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Buying a mill help

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  • Buying a mill help

    Hi, ive been thinking of buying a bridgeport for quite some time and have found one that has come into my price range. Any tips on what to look for? how heavy is an older bridgeport (pully driven, not variable) will my 1/2 ton pickup be able to carry it home in one piece? If the bearings are gone in the spindle how hard and how much work is that to fix and how do i tell they are gone without actually machining anything? any help would be greatly appreciated thanks in advance.

  • #2
    A Bridgeport weighs in the neighborhood of 2000 lbs so, no, you shouldn't plan to get it home in your truck. I rented a trailer rated for 5000 lbs from U-haul for $29 to get mine home. The seller put the mill on the trailer with a fork truck and I had a tow truck lift it off on my end then moved it to it's final spot with friend's Harbor Freight rolling hoist.


    • #3
      This is what I would do. File and stone the table smooth then wipe it clean. Lube the gibs and crank the table back and forth several times.

      Put a dial indicator in the chuck and Zero it on the table. Snug the gibs then crank the table all the way to the left a 48" table should sag about .0015". Tighten the gibs the dial indicator should read about .001" sag.

      Crank the table to the far right do the same test. If the table sags no more than about .0015" on the far end its a pretty good used machine.

      Move the dial indicator to the side of the table do another test.

      When I bought my Bridgeport Mill I hauled it home 40 miles in the back of my 1977 Toyota 1/2 ton pickup truck. I had it pushed forward all the way to the cab to try and get as much weight as I could on the front tires. I had it tied down good too. I drove very slow and no faster than about 3 mph around corners. I had to rent a fork lift to get it off of my truck. The Mill had the truck springs compressed all the way down to the over load rubber bumper pads so it could not tip left/right at all as I drover and turned corners the truck bed was all the way down on the axle. I made sure the tires had 30 psi in each one. Play it safe rent a good strong trailer.
      Last edited by gary350; 09-26-2011, 06:51 PM.


      • #4
        You can do some tests, but I'd look at things like how it was taken care of, if someone tried to rebuild it before, and try to get some history. I don't know how much of a job it is to replace bearings, but I can't imagine its that bad. I'd use your ears while it is running to see if you can hear anythign noisy/rattly and then with the spindle off try and mearure the runout of the R8 taper with a fixed indicator. It won't tell you if the bearings are good exactly , but it might tell you if they are horrible. I'd also check to see if the thing has been modified/hacked. Missing bolts, wrong bolts, handles half falling off, etc. Some superficial things are OK, but if every nut and bolt is stripped out from being repaired 100 times you might be careful.

        From my understanding just about anything is rebuildable, but unless you can do the work yourself and have the time it could cost you alot of money if the thing is really sloppy. With Bridgeports going so cheaply these days I would try to hold out for a good one if the one you are interested in is sketchy.

        I bought my Bridgeport (Variable speed head) for $500 and it has 0.040" backlash in the lead scew and about 0.003" slop in the table/saddle . The wear on the screw isn't bad, but the wear on the tables is mostly in the middle where the vice usually goes. Some guys lock it down with the gibs and almost limit the travel to get the machine tight enough to use. I haven't even adjusted mine properly yet but I can get halfway decent parts by locking down non moving axes and being careful.



        • #5
          I bought a 1964 step pulley machine two weeks ago and got it off the trailer on Saturday. I looked at the backlash and the overall condition of the machine. Most times I saw mills they were not under power, so listening for spindle bearings was somewhat impossible.

          I had a roll back winch the mill off my trailer and then the driver backed it up into the garage and set it on the floor. that was $85. Once I am done cleaning and re-wiring I plan to roll it into position on 2.5' lengths of 1/2" diameter black pipe, which was about $14 for a 10' section.

          I would make sure all the handles are there and all the functions mostly work. You get what you pay for so the price range makes a big difference regarding what it will be like. I paid $1200 but got 3 vises and a working DRO and power feed. My mill was missing the drawbar ($15) and the adjustable worm shaft which swivels the head was broken ($20) and I had to cut the swivel worm gear in half with an air saw to get the broken part of the shaft out ($50). My mill did include all the original parts to remove the power feed if I so wanted, I found that out while I was cleaning it.

          I looked for a long time in the south east and I never saw a mill for $500. I suspect there's alot more selection in the north east. There's one nearby now for $800 but I don't think it comes with anything, and I never called the guy so I don't know. Most of the other machines I saw were at at the junk dealers for $2000 and up. My machine came out of a washing machine factory which closed and the general manager seemed to know it's history.


          • #6
            Evaluating my Bport, I looked at the table first for "oopsies." A rough table usually means other issues as well IMHO. Then I looked at the ways the best I could. Scratches, gouges etc are a pretty bad sign if you can see them. Unfortunately, usually the underside of the saddle is 10x worse than any of the ways you can see, so if you can see very much of any damage you may be in serious trouble. Regarding the head, I believe the traditional way to tell is simply by listening to the bearings at low speed and trying to shake the spindle by hand. Luckily I didnt have to change mine, but I believe most spindle bearing sets go for ~$500, which is why IMHO this is the most important part.

