# M-head questions



## amuller (Mar 23, 2014)

I'm working slowly at bringing up my first mill, and round-ram M-head from 1942.  Hope I'm not asking questions already much-discussed.

Does anybody see this head casting as repairable? 
	

		
			
		

		
	




I've read that the heads were individually fitted to the quills.  This makes me hesitate to buy a head casting, for concern about the fit with my quill.  Can anyone advise on this?  What clearances did Bridgeport use?

I'm planning to use sealed, grease lubed bearings on the pulley and he upper spindle, and rather ordinary angular contact bearings (7205Bs) at the bottom, possibly drilling a hole in the quill for greasing. (I know the original lower bearings were side loaded 6205s, but....) Does this seem reasonable?  I don't like the mess of the original oiling system.  In any case, how do I arrive at the right preload for the lower bearings?

These heads were apparently designed for 3L (FHP) belts.  These have pretty limited capacity and I would expect them to slip pretty readily on the smaller sheaves.  There are several other belt sections that might work, available in raw-edge, cogged style:  M10, XPS, and VX (in increasing order of section depth).  Can anyone share experience with belts?

I saw a post mentioning, but not going into details on, approaches to damping out rattle between the spindle splines and the drive hub.  Any pointers on this?  I've thought of using some semi-hard plastic shims but not sure how to keep them in place....

Thanks for any guidance.


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## Terrywerm (Mar 23, 2014)

I do not know of a way to get that repaired properly in the average home shop.  

First, welding that casting will be tricky since it is cast iron. Proper fitment of the small piece back into the main casting will be difficult as you will need to vee out the edges of the crack to quite some depth. Preheating of the entire casting will be necessary,  as well as post heating during and after welding. No slag inclusions can be allowed whatsoever. After each bead is run it will be necessary to clean up the welded area and grind it lightly to make certain that all slag is removed before welding again. Keep the entire casting hot the whole time, and keep it hot after the final weld is done, then let it cool very slowly by burying it in lime. You would want it to cool over a couple of days due to its size, anything faster will probably cause issues. 

After welding is complete, it will be necessary to somehow machine the bore to make sure that the piece that has been reattached does not 'stick out' too far into the bore. Doing this without altering the intact portion of the bore would be difficult at best. 

In short, not a project that I would be willing to tackle. Not saying it cannot be done, but I would not attempt it and have any expectations as to level of success. I don't want to be a naysayer, but this project is definitely above the skills and abilities of most home machinists. You might be able to get some professional help and be successful, but doing so would probably incur more cost than what it is worth.


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## AR1911 (Mar 23, 2014)

There is a guy on one of the other forums that has a complete M-head less quill for sale.


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## amuller (Mar 23, 2014)

terrywerm said:


> I do not know of a way to get that repaired properly in the average home shop.
> 
> First, welding that casting will be tricky since it is cast iron. Proper fitment of the small piece back into the main casting will be difficult as you will need to vee out the edges of the crack to quite some depth. Preheating of the entire casting will be necessary,  as well as post heating during and after welding. No slag inclusions can be allowed whatsoever. After each bead is run it will be necessary to clean up the welded area and grind it lightly to make certain that all slag is removed before welding again. Keep the entire casting hot the whole time, and keep it hot after the final weld is done, then let it cool very slowly by burying it in lime. You would want it to cool over a couple of days due to its size, anything faster will probably cause issues.
> 
> ...



I agree.  It could be brazed or welded but does not seem to justify the effort, and the probability of unsatisfactory results.  But there is a lot I don't know so wanted some other opinions.

Thanks.  Now, about the other issues.....?


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## Terrywerm (Mar 23, 2014)

I believe you could get a different casting and maybe lap your quill to that casting with satisfactory results. On the other hand, with used equipment chances are that neither the casting nor the quill will be at original dimensions anyway.

As for the remaining questions, I will have to defer to others that have more experience in that area and with that particular equipment.  I've seen M-heads, but I don't think I've ever actually had the opportunity to use one, much less dismantle, repair, or maintain one.


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## chuckorlando (Mar 23, 2014)

Not sure what kinda price your looking for. But heres something I found for you. But thats all I could find

http://www.ebay.com/itm/BRIDGEPORT-...375?pt=LH_DefaultDomain_0&hash=item3a8b2fd2e7


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## amuller (Mar 26, 2014)

AR1911 said:


> There is a guy on one of the other forums that has a complete M-head less quill for sale.



Thanks!  I contacted him.  He wanted $400 without a motor (he didn't mention quill in his response).  This is above my budget but is a helpful data point.

Alan


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## WallyM3 (Apr 5, 2014)

Even when new, it would have been less than optimal to swap quills and head casings. If they've live together all their lives and you want to remarry them to others, fugedaboudit!

It's just the nature of the animal, I suspect particularly the M-heads. (BTW, I had another look at basic machine, meaning the colunm, knee and table #1, just a couple of weeks ago. Sure looks familiar.)

I have an M-head and its original quill that you can have. There aren't any more parts than that to it, but those are the critical ones. I just need to pull the quill return spring for something I'm working on, them I can ship it to you.

Lemme know if interested. 

I do not believe, nor can I ever be made to believe, that an M-head break like that can be repaired within the limits of the HSM's realm.

Edit: I think it's an 2MT spindle that I have, but I'll have to check. Either way, new collets are a small price to pay for a restored machine.


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## amuller (Apr 5, 2014)

WallyM3 said:


> Even when new, it would have been less than optimal to swap quills and head casings. If they've live together all their lives and you want to remarry them to others, fugedaboudit!
> 
> It's just the nature of the animal, I suspect particularly the M-heads. (BTW, I had another look at basic machine, meaning the colunm, knee and table #1, just a couple of weeks ago. Sure looks familiar.)
> 
> ...



That would be great!  I am totally interested.  I have enough parts to put a head together (so to speak.  Putting MY head together might be more challenging....).

Alan


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## WallyM3 (Apr 5, 2014)

"(so to speak.  Putting MY head together might be  more challenging....).

Alan"

I have that very same problem. Working on these things doesn't help.

I'll get that spring I need out and PM you for your contact information so I can get it to you.


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## chuckorlando (Apr 5, 2014)

Thats awesome Wally. The world needs more dudes willing to help out.


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## WallyM3 (Apr 5, 2014)

We're all in this together.


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## george wilson (Apr 6, 2014)

M heads aren't that expensive to worry about trying this difficult repair. Yes,quills were lapped to fit their hole. I don't think it feasible to try doing that,either.

To grease M heads,a Bridgeport tech told me to remove the plug screw at the top. Screw in the threaded end of a tube of lithium grease,and squeeze out a teaspoon of grease. Then,screw the plug back in. This is valuable and hard to find information.


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