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How do I make my lathe stand more rigid

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  • How do I make my lathe stand more rigid

    My Chinese lathe's stand is essentially two cabinets connected together by nothing more than a thin piece of sheet metal.
    I want to make it more rigid with some heavy rectangular steel tubes I already have.

    What is the best way to approach this project? Do I need a welder or can get away with bolted connections?




  • #2
    Hi Alex, your lathe looks the same as mine including the stands.

    I did not feel rigidity of the stand compromised the lathe at all and my machinists' level confirms the lathe is not twisted. What did concern me though was the possibility of something untoward causing the lathe to topple forwards so, not wanting to drill the floor, I took 4 pieces of timber 4x4 about 3 feet long and bolted the cabinets down to these, the end of the timbers extend out from the front of the cabinets about 12 inches. It now feels much more secure and incidently raised the lathe to a more comfortable height for me.

    John

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    • #3
      If you want to make the cabinets more rigid, add diagonal bracing. Personally if the stand is shoddy, then I would make some new ones.

      Here is a picture of my stand prior to trimming to show how it was constructed. It doesn't move. It isn't the best and certainly not the worst. I do like the drawer space a LOT. It was made from rectangular tubing then welded together. The sides, top, and back were welded to the tubing. All of the steel was drops from the local steel yard.

      Last edited by Richard-TX; 03-16-2010, 04:21 AM.

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      • #4
        Fill it with concrete

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        • #5
          Originally posted by RB211
          Fill it with concrete
          Or make one out of concrete. There are instructions over on PM from WWII on making a base out of concrete for precision work. They are in the South Bend section.

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          • #6
            My lathe is similar, and the base is worse than what sits on top of it.
            The doors are useless, nothing fits into them.

            1.) Tear out the 0,7mm sheet metal that is supposed to act like drawers.
            2.) Check that the top plate and the one or two stiffening ribs that should ... well ... stiffen the top plate are actually weldet together. Not tacked with 3 spots, but welded. Mine were not. There was a 2mm gap. Useless! Weld it!
            3.) Have a look at the base, where the holes for the bolts are. A few tacks only! Weld it! Whatever rect tube you find, you can weld into the columns.
            4.) Screw the lathe down to the floor. That makes an incredible difference. Surface, vibrations, depth of cut! And you can even twist and bend the bed in almost any shape. That takes a machinists level and a lot of patience and 6 bolts into the concrete floor.

            Don't weld the connection between the feet, it doesn't make a difference. That paper ... er ... sheet metal is only facade.

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            • #7
              Consider building a cross braced box section to install between the cabinet uprights, then maybe add a sheet across the full length of the back to tie it all together well. Something similar to this.

              In my case I was trying to use some cast end columns from an old Walker Turner gang drill, and added a steel surface to make a bench for my Atlas/C'man 12x42 lathe. It was flimsy, easily rocking laterally and twisting the surface:



              I built a box of 3/4" plywood. The internal cross braces sit in groves (dato's?) in both sides, plus have additional bracing fillets added:



              With both sides of the box glued and screwed to the inner cross braces it is very tortionally stiff. It is then squeezed between the two cast end columns with long all-thread top and bottom:



              It sucks loosing the possible storage space between the columns, but it worked great to strengthen the base against rocking and twisting in all directions:



              A similar box between your cabinets, with a long back section that extends across the back of your end cabinets, would probably work very well for you. You would retain the storage space of your cabinets, you could use the natural "V" of the internal bracing as a replacement chip catcher, and the front face of the new box section can still be used as a place to hang commonly used tools on pegs.

              Good luck,

              Bob

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              • #8
                With both sides of the box glued and screwed to the inner cross braces it is very tortionally stiff.
                From a carpenter's POV, it is stiff.
                From a structural POV, it is soft.

                Here's an experiment:
                Clamp a dial indicator stand onto the chuck. Adjust it to stick out as much as possible along the spindle's axis. Put a dead center into the tailstock. Put a dial indicator onto the stand and let its tip touch the center.
                Now lean onto your lathe. You will be ****shocked****

                There are only two solutions:
                1) Screw the lathe to the floor.
                2) Decouple the lathe from the stand. Boley's do only have 3 fixture points where the bed is screwed to the stand. No matter how the stand flexes, the lathe won't move.

