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  • #16
    Originally posted by Bob Engelhardt View Post
    I had this brilliant idea (?) that I could put a grinding wheel on my horizontal mill and do tool grinding, kind of. I'm thinking that with a spindexer to set angles and the 3-axis feed, I could do precision grinding, or semi-precision anyhow. For instance, grinding broaches for a rotary broach.

    The biggest limitation that I see is the arbor speed. But my mill uses a VFD that I could turn up - would that be a problem for arbor bearings?

    Thoughts?
    Two thoughts come to mind.

    First, as you suggest, speed becomes a factor. So why limit yourself to the speed of the mill? Would it be possible, practical, to rig up a lathe tool post grinder to the mill's arbor support structure?

    Second. As with a tool post grinder on a lathe, there is the concern about grinding dust getting into the ways of the mill and causing premature wear. Cleanliness becomes an issue.

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    • #17
      speed is easily solved....just duct tape a router to the arbor and get someone to hold your beer

      sorry, couldn't resist....I think its A ok to float different ideas, you never know. On this one, I think the feed screw based motion mechanism, lack of protection on the machine plus the impossibly of getting to high enough speed make it one I wouldn't try.

      in Toronto Ontario - where are you?

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      • #18
        Thanks for the replies - it was good to hear that it's not totally unreasonable. I wasn't thinking of surface grinder accuracy, most of my work is to thous, never to tenths. Being able to occasionally grind an HSS square or hex rotary broach would be nice.

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        • #19
          Originally posted by Bob Engelhardt View Post
          Thanks for the replies - it was good to hear that it's not totally unreasonable.....
          Ummm, Yes you are being totally unreasonable. What made you think otherwise??
          You would be better off surface grinding with a radial arm saw.

          -D
          DZER

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          • #20
            Originally posted by Doozer View Post

            Ummm, Yes you are being totally unreasonable. What made you think otherwise??
            You would be better off surface grinding with a radial arm saw.

            -D
            Dont finish all the popcorn. I may have finally found a use for my RAS in my workshop. .

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            • #21
              I grind tools, drill bits and such using a CBN or diamond wheel on my homebuilt CNC all the time. Works great.

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              • #22
                If I remember right, ny cnc did a factory tour of starret, they were and had been using a mill for grinding,.. somthing I’d been told no to, but needs must
                thinking toolpost grinder.
                mark

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                • #23
                  I have a low speed wet grinder I use for my wood working tool sharpening that works like a charm. So arbor speed isn't an issue if you feed it slowly enough and control the feed pressure. I think the risk would be that you force it a little too fast and crush the particles of the wheel and cause it to change size and shape. Most grinding wheels for metal work are the type that relies on fine cuts and fairly low pressure provided by very high RPM speeds.

                  As for the grit I'm thinking that it would not take a whole lot of time to lay a big mask of plastic sheet over the table and lower portion. And with the low speed of the arbor it's not like the metal filings and particles from the wheel will have the energy to travel far. So a good masking off of the table and controls should cover off most of the grit issue. And with a little finagling you could set up the mask with ramps and directors under the plastic so you could run the wheel wet with soluble oil which would totally capture and run the grit away into a catch bucket.

                  For a sensitive load feed that would push the work against the wheel with the right sort of light but firm force I think I'd wind some cord around the X travel wheel and hook up a bucket of weights. The weight being such that it turns the feed but you can reach out and hold back the travel with a suitable amount of force. Like maybe a couple of pounds? I have no idea how well this will work but the point is that you want a constant force rather than constant movement so the wheel doesn't become jammed.

                  Chilliwack BC, Canada

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                  • #24
                    Originally posted by Doozer View Post
                    Making popcorn.....
                    Time to make more snacks.
                    Maybe Pizza Bagels this time.

                    Others a being swayed by this OP and posting "helpful" suggestions.

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                    • #25
                      Originally posted by reggie_obe View Post

                      Time to make more snacks.
                      Maybe Pizza Bagels this time.

                      Others a being swayed by this OP and posting "helpful" suggestions.
                      What exactly is wrong with posting suggestions? Nobody is saying that this is a replacement for something meant for precision grinding, and most of the suggestions being made also point out the possible limitations. Whats wrong with engaging in the discussion in a constructive way and possibly finding a new use for a tool, instead of just tearing people down?

