Lathe purchase advice sought

RBnDFW fired this volley in news:hfbcpv$8ud$1 @news.eternal-september.org:

I have a (true) Atlas 618 with Timken bearing headstock, but wearing the Craftsman badge. I bought it new the year (1971) before they bastardized the machine with sleeve bearings, then soon ceased carrying the Atlas goods at all, infavor of some blocky off-shore stuff.

LLoyd

This should help:

I have the 109.21270, the one to avoid, though it isn't THAT bad. I put a 1/2" Jacobs chuck on the spindle and use it to polish small parts so I don't risk grit on the ways of my good lathe.

jsw

Far from being competent to give you advice, I am in the same club:

I have a Taig which I love and use more than I imagined I would. However, I quickly discovered the limitations of its size. More and more I find myself wanting to turn something just a bit bigger than what the Taig is capable of. Shaving off thou's at a time wears thin (pardon the pun) rather quickly. I went through the considerations of slowing the Taig down by various means, employing risers etc. but in the end I came to the conclusion that you cannot make a silk purse out of a sow's ear. I, too, looked at the 7X' and decided that the increase in size would be of minimal benefit.

I think the advice to get 10" swing lathe is a good one. It is on my list, probably in March, bar another surprise like Dubai etc.

Transport of a 400 lb beast is definitely an issue but as someone said I am hoping to strip it down to essentials and move it into position bit by bit.

BTW Southbend are supposed to be getting back to lathe manufacturing. They have been promising it for about a year but last time I looked at their web site nothing was happening.

Do keep us posted how you solved your problem!

message sent -

if anyone wants to find me, my email is displayed on my web page,

On Thu, 3 Dec 2009 00:25:38 -0500, the infamous "Buerste" scrawled the following:

Ooh, ooh, me want! (It's all I have room for.)

-- Follow the path of the unsafe, independent thinker. Expose your ideas to the dangers of controversy. Speak your mind and fear less the label of 'crackpot' than the stigma of conformity. And on issues that seem important to you, stand up and be counted at any cost. -- Thomas J. Watson

...

Based on specs and price this looks good:

anyone out there have one, or another dealer's equivalent?

jsw

This the one I am after:

There is an extensive discussion of it here:

Note the differences from the Grizzly item.

Here is a question: Given a 2" round steel bar (12L14), "ideal" speed and feed, HSS cutter freshly sharpened and a coolant/lubricant of your choice, what is the maximum reasonable depth of roughing cut one can manage on such lathe? Say reducing the 2" to 1" cylinder?

I don't normally go in more than 0.050" per pass (0.1" off the diameter) with whatever feed the lathe is comfortable with. The limit is the tension of the flat leather belts, which I keep low enough to slip without (usually) breaking a jammed tool.

On drill rod and stainless I reduce it to 0.025" per pass and speed up the feed with the QC box. The time to remove a quantity of steel doesn't change too much, tool point wear increases which would cost more with inserts, with HSS it only costs grinding time, which doesn't matter if you regrind before finishing anyway.

They are round numbers to make tracking the diameter reduction easier.

The lathe can cut 0.1" deep, especially with considerable top rake on the bit, but then it's more likely to dig in. That's a problem on an old worn machine with tight and loose places in the slides.

I don't know the answer for gear driven lathes. Most of the ones I've used had broken gears. I can feed quite smoothly and evenly by hand and at home where it's quiet I increase the pressure on the handle until I hear the motor speed decrease slightly.

At work I am an independent contractor machining parts I designed, with no one watching closely, so I can use a safe, slower feed like an amateur at home, and don't have to make as many spares.

jsw

What about the later (Mk II) version of the Atlas (renamed the 3950)? Is it the equal of the earlier 618?

Joe

Probably, but I much prefer the earlier one with the rounded headstock. The later one had plastic gear covers, much Zamac, a smaller belt. All the changes were in the headstock.

