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  • Bridgeport table

    The table on my bridgeport is in bad shape. I am getting about 5 thou deflection up and down the table. One side of the table is 3 thous higher then the other.



    What sould I do? Do I get the table ground?

    It's an old machine, series 1 from the late 60's. The ways are also pretty bad.





    Should I try to scrap them or just leave them. At what point is it not worth rebuilding? It works good but I can't cut anything true to within 3 or 4 thou.

  • #2
    Does your work require getting closer than .005? If not than I wouldn't worry about it, if so the machine needs some work. Is there a shop near that could grind the ways for you? Honestly I have seen what looks a lot worse than that.

    In those pics did you whipe the ways dry? They don't look like there is any lube on them? Do you have a one-shot type oiling system? If you are going to recondition the ways you don't want to have to do it again.
    James Kilroy

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    • #3
      How often are you going to be putting something that is the size of the table on the Bridgeport.
      mostly your working on something that is 5 or 6 inches long in the vice.....go back and measure the deflection ...on a small part .........then you will see that it isn't that big a deflection.
      BTW that table needs stoning ..them ridges around the dents and grooves are enough to to make it way out .
      Get a stone and move it around in circular motion with lube to take the high-spots off
      all the best.mark

      [This message has been edited by aboard_epsilon (edited 01-02-2006).]

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      • #4

        How did you measure the deflection? Have you repeated the same measurements several times and get the same results? Try locking the knee and taking measurements.. Try adding some tension to the x/y gibs and take measurements. Try moving the table, lock all axis, then take a measurement, etc.

        -Adrian

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        • #5
          I wonder if the bill for fixing this mill could be much less than finding another mill. I bought my mill for $1100. I admit it was a bargain, but I took a significant risk that it would work at all. I don't know what the expenses of a professional repair job on that mill would be, but I think you could find a better mill than that if you looked not very hard, and sell yours. Weigh that and the moving of the mills, against the repair expenses and the moving and disassembly of the mill.

          With the price of labor these days, and the lack of experts in the field, I don't think it will be a cheap prospect.

          You could do it yourself, but then you have to weigh the downtime, learning curve, effort, new tooling ect.

          I think a lot of us would end up doing it ourselves, mostly because we are cheap and because no one else is available to do it.

          Often you don't save any money, but you do gain a new skill and some new tools (if you live long enough to complete the job.)

          If you do tackle it, be sure and let us follow along. I'd love to watch and learn.

          Should I remove and inspect the wiper seals on my mill periodically? Any tips on keeping my mill from looking like that one?

          I mostly cut aluminum.

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          • #6
            Did you have the saddle lock on when you were checking for runout? You may need to adjust the gib on the "Z" axis,there is wear showing so some of your indicator reading is from that wear but may be not all. Have you tried to adjust any of the gibs? It's not hard to do just take your time and do a little at a time, you know adjust the screw on one axis and check to see that it is'nt too tight then adjust a little more until they are as tight as possible and still have easy movement when you turn the handwheels. I see that the gib screw on the "Y" axis seems to be sticking out quite a bit more then "normal" maybe you need to adjust them? Also you need to put the way scrapers back on.
            Since this mill has been around for a while the top of the table probably has numerous dings and dents on it, believe it or not this can cause the table to bend as the top is now slightly longer than the bottom,I saw this on a couple of machines that were overhauled at the shipyard I worked at ,the millwrights were friends of mine and I got to watch them rebuild several mills, all the tables had this problem some more than others ,a quick skim cut on a grinder an they went straight.You could send it out and have the ways ground/scraped but it is'nt cheap.
            Lumpsmith

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            • #7
              Man, I wish the ways on my Bridgeport looked that good!

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              • #8
                Thanks for the advice guys. I guess it is not as bad as I thought. The gib that is sticking out is a new gib that I screwed up trying to fit. I have to get another one and try again. This I know is half my problem. The original gib I could not adjust anymore. It had some tape on the back of it as well when I got the machine. I payed $1200 for it with the DRO. I think I will stone the top a bit and get a new gib fitted and see where I stand again. I am a bit of a perfectionist and hate it when I cut something and its not perfect.

