Carrige ways not level with bed.
Close
Login to Your Account
Results 1 to 7 of 7
  1. #1
    Join Date
    Jan 2012
    Location
    Savannah, Georgia, USA
    Posts
    1,649
    Post Thanks / Like
    Likes (Given)
    2623
    Likes (Received)
    628

    Default Carrige ways not level with bed.

    I am scraping the carriage and compound of a rockwell 14 lathe. Per MachineToolRec. I leveled bed and then found the carriage ways where not even close. Measuring with a depth mic from carriage ways to flat on bed the carriage is high .015" in the rear. I assumed that I had much more wear on front v but when I took carriage off it appears to have about equal wear on front v and rear flat about .002 measuring from unworn part of bearing that overhung the bed. Has anyone ever seen this? Could this be just poor manufacturing? I will next take down tail stock to see if that matches slant. Could this hurt operation? I was not planning on scraping bed yet as I don't have camel back large enough and there does not appear to have much wear.

    Am I missing something?

  2. #2
    Join Date
    Oct 2010
    Country
    UNITED STATES
    State/Province
    Oregon
    Posts
    5,001
    Post Thanks / Like
    Likes (Given)
    4157
    Likes (Received)
    1806

    Default

    It's quite important that the cross slide travel be perpendicular to the carriage travel. Unless you are doing something very unusual, it's not at all important for the cross slide axis to be level or even for the cross slide ways to be in a plane parallel to the plane of the bed ways. Consider slant bed lathes. So this is probably not a functional issue.

    What's functionally important about leveling is that things are made uniform, that the ways have no twist.

    Leveling can also be quite useful when reconditioning a machine, allowing the use of gravity as a datum. But that's not an operational consideration for most machines.

    Added in edit: The two inverted Vs on my machine (one for carriage, other for tailstock) are not the same height off the bed. But I lay a level across them when leveling the machine, regardless. It just doesn't matter what the absolute orientation of the bed (or cross slide!) is for functional leveling.

  3. #3
    Join Date
    Jul 2005
    Location
    Cottage Grove, MN 55016
    Posts
    7,567
    Post Thanks / Like
    Likes (Given)
    4085
    Likes (Received)
    4518

    Default

    The machine usually wears that way as the dirt is on that side. It could have been screwed up from the factory as Rockwell may have made a mistake from new.

    When the saddle is flipped over can you see any ridges that still show the original ways ..sometimes the flat hangs over the bed ways and it is original see if you can depth mike that...look for a ridge on the V way too. A super easy way is to put the saddle back on the bed on the tail stock end of the bed , just in case the bed isn't worn up by the chuck and compounding the error. But put the saddle on the bed and take a mag base and sit it to the front side of the bed under the rack area and under the saddle Then put the indicator on the area where the carriage bolts on. That surface has to be parallel to the bed so the shafts when going though the carriage don't bind up. I would trust that before trusting the depth mike to the bed. Check that and let us know what you have. Rich

  4. #4
    Join Date
    Jan 2012
    Location
    Savannah, Georgia, USA
    Posts
    1,649
    Post Thanks / Like
    Likes (Given)
    2623
    Likes (Received)
    628

    Default

    Richard, I took that measurement from under the carriage on the front, and I am close side to side, less than ,001. However, front to back is where the large difference is. I searched for the wear pattern as you said and found about .002 of wear compared to the unworn ridge. And the wear was fairly even on the front v and the rear flat. So I guess the carriage sloping front to rear was built into the lathe(low in the front).

  5. #5
    Join Date
    Mar 2005
    Location
    near Rockhampton, Queensland, Australia
    Posts
    5,503
    Post Thanks / Like
    Likes (Given)
    439
    Likes (Received)
    2048

    Default

    The carriage or cross slide does not have to be level with the bed... Think of a slant bed lathe...

    Of course if it supposed to be in the same plane and it isn't, you potentially run into alignment concerns with the leadscrew and there is the mesh of cross slide power feed gears and the rack gears... etc etc etc...

  6. Likes tdmidget liked this post
  7. #6
    Join Date
    Jul 2005
    Location
    Cottage Grove, MN 55016
    Posts
    7,567
    Post Thanks / Like
    Likes (Given)
    4085
    Likes (Received)
    4518

    Default

    I think he is talking left to right of the saddle flats. Not the bed being level like a slant bed lathe. Like I said the bottom of the saddle needs to be parallel to the bed for alignment of the carriage feed screws and if you keep the cross-slide and compound slides square or top and bottoms parallel the top of saddle has to be parallel. If not when you put a boring bar in tool holder it will not parallel to the bed. Or if you drill a hole from the tool holder the hole will get eggs shaped. I always make the front high about .0002 to .0005" high so as it wears it gets better. If the saddle is worn to much you will need to install a wear-strip to bring it back as RC mentioned. Rich

  8. #7
    Join Date
    Jun 2006
    Location
    South Africa
    Posts
    1
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default

    Hi I saw your post about reconditioning , we have done a couple of our machines and had some good success.

    the beds looked in good condition but the saddle had wear on the surfaces.

    we machined all the surfaces / flat and angles on our milling machine setting up to the machined faces.
    We then drilled some holes +- 4 mm deep at 20 mm intervals into the faces we had machined.
    we then cleaned the saddle with degreaser and then benzine to try and eliminate any oil
    We then got 2 mm thick high lube Vesconite ( ertalite) and cut it into strips to suit where had machined
    We then got a high strength 2 part epoxy glue and spread it on the saddle and on the strips
    We put a thin layer of grease on the bed in allow for glue that may spill
    We then placed the saddle in position and put weights on it leaving the glue to set for 24 hours
    we then checked the clearances between the rack and pinion and the feed and lead screw and spaced them to suit the drive system in the saddle.
    The saddle was positioned by adjusting the holding down blocks.

    The machine runs and machine very well and we have eliminated most of the problems.

    This worked for us as our beds were still in good condition.

    We didn't have to do any scraping or adjusting as the Vesconite has excellent wear and very low friction.

    It worked for us on two machines maybe some else could give it a try



    ........post edited by moderator.........
    Last edited by CBlair; 06-27-2014 at 08:32 AM. Reason: remove OT posting


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
  •