So How Did I Do & What Do I Need ??...

Round in Circles,
Thanks for the pics !! that clears up the question regarding the mounting orientation of the bearing, I wasn't sure if it was mounted as shown in the pics or if it was mount in the same way the rollers are on a steady rest. The pics clear it up quite nicely. So in operation it just touches the workpiece on one side and then is swung in a 180 degree arc to the same spot on the opposite side of the workpiece, then adjustments are made to the workpiece so that the outer portion of the bearing on the tool contacts the long axis of the workpiece fully each time on opposite sides when the procedure is repeated....correct ??

From the pics the bearing is just a press fit to the shaft ???
 
No not quite .
In the four jaw chuck roughly lightly tightening the jaws , set the work piece without switching the lathe on advance the bearing on the long shaft ( it is held in the boring bar's tool holder ) towards the work piece . gently rotate th chuck till you find a point that is the closest to the bearing , advance th bearing a tad further till it just touches this high point ., mark the chuck with a sharpie at a repeatable place.
Now rotate the chuck 180 degrees and roughly set the gap to the work place to about half way . gently rotate the chuck and advance the jaw till it pushes the work piece to the opposite jaw .
Now repeat this exercise after moving the chuck 90 degrees , always turn in the same direction
When it is well centered the bearing should just be able to be rotated as it touches the work piece I seen to remember I had it down to 1.5 thou when I last bothered to check the accuracy using my turned up test bar piece.

You'll soon be able to do this setting up in four or five adjustments .

That short stubby arm with a bearing on it . I though it might be useful in checking the trueness of the face plate , chuck front face or to be used when putting an already turned end faced bar back in the chuck . After using it a couple of time I found it got in the way so I unscrewed it and put it to one side just in case I ever do find a real need for it .

There are numerous You tube videos with people showing how they true up the work piece with a bearing on a shaft , one guy's video in particular " Doubleboost of Twastard Engineering " is rather good , but you might find his Northern English accent a bit heavy .

I'll see if I can locate th clip and post the details on the thread .

Se what you make of this ...


This one shows both axis being trued up .


Double boost has made so many clips for e tube it might take a long time to find the one I want . Finally found a slightly better one but it's not by double boost .

A bar / rod in four jaw chuck along the axis , you use the opposite end to that shown in this clip but I'm sure you'll get the idea

If you want to learn doing what some ne who earns their living doing it these " Double boost " clips are very useful.



Finally a different way but still very good for centering a plate or square profile .
 
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Round in circles,
Thanks for all the info. !!! I'm a "monkey see,monkey do" type that picks up things alot faster if I can actually see them being done. The links pointed out exactly how to use the tool for centering the workpiece.
 
OK, small update...After reading a few threads by some other members...http://www.hobby-machinist.com/threads/contouring-with-manual-machine-tools.34305/#post-289958 and http://www.hobby-machinist.com/thre...-holding-cutting-tools-on-small-lathes.32266/. I picked up a latern style toolpost off ebay for $35. Since I had no toolpost at all I thought this could get me started.

I used the search function but couldn't seem to find out which tool holders should be used ?? Seems as if there are quite a few using different size tool bits bits as well so I thought I'd check with the folks here before buying something I couldn't use. Was thinking some of the smaller bit holding ones would be suitable to the Atlas 6", maybe in the 3/16 & 1/4" bit size range?? Looks like I'll also need to learn to grind HSS tooling correctly since from what I'm seeing the Atlas 6" lathes don't seem to care much for carbide tooling.

I did pick up a cheap harbor freight dial indicator and magnetic base till I could fund a better one. Also picked up a piece of 1" round stock and have it set up in the 4-jaw chuck on center to within .001 to make a muzzle nut (soon as I get some tooling to actually cut with). Thanks.
 
Looking back at various Atlas catalogs over the past 3/4 century, it appears that the most common square or round tool or tool holder that Atlas sold for the 618 was 3/16" square or diameter.

Mind you, 1/2" square cutters would work fine on a 618 but any 0XA tool holder (looking down the road) that could hold 1/2" cutters is going to be pretty thin at the bottom. Which I would avoid buying. 1/4" would probably be a safe maximum.

What I mean about thin at the bottom is that first, the top of the cutter has to be held on center (of the lathes longitudinal spindle axis). And you don't want the cutter holder have to be so long (tall) that with the top of the cutter on center, the bottom of the holder will hit the top of the compound regardless of the angle you want to set the compound at. Meaning that you should be able to set the compound at any angle and then set the tool post at any angle without having any interference between the compound slide and the tool holder.
 
That's a great start, you'll learn lots by starting with the basics. Same with the indicator, nothing wrong with some inexpensive stuff to learn the ropes with.

I have a 6" Atlas myself, and yes there's a bit of a learning curve when you're a beginner trying to figure out just what is what and how to make sense of all the different sizes of tools out there. Your machine is sized well for 3/16" square tool bits. These fit the "Armstrong style" of holder in a #00 size. The older designation for this size holder was #1010.

1/4" square tool bits will need to have a larger tool holder -- in this case a #o or #2010 using the old designation. I myself do not use this larger holder on my Atlas although I do have a set of them for another machine. There might be challenges with the short centre height of the 6" lathe, I'm not sure. You also need to be aware that larger holders may need a larger lantern tool post, so exercise caution when buying.

Also, not all angles on tool holders are created equal! Most times the standard Armstrong style will present the tool bit at about 15 degree positive rake (the bit angles slightly upward as it exits the holder at the work). However, I do have a nifty little set of Williams holders in "00" size that present the bit with only about a five degree positive rake. And, to confuse you even more, anything with a "T" prefix, as in a "T-0-R" will present the tool bit dead flat with no built in back rake. These were made specially for carbide tool bits, the "T" being for Tungsten carbide.

Oh yes, the whole Left-Straight-Right thing. Right handed holders will angle the tool to the left toward the headstock, left handed holders will angle the bit towards the tail stock, and straight holders just point it straight ahead. Easy, eh? Just memorize it and get over it.

There are a few eBay sellers out there that specialize in Atlas parts and tooling, and even if you don't buy from a particular vendor you can learn a lot by looking at what sizes of tools, holders, etc they offer for the various sizes of lathes. With that, you can be a little more informed about what you're looking for.

And the really great thing about using 3/16" square tool bits? They're cheap, and they don't take more than five minutes to grind one! Good luck, and let us know how you make out.

-frank
 
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