# Atlas 618 Measurement Needed Please



## markba633csi (Jun 8, 2016)

Could someone with a 618 lathe tell me the center to center spacing of the two screws that mount the left side leadscrew bearing/bracket to the bed?  For a possible conversion project...
thanks
Mark S.
Mt. View, Ca


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## wa5cab (Jun 8, 2016)

I don't have a 6" bed to measure (101.07301 bed would be the same) but if no one answers in a day or two, call Clausing, ask for old Atlas parts, and ask whomever answers to look at the drawing and give you the answer.


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## westsailpat (Jun 8, 2016)

1.250 . What is  the conversion ?  Let me guess ball screw for CNC  . Did I get it ?


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## markba633csi (Jun 10, 2016)

Actually (just a second while I finish this jelly donut) I was looking into the feasibility of putting a 618 head on a Mk2 bed.  There are two issues with the Mk2 design: first, the spindle deflects easily due to the close bearing spacing. Secondly, the driving force from the main step pulley is coupled to the spindle through a single small woodruff key and zamak coupler which is a high wear point.  The 618 is better in both respects, and would fit providing two more holes were drilled in the bed; I'm not clear about the leadscrew and tumbler fitments however cuz the 618 spindle sticks out so far to the left compared to the Mk2. 
Are you sure it's 1.25"?  The pictures I've seen sure look closer to 1.5" (the Mk2 is 1.25")
Mark S.


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## francist (Jun 10, 2016)

I measured mine as well but you had already gotten the first reply. Anyhow, my 618 measured at 1.25" as well.

-frank


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## markba633csi (Jun 11, 2016)

Thanks Frank.  I may not do this conversion in the end, I like my Mk2 and have done some good work on it.
Might make more sense to get a bigger lathe.  SURE! says my bank account 
M


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## markba633csi (Jun 11, 2016)

here it is btw, keep forgetting to show it


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## wa5cab (Jun 11, 2016)

Nice looking machine.

If you do decide to go ahead with the conversion, I think that you will also need to know the location of the holes, probably from the left end of the way.


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## markba633csi (Jun 11, 2016)

Thanks Robert; you're correct of course, it all depends on the left-right position of the headstock mounting holes and whether the leftmost pair can be reused.  I wouldn't try it if I had to redrill all 4.  
Mark S.
ps These cnc mill conversions look so much fun I might do that instead, just need a mill...


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## westsailpat (Jun 11, 2016)

Hey Mark that is a clean machine , sorry a little OT . What is that motor  ?


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## markba633csi (Jun 11, 2016)

Thanks I've been piecing it together for about 6 months. The motor is a Torque Systems DC servomotor, they were a EG&G Rotron company long since out of business.  Probably about 1/2 horsepower; I got it from a local silicon valley surplus outfit called Halted specialties, 50$.  Lucky find.  Using a KB electronics speed control.  Better than this lathe deserves LOL
MS


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## markba633csi (Jun 11, 2016)

Here's a better picture of it- I'm sure I'll never find another one like it.  It has 4 brushes, plus a tach and encoder.
	

		
			
		

		
	



I could connect the tach back to the KB controller for better speed regulation, but the standard armature 
feedback is working fine for now.


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## westsailpat (Jun 11, 2016)

Awesome set up Mark . My set up is a bit vintage (but that's the way I like it , as long as it works proper) However I need a more powerful motor , I have to spin start (by hand ) my motor, it is like 60 yrs. old  . Pics to be posted soon  . ( paint is drying )


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## markba633csi (Jun 11, 2016)

Post some pix when you get a chance; we all like "tool cheesecake photos" ha ha
Be careful too spinning that motor, fingers are not replaceable (no user-serviceable parts inside) 
You're in Long Beach?  My best friend grew up in Culver City.  
Mark S.


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## wa5cab (Jun 12, 2016)

Pat, 

If your motor is a capacitor start type the problem is probably the starting capacitor.  Should be mounted on the side of the motor.  If that isn't it, second most probable will be the centrifugal switch.  And of course, it could just be mis-wired.


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## westsailpat (Jun 12, 2016)

Sorry Mark about getting onto my stuff , Robert my motor is a non capacitor type .I just tested it again and it starts ok but just not in some gears . I was all juiced up to start a new thd.  and show you guys my set up , but we just changed to win 10 and now my cam won't work . The guru will be over in a few days and we will get it sorted out .


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## Randall Marx (Jun 13, 2016)

I'm very interested in this conversion also. Will be watching to see how it works out. If it goes well, I'll likely be wanting to do a similar conversion on my Mark 2.


