Osborn Titanic (not Titanic II) Chuck conundrum.

I've obtained what appeared to be a complete outfit of an Autolock type Chuck, full set of collets and full set of threaded inserts all in the original box. It was something of an impulse buy whilst looking for something else entirely...

However I'm totally unable to figure out how it operates, it looks nothing like the more common "Titanic II" or Clarkson systems, and I have a sneaking suspicion that what I have is a very complete set of the correct collets but absent some other component(s)

My understanding of how these style of chucks work is that

1. the threaded inserts (or collets with an internal thread) go into the chuck first and are prevented from rotating by some internal feature of the chuck body.
2. The collets go in next and butt up to the threaded insert.
3. The external nut on the chuck is closed to hold the collet and insert in.
4. When a threaded endmill of the appropriate size is screwed in, once it bottoms out on a stop in the chuck body any further rotation is driving the threaded insert down against the external nut, causing the collet to close.

However:

• The collets are unthreaded with a smaller diameter than the threaded inserts, and sit so deep into the chuck that the can't touch the external nut and engage their taper, whilst nothing in the chuck body provides an anti-rotation feature. Also the taper is the wrong way up to be effectively closed by the action of a threaded endmill.

• The threaded inserts are a perfect fit on top of the collets, and in the chuck, but that setup would prevent the threaded endmill from actually engaging in the collet at all.

[For further descriptive photographs click here]

I'm totally stumped, if anyone had used one of these before and can give me a steer on if the parts are correct (and if they are, how I use them effectively) it would be most appreciated.

Edited By Jelly on 16/09/2022 02:18:10

You say:

"The collets are unthreaded with a smaller diameter than the threaded inserts"

Maybe a first step on the road would be to identify the shank diameter that the collets will accept. As you know, threaded shank cutting tools come in a limited range of diameters (1/4", 5/16", 3/8", 1/2", 5/8" and 6mm, 8mm, 10mm, 12mm and 16mm). If the collets do not suit these diameters, that points to an issue.

Similarly on the threads in the insert. I believe that all threaded shank systems followed the Clarkson pattern whereby the thread was 20tpi Whitworth form, whatever the shank diameter (even on the metric ones, so you could have M12 x 20tpi for example ) . Again, if they do not match this pattern, it points to something unusual.

If you have any screwed shank cutters, try them in the collets and in the inserts. What fits what might assist you in the diagnosis.

This patent may be relevant : **LINK**

https://worldwide.espacenet.com/patent/search?q=pn%3DGB856264A

[downloadable via the three-dot menu]

MichaelG.

Nice find by Michael.

Opening paragraph is a clear and concise description of how the beast works. Looks like you are missing the second sleeve, part 18 on the diagram that actually closes the collet.

Clearly this style of cutter holder was designed around the use of conventional draw in style collets with the closing taper on the back. Hence needing the closing sleeve to opearte it.

Possibly designed that way to get round the original 1943 Clarkson patent which covers most of the possible variations of the screwed into a collet end mill holder.

**LINK**

https://worldwide.espacenet.com/patent/search/family/035523252/publication/CA414067A?q=Clarkson%20Chuck

The separate closing sleeve and, possibly, the fixed point in the back would take the Osborn design clear of that patent.

Its not clear when, or even if, the Clarkson system as we know it was patented. If Clarkson relied on the original presumably Osborn switched to the simpler Clarkson concept with external closure on the collet.

Clive

Aha!

The second sleeve mentioned in that patent and shown in section, appears as if it is just part of the bore in the chuck I picked up; that explains why the design didn't make any sense perfectly.

It's obviously an extremely close fit, and has been locked in place by oxidised oil or similar, how to get it out on the other hand may be a challenge.

.

Allow me to repeat my frequent plug for PlusGas Formula A

… best stuff I have ever found for dissolving oxidised oils and greases.

MichaelG.

Firstly, apologies for not reading the thread, will be back later to read all. Scan reading, I don't think you have a solution, but I can see a few assembly errors, and youve missed a part that inside (it does need to come out, it will help you piece it together!)

I have the same set, instructions are printed on the lid (or perhaps on a card in the lid) - I will have a look when I'm home and or photograph them if needed.

Observations...... your photo showing a view inside the chuck - there is a hardened steel outer ring in there, fish it out and it'll all start making sense, as will the following paragraph. Also note, that bit at the bottom with the point, has machined flats on it's OD, these engage with the notch in the threaded part..... which you've put in upside down in your photo, notch faces in, rotate till it engages.

The shot of everything standing on the vice jaws, you collet is upside down, face the flared edge away from the notched/threaded part - the taper on the end engages with the taper in the hardened steel outer ring that you've left inside the body as per previous para..

The collet sits against the nut, as the endmill rotates, it does so against the hardened pin in the base, the notched/threaded part keying with the flats cannot rotate and the thread pushes it downward, which in turn pushes the hardened steel ring downward, this forces the outer tapered part to engage with the taper on the end of the collect, nipping the endmill.

I hope this makes sense, it's a bit rushed.

