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Auto quill feed problem on my Bridgeport

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Bernd:
Well when I went and bought the mill I asked. "Does the power quill feed work?" "Yes, it does." He shows me. Good.

After I finally got the machine in a running state I tried the auto quill feed. Worked fine until the drill touched the work. Then it stopped. I played around with it but couldn't get it to feed down. Ok, a problem to look into later. In the mean while I did a little research and found a good place on the interweb that has replacement parts for a Bridgy. I also found a schematic of the parts and part numbers. To bad you can't make out the pic to well since it is to small. So a little  :med:.

Well today I decided to investigate why it doesn't work. In about 3 hours time I had a majority of it a part and diagnosed what the problem was. Lets say it was  :jaw: and leave it at that for now. I've got a few pics to show and explain what I think happened. Yes, "Happened"  :bugeye:


This is the place that the engagement lever usually resides. Notice that bronze bushing in back? Also the gear at the top of the hole. This drives two sets of gears like on an outboard motor.


This is were the clutch resides with it's brass worm gear. The worm gear you see is the gear that drives the worm gear.


These are all the parts that fell out.  :bugeye: Just kidding. I had to remove them they didn't fall. :)


This is the shaft that the worm gear attaches to. Notice the pin and hole through the shaft? That my friends is a drive pin that apparently goes through the worm gear and fastens it to the shaft to keep it from spinning. If I stick the pin in the hole there is nothing sticking out on either side of the shaft. Conclusion, the pin is sheared. That's why the feed would only go down till the drill touched the work and no further. It was friction driving the quill. Now, why did the pin shear?


This is my conclusion as to why it sheared the pin. This is the drive clutch. Notice the spring? It's wound up tight. No spring movement at all. Somebody had screwed the thing together so tight that the clutch could not work when the down feed ran into something solid and couldn't go no further. Consequently the pin was the weakest point and let go.


Here's a view after I got the machine back together after the move into the basement. It's to help orient yourself on the parts of the previous 5 pics.

So, now I know what needs to be fixed, but, I need to get that worm gear out to pin it back on the shaft. Problem is that bronze bushing that you saw in the first pic is keeping from getting at the gear. From what I can deduce there are two ways of getting it out. One would involve taking the whole head of the machine. That's a big "NOT A OPTION" or remove the bushing. Problem is the bushing is stuck in there quite tight. I have in mind making a puller and getting it out that way.

That's about it for now. I'll post more as I get to fixing this problem.

Bernd

John Stevenson:
Those gearboxes are licensed from Timex   ::)

Done  many of these, just tap the first part of the bush and then pull it out with a length of studding, If you only put about 3 or 4 threads in you can still reuse the bush.

The book states that the power feed can only be used up to a 3/8" drill. That's pathetic on a machine this size.

John s.

CrewCab:
Bloomin eck John ................ is there now't you don't know  :bow:   .........   nice one, let's hope Bernd can now get his Mill sorted fairly easily then  :headbang:

CC

Brass_Machine:
A PITA I must say. Mr Stevenson has some good advice. At least at this point it looks like you just need to replace the spring and pin. Maybe the bushing if you wad it up. Thankfully (and hopefully) it isn't a hard to find expensive (more) gear or shaft or some such part.

I imagine with your ingenuity and skill it will be up and running by Sunday  :headbang:

Eric

John Stevenson:

--- Quote from: CrewCab on December 08, 2008, 06:33:25 PM ---Bloomin eck John ................ is there now't you don't know  :bow:   .........   nice one, let's hope Bernd can now get his Mill sorted fairly easily then  :headbang:

CC

--- End quote ---

When our local college packed the engineering side up we bought a lot of the machines, including 6 Bridgies, 5 manuals and one CNC.
Kept the CNC but sold the others on, everyone had the power feed stripped.
My manual has had the feed robbed to get some of the others working, To be honest i haven't bothered repairing it as i don't use it.

John s.

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