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                      • #26
                        Having just spent several thousand dollars to have the bed and saddle of my horizontal mill reground, I can say unequivocally that there's no freaking way I'd do any grinding at all on, in, for, to or around my machine tools.

                        The only thing I might do- and only at a last resort, and with significant preparation and protection- is grind worn lathe jaws. (Which I may have to do before too long.)

                        There is no home-shop, non-customer grinding job that I can think of, that I'd risk long-term damage to one of my hard-won machine tools to accomplish.

                        Doc.
                        Doc's Machine. (Probably not what you expect.)

                        Comment


                        • #27
                          Originally posted by epicfail48 View Post

                          What exactly is wrong with posting suggestions? Nobody is saying that this is a replacement for something meant for precision grinding, and most of the suggestions being made also point out the possible limitations. Whats wrong with engaging in the discussion in a constructive way and possibly finding a new use for a tool, instead of just tearing people down?
                          I tore no one down.

                          In well over a hundred years of milling machines being in commercial shops, in not one has it replaced a precision grinder when one was needed.
                          As pointed out already, it doesn't have the precision movement a T&C, surface, ID/OD, centerless or Blanchard grinder has.
                          Not to mention the unprotected ways .
                          If it doesn't have the requisite precision, then what use outside the one it's designed for does it have?.

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                          • #28
                            I'm a bit amazed at the negativity being shown here in a HOME shop forum. Not all of us have the money or room for a surface grinder? By its nature hobbies generally do not pay the bills. So a lot of us only have limited room and money to devote to our passion of metal working. So what is the big deal if some of us opt to try something out? And if it doesn't work that's a good lesson too. But at least it will be based on actual trials instead of just armchair quarterbacking.

                            I read a lot about how the PM forums are a nasty place to be. It seems like a bit of that is leaking through to HSM at times like this......

                            Some time back Joe Pie had a video on YT where he made some small broaches out of HSS drill blanks using a cup stone in his vertical mill. He pointed out that he was going to get a lot of flack about it and so he did. Yet while not ideal and masking off the machine was obviously an important step he was able to make perfectly good HSS tooling on his B'Port.
                            Chilliwack BC, Canada

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                            • #29
                              Originally posted by BCRider View Post
                              I read a lot about how the PM forums are a nasty place to be. It seems like a bit of that is leaking through to HSM at times like this......
                              I'd disagree with that, no nastier than here .....there is a lot more pin head dancing here where as there its more pragmatic. However the negatives on both sites is just a wee bit of it. Mostly a great bunch of guys, here and there.

                              What they don't want is beginners with a 7x12 lathe or radial arm grinder discussions etc: the entirely home shop stuff that doesn't belong where men who mostly know they are doing and have well equipped shops congregate. We get more a range of abilities here so are more tolerant - I'm not much interested in 7x12 or radial arm grinder either but its simple to step over the stuff that doesn't interest me. There you'll get an earful. Understand that and PM is great place with lots of very knowledgeable sorts.

                              otoh catching an earful from those who what they are doing might just be a good bit of tough love.

                              Last edited by Mcgyver; 07-03-2020, 09:38 AM.
                              in Toronto Ontario - where are you?

                              Comment


                              • #30
                                So what is the big deal if some of us opt to try something out?
                                -Because there are certain things that people have already tried many times before, that have now-well-known deleterious effects on the machine.

                                You can, and people have, actually drilled and tapped their mill tables for direct hold-downs. There was a photo on PM years ago where someboy had used an oxygen torch to cut a rough and gnarly "gap" in a lathe bed in order to turn a larger part. O my own large lathe, somebody roughly ground a notch in the rear prismatic way so that instead of an 18.5" swing, it'd have a 19" swing.

                                You certainly can use 3-in-1 or WD-40 in place of way oil. You can use fresh milk in place of soluble-oil coolant- and by some reports, that's actually an excellent cutting fluid when machining copper.

                                There's lots of things you CAN do, and that people have done many, many times before. But it's also well-known that in most cases, it's a bad choice and can easily lead to long-term damage to the machine.

                                John Stephenson used an old lathe as a welding spindle. There's no possible way I'd do that, unless I had a very old, and very ratty lathe. As I said, I just paid a small fortune to have several machines re-ground due to serious and excessive wear, and there is absolutely no way I would voluntarily reintroduce any sort of abrasives to those ways, short of a life-and-death scenario.

                                Doc.
                                Doc's Machine. (Probably not what you expect.)

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