Opinions on inspected 1.5 hp Bridgeport
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  1. #1
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    Default Opinions on inspected 1.5 hp Bridgeport

    Hey,

    So I just got this Bridgeport. The previous owner was really great about taking care of his equipment. He was a tool and die maker. Using some of the skills I learned in Richard King’s class I inspected the machine, but I am afraid I may have missed a few.

    I put the magnetic bases for my dial indicators under the table to check the front saddle and found that it was 0 to .0008” out. On the back of the saddle and found that at the very back it was about 0.001”. These seem like great values but there is a noticeable difference at the ends when moving the table in the Y direction. It feels very tight at the end, most specifically towards the rear ( or + Y).

    When I had the magnetic base on the knee and the indicator on the Y saddle and would press on the edge of the table to theoretically rotate it clockwise or counterclockwise from an aerial view, I would see up to .005” to .007” deflection with the lock virtually not on. When I really tighten the locks it dropped to about .0003” to .0005”.

    And lastly when I had the magnetic base on the table and indicator on the Z ways, it was almost perfect. There was a consistent bounce back and forth of 0.0005” as the indicator crosses over scrapping marks but when stopped it was dead on at 0.

    I have attached some photos and am look for some feedback regarding the re-build work on the ways. As you read for the most part it seems great, but the scrapping markings on the Y axis make me a little weary, especially with the tightness at the ends. Would all agree, that based on these specs and photos that this is a good machine despite not having chromed ways and it having a little sag in the Y on the knee. I do not plan (nor want to) rebuild this machine soon. I have other projects I need to get done and hopefully this machine helps me do so.

    1124141811.jpg
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    1124141813a.jpg
    1124141817b.jpg
    Attached Thumbnails Attached Thumbnails 1124141842c.jpg  

  2. #2
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    More photos

    1124141840d.jpg

    1124141840c.jpg

    1124141841a.jpg

    1124141846a.jpg

  3. #3
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    Wheel bearing grease?

  4. #4
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    I see you have the obligatory grease based lapping paste all through your ways....how many of these will we see before people learn?

    As this is the reconditioning subforum and you say you have no intention of reconditioning this machine, provided you can use it without doing it. Then lets keep the discussions to how to properly indicate the moving axis. You have done a pretty good job describing what you did but I think more is needed.

    Perhaps Richard or one of the other "experts" will offer you a better idea of how to use your indicators to properly check the accuracy of your machine geometry. There are already a few videos on Youtube of some of our members inspecting machines while they are apart but a discussion of measuring machines while assembled would be a very good discussion.

    Thank you for posting Whiz..

    Charles

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  6. #5
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    Quit screwing around with trying to measure the wear, it's an old BP, what do you expect? Make some parts and see if it will hold tolerance. If not is it you or the machine? I have made some pretty nice parts on some pretty worn out iron. It would have to be a real piece of junk to not work for most hobby use. You don't get new Makino accuracy for used Bridgeport money.

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  8. #6
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    As stated above the only real issue is the moly grease on the ways. I have a true way oil dispenser that has will pump vactra #2 in the zerks. The dispenser is similar to the one you can get from germay and mcmaster-carr except it works way better than them and was a lot cheaper and made to last( made by me ). I Plan on taking the table and saddle off to get all the moly grease out and start using way oil.
    I asked for the opinions of other rebuilders because I have taken Richards class and was worried I may have forgot a measurement here or there. I did not put dowels in the max and min of each axis dovetails to see if the tightness was due to binding in geometry because I didn't have a mic with me. I pulled it in a friends barn for the night because we had 65 mi/hr winds and I wasn't gonna try unloading it in that kind of weather. I paid 1600 for it, it has 1 owner and was purchased. DEC 18 1967 I have all original packaging and manuals. What I am asking for is, is this a reasonable deal for the price and the tolerance.I just need it to hold up and be tight enough to get some projects done, then I will get to tearing it down and scraping the machine in.

