# Evaluating bridgeport ways and what to do about them



## Xyphota (Jul 8, 2022)

Hello everyone!
I recently purchased my first mill which is a 1963 9"x32" Bridgeport Series 1, which I believe to be in generally good shape but as I am a complete noob, I wanted to hear some extra opinions.

Upon delivery the y-axis was incredibly hard to turn and after removing the y-axis gib, it came out covered in chips and has some pretty deep grooves in it. The X-axis was very smooth. The z-axis was missing the gib adjustment screw so I couldn't give it a fair evaluation. I have since completely disassembled the table down to the knee to inspect the ways, clean out all the chips, and double check that all the oil fittings aren't filled with grease or blocked.

I know the visual wear on the ways in some sense doesn't matter if everything is smooth and tight, but could I get some comments as to if the visual wear you can see in the below pictures is a lot or a little? I'm not experienced enough to comment on this matter haha!

Additionally are there any recommendations to clean up both the surface rust/patina and the high spots from the scratches? I have seen some videos about precision ground flat stones that are advertised as being able to cut/polish off high spots without cutting into flat surfaces


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## Xyphota (Jul 8, 2022)

Photos of the z-axis ways


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## Xyphota (Jul 8, 2022)

Photos of the y-axis ways and gib. I'm particularly worried about the pretty deep grooves in the gib.


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## Xyphota (Jul 8, 2022)

Photos of the x-axis. There is a bit of surface rust/patina on the saddle ways. It feels smooth to the touch.


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## Dabbler (Jul 9, 2022)

What you are seeing is typical wear on a well used machine.  The long grooves in the gibb are from trapped swarf.  It looks like the wear you get  if the way covers and wipers are not present.  As long as the ways don't have burrs they will do fine for hobby use. 

It would be good to check XYZ for tracking using a tenths indicator (something I didn't get a chance to do when I looked at it)

What troubles me (just a tiny bit) are the worn off scraping marks on the vertical ways.  They won't hold way oil and will wear faster.  You can scrape oil marks in the vertical ways 'in situ' enough to prevent excessive wear.  Since you won't have access to the mating parts, the marks have to be a little deeper to hold enough oil.  *** that being said***  not many guys move  a wide range in Z all the time.


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## Canadium (Jul 9, 2022)

Xyphota said:


> Photos of the y-axis ways and gib. I'm particularly worried about the pretty deep grooves in the gib.



If by the "pretty deep grooves" you are referring to what I think you are referring to, these are put in by the manufacturer to assist with the dispersion of lubricating oil. Nothing to worry about they are supposed to be there!


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## Mcgyver (Jul 9, 2022)

That's wear.  its hard to quantify from photo's, but depending on the extent, its quite likely the machine can still do lots of useful work.  Wear, or the transition of it from wear to unworn happens over a distance.   if the wear occurs over 10" and it is a 3 inch part, its effect  is somewhat reduced.  And it is milling not grinding, i.e. its never required to sub thou work and usually with a few thou is good enough, of course depending the drawing and use etc

The correction of it is only going to happen by scraping.  By scraping it you can restore it to original factory condition or better....but its a very big job and for the unsuspecting, a fairly deep rabbit hole as far as technique, knowledge, and to a lesser degree, equipment goes.  It is doable however, depends where you are in your life and pursuit of things technical.

barn doors are open and the horse is gone, but its a reminder that it really is worth it to put a pump oiler your mills gents.  Lots of oil every time you use it will make it last a very long time.


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## Canadium (Jul 9, 2022)

I'm assuming he means the deep curvy lines that go thru the oil weep holes. Not the lesser straight lines. The straight lines are wear, the curvy lines are for better oil dispersal put in by the manufacturer.


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## Mcgyver (Jul 9, 2022)

hi Ian, yes I got what you meant,  I was saying overall the problem he has is wear.  Kind of stating the obvious I guess


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## Xyphota (Jul 9, 2022)

Canadium said:


> If by the "pretty deep grooves" you are referring to what I think you are referring to, these are put in by the manufacturer to assist with the dispersion of lubricating oil. Nothing to worry about they are supposed to be there!


The deep grooves I am referring to are mostly on the y-axis gib, not the oil dispersion troughs.


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## Degen (Jul 9, 2022)

Here is the thing, gibs are meant to be adjusted to compensate for wear (and minor abuse).  As long as the ways are true life is good.

Clean, ensure they are burr free, same for the ways (use a light touch here).

Re-install and snug up just shy of binding while allowing allowing free motion.  You may have to redo  this after a bit of use (several times) as components settle into place.

After that run some test to see if you have any variances.


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## Xyphota (Jul 9, 2022)

Degen said:


> Clean, ensure they are burr free, same for the ways (use a light touch here).


