# In need of M-head "clock spring".



## WallyM3 (Apr 15, 2014)

In a recent fit of clumsiness or forgetfulness, I horsed a "clock spring" off its catch with too little skill and too much haste. This claw lookin' thing is supposed to be a slot that catches a hook in the OD of the spring housing. In intelligible terms, it's essentially the quill return spring.




If any one has one of these critters or knows how I can obtain one, I would be very grateful to know about it.

Many thanks.

Wally.  anic:


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## JimDawson (Apr 15, 2014)

I couldn't find an exact replacement but this looks pretty close. http://timesavers.com/i-8945370-7-16-x-0155-x-55-1-2-hole-end-mainspring.html

You could also just shorten it a bit and use a Dremal with a carbide burr to cut a new hole.


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## WallyM3 (Apr 15, 2014)

We may have a winner here, Jim.

Two of the published dimensions in the link you provided match: 7/16" and 0.015+" thickness. I'll tape the wind and see how close we get.

Many thanks. Interesting source.


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## RandyM (Apr 16, 2014)

Here is another option for you. It comes as an assembly but, very reasonably priced.

Clock Spring


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## WallyM3 (Apr 16, 2014)

Thank you, Randy. Unfortunately, that's the J-head spring. In the past, these folks have been very reliable to deal with. I think I used them for 2 J-head springs (among other assorted B'port parts) in past recondition jobs.

IIRC, many parts worked on a 3hp, 48" SuperMax I once had.


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## RandyM (Apr 16, 2014)

WallyM3 said:


> Thank you, Randy. Unfortunately, that's the J-head spring. In the past, these folks have been very reliable to deal with. I think I used them for 2 J-head springs (among other assorted B'port parts) in past recondition jobs.
> 
> IIRC, many parts worked on a 3hp, 48" SuperMax I once had.



Well, it was worth a shot, I didn't realize the spring is different between the M and J. Thanks for the lesson.


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## WallyM3 (Apr 16, 2014)

Yea, there's virtually... no, literally... no interchangeability between the Master Milling Attachment (M-head) and the J-series attachments. The J-head spring has some serious power behind it compared with the little 7/16" wide M-head.

It would be my guess that the modular J-head spring assembly was at least partly inspired by problems encountered in the M-head at repair time. This is the 4th spring I've "modified" in my M-head related efforts.

I should probably do a little show-and-tell on this particular head as it has factory sealed bearings, something which one hears B'ports _never _had.

Don't think that I don't appreciate both your search and the link. You reveal a great source.


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## RandyM (Apr 16, 2014)

WallyM3 said:


> I should probably do a little show-and-tell on this particular head as it has factory sealed bearings, something which one hears B'ports _never _had.



This is a GREAT idea Wally. I know I would appreciate your time and effort in this endeavour. I am sure others would enjoy the learning experience as well.

Are you certain that it is a factory sealed bearing unit? If so, how can you tell?


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## WallyM3 (Apr 16, 2014)

I can tell by the drive assembly components. 

The 99.99% of B'ports encountered employ "total loss" lube sustems. This requires drain ports in the upper bearing housing to allow oil/grease to make it through the column and lube the bearings. This head has no holes on the housing.

Reason being is that it's a 12,000 rpm unit configured to work on wood (as an optional material), wherein an oil-free environment would be quite necessary.

There are other interesting features in this head, 'frinstance, it employs a flat drive belt rather than a "V" belt.

Probably worth some pictures any way. Possibly next week. Got a customer coming by shortly and the balance of the week is spoken for, too.


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## RandyM (Apr 16, 2014)

WallyM3 said:


> Probably worth some pictures any way. Possibly next week. Got a customer coming by shortly and the balance of the week is spoken for, too.



:thankyou: for ALL the very good info. OOOHhh yeah, we need the photos. And then, you are going to make us wait for them? :nono:

Good stuff, keep it coming. Thanks again Wally.


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## amuller (Apr 27, 2014)

Wally:

Can you anneal the broken end of the spring and rework it?

Alan



WallyM3 said:


> In a recent fit of clumsiness or forgetfulness, I horsed a "clock spring" off its catch with too little skill and too much haste. This claw lookin' thing is supposed to be a slot that catches a hook in the OD of the spring housing. In intelligible terms, it's essentially the quill return spring.
> 
> View attachment 74521
> 
> ...


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## WallyM3 (Apr 27, 2014)

Well, back on line...finally. Had a hard drive crash. 

It looks like Bridgeport or Bridgeport's supplier did just that, i. e., took a stock spring, annealed the area and drilled/punched/ground the hole. I'm going to try that first, Alan, and if it fails, proceed to the replacement solution (which I may have to anneal and drill, in the event).


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## amuller (Apr 28, 2014)

WallyM3 said:


> Well, back on line...finally. Had a hard drive crash.
> 
> It looks like Bridgeport or Bridgeport's supplier did just that, i. e., took a stock spring, annealed the area and drilled/punched/ground the hole. I'm going to try that first, Alan, and if it fails, proceed to the replacement solution (which I may have to anneal and drill, in the event).



It is also possible that B'port bought spring stock and made their own.  I've never worked with springs much but people who work on clocks and guns often know to make and repair springs:   Here is one source for clock mainsprings:

http://timesavers.com/c-325731-cloc...ings-arbors-barrels-hole-end-mainsprings.html

Another source for spring stock is small engine recoil starters.

Alan


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