Doug, I have 3 working lathes set up -

7x14 MicroMark Minilathe 9x17 Logan 10x24 Enco - 25-year-old Chinese

I find myself doing 90% of my "work" on the 10x24. I think I could get it down into a basement with some care and a couple helpers. So based on that, I'd suggest you looked seriously at that

10x24 Grizzly

But any of the above can be resold without minimal loss if you find it doesn't work for you.

I confess that the minilathe is the most recent acquisition. It's the

3rd of those I've had. Can't stay away from them.

Beyond my budget, unfortunately, and there isn't anything I can do about that.

OK, that brings it into perspective.

I run out of the square stock for my dial bases so I decided to mill and turn a 3/4" square mystery bar from the scrap yard. I cut of a 3" piece - so far so good. It was quite clean yet rusty mostly covered covered with oxide. I tried to clean it up with the indexing mill but for some reason the head was misbehaving and rather than risk a broken gear I did it with end-mills. After a while the head saw reason and I was able to finish with the indexing mill afer all.

I chucked it then in my 4-jaw chuck (by now it is a 0.7" x 0.7" x 3" bar) and tried to turn a 1" x .350" step in the middle on my Taig. I am using indicators on both axes. I started with an HSS bit. It really did comofortably only 0.010" at a time but I noticed that during the cutting my slide was moving away from the headstock in spite of being locked. I did not believe it at first but true enough, there were definite shoulders at both ends of the bar. I could not find the reason for it so I switched to a carbide cutter (I know this defies logic but at this stage I run out of logical thought). Lo and behold, the carriage stopped moving even though the carbide cutter performed miserably as on all previous occasions. After I chipped two of the three corners of the insert (I thought carbide was supposed to be good for an interrupted cut!) I made a whole new left HSS tool and tried to finish the job. Somewhere along in the process I noticed that my spindle and motor pulleys were running well out of alignement - the headstock had shifted by a good 3/4"!! Repositioned, re-tightened, finished the job with a surprisingly good finish. I was able to drill the central holes at right angles by turning the piece 90 degs in the 4-jaw chuck.

The point of this rambling story is to show that a job which would have taken probably an hour even in my unskilled hands on a 10x22 took a whole day on the Taig.

I guess my point is that if I had my time over, the budget allocated to a small lathe and a small mill would have been combined to pay for a medium-sized lathe.

Other way around. Carbide is really hard, brittle. Use HSS for interrupted cuts. But you've got that figured out now :)

Common sense really. And I am old enough not to believe everything I read on the internet :-) I guess I am still hoping that those carbide cutters are actually good for

*something*.

Need to cut some HSS, maybe an old tap/die? That would be a good place to try them out.

I broke off an "Easy-out" maybe a year ago. Not only did I have a broken off, stuck bolt, but also a hardened easy-out in the way. Sigh... Remembered I had a small carbide cutter that fit my Dremel Tool, never done much with it, had it around for +10 years. Kinda slow going, sparks flew, but it chewed through the easy-out. Then I kept going and chewed through two sides of the stuck bolt too. Should have done that in the first place :)

That's OK, I don't believe everything I write. jsw

Oh, no, I take your stuff pretty much as gospel. I do not remember where the link to the "carbide is wonderful and especially for interrupted cuts" is. Probably just as well...

I am still puzzled about the plunging business though. Today it got even more bizarre: I was center drilling, pecking as usual, using a No. 3, when on the second peck I noted that the point of the center drill would not enter the hole cleanly (table locked, piece in a vise) and the machine would shake somewhat almost like during milling process. I then went to drill a No. 7 hole (to tap for 1/4-20) and the drill was not lined up with the hole - off by some 0.020". Of course it flexes and finds the pre-drilled centre hole, but the tap was also off by the same amount. This happened with three holes! I wonder if it relates to the behaviour of the end-mills when plunging.

On the lathe where the point is more visible I've seen a glob of steel form on center drills where the chisel edge of the web doesn't cut well. When it forms the drill will skate around until I stop and knock the glob off.

Sometimes I get better results from stubby split point drill bits like the ones for drilling Pop rivet holes. For the best accuracy I drill with collets instead of a chuck.

jsw