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Hobb'd a gear today

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  • Hobb'd a gear today

    I'm on call this week so I decided to fiddle some more with my thread dial project. I have a Grizzly G0516 combo lathe that doesn't have one, so I bought a complete unit on Ebay. The gear was wrong, so I decided to make one that fit.

    It took a long time but the spare worm gear arrived (cheap at only $35), so I hacked a piece off of it and made the hobb. I'll be revisiting this as it is not real efficient as built. With information I got here I cut a blank from some brass rod I bought for the purpose and went at gashing it with a file and dremel and a 48t gear for an index. I need 24t in the final gear. Then 10 minutes or so on the hobb and it was pretty much done. I cleaned it up with a file and wire brush.

    While I was in there I decided to add an oil cup, so having some 1/4" stainless rod and a check ball from an old carb kit, I zipped one out.

    So it works fine as is but I'm going to replace the Ebay dial body I bought with my own body design made from brass. The old casting just doesn't look right with all that nice brass!

    Pictures: http://TheVirtualBarAndGrill.com/machinery/

  • #2
    Nice job on that. I need one for my Clausing.

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    • #3
      Nice work. I like brass for the look of it. I particularly like the general look and design of older machines compared to the modern ones. I really don't like the look of lathes where the headstock is a big metal box with the chuck stuck out one side like a big wart.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        Originally posted by Evan
        Nice work. I like brass for the look of it. I particularly like the general look and design of older machines compared to the modern ones. I really don't like the look of lathes where the headstock is a big metal box with the chuck stuck out one side like a big wart.
        These are big reasons I ride a Harley. All the parts are hanging out there for one to see and appreciate (assuming they're driving at 90mph so they can see it at all). I confess I do like the looks of Hardinge lathes, tho - very clean lines and everything is tucked out of sight. I don't need one but I'm probably going to buy one

        I searched this forum for thread dials and I must say there are some very clever and artistic people here who have turned out some commendable work for this simple tool.

        Comment


        • #5
          Originally posted by dp
          These are big reasons I ride a Harley. All the parts are hanging out there for one to see and appreciate (assuming they're driving at 90mph so they can see it at all).
          So, I see you trailer it a lot?

          Just kidding. Sorry, couldn't resist. I've got a friend who's really into Harleys, we’re always poking fun at each other, and that's the first thought that came to mind.

          I also find I like the looks of the older lathes including most SBs, the Logan 11, Rockwell 11", Monarch 10EE (and others like it), Rivetts, Hardinge, etc as well as the old cone heads. Likewise, the Harley and old open fender street rod look appeals to the same aesthetic as the old cone heads with minimal shrouding, while the more modern aerodynamic shrouded bikes and sports cars align more closely with the sleek designs of the other lathes listed. The more modern “gear headâ€‌ designs typical of the imports, the Rockwell 14â€‌, and many others have the same graceless functional look of a box delivery van. Aesthetics aren’t everything, and I’m in no way putting down the functionality of the square designs, but it sure is nice to have something you take pleasure in the form as well as function...

          Very nice work on that thread dial too.
          Russ
          Master Floor Sweeper

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          • #6
            Originally posted by BadDog
            So, I see you trailer it a lot?

            Very nice work on that thread dial too.
            I'd like to say it's never been trailered but on a recent trip from Seattle to Ohio and back it spit out an ignition sensor (Hall effect transistor assy, as I recall - too damn hot in Ohio!) and crapped the bed. A gentleman in the Bomber's Diner in Lyons, Ohio gave me a lift to Toledo in his covered snow mobile trailer (no witnesses!) and it was running again in 30 minutes. 6,000 miles on an air cooled pushrod engine designed in 1904 or so. Damn but that was fun!

            And I couldn't have been more tickled with the outcome of the hobbing. It was my first gear and it is very gear-like. But I have to confess a problem with it. I don't quite know how this happened because the math is certain, but it has 25 teeth, not 24. Like a watch that's accurate twice a day, it has it's moments

            Rebuild in the works!

            Comment


            • #7
              Sweet!

              Having that lathe and wanting to add a threading dial (once the machine is off the floor and on a proper stand) it is good to see an "almost correct" unit. Hopefully the MK II version that results from the PIP will do the trick.

              Yea, I liked the look of my Rockwell and Rivett lathes from the fifties, but the little Griz is what I got now.
              Today I will gladly share my experience and advice, for there no sweeter words than "I told you so."

              Comment


              • #8
                DP,
                May I offer a bit of advise on the hob?

                From looking at the picture I see three things that won't help it cutting and can be improved on.
                One is there is too much thread that can cause rubbing so put more flutes in to reduce the amount of thread.

