Unimat 3 lathe

[steve_s]

I am contemplating purchasing a lathe and was wondering if anyone had experience with Unimat lathe's? Good, bad, otherwise?

 

[gmorse]

Hi Steve,

There's no such thing as a 'best' lathe, they vary so much in their design, applications and build quality. Before answering your question, I think we need to know more about your intended use for a lathe, whether you already have a lathe and if you have any experience with either machine lathes or watchmaker's collet lathes.

Regards,

Graham

 

[steve_s]

Well as for experience, none except for some classes with wood turning lathes and shop class in high school (50 years ago) with metal working lathes. The intended use is eventually to be able to machine a double roller balance staff for a 19 jewel Trenton that has a broken pivot and it is not a very common watch which I am finding extremely difficult to locate.

 

[steve_s]

I also have a Ball Hamilton with a broken regulator pin that I would think could be machined. It is a 999H with a Ball regulator and also hard to find.

 

[gmorse]

Hi Steve,

Thanks for the information, it makes your needs clearer.

The machine lathes such as the Unimat 3 or any of the Sherline lathes typically use a multi-jaw chuck, (mostly self-centring), to hold the work, and use a cutter mounted in a tool post that's manipulated on a cross slide, controlled by two or more lead screws; this is how the Unimat 3 is designed. It's possible to produce adequate results quite quickly, because the skill levels required are relatively easy to acquire. However, many of the cheaper lathes do not possess the necessary precision to turn watch balance staffs, and I don't know whether the Unimat 3 is capable of working to tolerances of 1/100mm or better.

The alternative is the watchmaker's lathe, which although produced in several basic forms, generally holds the work in collets rather than a 3 or 4 jaw chuck, and is primarily designed to be used with a graver supported on a tool rest, described as 'hand turning'. The two common groups are the Geneva pattern, made by Boley, Lorch and many others, mostly European and now no longer in business, and the Webster-Whitcomb or 'WW', a US innovation, the main difference being in the shape of the lathe bed. These have been used extensively by watch repairers for many years, but demand a steeper learning curve in order to gain sufficient skill to produce accurate work at the very small sizes involved in watch repair. Many such lathes in regular use today are in the region of 100 years old and still capable of precision work.

Watchmaker's lathes don't generally accept work much larger than 7mm in diameter and a range of collets is needed because individual collets are made to accept specific diameters of work, with small tolerances. This is perfectly adequate for most watch work, and there are accessories which can extend this size range.

I'm sure there will be other responses to your question, especially from some members here who are extremely experienced in using both types of lathe.

Regards,

Graham

 

[steve_s]

Thanks Graham

I bought Perkins book "The Modern Watchmakers Lathe And How To Use It" so much of what you say I am familiar with from a beginners standpoint. One reason I was looking at the Unimat was recent production vs a century ago I thought parts might be easier to find. The other reason was for the cross slide feature which I thought would be more accurate for turning than by hand. I did see that you can buy a collet holder and collets for the Unimat. A lot of the Levins, Boley's, Marshalls I see on eBay seem far from complete.

This all may be way over my head.

 

[wisty]

Not used a Unimat per-se, but you will not want to be turning watch sized parts using a 3 jaw chuck.
That said the Unimat did/does have a collet capability, so a Unimat plus a set of collets would probably work. Both Sherline & Taig are also available with collets as an alternative to their chucks.
I have 6 & 8mm watchmakers lathes, but for my clock scale work I much prefer the Taig with ER collets. In fact I have made adapters to allow me to use watchmakers collets in the Taig.

 

[Jerry Kieffer]

I am contemplating purchasing a lathe and was wondering if anyone had experience with Unimat lathe's? Good, bad, otherwise?

When I started out, I initially attempted to machine staffs on a Unimat SL with a ww collet holding watchmakers spindle. This was a factory accessory back in the early days of Unimat. However success was very limited and not satisfactory at least by my hand.

As such, I have never attempted to machine a staff on a Unimat 3 that has many of the same characteristics as the Unimat SL.

However, machining staffs on my Sherline and Cowells Lathes has been no issue and both are in production with full factory support.
My goal with these machines is to duplicate original dimension and surface finish.

Jerry Kieffer

 

[Bila]

The intended use is eventually to be able to machine a double roller balance staff for a 19 jewel Trenton that has a broken pivot and it is not a very common watch which I am finding extremely difficult to locate.

These staffs are still around

 

[gmorse]

Hi Steve,

As Jerry will confirm, the only way to really understand how well any given lathe will suit what you want to achieve and how you work, is to use it for a while. The obvious drawback to this is what to do if it doesn't work for you, and if you lose some money on the deal when you sell it on, so be it; it's the cost of learning. You need to be analytical and critical to avoid over-compensating for any shortcomings in the machinery by adopting poor practices; if it doesn't function for you, change it. This is where an experienced mentor who's willing to let you try their machines can be such an asset.

While many machine lathes will take collets in various adapters, they aren't necessarily best designed for this, and visibility and access aren't ideal as compared with a watchmaker's lathe, and I certainly wouldn't dream of using a graver on work mounted in a 3 or 4 jaw chuck, it's far too hazardous.

I have 6mm and 8mm Geneva pattern watchmaker's lathes and a Cowells 90ME, and I always turn staffs on the former, although the Cowells is very precise when used for larger work.

