Finally bought a J Head Bridgeport!
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  1. #1
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    Default Finally bought a J Head Bridgeport!

    I have been casually brousing the forum on and off for a while, but now I need to get specific and serious with my research.

    I picked up this mill at the estate sale of my wife's uncle, but he never had gotten around to setting this up and running it. As luck would have it, I did speak briefly to the fellow who sold it to him and got just a rough, recent history. Basically, the only tidbit was that the quill power feed did not work. Obvious issue is that the feed reversing knob is missing along with the quill lock lever.

    20190406_135546.jpg


    Anyway, the price was not terrible and I bought it $600. At the time, I had no way of hauling it, but did remove the head and brought it home. I am going back tomorrow to get the rest of the machine, which will need a complete disassembly and cleaning.

    I have started cleaning and inspecting the head and have found that it needs the collet alignment pin replaced in addition to whatever the problem is with the quill feed. The serial # of the upper and lower sections do not match. The lower portion is J20557, and the upper is J37597. I don't have the knee serial# quite yet.
    20190407_201721.jpg


    I believe I need the knee serial to determine the year of my machine?



    For one reason or another he also had a M head there also. But just the head. I picked it up too. I figure I will clean it up and verify the operation and probably sell it. It has the #2 MT spindle, and the serial #'s match, so the market may be there.

    Anyway, is green scotchbright and WD40 the preferred method of cleaning up the ways? Or possibly some light wire brushing? While I have the table removed, I plan on possibly media blasting the top surface and T slots, but that has not been decided yet. Good idea, or bad?

    Any other advice?
    Thanks20190407_201732.jpg

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    Sorry for the sideways pic - not sure yet how to fix it.

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    Sounds like a reasonable price for a BP in that condition. The missing parts from the J head can be replaced if you need to. Many heads had the auto quill feed removed/disabled/broken in factory use. If you are happy using the right hand lever like a drill press you could leave it as-is.

    The trick with a machine table is to recondition removing as little material as possible but do it evenly. In other words, do not use a flexible abrasive. By the look of your table it will need the high spots removing: get a flat file (I find the Nicholson brand are good for this, 8-10” length), grind the tang round for safety as you cannot use a handle, use this file flat on the table to scour it evenly of high spots and rust. Do this dry. If you have a long straight edge you trust you can check whether the centre of the table is worn but correcting this takes a long time by hand.

    If you have any deep machine marks or drill holes these can be filled with epoxy (e.g.JB-weld) then cut back flat with the file.

    The advantage of this technique is that the large area of the file will only cut the high spots. It will skim over flat areas without cutting metal but it will remove oxide as you work so expect to clean the file frequently.

    Don’t expect to get back to an even shiny metal surface. If you do, you’ve removed too much metal! As flat as possible with no high spots is what you’re aiming for. When you’re at this stage a final pass with the file and this time rub in oil with the file. This should leave you with a very usable table.


    Mal
    AKA The Felsted Skiver

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    Thanks for that advice on the file. I had something very similar in mind, but was thinking of a large stone, rather than file and had not considered the sandblasting until a local machinist suggested it to me. Does the file produce better results?

    I do think I will tackle the quill feed, as I think it will be very important for boring operations. I do understand that I may have to go very deep in the disassembly to get to the problem.

    1st on my list is to get the base here and start the disassembly/cleaning. I will probably make a bracket to hold the head on my workbench - separate from the base

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    You could use a stone but it must be flat (you can dress an alu oxide stone on silicone carbide paper on a flat surface e.g. thick float glass, not toughened though). A file will be a lot quicker though and uses the same principle of knocking off the high spots that a stone would.

    If you value the flatness of your table, and you will need it as flat as possible for accurate machining, don’t use any process that will remove metal indiscriminately, including blasting. Even plain water will erode metal with enough pressure and time!

    Mal

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    +1 to pretty much Mal's posts. If you want it shiny, send it out to get ground. Otherwise you wont be flat.

    The scotchbrite we keep at the shop is the maroonish color and that seems to work well to get light rust and gunk off of the ways/table.

    Hopefully you got the M head for super cheap. Aside from a collector trying to get a specific type/SN, we see many more people buying a J head to replace their M head.

    Jon
    H&W Machine Repair

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    Go here for a lot of good info:

    YouTube

    Ted

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    12000 rpm M head, that might be fun to hang on the back for occasional high speed drilling

    My first Bridgeport was the early bolts from the bottom casting, sentimental favorite for me

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    Quote Originally Posted by HWElecRepair View Post
    The scotchbrite we keep at the shop is the maroonish color and that seems to work well to get light rust and gunk off of the ways/table.

    Jon
    H&W Machine Repair
    It's my opinion that maroon Scotch Brite is too aggressive for precision surfaces. When used by people with more enthusiasm than experience, it can remove a few tenths in short order.

    Teryk


    Sent from my XT1710-02 using Tapatalk

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    Quote Originally Posted by mTeryk View Post
    It's my opinion that maroon Scotch Brite is too aggressive for precision surfaces. When used by people with more enthusiasm than experience, it can remove a few tenths in short order.

    Teryk


    Sent from my XT1710-02 using Tapatalk
    Very true Teryk. I’d only recommend the white variety (no embedded abrasive) on precision ground surfaces. But a rusty 50-year-old mill table? Maybe we need to cut some slack there?