I should have been more explicit in my original question instead of waffling around haha. What is the best way to deburr the gibs and ways without removing too much material?


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## Dabbler (Jul 9, 2022)

Xyphota said:


> What is the best way to deburr the gibs and ways without removing too much material?


Use a stone that is flat (true) and lightly stone them to take any high spots on any accessible areas.  I use a 150 grit stone.  Be sure to clean very thoroughly after stoning.  (most youtubers seem to not know this and they leave grit on their work).

The grooves you are worried about are unfortunate, but won't affect the use of your mill in any tangible way.


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## Xyphota (Jul 9, 2022)

I have a Norton 220/1000 used for knife sharpening, and a DMT lapping plate to flatten it but I’m not sure if it is sufficiently flat. Do you have any experience with precision ground flat stones such as these ones?









						4-inch x 1-5/8-inch PFG Stones — Kinetic Precision
					

Includes two PFG Stones, aluminum oxide, each ground on four faces. Storage tray included. Order lid separately. The Model PFG-4 nominal dimensions are 5/8" thick x 1-3/4 x 4 inches. The long edges are also precision ground square to the major surfaces and flat.  All stones are made to order, p




					www.kineticprecision.com


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## Dabbler (Jul 9, 2022)

Yes, but kind of pricy.  The ones  I use right now I hand lapped and then trued using the 3 plate method.  They behave properly on milling table and ways, so  I'm content for the moment.  When I get a diamond wheel for my SG, I'll touch them up.


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## Mcgyver (Jul 9, 2022)

if just burrs, use a burr file.  Scrapers tool.  A short section of a file that has been stoned down so only bits that project between the teeth get cut, it just skates over everything else


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## Degen (Jul 9, 2022)

If you are the cheap (I mean thrifty) emery paper and any flat surface (including the wifes counter as long as she doesn't catch you) 300, 400 and 800 grits.

Water to stick it down and water to  lubricate.

400 removes the highs and sharp edges.

Cheap effective and always new cutting surface, add more grits all the way up to 8000 and you can polish.


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## Susquatch (Jul 9, 2022)

Xyphota said:


> I have a Norton 220/1000 used for knife sharpening, and a DMT lapping plate to flatten it but I’m not sure if it is sufficiently flat.



Everything I have read says that once a stone has been used for anything else it should not be used for removing burrs on a mill table or ways. Buy a new stone designed for that and then don't use it for anything else. And as has been said, clean everything afterward. If you think chips are hard on your ways, try abrasive dust...... 

I'm in the camp that says clean up all the chips, get rid of the burrs, and use it to make stuff. That's what I did with mine. You can replace the Gibbs if you want, but I would not try fixing the ways if I were you. I bet the parts you make will never know the difference. 

How was the backlash?


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## Xyphota (Jul 9, 2022)

Susquatch said:


> I'm in the camp that says clean up all the chips, get rid of the burrs, and use it to make stuff. That's what I did with mine. You can replace the Gibbs if you want, but I would not try fixing the ways if I were you. I bet the parts you make will never know the difference.
> 
> How was the backlash?


This is my plan! I am not really interested in scraping anything, except for maybe adding some scrapes to the vertical ways for oil adhesion as per Dabbler's comment above, but I think that will be a later problem.

I think the x-axis at the dial had about 0.020" of backlash, I did not note the y-axis before disassembly. I removed the lead screws and they appear visually consistent throughout the screw, but I dont know how visually obvious it is if a screw is worn out. Fortunately the mill came with a DRO for X and Y so I am to believe backlash shouldn't be a huge issue? I understand the bridgeport machines use split nuts for backlash adjustment. Assuming the leadscrews were in good shape, what would be an acceptable amount of backlash?


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## YYCHM (Jul 9, 2022)

Where did you find a BP in the Calgary local?  How much did it set you back, if you don't mind sharing?


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## Xyphota (Jul 9, 2022)

After purchasing it, I realized it was the Bridgeport of contentious discussion in this forum haha:









						Colchester Student $3500 Calgary
					

https://www.facebook.com/marketplace/item/2147046365446629/?ref=browse_tab&referral_code=marketplace_top_picks&referral_story_type=top_picks  Same seller has a bridgeport for $5000. Both are in the basement of a house.




					canadianhobbymetalworkers.com
				




I'm into it for about $5K which included a bunch of accessories and more importantly delivery.


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## Dabbler (Jul 9, 2022)

Getting a name brand mill with some wear and a little Y way damage, you did fine.  

My big mill (clone)  has .050 backlash, and I paid a lot more to get it to my door and running. I had to make a VFD setup to run it -- and my X axis has more wear on it. I bought an extra X axis nut for it, but have not needed it yet...


