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Anyone made thier own rotary table?

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  • Anyone made thier own rotary table?

    Due to the enormous generosity of one of the board members, I've got a stack of old Home Shop Machinist magazines that i've been paging through. I've found plans in the January/February 2001 magazine for "the poor mans rotary table". I've been kicking around the idea of trying to make my own since i have a worm gear and worm plus some plate and pipe and whatnot lying around.

    I was wondering if anyone here has attempted this project and happened to have any tips to pass along.

    I'm thinking about modifying some aspects of his design, among the changes are a clamp to hold the spindle in place and some added material on "plate 0" to better handle lateral loads with out bending or damaging the spindle. Is a lock for the spindle really neccessary though with a worm gear drive? I was worried about backlash in the gears and thought a clamp might be a good thing to have to help elminate this potential problem.

    Also, with out a bull gear on my lathe, do you guys have any suggestions for accurately marking degree graduations on the surface?

    What other features should i have/ be aware of?



    Oh and he says to cut out the six inch (or 8") diameter circles from 1/4" plate with a torch, clean them up with a grinder then true them up on the lathe. How do i hold a disk thats a little over 6" by .25" thick in the lathe so i can turn the outside diameter down to a true, circuluar 6"?

    Should i be finding the center as best i can first, then drilling a hole so i can fit it on some kind of a mandrel and then turn it round?



    Thanks guys - any advice, whether you've built one or not, is appreciated!

  • #2
    A few years ago I built a 4" R/T using plans and the worm & wheel supplied by Hemingway Kits. Due to the enormous cost of mailing the complete kit of materials to Canada, I opted for just the items described above.

    To inscibe the degree marks I used the actual unit, having completed the pinion wheel degree marks in the lathe (using a gear in the headstock). I set the R/T up on the mill (Taig) and carefully scribed the marks. I got the actual numbers inscribed by a Sports/Jewelry store as I wasn't confident enough at the time to stamp them myself (still aren't!).

    Geoff

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    • #3
      It has been quite a while since I looked at that article. If all the plates have holes in the finished articles, drilling the hole first for fixturing is probably the best approach.

      The spindle lock, or some other means of locking the table is a must as when using the table with an end mill, it must be secured to prevent it from rattling around. There is nothing wrong with modifying the table to suit your preferences or materials at hand. The divisions can be done with the completed table itself.

      The worm gear should be 40, 60 or 90 teeth for best indexing, 90 being preferable. Assuming a single pitch worm that is.
      Jim H.

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      • #4
        The extremely talented Ishimura did one. If you haven't been to his site you're in for a surprise. He does absolutely amazing work with a 9x20 and mill/drill. The rotory table is #23.

        Enjoy!

        Marc -
        The early bird may get the worm but the second mouse gets the cheese.

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        • #5
          I've got one on the back burner. Not finished yet. It's due for completion when my mill is done. This is what I have so far. It's a four inch table. It's actually a little farther along than this pic but not much. It will be CNC. This was all done on my SB9.

          Last edited by Evan; 03-08-2007, 03:18 AM.
          Free software for calculating bolt circles and similar: Click Here

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          • #6
            Did one some years ago when first getting into this hobby as it was then doing bits for racing bikes.
            RT's were hard to find, especially small ones as this was prior to CNC and they were in everyday use.

            Model Engineering Services at Chesterfield who also made the Dore Westbury miller as a kit listed three models, a standard 5" and 6" and a model with no table but had a threaded spindle the same as a Myford to accept it's chucks and face plate.

            The kit consisted of the main iron castings with tee slots cast in, a worm cut on a blank shaft and a machine cut spur gear, not a worm.
            I think the reason it has a spur gear and not a worm was the fact they cut gears for the Dore Westbury and it could be done on the same equipment and tooling. One advantage of this method was the helix angle of the worm meant that the shaft pointed downwards and so made the handwheel below the table surface.

            I bought, for a reasonable sum, one of the small 5" models which worked out to be a nice size, pity you don't see this size nowadays.
            MES's main claim to fame was their kits could be machined on a Myford lathe and bench drill, anything requiring larger machining was already done, in the case of the RT's this didn't apply but the Dore miller had all the tables machines and just required finishing operations.

            Kept this a few years and it did good service, imports have basically killed this market with many kits costing as much or even more than a finished article and lacking hardened parts in many cases.

            .
            .

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



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            • #7
              Hey thanks for the encouragement guys! I think i'd like to give this a shot. Probably won't come out looking nice or working real great but a good expierence nonetheless ... hopefully...