                And wood moves with moisture. One day adjusted, the next day out of alignment.


                Nick

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                • #9
                  All true Nick, but I can only tart-up a sow's ear so far

                  I'd actually like to replace the steel surface with a thick maple one. I think that would add another stiff plane to the "box" and dampen vibrations down some too. The lathe bed legs sit on three points on the table surface and the wood box is well sealed against moisture penetration with several layers of paint. It's in my dry basement, and the temps don't vary much there either. Random movements are minimal, and it works pretty well for my use.

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                  • #10
                    The lathe bed legs sit on three points on the table surface ...
                    Then that's a different story.
                    In this case, the stand can't add much to the lathe's precision.Only some mass, a bit of dampening, but no stiffening at all.
                    At least, lotsa storage. :-)


                    Nick

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                    • #11
                      My 12x36 lathe is attached to the stand by 8 bolts.
                      For rigidity I can bolt the lathe first to a thick metal plate and then this assembly can sit on not so rigid original base even on three points. The minimum plate size must be 8"x 50" so both lathe feet can fit on it.
                      I am thinking to get 1" thick plate 16"x50"
                      Not sure how much it'll cost yet. I don't want to go over $200.
                      What do you think? Will it be sufficient, overkill?
                      BTW Concrete floor in my garage is only 1" thick so bolting to the floor won't do much.
                      Last edited by AlexK; 03-28-2010, 06:56 PM.

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                      • #12
                        My lathe is lower than I like when standing on its cabinets and them on the floor so presently they at standing on wooden 'feet'.

                        I do not see any reason why one could not pour a 4" or so slab of concrete (length and width of the lathe) on top on an existing floor and even seperated by a sheet of plastic if desired. This would give considerable mass and still not mean drilling holes in an existing or rented floor while raising the lathe to a more comfortable working height.

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                        • #13
                          Originally posted by Bob Farr
                          I'd actually like to replace the steel surface with a thick maple one. I think that would add another stiff plane to the "box" and dampen vibrations down some too. The lathe bed legs sit on three points on the table surface and the wood box is well sealed against moisture penetration with several layers of paint. It's in my dry basement, and the temps don't vary much there either. Random movements are minimal, and it works pretty well for my use.
                          This isn't perfect but it helped. I went down to the Habitat Re-Store that has recycled building items and bought a couple thick solid core doors. Cut to size, bolted together and banded around the edge with 1 x it makes about a 150 lb 3 1/2" base for the lathe. The stand doesn't do much except give some storage space and bring the machine up to work height.

                          ... and I've been struggling to resist the urge to suggest taping a packet of Viagra underneath.
                          Last edited by TGTool; 03-28-2010, 10:32 PM.
                          .
                          "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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                          • #14
                            I recommend remaking the stand entirely, those little cabinates suck, and whats all that room under the middle of lathe for thats unusable? your feet? do you really sit at a stool?

                            bolt on some drawer slides and make pull out heavy duty drawers for chucks and tooling! then make a giant frame outta giant peices of angle iron or even square tubing.

                            One kinda scary thing about a flexable frame is when the vibration sets in it can start resonating with the frame and bam, 10x the vibration at some rpm then others. Of course, you can just note down that RPM and never use it again for offset turning, but finding it can be scary.

                            But consider the 500lbs of tooling you will be able to add as a great 'vibration dampener', Especialy as its likey all loose with its own independant resonsances on dampening non slip pads.
                            How much tooling can you fit in those puny boxes? 100lb? maybe 200lb? blah! And you ever try and pull an 8" chuck or 10" faceplate outta one? not easy!
                            Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                            • #15
                              Originally posted by AlexK
                              I am thinking to get 1" thick plate 16"x50"
                              Not sure how much it'll cost yet. I don't want to go over $200.
                              What do you think? Will it be sufficient, overkill?
                              BTW Concrete floor in my garage is only 1" thick so bolting to the floor won't do much.
                              I'm not a structural engineer but I think it is both overkill and insufficient at the same time. A 16''X 50'' plate is going to be flexy even at 1'' thick and it is going to add a lot of top heavy weight to the foot print. I would work on making the cabinet/stand more rigid with some strategic bracing instead.

                              Steve

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