                Secondly make them deeper to clear chips and move back over the centreline so you get more rake and finally grind the front face with a Dremel to get a sharp edge, don't be frightened to undercut the front edge to hook the teeth, it's only cutting brass.

                Is this hob hardened or left as is ?

                This is a hob made from a Myford leadscrew, fluted with a ball nosed cutter, had some of the teeth backed off and then hardened.
                This hob has cut literally 100's of brass and bronze wheels with 40, 60, 72 and 90 tooth counts for Gert to sell on Ebay

                http://homepage.ntlworld.com/stevens...0indexer23.jpg

                No it's not backed off wrong it's a LH hob.

                .
                Last edited by John Stevenson; 09-11-2006, 05:13 AM.
                .

                Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                Comment


                • #9
                  Too bad on the gear, but hey, it's a learning process and so is "all good" right? I don't want to think about how many things I've had to do-over, usually because I over shot on the critical dimension that was the LAST operation to perform... <sigh>

                  Oh, and in case it wasn't clear, my crack was in reference to the "doing 90 mph" and alluding that a Harley couldn't manage that speed, so it must have been on a trailer. Yeah, I know the can, but just kidding around late at night...
                  Russ
                  Master Floor Sweeper

                  Comment


                  • #10
                    I don't want to think about how many things I've had to do-over, usually because I over shot on the critical dimension that was the LAST operation to perform...
                    I have this habit of becoming a bit lazy at moments like that and just cranking in a roughing cut with out measuring. I eyeball it. Then when the cut is done I measure and I don't know how many times it has come out exactly to the finish dimension. Then I have a dilemma. I can't do a finish cut to improve the finish without ruining the fit. I must decide whether to remake the part or use as is.
                    Free software for calculating bolt circles and similar: Click Here

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                    • #11
                      [[how many times it has come out exactly to the finish dimension.]] Yeah, don't you just love days like that?

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                      • #12
                        Funny, I saw the subject line and there were Lennon and McCartney in the back of my head singing, "I hobb'd a gear today, oh boy ..."
                        .
                        "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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                        • #13
                          The English Army had just won the war....

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                          • #14
                            Originally posted by John Stevenson
                            DP,
                            May I offer a bit of advise on the hob?

                            From looking at the picture I see three things that won't help it cutting and can be improved on.
                            One is there is too much thread that can cause rubbing so put more flutes in to reduce the amount of thread.

                            Secondly make them deeper to clear chips and move back over the centreline so you get more rake and finally grind the front face with a Dremel to get a sharp edge, don't be frightened to undercut the front edge to hook the teeth, it's only cutting brass.

                            Is this hob hardened or left as is ?

                            .
                            Thanks, John - these are exactly the improvements I'd envisioned. The rubbing was the big issue and was the first change I was going to make. The cutter produced mostly dust while working.

                            I didn't harden this one because I wanted it to remain workable as I sorted it out. It's also too long as it happens and a waste of the worm gear resource, so I'll be making the next one much shorter. Then I have to figure out how I came out with one extra tooth. I was using a 48t gear as an index and I'll bet I failed to skip one somewhere. I've decided to go with a 48t gear for the next grind and use an 8 point edge marked cylindrical dial rather than a 4 point radial dial.

                            There is a problem of access to the worm gear on the lathe which is located behind a full length metal swarf shield. Keeping the dial shaft horizontal will allow me to leave that shield in place but a radial dial in such a configuration would be difficult to watch from a normal operator's position, hence the horizontal shaft and cylindrical dial.

                            I learned quite a lot on this little project and not a little bit of that came from this forum.

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                            • #15
                              Originally posted by BadDog
                              Oh, and in case it wasn't clear, my crack was in reference to the "doing 90 mph" and alluding that a Harley couldn't manage that speed, so it must have been on a trailer. Yeah, I know the can, but just kidding around late at night...
                              Amazing that you can get 90 out of one of these.
                              It's a wonder it doesn't blow the flame out.

                              Anyway to get back to hobbing.
                              Blank size also plays a big part in getting the right tooth form.
                              Tooth parts are usually worked out on DP but thread gears have to follow TPI and not DP.
                              If you have an 8tpi thread that's the same as the Circular pitch and if converted works out to 8 x Pi = 25.13 DP

                              The OD for a worm gear which is different from a spur gear is the number of teeth plus THREE divided by the DP so a 24 worm needs to be
                              24 + 3 = 27 / 25.13 = 1.074"

                              a 48 will be 2.030"

                              .
                              .

                              Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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