rotary table options on bridge mill
Close
Login to Your Account
Likes Likes:  0
Results 1 to 7 of 7
  1. #1
    Join Date
    Nov 2014
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    336
    Post Thanks / Like
    Likes (Given)
    43
    Likes (Received)
    112

    Default rotary table options on bridge mill

    I am trying to make our bridge mill more versatile. We have seen a few similar parts come through to quote that are disk shaped and need minimal OD work to them. Like a finishing pass or a funny angle chamfer. Clearly a VTL or VBM would be the best option. But I am thinking we can get close with a big rotary table.
    We have 52ish Y travel and 58” between columns. The parts we are seeing are 54 to 56” diameter. So doable but with a second setup.
    I found some tables 42” to 50” diam on EBay. Standard worm driven, maybe 4-5rpm max.
    Should I stick with that and use a rotary tool in the mill?
    Or is there a type table with a different drive that could spin up a few hundred rpm? It would be cool to hold a lathe tool in the locked spindle?
    General thoughts of making a bridgemill more versatile are welcome.
    Thanks

  2. #2
    Join Date
    May 2017
    Country
    UNITED STATES
    State/Province
    Minnesota
    Posts
    1,738
    Post Thanks / Like
    Likes (Given)
    2248
    Likes (Received)
    1151

    Default

    I haven't seen any aftermarket rotary tables with turning capability, though there are several machines with them built in. Those machines also have special spindle locks that your mill won't have. My gut says just interpolate around the part with endmills. A rotary is for getting access to different sides of the part.

  3. #3
    Join Date
    Nov 2014
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    336
    Post Thanks / Like
    Likes (Given)
    43
    Likes (Received)
    112

    Default

    Neither have I, but it seems like a good idea in some cases. I’ve seen smallish CNC VTL’s like 12-18”. Seems like you could use a VMC in just that way if it had a spindle lock and a sturdy high speed rotary table.
    I made a manual spindle lock for when I was doing a poor mans right angle drive. I had a few 3/8 right angle tapped holes so I made some drill jig tool holders. Used the machine to position the jig and just hand drilled through. Sounds hokey but worked fine. The mental gymnastics of programming right angle tap cycle for a few simple holes was too much for me. Let alone a helical toolpath. 5 min of manual labor was much more appealing.

    I think a big traditional rotary table would be really useful, but if I could have one that would spin up to a reasonable turning rpm I think that would be slick! I would give up the “accurate positioning” feature for that. Very rarely is there not a feature I could pick up on the part for position after rotating.

    The one I am looking at is a Troyke NC-42. Says precious spindle bearings and turcite supports. Guessing that’s out at the table perimeter? Wonder if vtls have support under the table perifery or its just one big cast iron casting on bearings like a lathe. I’d be willing the bet the Tryke bearings wouldn’t know the difference between 5rpm and 300, but the turcite is another story.

  4. #4
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    12,434
    Post Thanks / Like
    Likes (Given)
    2847
    Likes (Received)
    8644

    Default

    Quote Originally Posted by vmipacman View Post
    Neither have I, but it seems like a good idea in some cases. I’ve seen smallish CNC VTL’s like 12-18”. Seems like you could use a VMC in just that way if it had a spindle lock and a sturdy high speed rotary table.
    I made a manual spindle lock for when I was doing a poor mans right angle drive. I had a few 3/8 right angle tapped holes so I made some drill jig tool holders. Used the machine to position the jig and just hand drilled through. Sounds hokey but worked fine. The mental gymnastics of programming right angle tap cycle for a few simple holes was too much for me. Let alone a helical toolpath. 5 min of manual labor was much more appealing.

    I think a big traditional rotary table would be really useful, but if I could have one that would spin up to a reasonable turning rpm I think that would be slick! I would give up the “accurate positioning” feature for that. Very rarely is there not a feature I could pick up on the part for position after rotating.

    The one I am looking at is a Troyke NC-42. Says precious spindle bearings and turcite supports. Guessing that’s out at the table perimeter? Wonder if vtls have support under the table perifery or its just one big cast iron casting on bearings like a lathe. I’d be willing the bet the Tryke bearings wouldn’t know the difference between 5rpm and 300, but the turcite is another story.
    If you were willing to go mad scientist (engineer), you could add periphery lube lines to the bearing with pumped lubrication, you might get reasonable life from it at speed. But you'd want to mod a used RT so you didn't void the warranty.

    You'd also need to upgrade the motor, and possibly the worm too. I'd be tempted to build my own if I really wanted good RPM on a large rotary table, what with the required mods to an existing RT.

    What's the maximum weight of workpieces you'd be cutting?

  5. #5
    Join Date
    Jan 2005
    Location
    The Netherlands
    Posts
    6,592
    Post Thanks / Like
    Likes (Given)
    356
    Likes (Received)
    1881

    Default

    Nearby is a compagnie with big machines They did just the opposite
    Added a 35kw milling head to their 14.5 mtr 145kw VTL as milling is much faster as turning

    Peter
    *

  6. #6
    Join Date
    Nov 2014
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    336
    Post Thanks / Like
    Likes (Given)
    43
    Likes (Received)
    112

    Default

    I was tempted to suggest “rolling my own” but wanted to steer clear of the buy vs build debates. I’ve been on both sides of that.
    The used RT I found would be a good candidate, but I would ditch the worm to get any reasonable speed I think. All doable, just need the right project to justify it.
    The heaviest thing so far is a 2” thk, 57” diameter plate. So like 1500lbs. The lightest thing is a 54” diam 3/16” thk aluminum plate with a simple 5deg(maybe 10) bevel down to a knife edge on the perimeter. That would be a pain to mill.
    I’d like to get a VTL, but as a poor mans VTL I think a Double column mill with a spinny table would work great! The column is certainly more rigid than a vtl column, so if I had to go one way or the other, I’d start with a VMC.

  7. #7
    Join Date
    Jan 2014
    Country
    UNITED STATES
    State/Province
    Washington
    Posts
    5,569
    Post Thanks / Like
    Likes (Given)
    1006
    Likes (Received)
    3129

    Default

    Since a rotary table is used at low speed, the platter is typically supported with oiled metal to metal or metal to Turcite surfaces and guided by a plain bearing, tapered roller, or angular contact bearings. It won't tolerate speeds running more than ~100SFM.

    High speed tables like on a "newish" VTL are typically supported and guided by crossed roller bearings. Really large VTLs probably use a hydrodynamic bearing but I've never worked on one so not sure.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •