# Bridgeport Vise pivot size



## tfleming (Jan 1, 2019)

First off, Happy New Year to all!    Now my question.  I was just given a swivel base that looks like I can use it on my Bridgeport 6" vise (I don't currently have one on it).  I have the vise trammed in on the table, so I really don't want to take it off unless I have to.  What I am looking for is the diameter (size) of the center pivot pin for the Bridgeport 6" vise.  The swivel base that I have has a 0.875 (7/8") pivot pin.  anyone have a Bridgeport 6" vise not mounted they could take a quick measurement for me?  Thanks!


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## Dynahoe Dave (Jan 4, 2019)

What do I measure to determine if I have a 6" vise?


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## tfleming (Jan 4, 2019)

Dynahoe Dave said:


> What do I measure to determine if I have a 6" vise?


There should be a round hole in the center of the bottom of the vise when the swivel base in not installed.   If you have a swivel base for it, I need the OD of the center pin.  If you don't have a swivel base, then I need the OD of the hole in the center of the bottom of the vise.  THANKS!


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## Bob Korves (Jan 4, 2019)

Dynahoe Dave said:


> What do I measure to determine if I have a 6" vise?


The width of the jaws.


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## Dynahoe Dave (Jan 4, 2019)

Ok, so I have a 6".  It is not mounted at this time, it does have the base that lets you set it at an angle.  I can measure the bolt tomorrow sometime.  It is a Bridgeport brand vise, which was a funny to me surprise, as I got it and a bunch of things with the machine, and only noticed the name on it much later.


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## Winegrower (Jan 5, 2019)

I suggest that putting together a dial indicator with a quill attached holder, and a little practice will let you align a vise in less time than writing a post.   Not being snarky, just thinking your enjoyment of the equipment will be enhanced if moving the vise sieems less of a hassle.


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## tfleming (Jan 5, 2019)

Winegrower said:


> I suggest that putting together a dial indicator with a quill attached holder, and a little practice will let you align a vise in less time than writing a post.   Not being snarky, just thinking your enjoyment of the equipment will be enhanced if moving the vise sieems less of a hassle.



Winegrower, your comment is well founded.  I have a tramming head, and also the quill indicator holder.  I am in the middle of a project and I would prefer not to mess with the vise right now.  This base was given to me recently and I was curious to know the Bridgeport pivot size.  My hope was that someone had one sitting off their machine and they could take a quick measurement.

Bottom line, when I am done with this current project, I'll just remove the vise and take my own measurement if no one responds prior to that.


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## Bob Korves (Jan 5, 2019)

tfleming said:


> Winegrower, your comment is well founded.  I have a tramming head, and also the quill indicator holder.  I am in the middle of a project and I would prefer not to mess with the vise right now.  This base was given to me recently and I was curious to know the Bridgeport pivot size.  My hope was that someone had one sitting off their machine and they could take a quick measurement.
> 
> Bottom line, when I am done with this current project, I'll just remove the vise and take my own measurement if no one responds prior to that.


The chuck can be trammed without the indicator being aligned with the spindle in any way.  Just use the quill (or any solid part of the head) as a mounting for the indicator (mag base works), and then indicate the vise jaws while you traverse the table.

Or are you trying to find the vise pivot center location for some reason?


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## tfleming (Jan 5, 2019)

Bob, I am just trying to find out the diameter of the pivot pin on a Bridgeport 6" vise.  I have the vise, but I did not have the swivel base.  I was given a swivel base, and the pivot pin is 0.875.  What I am just curious about, is what the pin diameter is for a Bridgeport vise.  I do NOT believe that this swivel base is a Bridgeport (there are no markings on it).  I can make a different pivot to fit if necessary...…….this is just lazy curiosity.   ;-)


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## Bob Korves (Jan 5, 2019)

I will go now out to the shop right now and take my Bridgeport vise off my mill and measure the pivot hole in the bottom of it for you.  Tramming a vise in, done properly, only takes a couple minutes.


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## Bob Korves (Jan 5, 2019)

Bob Korves said:


> I will go now out to the shop right now and take my Bridgeport vise off my mill and measure the pivot hole in the bottom of it for you.  Tramming a vise in, done properly, only takes a couple minutes.


1.250".  The vise is back on and trammed within .0005" over the 6".


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## tfleming (Jan 5, 2019)

Thank you.  Sheesh, this turned into a much bigger thread than I intended it to.


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## tfleming (Jan 5, 2019)

Post Script - I really never intended this thread to become something about tramming in a mill vise or head.  My shop is not at my home, so it takes travel to get there.   I also have the Bridgeport setup for a job I am working on.  I have all the correct tools to tram my vise ( and mill head, plus I know how to do it).  I was given a swivel base (actually, I pulled it out of a scrap bin, and was told to "take it").  It is a nice base, but I know it isn't a Bridgeport.  I was hoping someone had their vise off their mill and could take a quick measurement.  I was totally prepared to take my vise off, and take the measurement...……..just not until I finish what I have it setup for.  So, my impatience (and to a certain degree my "laziness") compelled me to post the question.  I am not offended or angry, I am just befuddled how this thread took the turn it did.  I didn't want to drive to the shop, disassemble what I have setup, then have to "dial" everything in again.  sigh.

Robert (Bob), I truly appreciate you taking time to get me a diameter.  Thank you.
Winegrower - your comment is well taken and I agree with you.


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## Dynahoe Dave (Jan 5, 2019)

The pivot pin on mine seems to be 1.000"  Not a lot of it to get a measure on from the bottom though.
Do replacement jaws exist?  The originals have been machined a bunch of times.  Or can I just get a nice piece of steel and make a pair?  What kind of steel?


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## tfleming (Jan 5, 2019)

Dynahoe Dave said:


> The pivot pin on mine seems to be 1.000"  Not a lot of it to get a measure on from the bottom though.
> Do replacement jaws exist?  The originals have been machined a bunch of times.  Or can I just get a nice piece of steel and make a pair?  What kind of steel?



Replacement jaws can be found, but you are probably better served to make a set out of mild steel like 1018 or 12L14 (unless you want hardened ones).  Both are easy to find and machine fairly well (12L14 machines the best)  You could also make them out of 4140 and head treat them if you wanted to, but they would have to be ground true again after the heat treat.  Personally, I would just make a couple of sets from mild steel, and replace them as needed.


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## Bob Korves (Jan 5, 2019)

My old BP vise also came to me without jaws.  I made new ones out of 1/2 x 2" 1018 steel, and finish machined the working faces when mounted in place, 7/8" 4 flute end mill on the faces, also finish cut the sides and tops of the jaws to match in place.  After about 7 years of use, the jaws still look like new.  I don't abuse them.  I have had no problems with the BP vise, it is carefully made from good cast iron and a nice heavy Acme screw.  It uses box ways for aligning the movable jaw with the full width bed (no hole in the bottom like a Kurt).  The vise can be finely fit by making the bed and the movable jaw slide flat, square and parallel, top and bottom, and then adjusting out any play between the bed and the movable jaw by carefully refitting the gibs to the bottom slides they ride on.  It was quite close as it came to me, well used, but not abused.  Now, with a 2" diameter piece of round steel mounted between the jaws and clamped as tight as I can by hand, the movable jaw lifts by a tested .0005".  It is cleaned up, painted, and looks and works to my complete satisfaction, no Kurt in my sights.


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## Winegrower (Jan 7, 2019)

Bob, I never thought about machining the jaws in place!   Thanks for the idea!


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## Bob Korves (Jan 7, 2019)

Winegrower said:


> Bob, I never thought about machining the jaws in place!   Thanks for the idea!


It doesn't work so well on hardened jaws, unless you have a grinder , but it works just fine on mild steel and soft jaws.


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