[v488]

After MUCH time and money rebuilding my V2XT head i'm not at all happy with it. (chair) I put all SKF brand bearings in it and the motor also. I replaced the front Veri-speed plastic bushings. The rear Veri-speed bushing was the Teal colored one, i pushed it out and made a replacement becaulse thay can not be bought without pulley. When i run it there is some vibration, it must not take much runout to caulse vibration. The NEW timming belt is very loud. After 1 min. running time at 1500rpm. i put my finger in the hole in the front top of the Veri-speed housing where the top support bearing is and that hollow shaft is HOT! Could the front Veri-speed pullies be getting hot from the Veri-speed belt? I have ran NEW, used & rebuilt B-ports and when there in good condition you can't hardly hear them run. Any Ideas? thanks

[machintek]

Noise is usually typical of some sort of problem. I have rebuilt many heads but I have to guarantee my work so I do NOT glue in new bushings. I replace the varidrive discs as units. This because I have not made a fixture to assist glueing in these bushings in such a way that the discs will run true. remember also that these are BALANCED at the factory.
Where did you buy your parts? Was it from Hardinge? When we were having problems getting parts during the Bridgeport bankrupsy, we found out that the vari-drive belts had a proprietary angle and the OEM would not sell to us. I have heard of people that purchsed generics and they have worked.
There will be some heat generated by the varidiscs as the belt is always climbing a disc and working against that spring. Friction causes heat.
Are the shafts in good shape? Keyways?
Run it in neutral ans see if you still have the noise.

George

[widgitmaster]

Try loostening the three screws that hold the bearing on thr top of the spindle, i have had re-builds that needed to be shimmed!

Eric

[NC Cams]

The words "bearing" and "press" in the same sentence send chills up the spines of most bearing engineers.

Why?

There is a tremendous problem and/or potential with/for damaging bearings while pressing them into place during installation UNLESS PROPER CARE AND FIXTURING ARE UTILZED.

For example, if one presses a bearing onto a shaft and does not press squarely on the inner race only, you can gall the shaft. This distorts the inner race and causes noise/heating problems.

If you press the inner ring on by applying force to the outer ring, there is a VERY high probability of brinnelling the inner and outer raceways. THis non reverseable phenomenon WILL cause noise and overheting problems.

Pressing outer rings into housings (especially bulky assemblies) is hard to do. It is easy ot brinnell the raceways and/or gall the housing if a press fit is involved. In such instances, thermal fit is the only safe assembly method (freeze bearing/heat housing/slide together).

Although it takes more time and preparation, I use/recommend the thermal shrink fit method of installing bearings WHENEVER possible. Stuff literally falls together when you do it that way.

Too difficult???

Union Pacific Railway shrink fits HUGE traction motor bearings into housings. They use a deep freeze to store the bearings and rosebud torches to heat huge cast iron diesel electric motor housings. The bearings are nearly 18" dia and they literally FALL into the housings and run 1/4 million miles with no issues. You haven't seen a bearing removal hassle until you have to remove the truck from a diesel electric locomotive.

I'm not saying that you DID ruin the bearings - the bearing would have to be professionaly inspected to determine that. But I can say the each and every bearing complaint we ever investigated where a bearing was noisey and or hot after installation was traced to installation deficiencies.

Interestingly, this mallady befell parties who "had done it that way for 20 years" as often as parties who'd done it for the very first time - sometimes more often.

PS: chances are the bearings were fine when they were manufactured - anymore, most mfrs do noise tests to certify "electric motor quality) prior to shipment hence it would be unlikely that that a noisey bearing would get out....

[machintek]

That top bearing should float in the housing. There is a wave washer on top of the bearing between it and the housing. If there is no room there, then there is a problem with tha way it was assembled.
Ditto for the bull gear bearings. There is a wave washer there as well. As I think about this, there is another wave washer on the pinion gear to the rear of the bull gear.

George

[NC Cams]

Wave washers apply preload to the bearings to keep them from "preloaded" (strangely enough). A cracked or omitted wave washer would result in insufficient preload which will allow noise/vibration to occur. I'd doubt, however that this would cause heat.

If the raceways were brinnelled due to assembly deficiencies (improper pressing or God forbid hammering on bearings), TOO MUCH preload (IE too many or wrongly installed wave washers) will result in noise (from brinnell marks) and heat from brinnell damage and/or too much preload.

[v488]

OK, thanks everybody for the info and advise. I was saying in my first note that the timming belt was wienning loud. Like the blower belt on a Hot Rod engine! I heard the timming belt noise and a rubbing sound by just turning the head pullies by hand. So, i took to hole head apart and removed the timming belt. Now theres NO rubbing or " gear belt" noise when i turn the front Veri-speed assembly. I put the top housing on to keep the front shaft straight when i did this. The belt is NEW, says made in USA but no brand name. This mill sounded the SAME way before i rebuilt it. Very loud belt. The timming belt in my other B-port is silent. Any ideas? I can't see that this has anything to do with the HOT problem, maybe its just normal heat generated by the Veri-speed pullies. The heat is in the front pulley an the rear stays cool. thanks Mike

[HuFlungDung]

I wonder if you have a problem further down in the reduction gearing? Maybe a bad bearing allowing the VS pulley to tilt, or something. That heat has to come from something that is fighting back and doesn't want to be turned by the pulley.

How does the angle of the belt match up with the pulley angle? It is a corrugated VS belt, I assume, not a timing belt, nor a timing pulley.

What about the brake? Is there a brake on that one that is out of adjustment?

[machintek]

I wonder if you are missing the bottom flange on the spindle pulley hub. The lack of this would allow the timing belt to slip down and rub on the aluminum plate that covers the bull gear cavity causing noise and heat.
It is common for the bearing supporting the front bottom varidisc to start eating away at it. This causes a lot of problems with the alignment of all the parts on the associated shaft.

George

[v488]

I do have the flange on the bottom of the pulley. The belt is ridding UP away from from the aluminum cover plate. The thick steel warsher/spacer at the top of the front timing pully has wear on it from the belt but so does the other mill i have that runs great. The belt does not track in the middle of the pullies but i don't know that any of them do on any mill. The big timing pulley had LOTS of wear on the teeth, i replaced it with a VERY good used one i had. The brake is in NO way dragging. thanks mike

[BptRoadman]

Run the thinnist feeler gauge you have around the nose piece... it's the hoobie that you unscrew to get the spindle out. I bet it's touching. Symtoms are the spindle gets hotter then hell and a high pitched noise but sometimes no noise at all

[PJB]

Here's my 2 cents:
the bearings you installed are perhaps RS for rubber shield. Lots of friction heat. Try metal shield (ZZ) or a low contact rubber seal.
Motor belt, probably a Gates with diffent pitch on the cog cutouts. Browning or Bando is good.
Good luck.

[v488]

I replaced the timing belt with a good used Gates from another Bport, the noise and grinding sounds are gone. The heat is still there, i'm going to run it untill whatever is getting hot " burns up " !

George, can you tell me about what i will pay for the 2 veri-speed pullies and veri-speed belt from Hardinge. Maybe who to call also. Thanks Mike

[BptRoadman]

It's your machine Dude.

[machintek]

Call Alan at my office at central time. 1-800-245-2598. He should be able to tell you.
1-800-243-4292 used to work nationwide to get you to the nearest Bridgeport dealer. i do not know if it still works.

George