# Help! Mill Re-assembly.



## mws (Sep 20, 2015)

Hope I linked these photos properly.
I'm re-assembling an older Bridgeport Mill.  It's obvious the oiling system failed and some undue wear has accrued in the knee ways and gib.  Do I need to true and scrape these surfaces, leave alone, something in between?  I'm comfortable scraping a surface flat. Getting all four of these contact areas planar and true, that's a little daunting. Any advice welcome.
Mark















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## sidecar580 (Sep 21, 2015)

I cant see your picture,,,,,so  I am not much help
JOHN


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## mike837go (Sep 21, 2015)

I'm just a n00b, but it is my understanding that the goal is to have ALL surfaces perfectly flat.

With X, Y, and Z perfectly perpendicular to each other.

Mill, file,  scrape and hone as needed.


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## mws (Sep 21, 2015)

I relinked the photos.  I understand that perfectly flat and square, as well as leaving sufficient impression to hold oil is desirable.  However, at what point is the wear sufficient to warrant taking another month )or two) to get this machine back in service.  I thought some folks more familiar with the tolerances of the Bridgeport could offer some judgment.


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## sidecar580 (Sep 22, 2015)

It looks to me....that it could use being  rescraped. The tolerances you expect out of this machine will decide if it needs to be done.
JOHN


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## mike837go (Sep 22, 2015)

That gouge can be filled:
Clean the gouge out thoroughly!
Lots of preheat.
TIG short, non-adjacent, segments.
1/2 day cool-down
Then grind, file, scrape, hone back to flat.

Or just ignore it.


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## tomh (Sep 22, 2015)

Look into  TURCITE B  There is some videos on how to use it and lots of discussion about using it.
Just saying it's a option.


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## mike837go (Sep 22, 2015)

Back up a moment.....

I was trying to figure out how such damage could have occurred....

It's looking more like those are deliberate oil channels.


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## John Hasler (Sep 22, 2015)

mike837go said:


> Back up a moment.....
> 
> I was trying to figure out how such damage could have occurred....
> 
> It's looking more like those are deliberate oil channels.


They are.  I assume that he is referring to the fact that most or all of the flaking pattern is gone from most of the surfaces shown.


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## mike837go (Sep 22, 2015)

Then, I will just shut my clueless mouth.


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## Andre (Sep 22, 2015)

IMO, unless you are doing aerospace work just leave it. Your ways are nowhere near as bad as they look, those flaking marks are probably only .0002-.0004" deep. For instance my mill has over 20 thou wear on the X and Y axis, and it can still do some good work.

If you do want to fix the wear, look into Turcite as others' have pointed out. Contact Richard King on another board and attend one of his machinery rebuilding classes. I've heard great things about them.


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## mws (Sep 22, 2015)

Andre said:


> IMO, unless you are doing aerospace work just leave it. Your ways are nowhere near as bad as they look, those flaking marks are probably only .0002-.0004" deep. For instance my mill has over 20 thou wear on the X and Y axis, and it can still do some good work.
> 
> If you do want to fix the wear, look into Turcite as others' have pointed out. Contact Richard King on another board and attend one of his machinery rebuilding classes. I've heard great things about them.



Thanks for your views. That is what I was thinking but didn't want to influence anyone else's evaluation. Since there's at least some flaking visible I figured I could get away with flattening the gib some since that's got some deep wear. I just want is to hold an oil film and it likely won't with such a surface.   

I'm planning on bluing it up just to see if there's any really high areas.  

I looked into Turcite on a lathe bed once.  Unless things have changed, it was required to mill down the ways enough to put down at least 0.050" of Turcite, or more.  You can't just lay down a few thou to bring the worn spots up.    Wouldn't that be nice?

And the curved grooves are oil delivery 'veins'.  They look a little funky around the edges because I had to wire brush some crud out of them.  I don't know what the hell they were using in this shop but everything is plugged up with what looks like charcoal, and it's hard!

Here's where we're at so far:












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## Andre (Sep 22, 2015)

The charcoal stuff is dried grease. Either the machine operator or shop helper was misinformed and took a grease gun to the oil zerks. I made the same mistake and had to rebuild my saddle. In all fairness , it had grease in there from the start  

Your ways will still hold oil just fine, just lube every use like you should and you shouldn't have a problem. 


Sent from my XT1053 using Tapatalk


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## coolidge (Sep 23, 2015)

mike837go said:


> Then, I will just shut my clueless mouth.



I got a kick out of your posts Mike, you were like I'll TIG that mother so its like new! lol


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## sidecar580 (Sep 23, 2015)

The back of the knee will show most of the wear at the bottom on the flats and the dovetails on the top, as gravity will pull it that way. The top of the knee will show most of its wear in the middle, with much flaking still visible on the ends.  When I rescrape a Bridgeport I tip the front of the knee up, out of square, .0015 so as the back of the knee wears, it wears into the tolerance.

John Fahnestock
J&L Scraping Service


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## mws (Sep 23, 2015)

Sidecar580: Thanks for the advice.  That sounds like the voice of a practiced hand. I don't know that I'd be able to assure that level of measurement given the equipment I have to work with.  Large surface plates and camel back straight edges have yet to materialize in my shop.  I'm sure I can get a decent feel for the condition of the ways once I start taking some measurements.  I've only scraped a cross slide and a small surface grinder so far, and they turned out well. This Bridgeport is a horse of another color. Guess I don't have much choice though, as I try to keep most tolerances in my shop to +/- 0.0005.  I'll post some more info once I get things under way. 

Thanks to all.


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