Need Help!- Replacing Bridgeport series 1 spindle bearings

[A.A]

Hello,

My Spindle was producing a lot of sound. i removed its belt to check whether this loud sound is because of motor or the spindle. The motor is running very smooth after removing the pulley. Then i tried to replace the spindle bearings but i am unable to remove the pulley highlighted by a black rectangle in the picture. i am trying to remove it with a three leg tool (same like bearing remover) with center at the spindle shaft it is taking too much force unless it jams hard. i have checked the drawings but there is nothing mentioned about any screw that may be gripping it there. Is there any one who has replaced the BP series 1 CNC spindle bearings ?

[mc-motorsports]

You probably need to properly support the pully from underneath and use a press. When you use a 3 jaw puller, most of the time in applications like this, you just bend the pully inward making it tighter on the shaft. In other words, you will "taco" that pully before you get it off using a 3 jaw puller.

Does the pully have threaded holes in the top? If it does, you can use studs threaded into those holes and a jack screw on the shaft to pull it off. Otherwise, alteast put a couple pieces of steel under the pully and use a shop press. A split ring on a shop press is best where you can support the pully 100% around it's diameter, that's if it's just press fit and there is nothing else holding it, of course.

[machintek]

To remove this, I usually removed the bottom aluminum belt housing. Turn it over and remove the two screws that hold this pulley assembly in the housing, Remove this pulley assembly from the housing.
Now I remove the snap ring, put it in a press and press the shaft down and out.

If the spindle needs to come out, remove the set screw in the back of the quill. Now the quill nose can be unscrewed. Then the spindle can be knocked out, bearings and all, as a assembly.

George

[A.A]

Hello machintek,

The spindle bearings will be replaced as per your instructions as i have removed the Aluminum belt bracket and taken out the pulley by press.

After doing that i observed that the actual noise problem was something else.The loud sound is coming out from variable speed system, the spindle motor during operation is also getting heated up. I have opened the motor pulley. The top pulley on the motor shaft which is fixed by key is OK, whereas the lower pulley which slide up and down compressing a spring has worn out bore. The soft lining on the bore is damaged. The portion of motor shaft traversed by sliding pulley is also worn out excessively.

Please suggest remedy i.e how to repair the worn out bore. The plastic key is also broken .Which plastic is to be suggested for the key ?

[gus]

buy em on ebay kit comes with glue, keys everything

[machintek]

3 things.
I replace the motor adjustable vari disc as an assembly. This because I have to guarantee my work and it is very difficult to glue in new bushings to run true in 3 dimensions. This applies if the original bushings were thin and black. The newer pulleys for the motor had thick green inserts which are not replaceable.
If the inside of the varidisc is damaged, i also would have doubts about gluing in new inserts.
If the shaft is damaged, I replace it with a balanced rotor and shaft assembly from Fife Pierce. Might as well replace the motor bearings too.

This motor adjustable vari disc problem is the most common problem with a bridgeport vari speed head.

George

[A.A]

Thanks machinetek for your help. Now i have came across another scheme. I want to make use of existing vari disc (2 Nos.) on spindle and (2 Nos.) on motor shaft with existing toothed belt and control want to control the speed of Spindle motor with VFD (Variable Frequency Drive). please give me your opinions whether it will work practically ? What problems can I face ?

"The idea is to fix the sliding Vari Disc on spindle motor and motorshaft permanently by using steel keys and set screws."

Regards,
A.A

[machintek]

I stick to stock machines and advice. Too many variables in modifies machines.
Many people have used VFD on these heads. Just search the posts and you will get a lot of data. So yes, it can be done.

George

[A.A]

Thanks macinetek for your help.