              What do you think i should use to clamp down the table. I had envisioned a collar around the center shaft that could be tightened down by a lever, kinda like whats on my milling machine to clamp down the head but that doesnt provide a whole lot of torque - especially with a six or eight inch table. What other options do i have?

              I could put some setscrews to lock it up around the circumfrence, but then i have to worry about the set screws marring the surface...

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              • #8
                The table needs to be as ridgid as possible and requires a bearing or bearng surface as high up as possible.
                Many commercial designs support the table on a steep taper just under the table
                This acts as a bearing, increases surface area and being conical retains it's self centering action.

                At the bottom it needs either a angular contact bearing or a plate type thrust bearing to set preload.


                .
                .

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



                Comment


                • #9
                  "At the bottom it needs either a angular contact bearing or a plate type thrust bearing to set preload."

                  A little more detail please ... i think i know what your talking about, but maybe you could walk me through setting the preload on it - the plans have essentially a bushing for the shaft to ride in and then a thrust bearing for that the gear rides up against.


                  For the top, since i don't think i can pull off the cone, i was planning on having a flat "ring" around the top that would act as a bearing surface for the table top (as the plan calls for) but then i'd also have a collar that extends down into the round body of the table. The inner diameter of the table body and the outer diameter of the collar would be polished to a nice fit and dabbed with a little grease. What do you think?


                  Also, what should i do to keep the whole assembly together? The plans have some set screws that hold the gear to the shaft and therefore the table to the body. To remove you have to stick an allen wrench inside the body and fish around for the set screws. I was thinking a recessed pocket on the underside with a retaining ring or little bolt and washer to to keep the whole thing together.


                  Thanks again guys for walking me through this - i appreciate your time

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                  • #10
                    So my worm gear worm set-up makes a 1:40 ratio. I'm thinking that i will mark off 40 lines on my table itself so i'll have it graduated from 0* to 360* by increments of 9*. Then the handwheel will be divided into 18 tick marks so i can look at my table, notice that its, say about 2/3 from 54*, then look to my handwheel to see that its 12 tick marks away, which would equate to 6* beyond 54*. Whaddya think? I'd just divide my table up into 1* increments or even 3* but i don't have a gear big enough to index them accurately.

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                    • #11
                      I am working on a small indexer. Got this idea from one that Sherline makes.



                      The gear is attached to the spindle of the indexer and moves the rack as it rotates. By measuring the total distance the rack moves for one turn of the spindle you can divide that distance by whatever division you want to make. There is some error, but for my use it will work.

                      I do have a question. The racks teeth come out to 20 per inch. The gears teeth seem to mesh real well it. But it also of course matches the threads on that piece of 20 tpi allthread.

                      What pitch might that gear be? I would like to find a metal one. The teeth are very pointed on it and it rolls very smoothly on the rack.
                      Gene

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                      • #12
                        with the price of metal so high at the moment I wonder how much this home made one would cost in materials alone? as John said they are very reasonable to buy at the moment I bought a brand new vertex 6 inch for seventy five pounds and paid another twenty five plus shipping for the indexing discs.Alistair
                        Please excuse my typing as I have a form of parkinsons disease

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                        • #13
                          well so far i've paid a total of $1.09 for an elevator bolt...

                          The plate i got from a junkyard awhile ago for $6 (this is a 8" wide by 6' long piece, plenty to make my table)

                          The shaft material is 5/8" and 3/4" hot rolled - two six foot lengths at $2 and $4, respectively.

                          Bearings - jacked from an old gearbox that also housed the worm and worm gear. Cost of gearbox: free (had two bent shafts and they guy was gettin rid of it)

                          so not too bad cost wise... we'll see what other costs i run into and how crumby it turns out

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                          • #14
                            I agree with the "can't afford to build it" crowd. I got a very nice Troyke 12" V/H that was pretty filthy but seems largely unused for $100. An 8" Horiz "Manex" (Taiwan import methinks) that's pretty darn nice for $20, and a 6" Hartford Spacer/Index for another $20. Other than some cosmetic skint paint issues, a bit of "patina", and a few drill hits in the Manex table, they are "as new". And that's in the South West Machine Tool Desert! Even if parts are free, it's just not worth it unless you just want the project...
                            Russ
                            Master Floor Sweeper

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                            • #15
                              Well since this Fasttrack we are talking about, he is on the "younger side" of the posters here, so if he wants to focus that youthful energy on a task, I ain't talking him out of it!

                              He will all too soon be "bogged down" with the burdens of ol'age!
                              Today I will gladly share my experience and advice, for there no sweeter words than "I told you so."

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