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Steel for hammer drill shank?

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  • Steel for hammer drill shank?

    I have a pretty ancient Milwaukee hammer drill that uses 7/16” shank bits like in the picture . While the bits are still available they a pricey and mostly only available from online places.

    I was thinking to make an adapter that has that profile that simply has a hole and key of some sort to be able to use SDS or SDS-plus bits that I already have and that are easily available.

    There is at least one place I can buy an adapter for $90 but are on back order until the end of next month. Ordering one is a bit less fun than making one.

    Any opinions on What sort of steel would make the most sense for this? The shanks of the bit I have are hardened, a file skates on them.

    I have a reasonably well controlled oven for heat treating.

    what does the collective mind here think would be a good material say available from Mcmaster or one of the online metal places in small quantities? How hard should it be?

    Click image for larger version

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  • #2
    Wow, you do have an ancient hammer! My guess is it’s a Milwaukee 5300 from the late 70’s to very early 80’s. I don’t recall any 7/16-SDS adapters but if you have a line on one I’d get it when available. Another option would be get an A or B taper adapter and grind the shank end of an SDS Max adapter to fit the taper adapter. That would make an already long and heavy hammer longer but if you are only driving straight down it shouldn’t be a problem. IIRC the 5300 has a spring actuated hammer mechanism and needs pressure on the bit to drill unlike the more modern electro-pneumatic mechanism hammers on the market now. Good Luck in the project.
    (Please note I never referred to your hammer as a boat anchor 😊)
    Sole proprietor of Acme Buggy Whips Ltd.
    Specialty products for beating dead horses.

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    • #3
      I think either S5 or S7 would be ideal for a job like that, it can be taken up to 60 Rc if I recall.
      Both are shock-resistant steels that are commonly used for impact tools.
      Relatively inexpensive, too.
      25 miles north of Buffalo NY, USA

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      • #4
        Yep, S7 or S5. About 55 RC should be good.
        Location: North Central Texas

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        • #5
          D2 also, but S7 shock steel is a good one.

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          • #6
            Originally posted by Beazld View Post
            Wow, you do have an ancient hammer! My guess is it’s a Milwaukee 5300 from the late 70’s to very early 80’s. I don’t recall any 7/16-SDS adapters but if you have a line on one I’d get it when available. Another option would be get an A or B taper adapter and grind the shank end of an SDS Max adapter to fit the taper adapter. That would make an already long and heavy hammer longer but if you are only driving straight down it shouldn’t be a problem. IIRC the 5300 has a spring actuated hammer mechanism and needs pressure on the bit to drill unlike the more modern electro-pneumatic mechanism hammers on the market now. Good Luck in the project.
            (Please note I never referred to your hammer as a boat anchor 😊)
            Yes, you got it right, it's a 5310, no idea when it was made but 70's to 80's seems plausible. I think in this case "boat anchor" is not unreasonable as it could probably anchor a small boat. I think the thing weighs something approaching 30 pounds with a bit in it. I have it only because the price was right at $0.00 and about ah hour of my time I spent on some reasonably minor electrical repairs. It is a beast of a thing.

            I found a "close to" adapter at the link below, but an email to the company got me a prompt reply saying that they have them but they are currently back ordered.

            https://www.bamanufacturing.com/page_35.htm

            It included a number of bits, and while those may suffice for the upcoming project I have for such a thing, it's nice to have options.

            Thanks Fastturn, Joel and NCF for the suggestions on the steel. I may just get a piece of something suitable and make a run at an adapter. By the time I find out whether or not it comes out to my satisfaction they will probably be back in stock at the place linked above. Then I can just buy one if mine fails.

            Thanks for the input guys, always appreciate it.

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            • #7
              My vote is for S7 at around 55 Rc, also. You get it as drill rod for a fairly low price. When heat treating, bring it to full hardness, then draw it back, the same as any other tool steel.
              Kansas City area

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              • #8
                You can buy SDS MAX to SDS plus adaptors. They are an SDS plus chuck with a female thread in the end of them and then an SDS MAX shank with a male thread on the end

                If your current shank fits totally within SDS Max profile, buy one and machine it down. If not, sacrifice a drill bit you have and cut a male thread on the end to go into the female in the SDS plus chuck. You might need to part-anneal it to cut the thread or it may just have a hard skin on it.

                None of the adaptors in the link you posted appear to accept an SDS plus drill bit. They all accept A- or B- taper bits, and some of the _adaptors_ will go into an SDS plus chuck.

                You will have great difficulty retaining and driving an SDS plus bit with some home-brew contraption. It relies on the balls for retention and the key for drive. See the Wikipedia page for a good cross-section of the chuck.

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                • #9
                  Another thing to watch with hex drive hammers. The hex part of the shaft of the bits will round off with wear causing the socket in the hammer to wear and the bits will get stuck. I would pitch any bits that the shafts are beginning to round. The one in your pic looks OK IMO.
                  Sole proprietor of Acme Buggy Whips Ltd.
                  Specialty products for beating dead horses.

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                  • #10
                    Just to come back to this I managed to make up an adapter. I used a piece of steel cut from a worn out stone drill that a friend gave me, similar to this:

                    https://www.miconproducts.com/drill-...ill_steel.html

                    I could not track down exactly what type of steel it was but presumed it to be something like S7 that several of you mentioned above. The rod was pretty hard, so I annealed a length per some instructions for S7 that I found online. It machined fairly well once it was annealed and I machined the outside profile, the hex shank and then drilled the holes to make a socket for the SDS bit.

                    Figuring that the bit can be rigidly fixed in the adapter socket as the adapter is what gets hit and rotated, I made the socket for the SDS by first drilling two holes that would hold pins that would fit into the full length splines on the SDS bit. Then I drilled the center hole that matches the OD of the SDS shank. I drilled and tapped a cross hole to take a set screw just to keep the bit from falling out.The setscrew holds the bit in but (unsurprisingly) vibrates loose. I may replace it with one of those setscrews with a detent ball in the end.

                    I re-hardened and tempered to what should give me good shock resistance, assuming this is anything like S7. It is pretty hard and just about skates a file on the surface.

                    After hardening and tempering, I put the two pins in the grooves formed by the holes I had drilled and fused them to the end of the socket with my welder. These engage the two full length spline grooves.

                    So it's not quite beautiful, but it seems to work just fine. I have not used it extensively yet, but it didn't shatter nor did the "hammered on" end show signs of getting peened over so far. Time will tell I guess.

                    A few pictures:
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                    • #11
                      That is very impressive, nice work! I don't think I'd want to wield that drill for a whole day 😳

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                      • #12
                        Nice work! The old dinosaur is still alive!
                        Sole proprietor of Acme Buggy Whips Ltd.
                        Specialty products for beating dead horses.

                        Comment


                        • #13
                          Thanks guys.

                          Agreed, I don't think I'd want to sling this thing around all day particularly if I had to drill any direction but down. I have not tested a great deal at this point, but that drill made pretty quick work of drilling some 5/8" holes in some hard local granite even with the cheap harbor freight bit I had in it. I can't say that all of my projects end up as well but I'm happy with this one thus far.


                          In any case I have pretty much nothing beyond some shop time invested and think that I successfully accomplished a bit of heat treating that I've never attempted before.

                          I appreciate everyone's input and comments.

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