Announcement

Collapse
No announcement yet.

What Do You Do When The OLD GIRL STARTS TO SAG

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • What Do You Do When The OLD GIRL STARTS TO SAG

    After responding to a recent post where someone asked why the lathe cut a slight taper on one end of a short piece of work, I started thinking why my lathe is showing signs of the same thing.
    I always thought it was because the bed ways are worn more right in front of the chuck where most of your work is done. However after checking the bed with a level I noticed that the center of the bed has started to sag over the years. In the past I have heard a few Clausing 5900 owners comment that "they made a good machine but they should have beefed up the bed a little more" Now I see why.
    I don't think there is really much I can do about it other than drill a hole in the center of the chip pan and post the center......... out of the question, however I'm open to all suggestions. The bed is level from front to back. I also have the base pads setting on some heavy pieces of hard rubber cow mats. Perhaps I should have just set the machine on the floor but I doubt that has anything to do with the sag. The reason I put the rubber mats under the base is to absorb any vibration. Before I found the 5900 I had a small 4900 series that sat on the floor on it's adjustable pads and it transmitted vibration throughout the work. Everything I turned had a slight herringbone pattern to it due to vibration.

    JL..................





  • #2
    Sorry dude, it's bad enough when it happens to the wife/girl friend/mistress/hooker with a weekly arrangement but to a lathe, that's unthinkable. There's nothing for it but to take it to the scrapper and put it out of it's misery.
    The shortest distance between two points is a circle of infinite diameter.

    Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

    Southwestern Ontario. Canada

    Comment


    • #3
      That's an easy fix - just get a push-up bra for it from Victoria's Secret.

      Comment


      • #4
        or implants maybe
        Ernie (VE7ERN)

        May the wind be always at your back

        Comment


        • #5
          So, does it really just sag from it's own weight / inadequate design, or has it moved because it wasn't properly stress relieved before final machining? If it's the later - well it's easy. You merely need to strip it down to the bare bed, send it out for stress relieving, send it out for way grinding, refit a few parts like - oh - headstock,saddle, tailstock etc, bit of scraping in here and there, repaint it, and you're good to go!

          If you don't want to cut a hole in the pan, maybe just block from floor to pan & between pan & bed? How much has it sagged?

          Comment


          • #6
            Originally posted by loose nut
            There's nothing for it but to take it to the scrapper and put it out of it's misery.
            As unpopular as it would be because of the work and expense, it could be reground, no need to scrap that beautiful piece of equipment. What could you buy for the price of regrinding that could match it?

            i will say, that since I am re-furbishing a Clausing 5914 this post is a bit disconcerting for me as well.

            Comment


            • #7
              try a couple of machinest jacks to bring it back to level again

              Comment


              • #8
                Thanks guys for all the comments............. I'm still wipeing the tears from my eyes.
                There is a place not too far from me that rebuilds machinery anf they have a huge machine just for grinding bedways but last time I asked for a quote they wanted $7000 to do the rebuild. Of course that included scraping the base of the headstock, saddle and tailstock.
                What do ya think ????? good deal........ I didn't think so.

                JL........................

                Comment


                • #9
                  Originally posted by JoeLee
                  Thanks guys for all the comments............. I'm still wipeing the tears from my eyes.
                  There is a place not too far from me that rebuilds machinery anf they have a huge machine just for grinding bedways but last time I asked for a quote they wanted $7000 to do the rebuild. Of course that included scraping the base of the headstock, saddle and tailstock.
                  What do ya think ????? good deal........ I didn't think so.

                  JL........................
                  NOPE! me either, not for $7000, surely, there are other places that can do that for much less.

                  Maybe Lazlo or macona, those two have been around the block a time or two can offer some suggestions.

                  Comment


                  • #10
                    Fwiw JL, I'd sure first put some effort into just trying to physically force it back into alignment. Possibly some kind of permanent heavy rigid base to bolt it to & shim where needed...?

                    As I recall, PM member Carla posted in the south bend forum there about how much the sb lathes could be improved by installing them on such a base.
                    Last edited by Herb W; 06-22-2010, 12:49 AM.