  9. #7
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    I don't know if I understand correctly what you've done for measuring. If the figure 0-0.0008 in is derived by resting the indicator's base on the table while measuring the ways on which it rides with the saddle is somehow equivalent to map the ups and down of a road by measuring the angle of the trailer hitch vs. the towing vehicle at any given point: you'd measure only potholes and sudden changes of incline, but not directly how much you're going up and down, unless you integrate through complicate calculations.

    Checking how the top surface of the table behaves compared with the spindle (after tramming the head at a particular position) would give you much more useful info.

    Paolo

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    For 1600.00 you did fine, you can't buy a good drill press new for that money. Use it for a while and find the problems, then sort it out when you have time.

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  12. #9
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    Being able to accurately evaluate a machine is paramount to the rebuilding process. You need to be able to check a machine before reconditioning and then compare it to the results after reconditioning. This is a valuable and useful exercise and I look forward to seeing other peoples informed opinions.

    I wouldnt be to concerned about your deal, as mentioned the price is fine and as you have take Richards class you have the basic knowledge to repair it later if it proves necessary. Even if you lack the confidence to jump right in. I am sure you will find it a rewarding experience when you get to it.

    Charles

  13. #10
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    Quote Originally Posted by Paolo_MD View Post
    I don't know if I understand correctly what you've done for measuring. If the figure 0-0.0008 in is derived by resting the indicator's base on the table while measuring the ways on which it rides with the saddle is somehow equivalent to map the ups and down of a road by measuring the angle of the trailer hitch vs. the towing vehicle at any given point: you'd measure only potholes and sudden changes of incline, but not directly how much you're going up and down, unless you integrate through complicate calculations.

    Checking how the top surface of the table behaves compared with the spindle (after tramming the head at a particular position) would give you much more useful info.

    Paolo
    Agreed. I could not take the table and saddle off to blue the knee nor do I a camelback that would fit it. however I figure by having my indicator on saddle and reading the displacement from the center to the front and from the center to the back i could verify that the knee is worn in the middle and try to quantify what I am visually seeing. It may not be dead nuts. but the saddle with travel parallel to the surface unless really messed up. Maybe I'm wrong here on this assumption. The z is perfect you can see in the pics all original scrape marks in it.The Z was never moved by previous owner. It may just require me to get the y dove tail on the knee built up with chrome and then matison ground for better fit and wear resistance.

  14. #11
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    I concur with other have said: at that price, it's very likely that you've done a very good deal. And the most important thing is to assess if you can do any acceptable work even before rebuilding it.

    Assessing the conditions of the ways on a machine, especially a milling machine without disassembling it is at least challenging.
    From what you described, you'd probably need to adjust properly the gibs.

    My personal approach would be a pragmatic approach: you need to do certain operations, therefore you'd better assessing the capabilities of the machine in doing what you need.

    There are two series of "quick tests" that I'd do: assessing run-out, straightness, and play of spindle and quill (by resting the base of your dial indicator on the locked table and playing with spindle and quill), and testing the table flatness, straightens, etc. using as reference point the head/spindle of the machine and the casting of the main body.

    You'll definitely need a square and at least a parallel. A surface plate and/or straightedge would be very nice for assessing the overall curvature of the table and spotting the burs and raised dents to be removed first in order to have decent readings.

    If you don't have it already, get a copy of Connelly's book, where all the tests on an assembled machine are described much better than I ever can.

    Paolo

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    who greased it? former owner who took care of it? you're going to have to take it apart to fully flush out the grease. If you've taken the class and not happy with the accuracy....you know what to do

  16. #13
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    Your column ways look like genuine bridgeport original, the top of that knee however definitely was reworked at some point in time. Not necessarily a bad thing but may be a good place to start investigations.

  17. #14
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    The column looks great at the very top, where it is seldom used. But all the fancy original scraping is long gone down below, in the greasy area...

    Paolo


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