FS: Bridgeport wired 110 single phase

Getting crowded in the garage and still need a decent lathe. So off goes my Bridgeport, you can see pics here.

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alright, downfeed needs something, has readouts I never hooked up, some tooling included. Russ
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Reply to
Awesomewiz
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Reply to
RoyJ

Thanks, I didn't even see where the serial number was. I know it's abit old, doesn't even have the chrome ways. Russ

Reply to
Awesomewiz

I think Roy is referencing the number on the "J" head. It's been a long time but maybe someone can tell us if it was dovetail or round ram in the mid 50's. There should be another number stamped, I think, on the lower vertical way surface. BTW the chrome ways were probably an option at the time your machine was built and for some reason this feature was slow to catch-on (at least around Chicago from '63 till around '76).

Reply to
rigger

A buddy got the round ram one from his uncle man is that a pain to find parts for, and the collets are abit small, but hey it works. This one takes the standard r-8 collets. Do you think the price is fair? I bought it for $1500, with the motor burnt and hooked it up this way but that was before the 9/11 attack and it seems like prices dropped because of all the places going out of the business. Russ

Reply to
Awesomewiz

Reply to
RoyJ

The knee ways are badly worn. It will take months of scraping work or many $1000s to get this machine back to anything but a glorified drill press.

Reply to
Richard J Kinch

Right you are Roy. These pix were loading so slowly I skipped a few.

dennis in nca

From: RoyJ

The pic of the horizonal ways at

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shows a serial number of BR29414 corresponds to 1955 at
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Reply to
rigger

Makes you wonder if some people have heard of way covers. This could make an interesting project. I doubt if "months" is the correct term to use here though. An "experienced" scraper hand could easily do the horizontal knee surfaces in less than a day (after the vertical surfaces of course) ,with the proper tools. On the other hand, if there is enough wear, you might want to send that knee out to be ground first.

dennis in nca

Richard J. Jinch said: The knee ways are badly worn. It will take months of scraping work or many $1000s to get this machine back to anything but a glorified drill press.

Reply to
rigger

Ten, count em, 10 surfaces to be scraped on that one axis alone. Flat, bearing quality, aligned up/down, tilt fore/aft, tilt left/right, all to better than 0.001", with the concave wear something like 0.010 in the extreme.

Assuming you disassembled, cleaned and shipped (both ways) out to an expensive grind job, the hand scraping would still be days of work. If you're removing the meat by scraping alone, then it is easily weeks of backbreaking labor.

Reply to
Richard J Kinch

Reply to
RoyJ

Paid $1,100 for a round ram of 1962 vintage with 2 axis DRO.

Clean with little wear with 1J head.

From a major shop closing down 100 miles North of St. Louis.

Hugh

Reply to
Hugh Prescott

Those knee ways are *the* major wear point for the Bridgeport machine. The very ends do not experience wear since they're near to (or past) the range of travel. Most of the wear is in a swayback pattern around 1/3 and 2/3 up the knee ways where the saddle rests on two bearing areas. You can always see the crescent-moon scraping marks, testifying to the original precision surface, at the ends, but depending on the degree of wear, these marks are more or less worn off towards the middle. On this particular machine, the photo shows they are completely obliterated except at the very ends of the ways, indicating extreme wear, concave where it should be flat. The mating surface on the saddle will have a somewhat conjugate wear shape, convex where it should be flat.

If you remove the table and saddle, you can place a machinist's ruler (the kind that has a precision straight edge good to a few tenths of thousandths) on edge along the ways, and measure the deviation. On an old machine like this, you will find concavity of several thousandths or more.

With this degree of wear, if you adjust the gib with the table positioned at the center of travel, the dovetail ways will bind up and not move after a few inches. If you loosen the gib to allow more travel, the table will be loose in the worn areas. Thus, the machine has either lost its rigidity, or its table travel, take your pick, and since you need both to do most machining tasks, the machine is broken. It is not merely that you lose dimensional precision or squareness; you either have motion but no rigidity and thus can't cut, or you have rigidity but no motion and thus can't cut.

There's a similar process with the wearing of the table ways, but since the table is much longer than the knee, and is protected from chips and dirt, the wear tends to be slower and spread out more and thus is not the limiting wear factor compared to the knee ways.

The usage pattern over the years can alter the process. If you run the table left and right with a power feed all day, while the cross feed is locked, then the proportions may be different. But typically the knee ways are well worn before the table ways are.

The leadscrews likely have corresponding severe wear, and these are not reconditionable.

The scoring shown in the photo is also extensive. A few dings, scores, chips, and even oops-drill-holes do not ruin ways, but if they're covered in scores, then the surface is way past being a bearing surface any more, and can't maintain lubrication, so you have runaway wear.