            I would also try cranking the table, knee, and head position mechanisms, but wouldnt necessarily lose sleep over these. IMHO dealing with worn leadscrews, nuts, and backlash are among the easiest things to deal with. When I bought my Bport the table would BARELY in ~10 inches, and it definitely felt heavy doing so. I wasnt worried however, as it came with an extra set of leadscrew nuts. I pulled the table (~20 minutes work) and cleaned the dried oil (now grease) nastiness out of the ways and leadscrews/nuts to allow the table to move freely. While in there, I also cleaned a TON of chips out of the knee elevating bevel gears, thereby making the knee go up and down very easily. I also discovered my "extra" leadscrew nuts were the originals, new ones had already been installed, so after just a bit of cleaning an extremely sticky table cleaned up nicely and currently has ~.003" backlash in both directions. Dont confuse dirty/nasty with worn or broken. Bring some paper towels and WD40, get under the grease and look closely if in doubt.
            "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."


            • #7
              As for the getting it home part,
              guy named rocrat posted a thread here awhile back about drop deck trailers. This link may or may not work
              I rented one from Sunbelt to get my BP home and it worked awesome.
              You may have hard time finding these not many places rent them but if you can it's the way to go.

              Oh and the one they had used a pintle type hitch. I hat to rent the part that goes into the receiver.
              Last edited by Cheeseking; 09-26-2011, 09:46 PM.


              • #8
                Also consider not only how heavy is it for a trailer, but where its intended location is at your place and how you are going to get it from the trailer to that place.

                Sometimes that is the biggest sticking point for some small home shops....

                Because my current shop is in the basement with a questionable staircase, I'm limited to machinery I can dismantle (which I usually do for cleaning anyway) and haul downstairs in more manageable sections. Tough to do for me with a full B-port, but there are some smaller units out there that are quite capable for my work and I can get them down there in pieces.

                In the process of putting a Rockwell 11" lathe down there right now.
                Last edited by T.Hoffman; 09-26-2011, 09:58 PM.


                • #9
                  T.Hoffman, my shop is in the basement as well. All the hassles getting things down there are WELL worth it in terms of comfort for the machines and the operator. The basement is cool and dry in the hot summer and relatively warm and toasty in the winter. Moving day will suck but that is not now hopefully.
                  Best $400 I ever spent was a 1 ton HF gantry w/ the 20% off coupon. Get one and you'll be glad you did. Before I bought it
                  I did my 11"x30 lathe using an engine crane and let say that was a bit more excitement.


                  • #10
                    I'm looking at a 8x36 'Super' Bridgeport clone, myself. But on my budget, I could barely afford to pay movers, so that would be a pain.

                    I doubt I'll get it. My current shop is a quarter to a third of the space in a one-car garage, since I have to share it with storage.

                    I'll probably end up with this RF45 clone for just a little less (not counting moving costs), since it really is big enough for pretty much all my projects. I'm just well aware that bigger is better.


                    • #11
                      Originally posted by Cheeseking
                      Best $400 I ever spent was a 1 ton HF gantry w/ the 20% off coupon. Get one and you'll be glad you did.
                      Already have the gantry crane in the garage. Cheap insurance instead of trying to horse things around with your back.

                      Another SUPER handy piece of equipment is a hydraulic platform hand truck. I found one for a steal on CL recently, rated for lifting 750lbs up to 54" high.

                      I love that thing, really built well.

                      I have the one on the right which allows the platform to go right down to the ground. That way I can slide heavy item onto it without needing to lift them. The one on the left has the wheels in front so the platform does not go down to the ground.
                      Last edited by T.Hoffman; 09-27-2011, 12:24 PM.


                      • #12
                        Yep those are nice little lifts. At work I just bought my guys one to help put punch press dies in and out of presses (not huge dies) I'd love one for the shop but it would have to be a steal like you got. I was surprised how well the pump jack works. It goes up pretty good not like a car jack that takes 8 million strokes to move an inch.


                        • #13
                          BP are pretty heavy

                          I think the estimate of 2000 lbs is not far off. I would guess a bit more. I bought a 70s vintage Bridgeport variable speed (project). I would have preferred a step pulley as a VFD powering a step pulley system is in my opinion better than a VFD powering a variable speed (split sheave system). As to the spindle bearings, power it up and listen to it. Run it at the higher speeds. If you can insert a piece of 3/4" dowel into the spindle and check the run out with a test indicator. If nothing else grab the dowel and attempt to wiggle it back and forth (powered off). Check to see that you can shift into the high and low gearing on the head. Make sure that the spindle power down feed works. If you have a test indicator and some accurate 90 degree angle blocks, check that the spindle moves in and out without shifting. Repeat the process for the knee travel. Check to see if there is excessive movement in the x and y directions of the table. Typically the in and out direction will have wear in the middle. If the gibs are tightened to get rid of the slop in the middle, then the movement will be really tight at either extreme. My BP suffers from this form of wear. Mine is usable but I would like to scrape the end portions of the ways to eliminate this flaw.

                          I really wouldn't recommend loading it in the back of your pick-up. It would make for a very top heavy load. I had access to tandem axle dump trailer. The seller loaded it into the trailer and I used my back hoe to unload it. I put it up on 2x4s so I can get a hand pallet jack underneath it so I can move it around my equipment shed. I need to install the VFD and either clean up the ways or start using it. For now I am still using my Grizzly knee mill (not a BP copy) as the tyranny of the urgent seems to win out over doing the important.


                          • #14
                            The 2000 lbs is pretty accurate for a J Head V Ram era machine. It varies slightly depending on table width and if it is actually a 12BR serial machine with the larger 12" knee then a little more than that, probably 2200 lbs. Way to top heavy for a pickup truck, look for a trailer. I used a sunbelt rentals lift deck for my first mill.

                            To rebuild the spindle is about $300 in parts (bearings) and another $100 to do the top end which would include two belts and the top bearings. Motor bearings could be toast too but those should be pretty cheap in comparison. Those prices assume everything else in the head is serviceable.
                            Central Ohio, USA