don't how long they could last without the quench....or maybe these micocfractures are so shallow they get stoned out.....or maybe i'm cooling it before it gets too hot and avoiding micocfractures.

                                good to be aware of in any event.
                                in Toronto Ontario - where are you?

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