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  1. #16
    Join Date
    Oct 2008
    Location
    Cairns, Q
    Posts
    666

    Default

    I don't have a DRO, and would like one eventually, but of the various accessories I do have, it is the H/V rotary table with the dividing plates which wins on all points.

    Some of the jobs which it has done would have been difficult or more complex without it (or in some cases a dividing head) were:
    Making additional lathe change gears, including a 47T/37T compound gear to allow the lathe to cut metric threads
    Drilling bolt hole circles in new back plates for the chuck mounting bolts (easy if you already have a DRO though)
    Drilling tommy bar holes in a 5MT ER32 chuck to stop it rotating while the nut is being tightened
    Making a 50 mm diameter four lobed dog clutch for the Blanchard lathe
    Making the actuating plate for the half nuts on the Blanchard lathe. This has two opposite short curved slots on
    different centres from the centre pivot. Pins on the half nuts, which project through vertical
    slots in the saddle and through into the curved slots in the actuating plate, are forced to move vertically as the
    plate is rotated, opening and closing the half nuts.
    Making hexagons on custom brass pipe fittings and adapters, and custom bolts and nuts to match missing ones on old cars
    and machinery (before I got ER32 collet blocks)
    Making centres for bicycle sprockets to use on a slow speed light load application - much cheaper than buying industrial
    sprockets and chains
    Graduating collars for feed screws
    Etc
    Etc

    Frank.

  2. #17
    Join Date
    Sep 2009
    Location
    Sydney
    Posts
    666

    Default

    I’m warming to the idea of a Rotary Table with dividing plates. I’ll mostly be doing rotary work and occasionally having a crack at gears, so it seems like the right tool for the job.

    Seems to be a bit more expensive than a Dividing Head but with a 90:1 worm gear ratio I’m sure I could do some custom dividing plates for things like a metric transposing gear for my lathe (127 tooth).

  3. #18
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    Quote Originally Posted by neevo View Post
    ... So I’m thinking a Dividing Head might be a good investment ...I’ve been eyeing up a Dividing Head on the auction site as it looks like it flips up 90 degrees and so would give me a rotary table solution too.
    A dividing head is not 100% interchangable with a rotary table -

    Quote Originally Posted by Michael G View Post
    A rotary table and a dividing head are not quite the same thing. The R/T has lower gearing so that you can mill circular arcs. A dividing head on the other hand is made for indexing, typically being locked while the machining goes on. (you can (and do) mill with a dividing head moving when doing spiral milling, but it is usually driven from the X feed).

    Quote Originally Posted by neevo View Post
    ... I could do some custom dividing plates for things like a metric transposing gear for my lathe (127 tooth).
    You won't get 127T from a semi-universal dividing head or rotary table as it is one of those awkward prime numbers that they can not cope with. You either need a special dividing plate or a dividing head capable of differential indexing (big $$$)

    Michael

  4. #19
    Join Date
    Sep 2009
    Location
    Sydney
    Posts
    666

    Default What would you choose? Milling machine mods

    Ah fair enough on the 127 gear. Clearly there expensive for that reason.

    I’m pretty sold on the Rotary Table but the DRO is looking like a solid next upgrade. Will have to save my pennies.

    Looking at bolt hole functions on DRO’s, is that something that could drive the coordinates of a 127 hole pattern?

  5. #20
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    Some drops can do linear grids of holes, but it's really simple to just make a spreadsheet of the coordinates and hit them manually

  6. #21
    Join Date
    Sep 2009
    Location
    Sydney
    Posts
    666

    Default

    Quote Originally Posted by caskwarrior View Post
    Some drops can do linear grids of holes, but it's really simple to just make a spreadsheet of the coordinates and hit them manually
    Do you mean list the degrees on the rotary table and just approximate them by eye?

    2.83
    5.66
    8.50
    11.34
    Etc

  7. #22
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    4,779

    Default

    I don't think that there would be many DRO's that would allow you to enter 127 for the number of holes..

    I just looked at an app on my phone but it only allows up to 35.

    Manually entering on a RT would be hit and miss. Don't forget you would need to convert from degree decimal to mins and sec of arc. Doing that 127 times would be a pretty good feat, probably not impossible though.

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  8. #23
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    I had a cheap Chinese DRO that would allow up to 250 holes, my Newall does not have a limit but has trouble finding the next point if you put heaps of holes on a tiny PCD.

    What I meant before was some Gros can lay out a grid of hole s, say you wanted a 20 * 20 grid with 25mm spacing it would just take you from one to the next.

  9. #24
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

    Default

    For general mill work I would go for the DRO, you don't need an expensive one, even a 2 axis DRO will improve your productivity dramatically.
    The DRO can replace one typical use of the rotary table, which is to drill bolt circles.

    I've been using a cheap DRO from AliExpress on my lathe (replacement for the original Easson) for the last 3 or 4 years without problems.
    There are old threads on here about low cost DROs.

  10. #25
    Join Date
    Oct 2008
    Location
    Cairns, Q
    Posts
    666

    Default

    neevo,

    Here is the table of available divisions for the Vertex HV6 rotary table with the standard dividing plates: from memory I think the HV8 and HV10 have a few less gaps in the available divisions. Remember though that as the size goes up so does the weight. Even the HV6 with a 6" 4 jaw chuck attached is surprisingly heavy.

    Vertex Divisions.jpg

    Simon,

    Quote: Manually entering on a RT would be hit and miss. Don't forget you would need to convert from degree decimal to mins and sec of arc. Doing that 127 times
    would be a pretty good feat, probably not impossible though.

    I had to do this with one of my 37/47 metric conversion gears which could not be cut using the dividing plates - think it was the 47T one. As you suggest, it is very slow and very prone to errors. It did work first time though, and the gear runs smoothly and quietly with the original change gears, so it is feasible at least with low speed lightly loaded gears. I would not have liked doing it 127 times though - 47 was quite enough thank you!

    Frank.

  11. #26
    Join Date
    Oct 2008
    Location
    Cairns, Q
    Posts
    666

    Default

    Quote Originally Posted by neevo View Post
    Do you mean list the degrees on the rotary table and just approximate them by eye?

    2.83
    5.66
    8.50
    11.34
    Etc
    neevo,

    Sorry, I missed this post earlier. No, you don't have to approximate them by eye, and yes, Simon is correct: you do have to work in degrees, minutes and seconds of arc. There is a vernier scale on the wheel which rotates the table which is graduated in, I think without checking, ten seconds of arc divisions. These graduations are widely spaced, so it is possible to split them into quarters by eye and get close to an average of about two and a half seconds of arc, a very small error for something like a low speed lightly loaded lathe change gear. It is a slow and tedious job, but quite feasible.

    Frank.

  12. #27
    Join Date
    Sep 2009
    Location
    Sydney
    Posts
    666

    Default

    I did a bit more reading. I didn’t realise the level of accuracy you can get to on a Rotary Table.

    127 looks easy if/once you get the coordinates for 127 holes!

  13. #28
    Join Date
    Sep 2009
    Location
    Sydney
    Posts
    666

    Default

    Rotary Table has been acquired. Already investigating 3 axis DRO’s What would you choose? Milling machine mods

  14. #29
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
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    4,887

    Default

    What size table did you purchase?

  15. #30
    Join Date
    Sep 2009
    Location
    Sydney
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    Default What would you choose? Milling machine mods

    Quote Originally Posted by pipeclay View Post
    What size table did you purchase?
    I bought a 6”. I only have an old Taiwanese Hafco Round Column Mill/Drill so thought that was a suitable size.


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