Problem- Clattering in 2J Head Variable Speed

[tcalef]

Hi All:

I got this machine a couple years ago, and have used it probably twice a year. When I got it, the key in the motor was broken, so I just replaced that. After replacing the key, and starting up the machine, it makes a loud clattering, seems louder in the lowest RPM. From reading everywhere, it sounded like I needed bushings on the vari-drive disks. I started ripping into it tonight, and have it down to the point where I pulled the timing belt gears off. The only kind of clunk i can hear, with all this stuff off, when moving the spindle, is when i change directions, there is a slight metal on metal sound.

I've moved all the shafts trying to determine if any of the bearings are shot but can't find anything. I've also powered up the motor off the machine, and it spins nice and quiet. The grease under the plate below the timing belt seems to be stuck pretty much to the plate itself, i'm not sure if that matters.

Also of note, it seems that the nylon key in the motor has separated from itself, meaning all 3 sides of the key are broken off from each other.

Anywhere else I should look? I can take pictures of whatever and post them, just let me know what to look at.

[Me2]

I had the same issue with my Varriable Speed Head. In my case there were two causes. The first one was the draw bar was machined with only a small amount of clearance on the bore in the head. This is the diameter where the hex is. If it was slightly of center when tightened up it would whip and rattle in the bore. Machined it down and recut a smaller hex and fixed that problem.
The second was the retaining rings on the timing belt pully's. These are only thin aluminium and had cracked across the screws and lifted slightly, enough to hit the overhead casting structure. This caused a rattleing sound in the head. Had some new ones laser cut out of thin plate and I machined to suit. Now have a very quiet head. Maybe two area's to have a look at.


Cam

[tcalef]

Is this the pulley that you're referring to? Where is the retaining ring?



When i grab the shaft on the other end of this (which is still connected through the lower shiv of the vari-drive pulley) there is a little side to side movement, maybe a couple thou. is that supposed to be there?

[Me2]

No, it was on the large pulley. Check out -
BptParts.com: Bridgeport Machine & CNC Machine Replacement Parts
You will see the timing pulley and the retaining rings that screw onto the face of the pulley.