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Okay,

I got a 40 taper spindle I'm disassembling for bearings replacement, apears the sleeve holding the inner races of the triplex bearing set at the taper end against pull-out forces is a shrink / press fit...I plan on trying to heat the sleeve with a torch while simultaniously cooling the spindle shaft proper in hopes that it will simply lift off...in the worse case, I spose I can simply turn the old sleeve off...

Soooo--in the case I do end up turning the old sleeve off.....(of course, I'll need to fab a new one)...this thing must bind solidly to the spindle shaft--under appx 2-1/2 tons of drawbar actuator force, otherwise the shaft is gonna get pushed out the front of the cartridge housing upon tool change...

Question...how much interferance fit should the new sleeve then have ?

Existing sleeve is ID of 65 mm and has an appx .25 wall thickness...and I'd guess its about 3 inches long...appears to be made of mild steel.

I'm thinking go about .005 undersize on the sleeve ID, heating the piss out of it then pressing it on should do the trick...but...

Reply to
PrecisionMachinisT
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BTW :

If anyone happens to have any bearings marked # 7013xxx or 2mm9113xxx sitting in their spares inventory, then I'd be interested in making an offer....

Reply to
PrecisionMachinisT

According to my Machinery handbook #26, page 625 (nice section on interference fits) this is a bit too much. The example shown on that page is similar to yours. The answer is .001 to .0012 in/inch of diameter or about .003 for you.

karl

Reply to
Karl Townsend

Er.... I considered doing the spindle rebuild myself on a Mori, a while back. Changed my mind once I really got into it, for some of the same issues you are looking at. The cost of potentially damaging and replacing the spindle cartridge far far exceeded the cost of having Pope spindle do it right. I just couldn't justify the risk. That's my advice....

ca

Reply to
clay

Do what I would do: Cheat and use Lock-tite...

--=20

-JN-

Reply to
J. Nielsen

A 400 deg temperature differential will give you about .006" increase in the ID of that sleeve. If you heat the sleeve to 500 deg, chill the shaft and don't screw up, I think it will work fine. I've done this kind of operation a few times and it can be screwed up. A big hammer and large press have never been enough to fix it once the stuff is in a bind when half way on, you just have to cut it off and start again. But, once on, I've never had a chinch fit slip.

Reply to
Polymer Man

Heating and chilling a precision spindle is not a good thing to do. There is a very good chance that it will deform it a little. If they are using a press/ shrink fit to hold the bearings in place, it sure is a very poor design. If it is the case the best way to remove the sleeve is to machine it off in a lathe and make a new one. Before I did anything to the spindle I would consult the mfgr.

Shrink fits are normally .001 to .0015 per diameter inch. Anything over that and you might either strech the metal or possibly crack it.

John

Reply to
John

Hardinge did put me into contact with an individual in Florida that had worked with these bridgeport on these machines back in the day, and he told me (quote) that is exactly what I'll have to do.

I'm expecting him to call back sometime today to let me know if the sleeve or blueprints for it are available from the former Textron folks England.

Reply to
PrecisionMachinisT

The british do some really screwy things when it comes to mechanical and electrical design and equipment. You're lucky you don't have Lucas electrical parts on that mill. :)

John

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Reply to
john

They already fanuc'ed the electronics enough as it were.

Reply to
PrecisionMachinisT

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