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Bridgeport vibes

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bill ellis14/04/2019 19:52:08
71 forum posts
2 photos

Getting near completion on the step head Bridgeport but I have an interesting symptom and I wondered if anyone has any ideas.

Everything on the head works as it should, except when I use the quill feed lever to manually lower the quill. If the head is set in low range (back gear) and I manually move the quill down everything is silky smooth. If however I'm in high (straight drive via dog clutch) I get a slight vibration through the quill lever, is that normal? No obvious wear in the teeth on the bottom of the splined pulley hub or the bit it engages with. Obviously only when the motor is running, If I stop the motor it is smooth in Low & High.

Any thoughts?

David George 115/04/2019 10:49:13
1193 forum posts
409 photos

Hi Bill I have been thinking about the vibration but without striping and looking i can't put a finger on it. Dose It do the same thing with power feed as well as hand feed. It isn't something I have come across personally but if it doesn't affect the operation I wouldn't worry.


Alistair Robertson 115/04/2019 11:51:57
89 forum posts
6 photos

Hi, All.

Vibration in high is usually caused by slight variations between the drive and spindle pulleys and most important the quality if the vee-belt. A cheap belt has quite a big tolerance on section size and width. A cheap belt is a couple of pounds and a quality and correct one is nearer £20!

I bought a Warco drill and just replacing the vee-belts transformed the machine with no vibration from the motor. Previously the whole machine had a vibration. I can now balance a £1 coin on the drill table when it is running.



bill ellis15/04/2019 12:36:56
71 forum posts
2 photos

Many thanks both,


Just tried it with power downfeed and it is exactly the same so I don't think it is anything much worth worrying about, not making any noises just a very small vibration through the handle. I think the dog clutch may be a little worn as that is the only other part in the chain which could possibly contribute. Not a biggie but I may change them out at a later date. Looking at the prices I may give making them a go, I may put a bit of grease rather than oil on them and see if that changes anything.


It still uses the same drive belt when in back gear (when it is smooth) so I have ruled out belt issues. I will replace the belts as a precaution once I've used it a bit as I don't know the history of the ones on there.



Alistair Robertson 115/04/2019 13:34:47
89 forum posts
6 photos

Hi, Bill.

What I should have added is that in the back gear the spindle pulley is not connected directly but through the gear train which dampens out the transmitted vibration.


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