Lathe - why freehand?

[Scouseget]

In my quest to educate myself about watchmakers lathes, I was confused about one aspect of it, and that is why it is used freehand, i.e., a handheld, albeit with the use of a rest, with a graving tool? You are machining tiny dimensions, with presumably little tolerance for error, yet there is no cross slide used, which would ensure parallelism and sharp shoulders, etc. A Unimate, or similar small centre lathe would seem to offer better accuracy and repeatability. I think Mark uses both a watchmakers lathe, and a centre lathe, so where does the overlap start? If money wasn't an object, would a centre lathe be better to use than a watchmakers lathe? Is it a matter of speed because the lack of really tight precision with a watchmakers lathe allows for a quick job, or some other reason? 

I should apologize now if I've insulted anyone by inferring that the watchmakers lathe is imprecise as that is not my intention, however I am confused by the issue so would appreciate your insight into the pros and cons of one over the other.

Rain in Edmonton today - again. Time to try to reassemble my son's Oris, which frightens me frankly as it's just so darn complicated. And small. 

[JohnR725]

Conceivably you may find there is not a correct answer. If you look at the history of turning things for instance specifically related to watches. Originally turning between centers with a bow very primitive device in some ways but capable extreme accuracy because turning between centers. To make a cross slide requires a lot of machinery which didn't exist conveniently at the time when people turning things between centers. Even with the modern watchmaker's lathe surplus used cross slide is still several hundred dollars. So probably not the right answer but my answer is cost. You can turn beautiful staffs very precise very nice without a cross slide.

[Ado213]

It all depends on what you trust, your eyesight or are calibrated scale!

[szbalogh]

I am just a beginner and dont have experience with cross-slide lathes. My feeling is that with a cross-slided lathe and by rely on the scale You cant keep accuracy needed for such small tolerances. Hand turning however is more about senses. With increasing experience You can feel how much material You turn from the workpiece. I think hand turning is faster and cheaper if 1-2 parts are needed. 

[dadistic]

Jerry Kieffer on the NAWCC watch repair forum is a great proponent of the Sherline cross slide lathe. He often debates the suitability of the Sherline for making watch components with people who prefer WW style lathes. The result seems to be that the Sherline would do just fine, if the proper techniques are used. The Sherline can also accept 8mm WW style collets, and a tool rest, so you could certainly freehand on it if you wanted too. 

I have yet to pull the trigger on a lathe, but a Sherline is currently at the top of my list. Ideally I'd have three lathes, ww style, Sherline, and something a bit bigger for case work and that would be beefy enough for "spinning" type work. But, I'm dreaming. I'll be lucky if I can afford a nice new set of screwdrivers as my next purchase.

[david]

Scouseget,

The best process to use is the one that gives you the most control. if you do your best using touch and feel, then a T-Rest and Graver would be a good choice. If you are better at relating to numbers, then a cross slide will provide a better way to produce your part. It is not a matter of one being correct and the other incorrect as the only thing that really matters is that a correctly dimensioned   part  is produced. 

If you are looking for a lathe to make small watch parts take a good look at the Sincere lathe. It is a good quality machine, comes with a cross slide, collet holding tailstock and, is very affordable.

david. 

[oldhippy]

My lathe experience started with a boley watchmakers lathe using gravers and a rest, started just learning to turn stuff and learn to sharpen the graver, in the end I could make balance staffs and re-pivot watch pinons. Many watchmaker’s lathes have cross slides as an extra, I would its cost. When I moved on to clocks obviously a bigger lathe was needed with a cross slide, in order to get the best out of such a lathe you need to learn how to set the thing up in the first place and learn the different cuts, different metals and how they react to being machined. I’ll leave it there; I could go on but I won’t.

[clockboy]

I have found lathe work requires a whole new level of skill. I have a cross slide but find it awkward to set up and removing tiny amounts of material difficult. The tip over rest once you are used to it is easy to use & efficient. One key element to successful lathe work is sharp gravers this is a must.