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                • #9
                  <font face="Verdana, Arial" size="2">Originally posted by SJorgensen:
                  I wonder if the bill for fixing this mill could be much less than finding another mill. I bought my mill for $1100. I admit it was a bargain, but I took a significant risk that it would work at all. I don't know what the expenses of a professional repair job on that mill would be, but I think you could find a better mill than that if you looked not very hard, and sell yours. Weigh that and the moving of the mills, against the repair expenses and the moving and disassembly of the mill.

                  With the price of labor these days, and the lack of experts in the field, I don't think it will be a cheap prospect.
                  </font>
                  One half of my shop specializes in machine repair, scraping and alignment. Our standard bill to take a worn out Bridgeport and take it to like new conditions and actually make it better than new, is $5500.00. The mechaninic goes thru the whole machine, scrapes alingnes and replaces all the worn out parts like bearings,etc, it also gets sanded down and repainted. Needless to say most of our customers are big business's that can afford that type of rebuild.With the amount of cheap chinese machine's out there we don't even see as many rebuilds from the big business's anymore either though, it is cheaper to just throw away or sell and buy a new chinese mill.

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                  • #10
                    I don't advocate buying any of the Chinese stuff yet. As a Home Shop Machinist in the United States I see a crap load of businesses shutting down. Great machines are being sent to the scrap yards. As bad as things are for the economy and future prospects for my nation in general, it is a boon for Home Shop Machinists. There are lots of old iron American machines available at bargain prices.

                    When I was considering buying my milling machine, I had a lot of negative advice. One of the positive voices was John Stevensen. I took his good advice and I had some luck going for me. I am a happy man. I didn't even have a home for it, but I made the connections necessary. I now share a shop with the most eclectic and interesting group of men that rivals those of you here!

                    There is nothing that can not be achieved by the mind of man, given some luck and a milling machine. (And a lathe, shaper, Mig, Tig, Grinder, Sander, Oh where does it end?)

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                    • #11
                      I fixed my old (1941) bridgeport. Serial Number 370 (Is this a antique) I installed a digital readout Like 17 years ago or so. I also had a friend help me with reconditioning the y axis gibs. Two dowel pins against the gib one per side measure across. Then use a file yeah a file file out the error. Few hours later we had the thing damn near perfect. I did work for many differant shops and never had anyone come back and say somethings wacky. The situation from your mill should require dissasembling the table remove it hand stone all nicks clean out the **** between table gibs and so on. You will be amazed whats in there. Get a Guy Lautard oil gun and pressure lube oil those ways . Align the oil nut and pump er good. First time i used my high pressure oiler on my old mill a wad of black **** just ejaculated right out the side of the table and hit my buddys shop coat. I just looked at him and said I think it likes you. The dro helps a lot. Also when the gibs wear badly ive shimmed them up with thicker brass shim on the backside, Its still in there and still works. Cheap repair also. I hope this gives you some ideas on how cheap i am .

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                      • #12
                        <font face="Verdana, Arial" size="2">Originally posted by madman:
                        I fixed my old (1941) bridgeport. Serial Number 370 (Is this a antique) </font>
                        Mine is a 1950 J-head, serial no. 12021. And I thought mine was an old timer!

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                        • #13
                          <font face="Verdana, Arial" size="2">Originally posted by x39:

                          Mine is a 1950 J-head, serial no. 12021. And I thought mine was an old timer!
                          </font>
                          ?

                          J-head came out about 1953. 12021 would have most likely had an M head, possibly an R. Many J heads have been stuck on older mills, of course.

                          [This message has been edited by sauer38h (edited 01-03-2006).]

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                          • #14
                            <font face="Verdana, Arial" size="2">Originally posted by sauer38h:
                            [B] 12021 would have most likely had an M head,B]</font>
                            Nope, most definitely a J head, R-8 collets and all. J-12021 is the number on the head itself.



                            [This message has been edited by x39 (edited 01-04-2006).]

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