Need Help!- Bridgeport Boss 4 loud noise in head. It is alive...

[gschoep]

I just fired up the 3 phase spindle motor on my bought off craigslist Bridgeport Boss 4.

Got the steppers working with Geckodrive G201s, built a power supply, cleaned the whole machine and installed an Automation Driect GS2 VFD.

Turned the spindle motor on for the first time (in I have no idea how long) and there is a large thumping from the head. The spindle turns and the variable speed works (mine is manual with a handle that changes the speed) but the head sounds like a small airplane.

I did not run it long because I was worried about damage.

The belt is old, do they get so stiff that they need to be replaced?

I am very comfortable with the electronics of a CNC machine but the head of my Bridgeport is something I hope just works...

Is there any maintenance I should do before running a machine that has sat for quite a while?

[gschoep]

I did search for this topic before my post but found little. Searching again (at google using "bridgeport head noise site:cnczone.com") I found much more information. Here is a summary.

Head noise is commonly belt, bushings, bearings or something broken.

Belt noise is reported to be from when the spindle gets stopped and the varispeed pulleys keep turning and round out the belt. Belts also squeal. I assume that they also get old and hard but this is my assumption only.

Bushing noise (or broken keys) is what I was getting. It is a rhythmic thump or vibration. My machine sounded like a small airplane. Bridgeport vari-speed heads (mine is a 2J) have plastic bushings so one half of the pulley can slide on the shaft when the speed is changed (without having grease in the head). If the key breaks and/or the bushing wears out there is play both rotary and laterally.

In my machine the motor key was broken and the spindle pulley key was worn. Both the bushings need to be replaced too. I found a kit at H&W Machine Repair for $45. http://www.machinerypartsdepot.com/s...roduct/1036-20.

I will post my experience with this kit when it arrives. Tips or tricks anyone?

Bearing noise is reported to be a whir or a whine.

Things being broken (besides a pulley key) is reported to be a grinding noise.

It is reported that play in high gear (which I find the gear box to be 1:1) can be fixed by adjusting the gear change knob. My machine is old and the knob has to be loosened and rotated on the shaft so the detent is at a place that play (due to wear) is absent.

In low speed the ratio seems to be in 9:1 based on turning the spindle and watching the pulley turn. This might be useful if one sets the vari-speed to 1:1 and then uses a VFD to change speed.