    Mal

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    Quote Originally Posted by gustafson View Post
    12000 rpm M head, that might be fun to hang on the back for occasional high speed drilling

    My first Bridgeport was the early bolts from the bottom casting, sentimental favorite for me
    i thought my high speed J was cool for small mills at high speed had no clue M heads could be had that coudl run that fast

  16. #12
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    Quote Originally Posted by mTeryk View Post
    It's my opinion that maroon Scotch Brite is too aggressive for precision surfaces. When used by people with more enthusiasm than experience, it can remove a few tenths in short order.

    Teryk


    Sent from my XT1710-02 using Tapatalk
    I was assuming that not much on this machine is "precision" at this point and was looking for help getting the machine to a not as rusted version of itself.

    Totally agree that the maroon scotchbrite isnt something I would use on a freshly rebuilt table or ways.

    Jon

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    Quote Originally Posted by HWElecRepair View Post
    I was assuming that not much on this machine is "precision" at this point and was looking for help getting the machine to a not as rusted version of itself.

    Totally agree that the maroon scotchbrite isnt something I would use on a freshly rebuilt table or ways.

    Jon
    Agree, and not saying I wouldn't use maroon Scotch Brite with some care on a machine in that condition. Since you have the experience and skill to use it, I am sure you could use it effectively as well.

    Having worked in a couple school shops, I've met more than a few people who thought Scotch Brite (all colors) was too soft to remove metal so could be used aggressively on any surface to remove rust. Even on a table or ways as rusted as those, there might be some precision under all that crud.

    Teryk

    Sent from my XT1710-02 using Tapatalk

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  19. #14
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    You mean you cant just use a wirewheel to get the rust off and not take any metal? Wha? lol

    Jon

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    Quote Originally Posted by HWElecRepair View Post
    I was assuming that not much on this machine is "precision" at this point and was looking for help getting the machine to a not as rusted version of itself.

    Totally agree that the maroon scotchbrite isnt something I would use on a freshly rebuilt table or ways.

    Jon
    You are pretty close to the mark. I removed the heavy dirt/rust with a light application of a wire wheel. Scotchpright will follow, after I get all of the dirt out of the crevices.


    It looks like my machine is a 1957 model.


    I have removed the ram adapter and the ram/turret assembly. Unfortunately, I have yet to find the missing step to get the ram separated from the turret. I have watched a few videos, and found nothing. I guess I have to remove the pinion gear? I didn't think so as the ram is geared all the way to the back, but something between the ways is hitting.

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    To remove the ram from the turret you need to remove the ram handle/ram pinion out to get it off. Now it could be hella rusted and stuck, in which case you will be pounding the crap outta it for a while. Now sometimes when you are getting it off, it starts hitting the ram clamps as they are just barely moving when they are loosened.

    Jon
    H&W Machine Repair

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    My machine was in pretty rough shape too. I just got my ram and turret apart yesterday. It did not move at all until day four of pb blaster and way lube. I tried clamps, plastic mallet, sledge hammer against wood and it would not move. I used the engine hoist to suspend part just enough to clear wood. I then used a piece of wood to leverage against the front of the turret and the casting inside the ram. I hit the wood with a mallet and it finally moved. I had to use different pieces of wood against the front of the turret to get the correct leverage each time. It didn't take a very hard hit to get it moving. Be careful once the turret is almost off and make sure to support it.

    Shared album - adam kington - Google Photos

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    Well, as I have been taking this machine apart, I have been pleasantly surprised that all of the fasteners are coming loose just fine. No deep rusted seized parts. No paint in my plans, just cleanup and adjust. I am not sure how I missed it, but I was mistaken about the gears on my ram. They do not go all the way to the back. Removed the set screw on top and the pinion slid right out. I disassembled the vertical worm screw assy and cleaned and lubed it also.

    Anyway, the turret, ram and head adapter are all cleaned up, oiled and back in place. Table is off and I do see the anticipated evidence of grease, rather than oil being used in the past. So lots of cleaning. Will post a few pics later.

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    On a side note, this forum certainly stinks when using a mobile device. aggravating and surprising this day and age to loose posts after spending time composing messages.




    Anyway, I have the knee and apron assy back together and although I have not taken any actual measurements, I have determined that my mill is pretty well worn. I suppose this is to be expected. Had it been in much better shape, would have been very surprising. The knee gib adjustment is bottomed out, so no matter the reading, no adjustment is available there.

    20190412_124348.jpg
    20190411_220254.jpg


    Also as expected, the apron gets tighter as it travels away from the operator, but there is adjustment left in that gib. It seems the worst of it is the backlash on the apron screw. Just from the dial, it seems there is .030. When I had the split nut assy apart I thoroughly cleaned it and pre-adjusted it a little and determined the two halves are touching, so no more adjustment there.

    Here, you can see the wear in the leadscrew.

    20190412_194712.jpg
    20190412_194707.jpg


    Without wanting to spend the $ right now, what can I expect if I where to remove the front half of the split nut and face off several .001's and re-assemble? Certainly will allow me to tighten it up some more, but I know the material could be getting rather thin.

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    I see the nuts are about $50, maybe I seem like a cheapskate.

    But, this is just going to be home shot useage for the foreseeable future. Likely will be installing DRO


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