Trouble with high speed table travel- need advice-

[Bob V]

Hi,
I have a friend who is not connected to the internet.
He is working on the traversing mechanism for a Bridgeport mill.
I don't have a Bridgeport mill (I do have a Van Norman), but since he can't get advice on the internet I am trying to help him.
I will try to explain the problem as well as I can-- he told me about it on the phone.

The low speed table travel works fine. When the high speed is engaged, apparently two gears that are held together by a spring begin to chatter and disengage. The spring and gears are fine (not damaged), and the low speed travel is fine.
Two questions:
1. Where should my friend look for the cause of these gears skipping when the spring pressure should keep them together? Should he look for a stronger spring?
2. Does this "spring" act as a clutch of sorts to protect the machine from damage when there is too much resistance downstream?
Thanks in advance for the advice.
Bob

 

[T Bredehoft]

I'd disengage the power drive and see how hard it is to turn the crank by hand. Sounds like High Speed encounters resistance that Lo Speed doesn't. Check the gibs.

 

[Bob V]

Thanks, Tom
I had already told him to check the gibs. I also suggested he check the backlash collars on the lead screw for the traverse--but I don't know if the setup is the same on a Bridgeport as it is on my Van Norman.
Much appreciated
Bob

 

[seasicksteve]

Lyman MK 7 power feed attachment? I had this unit on my old BP there was a tension adjustment on the underside that would require tightening on occasion

 

[Bob V]

Sorry, don't know if it's a Lyman MK7. I just know there is a spring that keeps a couple gears meshed, and if there is too much resistance in the system the gears can skip.