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  • rotary tables

    What can anyone tell me about the 6,8,10" rotary tables like Grizzly sells. MSC and J&L also list them. $200-$400 approx. Would Put it on a Smithy 3in1 machine. Any ideas?
    Thanks, Todd

  • #2
    I don't know anything about those particular rotary tables, but I would encourage you to get the biggest one that's feasible. You need space to fit clamps and such, and the bigger the diameter the better. The table does have to be in proportion to your milling machine, of course, and it's also nice if you can install it without a crane, so don't just automatically get "the biggest one."

    You may also want to look at horizontal/vertical models, which can somewhat take the place of a dividing head, especially if you can rig up a good way to mount a chuck on it.
    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    There are lots of people who mistake their imagination for their memory. - Josh Billings
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.
    Don't own anything you have to feed or paint. - Hood River Blackie

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    • #3
      Thanks, SGW. I meant to say in my post that I was looking at horizontal/vertical units. Anyone else?

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      • #4
        I got a horiz/vert job from Enco. 6" dia fits nice on my Mill/drill table. Works good, no complaints, except I had to make some T-nuts for the little slots on the table. Probably coulda bought em, but didn't feel like waiting.

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        • #5
          Tslot,
          I got one of what Enco calls the 'Super Spacers' a while back. 6" chuck, 8" face plate. It does everything I've asked of it.
          I don't know the Smithy tool you mention. It is just barely a fit on the 7" x 30" knee mill I have.

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          • #6
            What's the difference between a rotary table and a super spacer?

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            • #7
              The Super Spacers have index plates for simple indexing.

              A Rotary Table or Semi-Universal Dividing Head is worm drive and cannot do every division directly.

              A Universal Dividing Head can do all divisions (even & odd) to the max # it is designed for

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              • #8
                Super spcer vs. rotary table or index head:

                The super spacers have a set of plates with holes in them, so you can index to whatever increment the hole spacing is. For a lot of work that's perfectly adequate. You need to index 2, 4, and 6 a whole lot more than you'll ever need to index 17 or 43, for instance.

                An dividing head throws a worm drive into the equation (typically 40:1 ratio), so one turn of the crank gives you 1/40 a rotation. If you put, say, a 24-hole plate on that, moving one hole on the plate gives you 1/(40*24), or 1/960 division. You get a lot more combinations out of it. A dividing head oftentimes can pivot up/down, which gives more flexibility in the kinds of work it can handle.

                A rotary table has a worm drive (typically 90:1) and a dial graduated in degrees and minutes (and seconds on really good ones). You can do any number of divisions you want; you just have to figure out the number of degrees, minutes, and seconds for each position. For say, 6 divisions, it's pretty easy: 60, 120, 180, 240, 300, 360. For 7 divisions...well, you work it out. :-) But it can be done, especially these days with a computer. You're limited by the accuracy to which you can set the dial, but for any normal work in a home shop it will be plenty close enough.

                Sometimes index plates are available to fit on a rotary table, too; then it's about the same as a dividing head, although because the wormgear ratio is different the settings will be different.


                [This message has been edited by SGW (edited 09-05-2001).]

                [This message has been edited by SGW (edited 09-05-2001).]
                ----------
                Try to make a living, not a killing. -- Utah Phillips
                Don't believe everything you know. -- Bumper sticker
                Everybody is ignorant, only on different subjects. -- Will Rogers
                There are lots of people who mistake their imagination for their memory. - Josh Billings
                Law of Logical Argument - Anything is possible if you don't know what you are talking about.
                Don't own anything you have to feed or paint. - Hood River Blackie

                Comment


                • #9
                  You can always put a larger top on a small rotary table, 6" table with a round 1 1/4" thick aluminum thats 12" in diameter, then put your own hold down holes where you want them.

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                  • #10
                    A note on the Super Spacer;
                    I don't know the ratio of the worm drive, but I have been able to use it as a rotary table, meaning I can start a cut at some specified radius from center and turn the work piece to get a large radius cut.
                    And, yes, it does have several plates to positively index at various degree specings.

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                    • #11
                      Buying a larger table is better, remember the table not only has to support the work but also has to hold the clamps. I have an 8 inch phase2(enco) table and have a large aluminum plate mounted on top to effectively provide a 16inch table. This works pretty well and is lighter and costs much less than a "real" 16inch rotary table would.
                      Cheers Keith

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                      • #12
                        Thanks for the information guys. I think I know what I need now. Not to clear on the ratio difference between rt and indexing plates but I guess I can figure it out when I see one

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                        • #13
                          The ratio difference between a rotary table and an indexing head....

                          Nothing magic about it. A typical indexing head has a 40:1 wormgear in it and a typical rotary table has a 90:1 wormgear in it. That means, if you want to do 7 divisions, for example, you'll need to turn the crank of the indexing head 40/7, or 5 5/7 turns, or turn the crank of the rotary table 90/7, or 12 6/7 turns.
                          Therefore, on the indexing head you'll need a circle of holes on an index plate that is a multiple of 7 so you can do the 5/7 turn. If the rotary table has povision for indexing plates, you'll also need one with a circle of holes that is a multiple of 7 so you can do the 6/7 turn.
                          Or, more likely on the rotary table, you'd figure out that 1/7 turn is 51 degrees, 26 minutes (to the nearest minute), 2/7 is 102 degrees, 51 minutes, and so on, for all 7 divisions, and do the dividing by setting the degrees and minutes for each 1/7 rotation.

                          Does that clarify anything?
                          ----------
                          Try to make a living, not a killing. -- Utah Phillips
                          Don't believe everything you know. -- Bumper sticker
                          Everybody is ignorant, only on different subjects. -- Will Rogers
                          There are lots of people who mistake their imagination for their memory. - Josh Billings
                          Law of Logical Argument - Anything is possible if you don't know what you are talking about.
                          Don't own anything you have to feed or paint. - Hood River Blackie

                          Comment


                          • #14
                            Thanks SGW, that clears it up. Think I'll opt for the rotary table. Seems to be the most versatile. Don't know how accurately you can set the dials, but it's probably close enough.

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                            • #15
                              T-Slot,

                              If the table you end up buying does not have division plates available you should consider a different one that does. Making new divison plates are not that difficult if you use the draftsman's "magic division strip". Of course, you could do the divisions with the "magic division strip" taped to the rotary table as well.

                              The whole point to a rotary table is to produce an accurately divided workpiece. You can do as SGW suggests, but adding all the degrees, minutes, seconds (*, ', ")up to index a prime number division (say, 67 teeth for a gear = 66 possible math errors) is going to drive you nuts. And, in all likely hood, ruin the work from from a simple error.

                              Even though I am a Medium-Crusty olde Fart with Bifocal disease I still get pissed when I make a boo-boo on something with a lot of work in it already.

                              Brown & Sharpe had a good point, K.I.S.S.

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