Beginners Lathe

[jeffeosso]

i've since left the smaller machines, but the "won't rip your arm of" is VERY important.

remember it was Me that said "don't EVER let go of the chuck key when it's in the chuck"

a 7x10 or so probably won't kill you, but it COULD when an 8oz key hits 90mph and hits you, the person watching, the window in the new car, ... i think you get my point.

if you are a person that grabs are mistakes or brushes away chips from a drill, with your hands, you'll have some learning to do.

oh, and just some advice, if there are sparks, you are cutting too hard


interesting thing on the minis, their motors are 110 DC... yes, DC... if you ever happen to tinker with one, and you may, NEVER EVER touch the wiring... DC don't let go

jeffe

 

[sch]

If you are an ME student at a research
facility there should be a machine shop on
site that you may have some access to. If
so they should have some pretty good equipment from an HSM point of view. Another point: any machine assumes a variety
of measuring and set up tools. A few dial
indicators, magnets to hold them in place,
set of drills, files and some way to cut up
metal stock into usuable sizes. You will
need some cutting bits for the lathe. A
book or two for pointers, center drills,
scribe, rulers (6" are best, longer ones
won't fit the lathe). Micrometers, vernier or digital calipers, live center, lathe dogs,
thread gauges, etc etc. Lathe work will
quickly demand a few of these, and more and
more as time goes by. The machine is just the
start and not much real use without a few or
a lot of auxiliary devices. Steve

 

[Unregistered]

Unless you know what youre doing, or you are extreamly lucky you are not going to find a fifty year old lathe in good shape.(Ask me how I know). I have an Atlas 10F, a Logan 820, and a HF 7 X 10. I have had to work on all of them. The good thing is I have learned a lot about how a lathe works in the process of trying to fix them. IMO if you go with the Asian get a least a 7 X 12. Learn how to fix it, learn how to use it and then move on.
Larry Backer

 

[71CJ5]

At my campus, University of Cincinnati, we do have a great machine shop. However it is strictly used for senior design projects and for classes. I've tried to get access to it for personal projects, but they won't let it happen. It has a nice variety of Cincinnati engine lathes, Cincinnati horiz. and vert. mills, a few radial arm drills, 2 surface grinders, overhead crane, shears, press, etc...

It sounds like one of the asian 7x10 or 7x12's may be just what I'm looking for right now. I've read all the info at mini-lathe.com and it doesn't sound that bad to tighten up one of the lathes to a decent machine. Thanks for everyones input and I'll let you know how my journey turns out. I'm sure I'll have plenty of questions in the future.

Joe K.

[This message has been edited by 71CJ5 (edited 03-04-2004).]

 

[71CJ5]

Thought of a question already:
Are these mini-lathes capable of turning a taper?

Joe K.

 

[Evan]

Harold,

Don't put an aluminum plate under your lathe unless the lathe is aluminum body also. The different coefficient of linear expansion will warp the lathe with even small changes in temperature. I put my SB9 on a piece of channel iron, 4' long, 10" deep and 2" high. Made it easy to shim and stiffer than John Holmes.

 

[JTToner]

Another question, I know the 7x will do left handed threads, but how would it be done with the 9x that lack reverse tumbler for the feed screw?

 

[lathefan]

71CJ5. you can turn short tapers using the compound rest, however from what I can see in pictures, the 7x doesn't provide for setting over the tailstock for turning longer tapers. Worse yet this means you can't adjust the tail stock to true the centers to not turn a taper. JTToner, the 9x will not cut left hand threads without modifying the lathe. This consists of adding a shiftable gear to the geartrain that drives the leadscrew to reverse it's rotation. I don't think the modification is very hard to accomplish.

 

[Harold Hunt]

Evan, yea I should have thought of the different expansion rates. I have too many projects going on at once so the aluminum plate idea had not been fully thought through.

The plate is from a old production machine at work and is milled flat on both sides. I'll use it for something else!

