Want to hang from v2xt

[9 1/2]

Thanks NC,
The vendor indicated this unit was all original including the rotary.

[v488]

NC Cams, great infomation! I'll check on my bearing #'s. I tossed the boxes. The bearings i'm running now came from Hardinge and i was told thay are the same parts thay are using in the new built Mills. My biggest upset is that i'm flat broke $$$ with the mill now. I have another set of bearings sealed in plastic bags. NSK DM177 7207C SUMP4 JAPAN D also NSK DM180 7207C SUMP4 JAPAN D #'s on box are 714072075 7207CD/P4DBA Boxes where taped together and says 1 pair. I'm sure these are Angular Contact. Are all angular contact bearings unsealed? Without re-inventing the wheel it would be HARD to get oil to unsealed bearings. On a V2XT there ia a Ball Screw bolted to the top of the quill and this blocks off any oil cup and drip set up. WELL as i'm typing and thinking, it could be possible to do! Could the unsealed bearings be greased, one time i made some delrin rings that pressed onto a spindle bearing spacer and set against the bearing to help hold grease in.
If the angular contact bearings are the way to go i would put the effort into the mill housing for oil. I've read many places that the DEEP GROOVE bearings don't make good spindle bearings.
I've got another b-port mill that was rebuilt in the early 90's and i bought it from the shop where i was working. It has angular contact bearing and theres never been a problem with it. I'm sure the rebuilder KNEW what he was doing!! I think it was somewere in RI. ? Thanks

[NC Cams]

The 7207SUMP4's are 207 sized, single universal ground (mountable in single, DB or DF position) and a medium preload with P4 (ISO equivalent to ABEC 7).

These should give you great performance and accuracies in the lower spindle mounting position, espcially compared to the 11190238 OEM bearings that were in there if/when Bridgeport made the machine. These bearings were originally modified 6207's that were hybrid ABEC 3's in some areas and 7's in other areas.

If you use the 7207 NSK's, make sure the lower bearing spacers (12193513, inner and outer) are ground EXACTLY the same axial length as each other and the ends are ground perfectly parallel.

You could grease them with about a 25% or so fill and this should be fine. I suspect that the oil that is in the original reservoir actually provides lube to this lower bearing - the OEM bearings did not call out for a grease lubed hence the lube must have come from the spindle reservoir.

If the spindle bearings were dry (not oily at removal), the grease pack should suffice. USe a grease that is compatible with the spindle oil that you're using. As in a mineral grease with mineral spindle oil. Not a good idea to mix synthetic with mineral unless you KNOW it is OK

Yes, deep groove ball bearings (DGBB), AS IS, are not good spindle bearings because they are not preloadable and not of the accuracy potential of A/C's. Bridgeport used DGBB"s but they had them specially modified to have them preloaded. A/C's are far superior in accuracy but more costly.

Bridgeport got psuedo A/C performance at almost DGBB price with the special bearing tune ups they did. In the day, this was viable - in today's environment, it is more cost effective to simply install A/C's. More costly but far better performance and accuracy with "bolt in" parts.

IN the long run, you pay more for A/C bearings but don't have to futz with assembling the machine over and over to get it to cut accurately as you do with DGBB"s.

Now, once you install the bearings, where do you plan to have the spindle ID reground??? Unless you do that (grind spindle to run true with new bearing axis), you'll never cut anything smoothly or accurately. Hardinge and Bridgeport ground the spindle ID's whenever they assemble a machine tool spindle. This IS the ONLY way to assure accuracy.

If you want a dead nuts spindle in Z direction, replace the 11770118 screw support bearing on Z axis with a 7014A5TYDUMP4 or P5 grease lubed A/C bearing - mount it in DB. These 7014's will be smoother, more accurate and stiffer than the 9114 Fafnir's that Bridgeport originally used in this position

[NC Cams]

9.5: did you get the machine yet? What can you tell me about the 4th axis?

Is your machine a BMDC based unit? Can you identify who made the 4th axis? OEM system was supposedly Troyke. Is yours an indexer or true servo driven 4th axis???

Any interest in selling the 4th axis, especially if it is plug and play servo system with a BMDC based system?.

We've been looking for a 4th axis and can't find a lot of info on/about the OEM version. Anything you can do to help/share info would be appreciated.

[9 1/2]

No I've not yet recieved my machine. Last word was it is now enroute via truck freight.
The 4th axis is a troyke.

[9 1/2]

but when i get it. I'll be happy to offer what ever help I can with it, pictures, numbers, general info as you may need.
Sorry I'm not planing on selling it though.

[NC Cams]

I'm looking for a 4th axis for mine and haven't scored or found any yet.

Tried HAAS but they are too much of a PITA to deal with and, besides, the HAAS units don't have the tach needed to interface with the BMDC system even if you could get them to provide one with a DC motor.

Where did you find yours? If its not too personal, what did you pay for the package? I'll probably have to contact Troyke - they said they'd be able to build me one if I sent them a servo motor - I scored a full set of 3 OEM servo's and Motion Science servo amps from a guy who was converting an older FMDC based V2XT system to MACH and steppers.

[v488]

NC, I'm getting ready to try my 3rd. spindle rebuild for the v2xt. I like the A/C top support bearing idea, thinking about doing it. Do you know of a good bearing seller to go to for them? I got a used spindle shaft off Ebay i'm going to try to use this time. The last guy that ground the taper said there was nothing left to grind on the other one ! Thanks Mike

[NC Cams]

Before you get too far into the process, look up "Bridgeport spindle" or "Bridgeport spindle rebuild" on the 'Zone. If you can find the thread, I explain exactly WHY they used selectively sized bearings on the OEM spindle builds.

If I were doing a spindle tune up, I'd first check the spindle OD size and make sure it is NOMINAL for the particular bearing fit desired. If not, I'd find someone who does jig grinding and grind an oversize OD down or chrome plate oversize and then regrind to size an undersize spindle. This way, you could chuck on the ID to some extent and not have to do a tremendous amount of ID grinding to make the collet register properly.

However, when you get the whole thing reassembled, you WILL want to have the ID touched up by a GOOD spindle shop. At one time, Pope had shops in various places around the country. You might even find a jig grinding shop who could do the work for you.

Don't just drop off the spindle - ask around and go visit some shops. Ask for and then consult references. If you do that, you should be able to get a dynamite rebuild without having to go thru a lot of grief and/or heartache.

As far as bearings shopping, buy quality bearings (SKF, NSK, Barden, Fafnir or the like). Stay away from Ebay or generic bearings. You already know what bargain service can do to the performance of a spindle. Buy the best that you can't afford and you won't be disappointed.