Regards,

Graham

 

[Mike Phelan]

I am contemplating purchasing a lathe and was wondering if anyone had experience with Unimat lathe's? Good, bad, otherwise?

Steve, I have used a Uinimat 3 for clock work, making wheels etc, but would hesitate for finer work like watch work.

 

[steve_s]

Thanks all of you. I have much to learn but it's becoming clear that there is a better lathe. I looked at Sherline's and Taigs website and will take a closer look at both.

 

[Bruce W Sims]

Hi, Steve: FWIW I spent quite some time looking around for a lathe but elected to go with more modern technology for the reasons you gave. The final decision was made for me when I asked around about what some of the watch schools use and heard SHERLINE come up a few times. I went with the SHERLINE which came as a kit with quite a number of the bits mentioned by others including the tool holder and the cross-slide. In addition I also purchased the set of collets, though the smallest is 1.5mm so I will need some additional purchases. I would like to go your route and build the skills necessary for close-tolerance reconstruction. Best of Luck.

 

[Bruce W Sims]

BTW...a general question ......

I have a set of 8mm colletts but as mentioned earlier my smallest is 15 and I will probably need to purchase smaller sizes. Are these pieces I only want to purchase new?
I know there are some watchmaking tools that it is not advbiseable to purchased used.
Thoughts? Thanks in advance.

 

[gmorse]

Hi Bruce,

Are these pieces I only want to purchase new?

Ideally, yes, but the smaller sizes, from about 0.9mm downwards are very costly, I think Sherline charges around $50 each for these, and Cowells charge over £170 + VAT each for these very small ones, (over 1.5mm they're only £98 . . .).

There are still lots of collets by Boley, Lorch Schmidt, Schaublin and various good US makers out there second-hand, but without a close physical examination it's hard to tell if they've been abused and are distorted ('sprung') or worn. There are also Chinese collets which seem mostly not to fit the standard WW or Geneva pattern drawbars; I have a fair idea what Jerry Kieffer or DeweyC will say about those! Collets which don't allow the work to run true will be a source of much frustration.

Regards,

Graham

 

[steve_s]

So with all the information received I am leaning towards a new Sherline rather than a vintage lathe. As far as I can tell I don't see any of their lathe packages coming with any collets. Sherline offers three accessory collet sets. The first has a smallest size of 2mm, the second at 1.5mm and the third at 0.3mm. Of course the last set is one with 77 collets and runs just over $1000.

As Joe Pesci says in Lethal Weapon, they "get' you at the drive thru! Not a direct quote.

 

[steve_s]

Looking further they do sell individual collets so I am breathing now.

 

[wisty]

Depending on the kind of work you plan to do, it might be worth considering Sherline's ER16 collet headstock as an alternative. The collets are not quite as precise as WW collets, but each collet can cope with a 1mm range of size. A quality set of collets at <£60 will cater for 0.5 -10mm. They also do chucks and accessories that fit the ER16 (22 x 1.5mm) thread,

 

[gmorse]

Hi Steve,

The collets are not quite as precise as WW collets, but each collet can cope with a 1mm range of size

I've never tried to turn a staff in one of these collets, has anyone here done so? Because they hold the work at both front and back of the collet, unlike the traditional split collets, a short workpiece may not be held so precisely. It depends on the sort of work you intend to do.

Regards,

Graham

 

[steve_s]

Checked out the Sherline's ER16 collet headstock. Then had to go to MSC's website for collets and was overwhelmed with a dozen different collets for that headstock. That was too confusing to me with my limited knowledge.

 

[Jerry Kieffer]

Hi Steve,


I've never tried to turn a staff in one of these collets, has anyone here done so? Because they hold the work at both front and back of the collet, unlike the traditional split collets, a short workpiece may not be held so precisely. It depends on the sort of work you intend to do.

Regards,

Graham

Graham
You are correct in that they would not work well turning a staff or at least the way I machine a staff. I first machine a blank the overall length of the staff to avoid major fitting issues. In this case the collets are not designed to hold short work pieces shorter than the full length of the gripping surface. Thus they will attempt to spit the staff out the front of the collet. In addition, the size of the closing nut obstructs cutter positioning close to the collet nose.

Jerry Kieffer

 

[wisty]

gmorse - I don't do watches, so have not turned a staff, but I have turned <1mm diameter arbours. One way to deal with short items is to put a similar/same size piece of material in the back of the collet. I often use an appropriate drill shank. Runout on mine are spec'd at 0.008mm (0.0004").
steve_s - don't get confused. MSC supply a range for industrial/special purposes. Take a look at ER16 Collets - Arc Euro Trade They're in the UK, but the information is helpful.

PS I defer to Jerry's view.

 

[gmorse]

Hi wisty,

When turning a staff, it's often necessary for some of the stages to hold it by a very short section, probably shorter than most arbors, and also very short sections in other parts such as jewel settings, sometimes down to 0.2 mm long.

Regards,

Graham

 

[Bruce W Sims]

Thanks, Graham: Those beginner lathe courses (see: NAWCC) are looking better and better. I had also heard about how the Chinese bits don't work with the WW system. I think there is also some issues with what their tools will and won't do (see: Mainspring winders). There is a NAWCC Chapter meeting here in Chicago this weekend. I'm thinking you'll be able to pick me out by the number of times I have my hand up for a question.
Best Wishes,

Bruce