Swapping Bridgeport Mill Table

[widderj]

Hi Everyone,
I have 1963 vintage J head with a 36 inch table in atrocious shape. The ways on the machine are chrome and in reasonably nice shape but the table is not. I was wondering if anyone could tell me what is involved in putting a table in better shape on the machine. A friend of mine said that the table could not be replaced without having to scrape the saddle, and someone else who has a 36 inch table in better shape then mine but with the saddle said the same thing. Does anyone one know if the some holds true for the saddle and knee. That is can I put the better condition table and saddle on my machine or will there be problems with the fit? Any suggestions or comments welcomed.

Thanks in advance

Jeff

[Marty_Escarcega]

I would say keep the table you have and have the surface ground or rescraped by someone knowledgeable in the trade. Your friend is correct. Those tables were scraped to the saddle.

[jan3]

Hi New or used parts installed on this machine need to be fit.If it is a matter of the table top being in poor condition due to miss use ie holes drilled in it,I've seen good results by boring the hole for a tight fitting plug which is pressed in and machined close to table surface then stoned to a finish dimension.Any more than a few holes or if table needs to be welded will require grinding.

[Jon_Spear]

Maybe you can just mill the top of the table. You will have to swivel the head and extend the ram to reach the far edges.

For this to work, the swivel that supports the ram will have to be parallel to the horizontal ways of the table. If your original ways are in good shape, this should be true.

What do you al think about doing this?

Jon
San Francisco, CA

[Marty_Escarcega]

No, its not recommended. Because of the wear in the table/saddle ways, not to mention having to keep moving the turret. Having it reground by a competent grinder won't cost that much. I was quoted $100 some time ago. They will indicate it in and support it from the non worn areas on the machined surface that ride on the saddle.

[Bill_Cook]

Does the custom terrain on the table affect the accuracy or utility of the mill?
Taking something apart that's on line and ready, for a cosmetic issue, is a scary thought around here.
Will it become a tar baby? How many while I'm at its?
Alltime big fear..."It's over there in those boxes".

bc

[Doug_C]

I'd second that thought too.

Not only not recommended, but would create a nice looking severely warped/rutted surface, worse than an ugly one with swiss cheese holes.

Even as manufactured BP only warranted the accuracy over the saddle. Problems are caused by listing of the overhung weight as the table drops off each side of the saddle differently. Another factor would be no true reference to re-tram the head that would be reliable enough to make do. Creating a large flat surface on a worn machine is hard enough.

I have seen the plug method as mentioned previously, work the best. Depends on area and proximity to the T-slots so minimal strength is lost. With malible cast iron, one can form fit a shaped plug a bit high and peen the top surface to swell it tight. Once decked to height and scraped in flat, it is hard to see the repair.

DC

[widderj]

Hi everyone,
I want to thank everyone for their replies. My concern about the table is not cosmetics but function. In the middle T slot there is a mill cut that goes parallel to and directly over the slot along its edge and gets progressively deeper as the cut was made. The result is a weekend and widened T slot were my vise clamps to the table. If there is no acceptable solution I'll just work around any short comings as the need arises. I am on travel till the end of the week but when I get back I can take a picture of the table and post it. However I must pre-warn those with a week constitution that it is not a pretty sight.

Thanks again

Jeff

[AndrewMawson]

Jeff,

I would be tempted to mill out a suitably sized pocket on the table, and bolt in (socket cap scews)a piece of either decent quality cast iron or carbon steel.

I had a table that was covered in 'carelessness' drill and mill cuts on my Bridgeport, and I had them cast iron welded and reground, but I am far from satisfied with the result. The welds are very porous and themselves look unsightly, though probably don't cause any strength problems.

[mspaeth]

Hi
I have a bridgeport with a 36" table. When I got the mill the table was full on dings and dents with a couple of drill holes. I took the table to a machine shop recomended by my bridgeport parts supplier and had the table planed down to clean it up. Now the table is flat and smooth with just some minor drill holes. When I put the table back on I made a couple of 1/4" plywood guards to cover the table to protect it. The table is also very heavy so be careful when removing it.

[Doug_C]

Hi Andrew,

I had thought of that too. It would be strongest if the insert could be keyed to fit its own slot.

Yet, strength in the use of such an insert may be a non-issue. As anything clamped to the table should grip the casting in compression, never putting the T-slots in tension.

I have seen some tables where the T-slots are popped out due to driving a bolt through a T-nut that eventually creates enough pressure to fracture the casting.

DC

[DFWKen]

I'll want to have the table re-surfaced on my Bridgeport. At the same time, maybe I can figure out why the X and y axis both have .04 to .05 freeplay. Not much of a problem, but a nuisance.

The table of my 9x49 table looks quite heavy. Just how heavy is it? And are there any tips regarding disassembly?