Broken brake: what all goes into getting at it?

plastikdreams · Oct 11, 2020

The brake on my bridgeport at work was acting weird, sometimes it would not rotate, and the rotation the get the brake to engage was over half a turn. Well the roll pin let loose, I can pull the handle out and see the remaining piece still in the hole. So my question is, how hard is it to get at the brake mechanism and how does one go about it? Are there any tips or tricks or is it just take it all apart, replace part, and put it back together?

For posterity it's a 2 hp series 1 J head varispeed with the open dial not the plastic cover.

The last approved vendor dropped off the list so getting them or another on takes basically an act of congress. I'd rather not have maintenance mess with it as I know how they work...so if it's gotta get done, I'll just do it myself. It's been down 2 weeks already and I'd like to get back on it.

Thanks in advance.

jhruska · Oct 12, 2020

The top end has to come off, motor, housing, ect.
Run head to lowest rpm.
Lock-out and tag the electric.
Separate forward-reverse switch from housing.
Remove motor, invert it and stand it on the table if the electric cable is long enough.

If the lock nuts are removed from the speed adjuster the rpm will have to be reset to match the dial.
If adjustment is needed just match the low end rpm to the dial. Should be good for both Hi and Low range.
Regards, John

plastikdreams · Oct 12, 2020

Oh man that's great info, thanks so much!

Newman109 · Oct 14, 2020

What Jhruska said!

I didn't have a brake problem when I got my Webb clone, but I had a broken bevel gear on the down feed worm cradle, So, I striped the head down to the brake level to clean it up and replace the belts while I was at it.

Working alone as I have to, I had trouble removing the motor and top housings. I turned the head over 90 degrees and worked on it that way. It made the job a lot easier.

If you do rotate the head to do the work, make sure to give some support when raising the head back up since the gears can be damaged if too much strain is put on them.

The manual is available online if you haven't yet picked one up.

Happy wrenching!

jhruska · Oct 15, 2020

The bevel gear problem is a surprise as that is reasonably indestructible. Perhaps there was feed engagement at high rpm?
I worked on a CNC Webb mill that is essentially a beefed up Bridgeport without the rotating-nodding head. It was always difficult to
pull the motor out. The last time I removed the top end, housing - motor - front disc as one unit rather than pull the motor.
John

Newman109 · Oct 15, 2020

jhruska said:
The bevel gear problem is a surprise as that is reasonably indestructible. Perhaps there was feed engagement at high rpm?
I worked on a CNC Webb mill that is essentially a beefed up Bridgeport without the rotating-nodding head. It was always difficult to
pull the motor out. The last time I removed the top end, housing - motor - front disc as one unit rather than pull the motor.
John

When I got the mill, he down feed was intermittent when tested. Disassembly showed that one of the two gears had three teeth missing. I replaced both gears and all was well. The pair cost me $90.00.

The bevel gears are quite tough but can get damaged when operators use the down feed for large drills. The manual sates that drills larger than 3/8" should not be used with the automatic feed.

I now only ever use the down feed for boring work. For drilling, I use the hand lever when I don't use my drill press.

gustafson · Oct 15, 2020

If yah have real three phase, who needs a brake.....

Newman109 · Oct 15, 2020

I use my brake to hold the spindle from moving when I tighten up the drawbar.

gustafson · Oct 15, 2020

Newman109 said:
I use my brake to hold the spindle from moving when I tighten up the drawbar.

Wussy!

I think only on step pulleys did I need to do that

Newman109 · Oct 15, 2020

gustafson said:
Wussy!

I think only on step pulleys did I need to do that

Well, the damn drawbar is about 8' in the air and I've only got 2 hands. LOL.

Just holding the brake lever down gently allows me to tighten up the drawbar. Someone else may have a better idea.

Wussy? It sounds like you've been talking to my wife, although she's more colorful in her language.

:rolleyes5:

plastikdreams · Oct 15, 2020

gustafson said:
If yah have real three phase, who needs a brake.....

Oh we have plenty of real 3 phase here lol. I think we have direct feeds from 2 separate sub stations.

CarbideBob · Oct 15, 2020

Rarely if ever touch this lever. One just plugs a stop.
But hand tighten drawbar one would need to lock the head so I can see that need but this is a dance.
Maybe drop into low speed and hit the wrench with a deadblow.
If gone it is not hard to take apart and find the failed competent. I always suggest people take many pictures as they tear in.
Bob

metalmagpie · Oct 15, 2020

H&W have posted lots of really good videos on working on Bridgeport mill heads.

H&W Machine Repair and Rebuilding - YouTube

I encourage you to take it apart. To get down to the brake isn't a hard job, nor does it require anything precision. The BP spindle brake is a very simple mechanism. You probably just need a few bucks worth of parts. Once you do the repair, you will gain a lot of confidence.

metalmagpie

Zap921 · Oct 15, 2020

gustafson said:
Wussy!

I think only on step pulleys did I need to do that

That's hilarious cause I must be a Super Wussy, mine tightens with air. I haven't heard that, Wussy, since the mid 70's which would have been middle school.

plastikdreams · Oct 28, 2020

So me and one of the maintenance guys tackled this job yesterday. Fortunately I find the maintenance manual for the bridgeports so we had that to use on paper. It took some trial and error in some places but we got it done in about 6 hours (we had to undo and redo progress of assembly a few times, some cleaning, and inspecting). Thanks to all who helped out, I now have my brake back and working as it should.

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