[david]

Scouseget,

The best process to use is the one that gives you the most control. if you do your best using touch and feel, then a T-Rest and Graver would be a good choice. If you are better at relating to numbers, then a cross slide will provide a better way to produce your part. It is not a matter of one being correct and the other incorrect as the only thing that really matters is that a correctly dimensioned   part  is produced. 

If you are looking for a lathe to make small watch parts take a good look at the Sincere lathe. It is a good quality machine, comes with a cross slide, collet holding tailstock and, is very affordable.. 

[david]

There is a website called THE GREAT BRITISH WATCH COMPANY by Colin Andrews. Colin completed both the BHI and WOSTEP courses and is now a professional watch repair technician. His website covers many of the challenges  he faced getting through these schools and his employment situation after graduating. The part that is of interest for this topic is his discussion of what he went through learning how to turn watch pivots with a graver and T-rest. All of his articles are very informative but the article on making watch pivots is of particular interest for this discussion. 

As different people have different backgrounds, budgets, skill ranges, and different ways of attacking a machining problems, the really important issue is having control over the process and producing a correct part.

 Using a cross slide requires requires more equipment but an understanding of how to adjust, and in some cases repair, the cross slide mechanisms is really needed to get the desired result. The cutters used in a cross slide can be more critical and complex because they are mounted in a fixed position and will not cut properly if the relief and cutter angles are incorrect. This requires additional skills and equipment. Once everything is properly adjusted and set up this process can produce extremely precise and repeatable results.

Using a graver requires less equipment to adjust but requires more hand manipulation during the metal removal process. Since the graver angles are adjusted during the cutting process the angles on the cutting tool itself are less critical. The  approach to removing metal is very different as you are physically moving a cutting tool a distance that can not really be seen. This is why a shaft is first cut to a taper and the part to be fitted is moved up the taper during the cutting process. If the process was more controllable you would simply turn the shaft to the correct cylindrical diameter and press on the balance wheel.

Removing metal with a graver was around centuries before cross slides were invented. Products were made by hand fitting on part into another part. The system worked but problems arose such as slow production and a lack of interchangeability. During the American Civil War Eli Whitney came up with the concept of interchangeable parts for the manufacture of rifles.

 The cross slide allowed the application of mathematical concepts such as the Cartesian Coordinate System, Trigonometry and Analytic Geometry to be directly applied to the manufacturing process.

david

[Geo]

Couldn't have put it better myself!  David, the above was was an excellent post.

[RyMoeller]

Thanks @david for that wonderfully informative post. 

On a side note I know now why I never use the the cross slide that came with my lathe- I never was very good at math!

[Scouseget]

Thanks for all the great advice and comments you have given to this topic.

After much procrastination, I decided to bite the bullet, and bought a lovely Peerless watchmaker's lathe, complete with motor and a good selection of collets, etc., from good old Uncle Larry. Despite its age, it's in great condition, with tight and non-binding bearings in the head stock and no damage or slop in the bed so there's really no excuse for not being able to produce usable parts other than by my own lack of skill. I decided to go with the "normal" way of making parts, this being freehand using a graver, and NOT by purchasing and using a cross slide, though I might acquire a cross slide, and a three jaw chuck, at some point in the future, but not while I'm still learning how to use the basic lathe.

I started by making my own gravers, which took several hours of trial and error before being able to produce an effective cutting edge. I assume then, given this example as being typical, that the secret to mastering the lathe is practice, practice, then a bit more practice. Then repeat. Ad nauseum!

My ultimate goal is to be able to fabricate replacement balance staffs for, at least initially, pocket watches. Realistically, I think it will be months before I will be able to get to that level of expertise but it will be fun building up my skill to that level in the meanwhile. And to that end, i purchased the John Tope Lathe Basics on-line course, and am happy with this as he takes your through each step comprehensively and as I have no physical person to tutor me, this is the next best thing. 

Another good thing is that winter has arrived with a vengeance in Edmonton, and it's currently minus 25 degrees and I'm not going anywhere so it's lathe practice all day. See, who said cold winters are a nuisance.

Roger

[JohnR725]

Just as a reminder to keep your new lathe running nicely remember to lubricate the bearings from time to time.

[clockboy]

Nice lathe Roger. See attached an interesting article on gravers.

Gravers.pdf