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## Susquatch (Jul 9, 2022)

Xyphota said:


> This is my plan! I am not really interested in scraping anything, except for maybe adding some scrapes to the vertical ways for oil adhesion as per Dabbler's comment above, but I think that will be a later problem.
> 
> I think the x-axis at the dial had about 0.020" of backlash, I did not note the y-axis before disassembly. I removed the lead screws and they appear visually consistent throughout the screw, but I dont know how visually obvious it is if a screw is worn out. Fortunately the mill came with a DRO for X and Y so I am to believe backlash shouldn't be a huge issue? I understand the bridgeport machines use split nuts for backlash adjustment. Assuming the leadscrews were in good shape, what would be an acceptable amount of backlash?



The typical check marks that are put on the ways to hold oil are called "Flaking".

20 thou of backlash would not upset me one iota. Ya, everyone wants less, but machines wear if you use them. So if you don't want backlash to creep in, don't use your machine. 100 thou would bother me a lot. 50 thou would bother some users, but those with good skills would prolly be happy. Some Bridgeports have adjustable leade nuts, some don't. You can tell looking at them. Post a photo if you want help deciding. But keep in mind that a tight nut prolly won't work at the ends of your travel. You have to find the right balance.

If you cannot easily see that the threads are thicker at the ends than in the middle, the screws are not worn enough to worry about. Again, post a photo. Or use a Caliper to measure them at some common point on the thread profile.

If you have a DRO, you don't need to worry about where you are, but you still need to learn to accommodate whatever backlash is there when you are machining. It is easy to break an endmill when the machine decides to take up the backlash on its own. Ask me how I know. It's a very bad experience that can easily destroy an endmill and ruin a part. The bigger the machine, the worse the experience. So ya, learn all you can about climb VS conventional milling and locking the Gibbs on the opposite axis from the one you are using. These are important fundamental pieces of knowledge.

So far I think you have a great machine that you will LOVE using!


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## Xyphota (Jul 9, 2022)

The lead screws and nuts are quite greasy so once I clean them I'll share some pictures. I'm reading through the bridgeport manual and it says the lead screws are to be lubricated with way oil. Is there a local supplied that sells Mobil Vactra No. 2? Some online research suggest that ISO 68 oil commonly used for compressors (and available at canadian tire) is an equivalent oil if it is free of detergents.


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## Degen (Jul 9, 2022)

Backlash occurs in two locations, the nut on the lead screw, if adjustable tighten it to the point where it moves freely without binding, if not slit it and make a split nut and adjust it.  The second is in the bearings for carrying the screw and how the screw is attached to those bearings.  Snug those up without causing binding will remove play.

As an example I have a BB mill and when I did the CNC conversion cleaned adjusted everything.  The play on my machine is less than 0.004 ( if not better).  On a recent job the I had the mill machining 0.5" hole with a 1/4" end mill,  measured hole size 0.4995 to 0.5010


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## Susquatch (Jul 9, 2022)

Xyphota said:


> The lead screws and nuts are quite greasy so once I clean them I'll share some pictures. I'm reading through the bridgeport manual and it says the lead screws are to be lubricated with way oil. Is there a local supplied that sells Mobil Vactra No. 2? Some online research suggest that ISO 68 oil commonly used for compressors (and available at canadian tire) is an equivalent oil if it is free of detergents.



I don't agree with that. ISO 68 oil is not the same as way oil. Way oil has additives in it to make it sticky.


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## Dabbler (Jul 9, 2022)

Xyphota said:


> lubricated with way oil.


Shell Tonna 68 is also a way oil and is what I use.  I can give you a litre to try out.


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## RobinHood (Jul 10, 2022)

Xyphota said:


> I understand the bridgeport machines use split nuts for backlash adjustment. Assuming the leadscrews were in good shape, what would be an acceptable amount of backlash?


Yes, they do. Manual says set backlash between 4-5 thou.


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## Brent H (Jul 10, 2022)

As a note - somewhere on here I did a change out of the feed screws and nuts on my mill and did some explaining .  I did this as the backlash was unacceptable to me and was hard to drive a power feed as towards the end of the table it was rather stiff.  Setting a sloppier fit resulted in horrible operation of the power feed as it would be great at the ends and fly like the dickens in the middle. 

With a new x and y axis feed it is like a new mill.


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## Degen (Jul 10, 2022)

RobinHood said:


> Yes, they do. Manual says set backlash between 4-5 thou.
> 
> View attachment 24879


When I adjusted my split nut, I had no information (re service manuals)  it was take it apart see how it works.  My spec was simple, least amount of backlash possible without restricting motion across the entire range.  I do suspect that this will reduce the life of the split nuts and lead screw as it loads both side of the thread constantly, a little play greatly reduces this.

In my case it was simple, expect to put in ball screws as a replacement at some point, currently maximize performance and accuracy.


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