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## markba633csi (Jun 13, 2016)

Hi Randall- So you want to do a head transplant too?  Which Mk2 head do you have the roller bearing or the ball? 
Mark S.


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## wa5cab (Jun 14, 2016)

There are actually three headstock variants.

Atlas 3950 and Craftsman 101.21200 have ball bearings and cast iron headstock 383-017.
Atlas original 10100 and 10200 have roller bearings and cast iron headstock 383-020.
Atlas final version 10100 and 10200 have roller bearings and Zamak headstock.  May still have 383-020 case in.  Few of these were made and very few still survive.

According to all of the parts lists, headstock type will not affect what you would have to do to put a 618 or 101.21400 headstock on the machine.

If you are serious about doing that, I would call Clausing and ask for PDF or TIF copies of the 618 and 10100 bed drawings.  You are also going to have to have the complete lead screw and left bearing assembly including change gear bracket (banjo) off of a 618 or 101.21200.  The change gears and the right bearing are the same M6- parts on both vintages.  You will also need the 618 tumbler assembly as nothing on the one on the MK2 will fit.


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## Randall Marx (Jun 14, 2016)

Mark:
Yes, I've been wishing my Mark2 was a 618 since I got it. I also have an early Craftsman 12-inch and like how the headstock is built much better than the MK2 along with speed selection. I may or may not actually do the conversion, but that will partially depend upon success and difficulty of the head transplant. I currently have the cast iron headstock with Timkin Roller bearings on my Mk2. It's really in excellent condition right now.
Robert:
Thank you for the information so far. I like the idea of asking Clausing for copies of the bed drawings. Sounds like there will be more parts swapping than I had imagined, but if parts swapping is all that is needed...should be manageable.


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## markba633csi (Jun 14, 2016)

Robert: I've heard there's a zamak version but, yuk.  Surprisingly though, some of the Emco-Maier machines have alloy heads and perform well.  I wouldn't mind a Compact 8 or FB-2 mill at all. 
Randall: Remember you at least have to drill two more holes in the bed. I'm still not sure if I want to do the conversion anyhow,  the prices on used headstocks keep climbing up and up- I just missed one on Ebay for 150.00 and someone bought it before it even went to auction.  And I like the idea of getting a mill instead considering the little I use the lathe these days.  And I mostly make small light duty parts anyway.  The Mk2 is fine for that.
Mark S.


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## wa5cab (Jun 14, 2016)

The problem with the Zamak headstocks is probably that they tried to save too much money by switching to them and made all of the sections too thin.  In other words, the bean counters sharpened their pencils 'way too much.  The only excuse for doing it had to have been financial as they made no other changes to the lathe except for making the headstock and legs out of Zamak.

If you really don't use the lathe that much and think that you would use a mill, then that would probably be a better place to spend your money.


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## markba633csi (Jun 15, 2016)

They changed the molds slightly for the zamak I think, but didn't seriously consider the forces involved and didn't add enough webbing to at least give it a fighting chance.  Has it ever been really determined if zamak was in fact the alloy they used or was it another aluminum alloy;  The application would be a bit different than that for gears.  
Mark S.


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## wa5cab (Jun 15, 2016)

First, I assume that the cast iron parts were all sand cast.  So the molds for the Zamak headstock had to be made new.  But in any case, there were significant differences between section thickness of the cast iron headstocks versus the die cast ones.  Wall thickness's reduced probably by 2/3 at least.


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## Steve Shannon (Jun 16, 2016)

Randall Marx said:


> Mark:
> Yes, I've been wishing my Mark2 was a 618 since I got it. I also have an early Craftsman 12-inch and like how the headstock is built much better than the MK2 along with speed selection. I may or may not actually do the conversion, but that will partially depend upon success and difficulty of the head transplant. I currently have the cast iron headstock with Timkin Roller bearings on my Mk2. It's really in excellent condition right now.
> Robert:
> Thank you for the information so far. I like the idea of asking Clausing for copies of the bed drawings. Sounds like there will be more parts swapping than I had imagined, but if parts swapping is all that is needed...should be manageable.


Randall,
I've been looking for a cast iron head for my mk2, so when you no longer need it I would be interested in buying it. My headstock is the Zamak one.


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## markba633csi (Jun 16, 2016)

Looks like I was incorrect about the Compact 8 lathe, it seems it has (had) an iron head.  Not positive about the FB-2 mill however. Maybe an owner of one will chime in. 
Mark S.


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