Bridgeport head noise

[mwill135]

Bought my first BP. J head step pulley 1hp. When I was buying, it was known there was a noise that appeared to be coming from the front pulley. Seller said they thought/assumed it was a bearing. The only thing that would alter the noise was - the lower the belt was on the pulley the louder and more prevalent the noise. As you raised the belt on the pulley it seemed to abate. I’ve begun the disassembly and the front pulley seems to be fine. Bearings and all other parts seem good. I know it’s hard to diagnose from just a written interpretation but was hoping someone may have had similar experience and could shed some light. Thanks

[oxford]

Step pulley or vari-drive head?

[Fasttrack]

A grinding, gravelly noise?

It's probably the dog clutch dragging. First thing to check are the two pins that track along a slight spiral on the collar that you turn to disengage / engage the clutch when going into backgear. They will loosen up and / or wear out with age, causing the clutch to never fully disengage - the result is a gravely noise or even a distinct clacking noise at lower RPM.

[Rich Carlstedt]

He mentioned it is a step pulley
What kind of noise, Clinking , knocking, rumble ?
Same noise in reverse ?
same noise with quill fully extended ?
Same noise with belt tension loose or tightened ?

Rich

[Doozer]

A grinding, gravelly noise?

It's probably the dog clutch dragging. First thing to check are the two pins that track along a slight spiral on the collar that you turn to disengage / engage the clutch when going into backgear. They will loosen up and / or wear out with age, causing the clutch to never fully disengage - the result is a gravely noise or even a distinct clacking noise at lower RPM.

These pins you mention are sometimes a problem.
They are in a thin section of the aluminum casting.
The threads are 1/4-32 or 5/16-32 if I remember
and sometimes pinned in place. I have seen
Bridgeport heads with an extra set of tapped holes
from the factory, presumably to use when the
original holes strip out. Seen this a few times.

-D

[Fasttrack]

These pins you mention are sometimes a problem.
They are in a thin section of the aluminum casting.
The threads are 1/4-32 or 5/16-32 if I remember
and sometimes pinned in place. I have seen
Bridgeport heads with an extra set of tapped holes
from the factory, presumably to use when the
original holes strip out. Seen this a few times.

-D

Yep. I just rebuilt one at work that had 3 sets of pins, one set 90* out from the other, and one about 60* out, presumably drilled by someone else after the other two(!) sets wore out.

[mattthemuppet]

there's a plastic (delrin? phenolic?) pulley sleeve that commonly wears out in those step pully heads. There are alot of guides out there for diagnosing and repairing it. It's pretty straightforward from what I've read. I even had someone offer me a BP step head for $800 or so that had that noise. Would have jumped on it if we weren't about to move across the country

[Doozer]

there's a plastic (delrin? phenolic?) pulley sleeve that commonly wears out in those step pully heads. There are alot of guides out there for diagnosing and repairing it. It's pretty straightforward from what I've read. I even had someone offer me a BP step head for $800 or so that had that noise. Would have jumped on it if we weren't about to move across the country

Not in any step pulley head I have ever seen.

-D

[Dave C]

Not in any step pulley head I have ever seen.

-D

Right. Those plastic bushings are part of the vari drive setup. +1 on the dog clutch dragging.

[mattthemuppet]

my apologies, I had confunded myself

[Tobias-B]

I've had the (old, worn, a bit chewed up) timing belt climb up on mine before- makes a hellofa racket.

Usually when I forget it's engaged, and run it backwards, then forwards, then backwards again.

t

[Peter N]

Have you run it without the drawbar in?
My J-Head Bridgy has a rattly drawbar, quietens down a bit with a plastic bush I made, but whisper quiet with the drawbar out.

[aribert]

Is there a difference in noise between back gear and direct?

On my step belt B'port head the splines or gear teeth (to lazy to pull up an exploded view to find the parts right now) are worn out. I can hold a tool in the spindle and rock the forward pulley at the top of the head back and forth in direct - and it makes quite a noise in use. Quiet in back gear. With too large of a cutter and too large of a cut, I have had the splines/teeth skip while in direct - that is an intense racket. Fortunately I was able to buy (2) step belt heads (no motors) at auction earlier this fall (for $45 +6% tax + 18% auction premium) and I will dig into my B'port head issue in late winter.

Several posters mentioned the pins in the slotted cam that raises/lowers the forward pulley. On my B'port head, these pins were worn flat and also caused a noise - I was able to diagnose this issue by slowly adjusting the lever that actuates the pins in the cam. As I moved the lever, the noise changed and then became much less.