                    Comment


                    • #11
                      A suggestion- if you pulled the mounting feet towards each other, you would be tending to warp the sag in the bed upwards. I can't see how that lathe is mounted, but if you sandwiched a piece of plate under both ends of the bed, then arranged a turnbuckle to pull those plates towards each other, you would be transferring that pull to the lathe through the mounting bolts. Maybe this could be arranged under the chip pan and wouldn't be seen- you might need to enlongate the bolt holes in the stand to allow the bolts to actually pull against the side of the mounting lugs without interference from the stand. Of course, the alignment of the bed is going to be part of this procedure, since the bolts will have had to be loosened and probably taken right out. Good time to do a comprehensive check of it all.
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                      Comment


                      • #12
                        JoeLee,
                        I was thinking loosening the tail end and putting a large block centered under it, then tightening, much as Herb W's solution was referring to, however airsmith282 mentioned a simpler suggestion, also put down a heavy steel plate on the tray so you aren't just displacing that.

                        Comment


                        • #13
                          A couple of comments:

                          First, the level that you're using looks to be a Starrett 98-8. If so it doesn't have a lot of precision, just .005"/foot. For comparison of lathe bed you need something quite a bit better.

                          Second, the cross wise test doesn't tell you anything much without relative comparisons. Comparing one end of the lathe to the other and both to the middle might give you something - if you were comparing the flats, or if you were comparing with blocks riding on the V-way. Measuring across the tops of the V way very likely doesn't say anything as they are not usually ridden by the saddle. Your Clausing may be different, I don't know, but you might want to check the saddle to make sure that it's expected to be a precision way before anything is done as a result of treating it as one.

                          Third, you want to be sure that there's no twist to the bed before using a precision level along the length of the bed, otherwise you can be fooled into thinking that there's a lot of wear. One thing that you can do is to level the lathe bed using the flats near the headstock and on the far end of the bed, choosing locations likely to have less wear, then check intermediate locations with a precision level and finally confirming wear with a precision rule or flat (both checked on a precision surface plate).

                          Finally, you really don't know what you have until you attempt to level the bed to remove warp *then* mark out the flats with a flat. If the wear is anywhere near as significant as the level you have indicates you should be able to slip a .005" feeler gage between the flat and the lathe bed at the worst spot. To me the bed doesn't appear to have that much wear.

                          Comment


                          • #14
                            Alignment?

                            Originally posted by JoeLee
                            After responding to a recent post where someone asked why the lathe cut a slight taper on one end of a short piece of work, I started thinking why my lathe is showing signs of the same thing.
                            I always thought it was because the bed ways are worn more right in front of the chuck where most of your work is done. However after checking the bed with a level I noticed that the center of the bed has started to sag over the years. In the past I have heard a few Clausing 5900 owners comment that "they made a good machine but they should have beefed up the bed a little more" Now I see why.
                            I don't think there is really much I can do about it other than drill a hole in the center of the chip pan and post the center......... out of the question, however I'm open to all suggestions. The bed is level from front to back. I also have the base pads setting on some heavy pieces of hard rubber cow mats. Perhaps I should have just set the machine on the floor but I doubt that has anything to do with the sag. The reason I put the rubber mats under the base is to absorb any vibration. Before I found the 5900 I had a small 4900 series that sat on the floor on it's adjustable pads and it transmitted vibration throughout the work. Everything I turned had a slight herringbone pattern to it due to vibration.

                            JL..................






                            For the OP:

                            Just hope that you wife doesn't see the thread heading - or some of the replies - but in the meantime taste everything she gives you to eat, and eat it with a long spoon and very slowly.

                            I don't think that the "sag" (in your lathe) is of any concern as running the saddle with a tool in the tool post may cause the tool centre height to change a bit but it will need to be a lot to effect the diameter or taper of a part.

                            If you were to put your lathe tool spot on centre height and turn a shaft to precisely 1.0000" diameter at one end and if the saddle "dropped" by say 0.020" over the length of that turned part - so that the tool was now 0.020" below/under centre height, the diameter would increase to 1.0008" (8 "tenths") a difference of 0.0008"

                            For a 0.500" shaft the 0.020" "drop" would cause an increased diameter of 0.5016".

                            For a 2.000" shaft the 0.020" "drop" would cause an increased diameter of 1.0002"

                            My gut feeling is that if that level is a Starrett 101 or similar the graduations are approximately in the order of 0.0001" per inch or 1 in 10,000 so I think the bed "sag" is minimal and of no real effect.

                            I think that the fault may lie with the head-stock axis (mis?)alignment with the lathe bed axis. It is not likely to be a vertical (tilt) error but rather a horizontal - "left/right" error.

                            If that is the case the head-stock may need to be re-aligned.

                            But wait for comments by others - hopefully Forrest Addy - before tearing your hair out or making what may turn out to be unnecessary adjustments.

                            Comment


                            • #15
                              oldtiffie, if correct and I bet it is, would not also the carriage spacing even average that error out?

                              Comment

                              Working...
                              X