# Bridgeport 9X42 Table needs to be Re-Ground



## Janderso (Apr 5, 2018)

I would like to know if any of you have had this done, if so how much does it cost?
I love this old beast (1970 step pulley system) and I don't mind putting some money in her to freshen up the precision.
I have heard of Chicago Grinding and they suggested someone in the West Coast to save on shipping costs. I have not found anyone. There are several companies that look down at this kind of work I recently found out.
Thank you very much.


----------



## benmychree (Apr 5, 2018)

I was told that regrinding (only) the table top can cause the whole table to distort, this by a machinery rebuilder in Berkley Ca. who is no longer in business.  There is or at least was a rebuilder in Fresno; also a good question to ask Richard King on this forum.


----------



## Janderso (Apr 5, 2018)

Calling Richard King.
 I have read good results from regrinding, that's interesting. I was told also by Chicago Grinding and Machine, the flatness depends on the underside as they lay the table on a flat surface of the grinder and go to town. "As long as the table has not been butchered up on the bottom it should clean-up good".
To Chicago and back it's almost $400 and 15-20 days in transit.


----------



## benmychree (Apr 5, 2018)

Rich is teaching a scraping class in Vacaville right now; I forwarded this thread to him at his e mail address.


----------



## tertiaryjim (Apr 6, 2018)

You havent given any information of the table top condition or any pictures.
If it's warped even  a small amount on top it will be warped on the bottom also. Hey, its one big hunk of iron.
So, the dovetails need to be checked and if you repair those of the table the knee must also be done.
Some warp can be peen'ed out to help it. Don't peen working surfaces. If it's not bad it can be scraped.
Rich is the person to talk to.


----------



## Richard King 2 (Apr 6, 2018)

99.9 % of Bridgeport tables and other brand machines, that are off the old machines.  (older then 15 years, as I have never rebuild newer then that) the Bridgeport table is bent or bowed high in the middle.  I used to think it was because they were so long and unsupported.  But a friend and who used to teach Engineering at Penn State I think it was, Archie Chiba who used to be a frequent advisor on PM, told me they bow because when the machinist vise is tightened so many times over years the T slots stretch the metal. Or he called it "peen" the table..I only thought peening was from the hammer.  At first I thought that was BS, but as I worked on them and asked other rebuilders I discovered he was right  (unlike what some think I listen and test others ideas.  As my Dad used to say "when you stop leaning your dead"!

I have tested peening the bottom of Bridgeport tables and have successfully bent them back by peening the bottom ribs and middle sections of the table advoiding the dovetail castings.  The 20 or so tables I have tested average about .008" bow.   

I have experimented on how to test them.  after you stone or sometimes file the table top because the T-stots are raised up or burred up or some bozo (Tom Lipton says that a lot as he is one of my students this week)  some bozo dropped or scratched the table.  Then set it on 4  1-2-4 blocks on the flat ways on a granite or cast iron surface plate.  Then using a height gage / .0005" indicator make all 4 corners the same height height.  You set the 1 2 3 blocks at the Airey points (approx. 30% from each end) and tap the blocks  with a rubber hammer to move them on the curvature to raise and lower the table corners and then check the entire table. 

More later as I need to get to class.  Gluing Rulon (Turcite) today and the students start there projects.  Oh,  and John thanks for  the scrapers.  I hope you can make it to the class in Oakland.   John is a great machinist and good rebuilder who helps me in the Oakland classes.   Rich

PS:  There is super grind shop the CA rebuilders use between SF and LA called Shafer Grinding.  They do great work and are reasonably priced.


----------



## Janderso (Apr 6, 2018)

First of all, I am new to machining. I don't know the questions to ask. Regarding accuracy, I have no illusions, this machine and table are well used but, the head is quiet, the back gears are also running with no objections. The table has milling marks, drilled holes and has no flaking left except on the outboard edges. I assumed out of ignorance a regrind would bring it back to plum. For the price I paid I am very happy with what I can accomplish with this analog piece of equipment, the backlash is not bad, I do not have a DRO. 
I appreciate the information, especially excited about a west coast shop!!


----------



## tq60 (Apr 7, 2018)

Is the table not true or ugly?

If re grinding because ugly pause...


If because not flat above postings are new and interesting things to consider. 

Richard always brings interesting things to cause us to think more.

One must consider their planned operations and needs before attempting to bend the table true or regrind and hope it stays true after grinding, read what Richard has posted relating to these things as he is the expert there.

If one is primarily doing small work in a vice and the limited movement of table varies much less than expected tolerances than spend time and effort on other things for now until the need for true table warrants it.

If due to ugly...

Ours had a few places where an end mill shifted hole cutting and cut into the table and that was deemed ugly.

Went over to the bench grinder with a magnet and collected a bit of ground up iron then cleaned table with acetone and mixed a small batch of epoxy then added the iron and made a paste.

Filled the holes then later made flat to table.

Hard to find them now and supports things on table fine.



Sent from my SAMSUNG-SGH-I337Z using Tapatalk


----------



## Janderso (Apr 9, 2018)

First of all, I am frustrated with tramming. The table has so many milling gouges and drill holes I’m not sure how to do it. I trammed the vice to get square and 90 degrees to the head.
I guess I could lay a precision ground straight edge on the table to make an effort.
I don’t plan on doing any precision milling but I need to have confidence a pass from one side of a piece produces the same depth.
Squaring up stock, I haven’t tried that yet, I have a 2x2 piece of cold rolled stock a foot long, I could cut it to 2 inches and make a squaring effort.
Ugly or not true? Ugly! True? Not sure yet.


