Milling Machine stiff to move side to side
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  1. #1
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    Default Milling Machine stiff to move side to side

    Hello everyone,
    I have basically no experience or knowledge on milling machines or machining in general so excuse me if this is an obvious question. But I am a mechanical engineering student and I have a co-op job that has a mill that needs to be brought up and running. It's an old Enco 100-1525 mill from the mid 90s and literally nobody makes parts for them anymore. I've managed to get it pretty much up and running except the bench is very stiff to move side to side. I had the machinist that works with our company from time to time machine me a bearing retainer and he also gave me an old dial holder from a pile of miscellaneous parts he's had laying around for like 20 years that just happened to fit. I put these on and I go to turn the handle to move the bench to the right, finally having gotten the parts together and getting it in working order (or so I thought), just for it to be incredibly difficult to turn. I thought it was just that the lead screw needed greased up or something so I went to take the whole lead screw assembly apart for the x axis, and it moved fine after I took the right side assembly off of the lead screw. I then put it back together piece by piece so that I could figure out where the stiffness was coming from and it seemed to be when I put the end cap with the bearing in it that it got stiff and hard to turn. I checked the bearing and it rotates just fine by itself so I'm not sure why it gets hard to move the whole assembly when I put the bearing on, even without the bearing retainer. Does anyone have any ideas as to why it's hard to turn when I put that part on, and maybe have some advice on how to fix this? Anything would be appreciated, even just some resources on where I can learn more about this stuff (specifically this particular enco machine).

    Also if anyone knows where to find parts for old Chinese milling machines like this one, that would be spectacular. The only thing I have left that I really need to find is the end cap nut on the left side of the x axis lead screw. I can't even tell what size it is because it's so weird. I thought it was a 9/16 inch nut but that was just barely too small. My next guess is a 14.5mm nut but I don't even know where to find something like that.

  2. #2
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    Pictures of what you are working on would help. Also I believe the item you are referring to as the "bench" is generally referred to as the "table".

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    Thank you.
    Here's the piece that I referrd to as an "endcap" with the bearing retainer. It's only when I put this part on that it becomes hard to turn the handle, even without the bearing retainer put on it.20190524_163956.jpg20190524_163956.jpg20190524_163949.jpg

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    When the shaft is free from the bearing and you turn it does it wobble a lot? If so then the shaft is bent and the pressure when fitted is making it hard to move.

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    When it's free from the bearing on both sides I can wiggle it pretty easily but I figured that was just because it's not supported on either end. When I have it in the bearing on the left side but not the right side it seems to move fairly freely but then when I put the bearing on it is much harder to move. I'll try removing the lead screw next time I get a chance and seeing if it's bent.

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    Did you rotate it 1/3 or 2/3 of a turn to see if it lines up better?

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    I’m not that knolegable on the Bridgeport mills but I did have a similar problem with a Millrite mill. First check as already mentioned for a bent feed screw by removing it and rolling it on a flat surface, it will be obvious if bent. Another potential source of the problem may be alignment of the two table end bearings and the feed nut. If it is this alignment then it can become tighter at the extreams of the table movement. The feed screw will bend causing stiffness due to the three points of contact not being in a straight line. Misalignment of the bearings and feed nut can be caused by a number of things like excessive table ware, incorrectly installed parts etc.

    On my Millrite mill the binding was caused by the various bushings and bearings installed in the wrong order. Find a parts manual and check that all of the parts are there and that they are all installed in the correct order.

    One last possibility is just being gummed up from dried lubricants. With the end bearing off see if the bearings are turning freely.

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    Is the table un-locked?

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    Quote Originally Posted by dalmatiangirl61 View Post
    Is the table un-locked?
    And are the gibs properly adjusted?

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    Has the machine got a backlash eliminator ? If I had a £ for everytime I've been called out to a milling machine with a stiff long travel lead screw when the operator had allowed the backlash eliminator to lock up I'd be rich.

    Regards Tyrone.

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    since it's *kind of* a BP copy you might consider asking in the BP section.

    parts should not be an issue, those things have gone basically unchanged forever....Jet,Griz,Shop Fox...

