Herbert Cridan lathe

Herbert Cridan lathes.

I have seen several of these on ebay but have no idea what they do or how they work. There must be someone here who could give a brief explanation. I should point out that I have no intention of buying one but hate that I don't know anything about them except that screw cutting is always mentioned.

So what is special about them. Why were they made and most importantly....

Do I need one?

Thanks in advance.

David

Dunno! The best I could find is:

**LINK**

Looks like a specialised lathe primarily for rapid threading of parts?

There is still a Herbert and Cridan company in existence, but they look like a small spares and repair outfit rather than manufacturers.

Andrew

Production machines for high quantity single point threading. Mostly for parts too large to be done with self opening die head ( Coventry et al ). Think cross breed of EMI-Mec and cam auto to get some idea how it operates (sort of). Cri-Dan / Cridan machines made by various firms who licenced the concept and basic design. Cam auto and screw machines can cover pretty much same work but the specialised Cri-Dan is some what faster so if you have the work for it it makes economic sense by freeing up spindle time on more versatile machine.

Search for CriDan and/or Cridan on Google will turn up pictures and video but little hard info. Surprisingly nothing in the Lathe / Machine Tools / Engineering book series published by Newnes and Caxton despite being pretty much right era.

These days you'd go CNC unless you had a ton of work for one.

Clive.

When I joined Rolls Royce at the Sentinel Works, Shrewsbury, in 1958, CriDans (two models) were still being made there. (A left over contract from the Sentinel ownership days). With the tool controlled by hand stoned cams, they would cut a 1" Whitworth thread, 10 inches long in little more than a minute or so. Machines on test were an obligatory stop when we took visitors around the factory. The swarf came off as a continuous blue wire, until the cam caused the tool to withdraw and return to the starting point for another cut.

They were a special purpose machine, unsuited for general turning work.

The machine tool expertise was then used by R-R to produce special purpose machines for producing jet engine parts.

Howard

I finished my apprenticeship at Sentinel (Rolls Royce) in 1959 and during that time I worked on the smaller Cridan as a fitter.

The people who taught me were extremely experienced and when Rolls Royce took over, were very critical of the standard of stuff that they sent us to work on with oil engines.

At the end of my time I was called up for National Service staying in an army band for 14 years when I left to pursue a musical future with various orchestras around London. For the Last 40 years I have put my Sentinel skills to work making Trumpets and I'm glad that I did my time with such a good firm

David Edwards

David Edwards, you must have left shortly after I joined in September 1958.

The Apprentice Instructors, such as Alf Neal, (Turning) ,Jack Baker (Milling) and Eddie Candlin (Grinding) were highly skilled and experienced. Can't remember the name of the Inspection Instructor.

We were given a sound base in machine work, (I still have my notes and refer to them from time to time)

I remember those folk with respect and affection.

The design of Sentinel products was good. Sentinels were the last manufacturers of steam lorries, and they pioneered underfloor engined buses and coaches. Rolls Royce continued to use Sentinel lorries to deliver their Oil Engines for several years afterwards.

How good can be judged by the fact that the Rolls Royce powered Sentinel shunters captured 50% of the market for such locos. Some are still in use on Heritage lines.

Howard

Welcome to the forum David, life can take us on some surprising journeys!

Neil

https://www.trumpetherald.com/forum/viewtopic.php?t=133405

Neil/David,.......if you ever feel like writing an article for MEW on making a natural trumpet then I for one would very much like to follow the said articles and make a trumpet......

Cri-Dan was a French company who licenced machine tool manufacturers around the world to build their machines (companies such as Kirloskar, Gisholt, Realmeca, there was also one produced by Lees-Bradner and called the Sentinael [spelling correct!]) . The Herbert Cri-Dan was manufactured at the Alfred Herbert, Edgwick plant, Coventry between about 1960 and 1975. The novelty of the Cri-Dan was it used a 'drag bar' arrangement - at least on the model 'A' - which had the threading slide sit at an angle above the workpiece. The slide was hydraulically controlled.

I served my apprenticeship at Edgwick and would often look on in bewilderment at the speed these machines could operate at. Not really a practical machine for the home workshop though!

As an apprentice in the mid 1970's I operated a cridan as machine shop experience in the turned parts shop, not long after that CNC lathes started to appear and I guess their time was up. I seem to recall it relied upon a spring loaded cam but I might have misremembered, it was a long time ago.

I remember watching a similar machine work. I believe the brand name was Man au Cycle. Since the advent of CNC the threading lathes have almost disappeared.