I bought my Bridgeport machine cheap, realizing it was well worn and in need of reconditioning by a laborious scraping process. On disassembling the cross-travel gib, I discovered that the wear was worse than appearances: The gib, long past its adjustment range for wear, had a shim, consisting of some steel pallet strapping, shoved alongside it by the previous owner. The mating dovetail was ruined.

With scraping, and epoxying on Teflon bearing surfaces, and $$$$ for some new ballscrews, my machine now works better than when it was factory new.

Note that the photo of the OP's machine was very clear and in high resolution to show the state of wear. Most snapshots would not give you enough to diagnose the degree of wear on the ways.

Reply to
Richard J Kinch

Round ram from 1962? Didn't they end in the mid-50s? What's the S/N?

Reply to
Richard J Kinch

Hi Richard, Have you done much hand scraping? I've done a little myself when working for others. I wouldn't call myself a journeyman but have worked with many and through training and observation have , at least, begun to develop a technique. Some get good rather quickly (not I) and for others it takes a while. When someone first begins to learn scraping it goes slowly because of the technique involved in the sharpening component, the actual scraping and the extra care in measurement. But an experienced scraping hand (which you become after a while) goes through these small items very rapidly. Has your experience been with a hand or power scraper? When scraping a Bridgeport knee you don't move it much. You bring your flats and straight edges to the piece which saves a lot of time.

dennis > An

Ten, count em, 10 surfaces to be scraped on that one axis alone. Flat,

bearing quality, aligned up/down, tilt fore/aft, tilt left/right, all to better than 0.001", with the concave wear something like 0.010 in the extreme.

Assuming you disassembled, cleaned and shipped (both ways) out to an expensive grind job, the hand scraping would still be days of work. If

you're removing the meat by scraping alone, then it is easily weeks of backbreaking labor.

Reply to
rigger

Just an FYI:

The crescent shaped marks on the way surfaces are standard on a new Bridgeport (and many other machines as well) but are not necessary according to many. The sliding surfaces are first precision scraped using a method which leaves very little distinctive markings. After the surface is as close as you need it, some apply a oil holding pattern composed of marks (not always crescent shaped). The idea here is to let people know that not seeing the usual pattern on a way surface is not conclusive evidence of wear especially if the machine has been rebuilt previously.

dennis You can always see the crescent-moon scraping marks, testifying to the original precision surface, at the ends, but depending on the degree of

wear, these marks are more or less worn off towards the middle. On this particular machine, the photo shows they are completely obliterated except at the very ends of the ways, indicating extreme wear, concave where it should be flat.

Reply to
rigger

My scraping experience (per se) is limited to hand scraping, for flatness and for bearing quality. However, when I reconditioned the Bridgeport, I used a combination of milling and grinding to get the bulk off of the knee.

I don't know about "very rapidly". Just the cross-travel ways alone on a Bridgeport consist of 14 precision surfaces as large as 2 x 18 (being

2 flat knee ways, 2 knee dovetails, 4 saddle flats, 4 saddle dovetails, 2 sides of a gib). Each of these surfaces must be scraped to alignment with the others in 3 degrees of freedom (height/pitch/roll), then to flatness (2 more degrees of freedom), and finally to bearing quality. So you essentially have a task of 14 times 6 = 84 specific goals. Each goal must be proved by at least two independent measurement techniques or instruments. So you're at 168 indication tasks. Each such task must be achieved by a significant number of scraping cycles. Unless you're a scraping god, errors will happen and re-do's will be needed, and some re-do's require re-doing not just the original error but a number of dependent surfaces.

The upshot being, you have literally thousands of steps involved, each taking from minutes to hours, if you are genuinely reconditioning the machine to factory quality, not just touching things up.

Supposing you get all this aligned and finished, then you have the new problem that the old leadscrews and yoke do not fit the new alignment.

If you have the luxury of starting with a precision reconditioned surface from a regrind that is already aligned and just needs scraping for the final degrees of flatness and bearing qualities, then I suppose it can go "rapidly". That is, after all, how the factory can make them at the economical price of $13K. But that requires tooling that most of us don't even have available in our locale.

One of the tools I made was an 18 inch long by 3/4 wide flat to mark the dovetails, starting will run-of-the-mill steel angle. This one tool took me an entire day of laborious scraping to get to a precision flatness. I'm sure that time would improve with experience, but it is inevitably a significant task.

I spent weeks just buying and/or making tools for the Bridgeport reconditioning job--granite surface plates, height gages, straightedges, gage blocks, levels, indicators, squares, etc. I suppose you shouldn't count that overhead but once.

Reply to
Richard J Kinch

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