Thanks
Harold

 

[bob]

Evan, did you go to the same school as Donie of the 1/2 millionths Monarch fame?
Bob

 

[DDS]

The criticism of the mini lathes is a little over done IMO. Of course if you can find a South Bend that is in good shape at a reasonable price and can get it shipped and set up then by all means - do it. But the mini lathes are surprisingly accurate little machines for the money, if they are used with in their limitations. I bought one just to have the ability to move it from garage to basement and found it more accurate and functional than I had expected. The three jaw will chuck up to within .0015 max TIR repeatedly, and small parts can be held to within .0005 Dia (albiet not quickly). Yes you must constantly re-adjust the many fitting screws and nuts on the slides and ways to keep things tight, and no you can't take any serious cuts - about .020 for roughing and .003 for finishing, but you can make good small parts. I agree with J Tiers comments that there is no such thing as a beginners lathe - buy the biggest highest quality lathe you can afford and can get set up. But the mini lathes are legitimate products and IMO good buys for the money. And being able to carry them around is great. They weigh only 80 lbs soaking wet.

 

[Evan]

Bob,

The difference in expansion of aluminum compared to steel over a distance of a few feet is significant even with a small temp change. And yes, I worry about .0001 and work as close to it as often as I must. The telescope I built recently is graphite/epoxy truss and aluminum because the combined coefficient of expansion equals zero with temp change through a long picture taking session.

[This message has been edited by Evan (edited 03-05-2004).]

 

[bob]

Evan: What does this have to do with bolting a lathe to aluminum?
Bob

 

[Evan]

Bob,

Coefficient of linear expansion is the problem common to both. An iron lathe bolted to an aluminum plate will be distorted when the temperature changes from what it was when the lathe was mounted on the plate. This will warp the lathe. The telescope is constructed to avoid CLE effects changing its dimensions in an adverse way.

 

[bob]

Yeah, and if I am nor wearing my tinfoil umbrella when running a 100 year old SB the subatomic particals in the ether will prevent me attaining Donie tolerances. Get real
Bob

 

[Evan]

We aren't talking .0001 here. If my SB was mounted on an aluminum plate a 10 degree change in temp would shrink or expand the aluminum about 5 thou more than the lathe. That's enough to misalign it noticably.



[This message has been edited by Evan (edited 03-05-2004).]

 

[Harold Hunt]

Gee, I didn't know this would cause such a fuss.

Bob, no need to be so rough. Do some research and calculate linear expansion for cast iron and alumimum the post the results.

For proper foil use go here http://zapatopi.net/afdb.html

Evan, I wonder if Bob bolted aluminum to cast iron and said it would be OK during the original Hubble build ;+)

My shop area will see much more than a 10*F swing, more like 50*F.

Harold

 

[bob]

Little common sense needed here. The bed, even on a 9" SB is about 4" deep. Now if you bolt that to a piece of 1/2 or 3/4" aluminum what if anything is going to bend with changes in temperature? I'm just a simple farmer don't know much about coefficients of expansion etc but I would bet on the al. Secondly, most work is done within a couple of inches of the chuck so a little twist in the bed has almost no effect. In addition, I would be willing to bet a bundle that the induced twist would be minimal compared to what is already there. Thirdly, if you are working to the kind of tolerances you guys are talking about why would you want to use a lathe that was the bottom of the barrel when it was new and sure as hell hasn't improved with age. Fourth, a new guy was asking for an opinion on a possible lathe purchase, why start with the irrelevant bs before he has a chance to take a cut. Come on, the guy wants to make some big pieces small why intimidate him with questionable theory?

Bob

 

[Evan]

Bob,

As a simple experiment you should rivet or bolt together two pieces of metal, one aluminum and one steel, same thickness, bolt at each end. Say about 1/16 thick, 6" long and 1/2 wide. Then warm it and cool it. You will be suprised at what happens.

If the aluminum warms it will expand and the thickness of the lathe bed will not stop it. Something is going to bend and it will be the lathe.

BTW, I routinely work to finger press fit tolerances on bearing blocks and other similar jobs on my SB. That is tolerances in the better than .0005 range. Old doesn't equal crap and mine isn't much worn either. Remember, all new tools are made with older used tools.

[This message has been edited by Evan (edited 03-05-2004).]

 

[bob]

Evan: I guess I'm in the mood to argue. I think you are full of it on the bend question but I guess its an empirical problem and not one that I would waste time solving

On your fits statement I have no doubt you can do what you say but how long does it take, how much file and emery etc. Can you measure cut and repeat quickly enough to make a living??

Bob