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    Sounds like all of the slides have not seen an oil can since they were installed. It looks dry with what little is shown in the pictures. Give it a good bath with some sort of oil. Don't worry about what kind, just some oil, hydraulic oil if available for now. WD-40 is not oil, but maybe used to help clean up dried up crud on the ways. If you understand what the table gib is, loosen the screw located at each end of the gib, better yet, take the screws out and remove the gib. Dryness or crud will tell you what to do next. If surfaces are fairly clean, oil real good and reinstall loose. Pull the screw and oil and reinstall. By hand slop oil on the underside way surfaces. After doing this try to move table to one end of the stroke. Next reapply oil the the underside again, then move the table to the other end. By now, it should be well lubricated. Last adjust the gib screws to where the table can still be moved without binding. You can also set the gib sliding a 0.002" feeler gage between the table dovetail and gib until it is slightly tight but still pull out. Snug the gib screws at each end of the gib, but not too tight. This should correct some of the problem.

    The other issue is the missing graduation collars that should be on each end of the lead screw. At least on the end shown in the picture. There is a seller on eBay that sells the collar and dial.

    Ken

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    i am reasonably sure this manual is the same as your machine....in addition to what Tyrone and 4GSR said, are you simply missing a spacer?

    https://content.jettools.com/assets/...036_man_EN.pdf

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    UPDATE:
    I've gotten the lead screw out and it didn't appear to be bent. My next guess was that the table was dried up as someone suggested and so, after some trouble trying to figure out how to get it off, I've finally gotten the table off and here's the result. I haven't done any further work on it but I figured I would put the pics here for anyone to see and give input on who wanted to, since maybe someone with more experience sees something that would tell what the problem is by looking at it.
    Thanks everyone for their help and suggestions so far.
    1.jpg2.jpg3.jpg

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    Quote Originally Posted by samuel.stroth View Post
    UPDATE:
    I've gotten the lead screw out and it didn't appear to be bent. My next guess was that the table was dried up as someone suggested and so, after some trouble trying to figure out how to get it off, I've finally gotten the table off and here's the result. I haven't done any further work on it but I figured I would put the pics here for anyone to see and give input on who wanted to, since maybe someone with more experience sees something that would tell what the problem is by looking at it.
    Thanks everyone for their help and suggestions so far.
    1.jpg2.jpg3.jpg
    So you're a mechanical engineer. Do you understand the adjustment of the table gib and the table lock screws?

    The slides don't look all rusted up, so that is good. With some oil and adjustment of the gib, it should be fine. The screw turns harder with the endcaps on because you are actually moving the table, instead of just having the screw freewheel through the nut.

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    Quote Originally Posted by HuFlungDung View Post
    So you're a mechanical engineer. Do you understand the adjustment of the table gib and the table lock screws?

    The slides don't look all rusted up, so that is good. With some oil and adjustment of the gib, it should be fine. The screw turns harder with the endcaps on because you are actually moving the table, instead of just having the screw freewheel through the nut.
    Im a mechanical engineering student but I'm only in my second year lol, so excuse me if this makes me look stupid but no I am not familiar with the parts to which you were referring. And I do know that the screw is harder to move with the endcaps on since I am moving the whole assembly but it shouldn't be THAT hard to move. I have to put most of my body weight into turning the screw just to get it to budge. So my next step is to remove the housing for the lead screw (Is that the gib?) and clean it and then try to make sure it's properly aligned, as well as make sure the table is properly oiled.

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    Flood every thing with some oil and I feel you will immediately see a difference in how it moves. It has to do with friction, probably have not studied that yet in statics class. Every thing is dry, not good, creates lots of friction and makes the table difficult to move. The lead screw is dry, too, it needs lubrication for it to turn. The mill has a lubrication installed by the looks of all of the oil lines I see in the pictures. Add oil to the hand pump and pump it until oil is flowing out at all of the openings the hoses are going to. Ken

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    You need to figure out what the table locks are, and the gib before going any further, if gib is not adjusted correctly, or the table locks were engaged, its going to be hard to move the table.

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    I've made sure the table locks are not engaged. and yes I do think it probably is just dry parts that need oil but now I just need to get it cleaned and back together and refill the oil reservoir.
    P.S. Ohhh ok I know what the gib is now and now that I know what it is, I realize that could be what was keeping it from moving because after I loosened the screw all the way the table came right off. Thank You!!

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    It did look a bit dry but other than that no comment to make. When it's all back together you should be able to move the table easily without too much effort.

    Regards Tyrone.


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