----------



## Eddyde (Apr 9, 2018)

Janderso said:


> First of all, I am frustrated with tramming. The table has so many milling gouges and drill holes I’m not sure how to do it. I trammed the vice to get square and 90 degrees to the head.
> I guess I could lay a precision ground straight edge on the table to make an effort.
> I don’t plan on doing any precision milling but I need to have confidence a pass from one side of a piece produces the same depth.
> Squaring up stock, I haven’t tried that yet, I have a 2x2 piece of cold rolled stock a foot long, I could cut it to 2 inches and make a squaring effort.
> Ugly or not true? Ugly! True? Not sure yet.


You can use a trued brake rotor as a tramming aid, just lay it on the table roughly centered on the spindle and you can sweep the indicator all the way around.


----------



## Hukshawn (Apr 9, 2018)

Isn't it better to tram to the vise than the table? Or at least retram to the vise?


----------



## Eddyde (Apr 9, 2018)

First tram the head to the table then tram the back jaw of the vise to the X axis.


----------



## woodchucker (Apr 9, 2018)

Janderso said:


> First of all, I am frustrated with tramming. The table has so many milling gouges and drill holes I’m not sure how to do it. I trammed the vice to get square and 90 degrees to the head.
> I guess I could lay a precision ground straight edge on the table to make an effort.
> I don’t plan on doing any precision milling but I need to have confidence a pass from one side of a piece produces the same depth.
> Squaring up stock, I haven’t tried that yet, I have a 2x2 piece of cold rolled stock a foot long, I could cut it to 2 inches and make a squaring effort.
> Ugly or not true? Ugly! True? Not sure yet.


I stick some thick parallels on the table to tram. This averages out the table to the top surfaces, which is where your parts will ride usually.


----------



## agfrvf (Apr 9, 2018)

Stupid thought of mine for beautifying old tables; how about silver soldering the holes and gouges then sanding them smooth?


----------



## bfd (Apr 9, 2018)

I have seen tables filled with a high grade metal epoxy then smoothed. this worked very good. the epoxy is a commercial brand called belzona. I don't know if you can find it. note: the dust of this epoxy is magnetic. bill


----------



## Janderso (Apr 9, 2018)

Interesting you should mention epoxy. Someone has performed this fix on the vise and the table.
Ugly but fills the void.


----------



## Alittlerusty (Apr 9, 2018)

Ugly tools can make beautiful parts too


----------



## bfd (Apr 9, 2018)

janderso, above you said "fills the void" is that an intentional pun bill


----------



## woodchucker (Apr 9, 2018)

agfrvf said:


> Stupid thought of mine for beautifying old tables; how about silver soldering the holes and gouges then sanding them smooth?


I doubt that would work. The large cast iron table would be a heat sink and suck the heat away giving a cold solder joint... just my opinion.


----------



## dlane (Apr 9, 2018)

JB weld, table covers, disk brake rotor, good to go !


----------



## Dabbler (Apr 9, 2018)

> Stupid thought of mine for beautifying old tables; how about silver soldering the holes and gouges then sanding them smooth?



I think it is a idea that is pondered by a lot of guys.  I agree with woodchucker, and worry that using enough heat to make it work might have some unintended consequences for the straightness of the table.

If your surface is pitted it may be enough to ensure all the upraised burrs are stoned flat.  You only need 4 good points on the table to get it right, any intermediate points and pits are a pain, but don't matter so much.


----------



## Cadillac (Apr 9, 2018)

If you have drill marks or worse slots or sorts. Mix up some good high strength epoxy and grind up some cast iron and mix in with the epoxy then fill voids. Follow up with sanding and stoning. Might not see depending on your mixture?
A rotor will get you in a good ballpark. But not dead on! Your table is trammed in the spot you performed it,when you move the table depending on wear your tram goes out. Just something to think about. Fill the voids if there,stone the table,mount the vise and make some chips. We'd all like a freshly scrapped table


----------



## Richard King 2 (Apr 11, 2018)

I have epoxied and milled or drilled out and made cast iron inserts and pressed or epoxied them in.  If you only have a few I would recommend Devcon Aluminum metal filler as it shines like cast iron.  If you used plastic steel it turns black and it is easy to see it's a fix.  I have had bad luck with Belzona and it is spendy as heck.   Recently I have filled voids in Cast Iron with Muggy weld alloy 5 solder.  It melts with a propane torch.  With all fillers you need to open the bottom of the hole wider by grinding it like a cone or bottom is wider then top to help anchor it in.  Also you should use a heat gun or propane torch to sweat out any oil that has crept into the pours of the iron.  I use a propane torch and after it cools wipe with white cloth and use brake cleaner or an arosol that gets cold as it evaporates.  BE SURE IRON IS COOL or you may burn down your shop...lol.

If you mill or drill out the table and your going to use an insert, be sure to drill a small hole thru the table so the air can escape as long as it's not thru and into the ways.   I have also mixed cast iron into epoxy and I never heard back from the machine owner.  In my business, no news is good news.  
Rich


----------



## Janderso (Apr 11, 2018)

Great ideas and thank yo Mr. King.
I think I will try to find a couple points on the table that aren’t marred. It should be doable to tram that way.
I have decided to get to know this old girl a bit more before I spend the money. Heck, ugly makes good stuff right?


----------