Edited By Russ B on 16/09/2022 10:12:02

In the time it took me to write that between jobs at work, I think you've solved it!

Success!

Just popped out to the workshop to put my welding PPE away (was out yesterday evening/night doing some welding elsewhere) and thought I'd have another crack since I was out there.

Filled it up with EZ-Start whilst I sorted out my putting away, then as that had drained/evaporated did the same with penetrating oil for a few minutes whilst listening to R4.

Then used a length of brass rod as a drift to push the central pin out (it's a perfect light transition fit by feel), which revealed a lip formed by the bottom of the sleeve overhanging the relief for aligning the pin.

Using an allen key as a stiffer alternative to a pick tool i was able to get enough purchase to get the collet sliding slightly, making space to put one jaw of an extra-long nose needle-nose pliers in and hook the serrations on the edge of the collet, giving me a good handle to pull firmly, and out it came just like that.

From what I can tell the sleeve is extremely close fitting to the bore and just a tiny buildup of crud in the bore results in it binding tightly.

It wouldn't go back in initially, but little more than wiping my fingertip round the bore was enough to remove the detritus and restore it to a perfect sliding fit (I can't get over how well made and well preserved this thing is, a number of the ground collet and insert surfaces will wring together from their smoothness).

Posted by Michael Gilligan on 16/09/2022 09:45:45:

I will bear that in mind, my Heath-Robinson solution of using EZ-Start was effective enough, but extremely cold.

It's only about 13C in there today anyway, but allowing a vast quantity of Ether to evaporate on a steel part brought it's temperature down low enough that it was uncomfortable to hold with bear skin when adding the penetrating oil; possibly that thermal cycling actually helped make room for the oil to get in.

I need to organise the collets and inserts, which is a task all of it's own as the seller's storage approach left something to be desired...

They did at least cushion them with shredded newspaper for shipping but i took that out ASAP as paper would just attract and retain moisture.

.

Based on just a visual inspection and count, it would appear that I have a full complement of metric and imperial sizes (including the less common 16th and 32nd's intermediate sizes and metric equivalents), plus duplicates; but as everything is unmarked, I will need to sit down the the bore-mic and measure to separate them out...

I could have 4 sets of the standard 5 imperial or metric collets for all I know right now, something I'm placing firmly in the "nice problem to have" category.

.

There aren't actually any (appropriately sized) threaded shank cutters in the workshop at the moment (plenty in 1" - 1.25" shanks though) having donated them to a friend who was starting out, because I had moved over to using solid carbide endmills at the time.

However, the Harrison I just acquired doesn't have the speed required to run smaller diameter non-insertable carbide endmills, so I'll need to get some more HSS ones if I want to be able to do any end-milling operations in the Horizontal Spindle; but I'm sure Ericks, Cromwell or the Tooling Stores on Attercliffe Road will be able to sort me out with them as required.

Jelly, I see you mention Attercliffe; are you around Sheffield somewhere?
I was in Crookes, but moved to Buxton when we retired.

Some time ago, I made an album on here showing different types of milling collet chucks;
I've left it open for other members to contribute, so that it might assist others in the future.
If you get the chance, or anyone else with something unusual, please feel free to supplement the album.
https://www.model-engineer.co.uk/albums/member_album.asp?a=53353

Bill

I'm right at the far south of the city, used to live in Crookes when I first moved to Sheffield as it happens, small world!

I will try to get some better framed pictures of my chuck to add to that album when I have a moment, fairly sure you haven't captured one in there so far.

​

I must say I've found Sheffield remarkably convenient for any kind of metalworking hobby, side-line or business, despite the relative decline in manufacturing, there's still just about every kind of supplier and subcontractor you might ever need spread across the east and south of the city...

Looking at the instructions posted by Richard shows what an improvement the Titanic II was. I use that type and if collets are needed, Posilock are identical to the Osborn.

I was half expecting to read "... and when I regained consciousness the sleeve had popped out!"

I have a TItanic II, rarely used in anger, but yes easy to use.

Neil

Given the potential for friction from all the sliding surfaces you have to wonder just how good a grip the collet has on the cutter after initial installation. Especially in the smaller sizes.

I've shattered the back end of a cutter on the point of my Posiloc one a time or two when I failed to make properly sure that the collet had been driven firmly against the nose piece by screwing the cutter in properly. Compared to the Osborn 1 a Posiloc / Clarkson has virtually no internal sliding surfaces to generate friction so it ought to take much less effort to get things firmly seated.

Think I'd be investigating some sort of soft(ish) gripping sleeve with turning handle to get a bit more torque into the Osborn system so the collet starts out with a better grip on the cutter.

Clive

Hi, I’m fairly new to model engineering. I have recently bought an Osborn type one Titanic milling chuck which came with one 12mm collet. My mill came with a large amount of threaded cutters of 6, 10 and 12mm shanks. Does anyone know where I can obtain 6 and 10 mm collets for the type 1 chuck? I have been watching on eBay for weeks now with no joy. Does anywhere still stock them? Thanks in advance.