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  • Milling machine wear

    I've been looking at this 1970 model Ajax No 1 milling machine and it looks OK it has done a lot of work I guess and I ran a dial indicator along the table and it has about a 1 thou drop in the middle. Is this a lot of wear for the slides or not???? It has a lot of small dents all over the table plus a gouge where someone has run a side and face cutter into the table as well. It does run OK with all three power feeds plus the rapids work as well.
    Precision takes time.

  • #2
    Ringer, 1 thou isn't much depending on what you are doing. Where i work one of our old bridgeports has alot more than that and it isn't really noticeable. In fact i would say that only 1 thousandth is pretty darn good for a machine that old.

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    • #3
      I recently checked the table of my Grizzly import, about 2 years old, and that's about what I measured - within 1 thousanth over about 95% of the table. A little more at one corner. I guess I would expect a new US or other high quality brand to be better than that when new but then, I don't know if they really are. It has not been noticable in the work I have done.

      As for any dings and scratches, please notice that ALL brand new tables come with 2, 3, or 4 really deep and wide grooves in them. They are called "Tee Slots". And they do no harm. The main idea is if the areas between the dings, scratches, and Tee Slots are flat then the work sits on those flats and is positioned OK. It is a good idea to inspect for any raised areas on the edges of the defects and lightly stone them if necessary.

      I'd be a lot more worried about any uneven wear on the ways and lead screws and the spindle side play and runout.

      Paul A.
      Paul A.

      Make it fit.
      You can't win and there is a penalty for trying!

      Comment


      • #4
        <font face="Verdana, Arial" size="2">Originally posted by Paul Alciatore:
        It is a good idea to inspect for any raised areas on the edges of the defects and lightly stone them if necessary.

        Paul A.
        </font>
        As a newbie to machining... May I ask what is meant by "lightly stone"?

        My sherline lathe's crosslide has ranged edges on the tee-slots from overly tightening the tool post. (oops!) About 10 thous worth. It causes problems with some toolposts now because they rock back and forth and chatter... So whatever this lightly stoning business is, I could use some of it!

        Thanks!

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        • #5
          Take a silicon carbide stone or other abrasive stone and smooth away only the high spots. The idea is to lightly abrade the high spots ONLY down to the level of the table, so that everything is flat again.

          If you have a small dent, no problem as long as there is enough original flat surface available to clamp parts to.

          Usually, when you get a dent you'll find a ridge of high metal around it (the metal has to go somewhere). You want to remove that ridge so that as much as possible of the table surface is at the original level.

          cheers,
          Michael

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          • #6
            <font face="Verdana, Arial" size="2">Originally posted by retep:
            As a newbie to machining... May I ask what is meant by "lightly stone"?

            My sherline lathe's crosslide has ranged edges on the tee-slots from overly tightening the tool post. (oops!) About 10 thous worth. It causes problems with some toolposts now because they rock back and forth and chatter... So whatever this lightly stoning business is, I could use some of it!

            Thanks!

            </font>

            You might watch out....isn't a lot of the Sherline made out of aluminum? That "lightly stone" works way different on aluminum than on cast iron...............
            1601

            Keep eye on ball.
            Hashim Khan

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            • #7
              Alright, so really the silicon carbide stone is just used because most milling machine tables are hardened correct? In my case, the sherline is all alluminum as J Tiers suggested. So really a standard file should do it if I just use it carefully...

              It's interesting, I used the same force on the allan key clamping the toolpost down as I normally do on my sherline milling machine. But I think the extra torque that a lathe toolpost gets is what pulled the t-slots, not so much my clamping directly. Perhaps adding a hold-down clamp opposite the tool would help things?

              Either that, or not frequently doing stuff like boring 1" dia by 1" deep holes in 303 stainless...

              Comment


              • #8
                What was said above about stoneing is 100% as far as it goes. But I did not realize the table was aluminum.

                I'm not sure what is the best way to remove the small raised areas on an aluminum table. But consider this before using a file. A stone will remove steel or CI (cast iron) much slower than a file will. A file will remove aluminum much faster than it will remove steel or CI. I would not use a file on an aluminum table.

                Also, the stone will be a lot smaller than a full size mill table. It will be fully seated on the table during the stoneing. A file will likely be longer than a Sherline mill table so it will overhang on two edges or at least one. It will be hard to prevent removing more material at the edges of the table than the center. Also, files are never completely flat. One side is usually convex and the other concave. All together, this will tend to produce a convex table. Not a good idea.

                My best suggestion: whatever you use on this smaller, aluminum table should be a lot smaller than the table itself and should cut very slow. It should also be reasonably flat. A small stone still sounds like a good idea or perhaps a small piece of very fine sand paper on a small, flat, hard sanding block. Light pressure and as few strokes as possible. You are trying to remove the bumps, not dig into the table. Inspect the job by running a straight edge lightly across the table and stop when no more raised areas are detected. Again, that's my best suggestion. Others here may have a better one.

                Paul A.
                Paul A.

                Make it fit.
                You can't win and there is a penalty for trying!

                Comment

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