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Forum Home > Non-Seiko 7Axx Discussion Area (Re-branded mvmt's) > Cartier Ferrari Formula case-back removal tool - coming soon !

Seiko7A38
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Posts: 9329

I could just as easily have posted this topic in the Workshop Tech Tips section, where it possibly belongs, but as it's very specific to one particular brand of non-Seiko 7Axx - the Cartier Ferrari Formula Cal. 531 / 532, it's more likely to get the views it deserves here.


I have too many unfinished projects on my bench. A couple of watches belong to friends / forum members who have been very patient.

One of them is a Cartier Ferrari Formula belonging to Nathan Beehl. You may remember this thread, where I wrote back in January:

 

As I wrote in my email, it looks like I'm only going to be able to fix this one. My tentative plans to fit the Junghans pushers to your other watch have been kyboshed. I simply can't get the case-back undone. It's absolutely solid and won't budge, even with aerosol freezer.

I suspect whoever refitted it (after the last battery change) used the proprietary Cartier case-back wrench - to extremely good effect. Apart from the fact it's done up murder tight, there are no extraneous marks on it at all. It's almost pristine - unlike your other one.

For those of you who aren't familiar with the Cartier Ferrari Formula case-back, here's a (library) shot of what they look like:




The circular flange sits flush with the back of the watch case. The very slightly raised area (<0.5mm) is a tetradecagon (14-sided) measuring 32.0mm across the flats. Basically, if it won't unscrew using a 'sticky ball', you need the proprietary Cartier wrench. 


September 28, 2013 at 3:27 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

In February, I did my own 'back of a fag packet' sketch of how I thought such a tool might look:




The Polygon Calculator I used was similar to this one: http://www.calculatorsoup.com/calculators/geometry-plane/polygon.php




In a nutshell, it was going to look very much like one of those flat spanners you used to get supplied in bicycle tool kits years ago ....

Except that this one was going to be rather more precise. ;)


I'd planned to have the prototype made in 3mm thick 316L Stainless Steel using the EDM Wire Cutting technique - for accuracy.

Swindon, where I live, used to be a thriving engineering centre, with dozens of workshops who could have undertaken the work.

Unfortunately, there were only two companies who said they might be interested - but their estimates were extremely prohibitive.


September 28, 2013 at 4:00 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

So I started casting around looking for a (much) cheaper solution. Searching on eBay, on watch case-back removal tools, worldwide .... I came across a range of palm held tools, to suit Breitling, Rolex, Panerai, in various sizes, offered by a Far East seller - WatchmeHK

He's only listing one, currently:

http://www.ebay.co.uk/itm/Professional-Watchmakers-PANERAI-Handheld-PAM-OPENER-New-PAN-12-040-GOLD-/251346417118


(Their distribution appears to have since been taken over by other HK and US eBay sellers).


Back In April, I contacted Thomas Leung of WatchmeHK and asked if he might be interested in producing a similar case-back tool for the Cartier Ferrari Formula chrono's. Sent him a few emails, including all the dimensions. Then everything went quiet for a few months.


September 28, 2013 at 4:32 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

It had got to the point where I'd almost given up on Thomas. I'd even recently contemplated trying the ultimate bodge of super-gluing a hex nut onto the back of Nathan's watch case-back, and trying to undo it with a ring spanner.

This morning, to my surprise, I received an email from Thomas:


Hello Paul,

How are you ??? Good news for you, the Opener of Cartier Ferrari Formula is finished ( attached picture ).



 



The original plan had been to send the prototype case-back opener to BigglesMcLee in Hong Kong for appraisal. See his thread.

But as he posted on 2nd June that his watch is now sorted, I've asked Thomas to post it to me instead. I have the greater need. :D


September 28, 2013 at 4:55 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

You'll note in the above photo that the WatchmeHK's prototype doesn't have precisely machined corner angles (as I'd have preferred).

This doesn't entirely come as a surprise. ;)


Back in March, prior to contacting Thomas, I'd been talking to Bryan Hibbins about my plans for such a tool. In one email, he wrote:

 

Paul, 

I'd drill the corners out with a 1.5mm dia drill prior to milling the edges.



 

And would ask a good machine shop to quote for CNC milling. Gotta be cheaper.

You should easily be able to get a quote for £xx tops for machining up a few tools. 

I know from past experience EDM can be VERY expensive. It used to cost the gaffer silly money when our firm had tooling EDM'd!

Bry. 


September 28, 2013 at 5:20 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

It's always nice to get packages in the post. :) This one wasn't exactly a surprise, but had taken rather longer to arrive than expected:




First impression is that it's well made, machined to accurate tolerances, a decent weight and fits nicely in the palm or between fingers.

I am going to make one small recommendation to Thomas, before he goes into full production with it. Of more anon. ;)


It's not likely to be before next weekend, when I give it the 'acid test' and attempt to use it to undo Nathan's recalcitrant case-back, but I was itching to try it out on something. So I selected one of my own Cartier Ferrari Formula chrono's - one with a case-back which was already a bit marked, deliberately. I'd bought this watch, which allegedly once belonged to someone involved in F1, on eBay for a very reasonable £205, back in September 2011. The gamble was that it was sold with a flat battery. Turned out to be squeaky clean inside. 

This is a photo I took at the time:


November 4, 2013 at 1:04 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

So, if I'd replaced the battery two years ago and the watch was running fine still, why would I want to undo the case-back ? 


I didn't. :D

At the time, the case-back had unscrewed fairly easily and once I'd replaced the battery, greased the seal and threads, I tightened it up, best I could, using a 'Sticky Ball'. But I was never completely happy that it was as tight as it could be. Here's how it looked before:




Here's how it looks now after using WatchmeHK's tool, with both watch and tool just held in my bare hands, to tighten it up a bit more:




Rotated almost another complete flat. :)


November 4, 2013 at 1:43 PM Flag Quote & Reply

garacs1
Member
Posts: 508

Paul, what would be the price range for something similar, but made for normal 7Axx Seiko backs? you know, with the 6 notches. I know there are a lot of tools that can be adjusted to fit any case back, I also have one, but I never quite liked the "one for all" approach. Plus, they always tend to slip somehow, so a scratched case back is always a possibility. With a tool like the one you  tested here, but with 6 notches, it would be almost impossible for it to slip off... or yes?

--

My personal Blog: www.onlyvintagewatches.com/blog

November 4, 2013 at 2:11 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

I'm not sure there's a need, or that there would be sufficient demand from the market for a Seiko 7Axx specific tool, George. :/

There are plenty of cheap Jaxa copy 3-prong tools out there and mine has served me well for the last 5 years. 

The 14-sided Cartier Ferrari Formula case-back is quite unique and a specific tool was (and still is) needed - because nothing else fits.

Have a read of this thread:

http://www.seiko7a38.com/apps/forums/topics/show/8851065-yema-n7-n8-spationaute-iii-etc-specific-case-back-tool-anybody-

Now from the lack of replies to that thread, I would assume no-one else is interested in a Yema (Spationaute, etc.) specific tool. :(

But may I suggest you go and check out that eBay seller's other offerings. ;)


November 4, 2013 at 2:22 PM Flag Quote & Reply

garacs1
Member
Posts: 508

I followed the thread for the Spationaute, but always thought that the common Jaxa would still do the trick - does it not? I do not own still a Spationaute, so I  cannot try it out, but the 6 holes are lined out as the notches on the normal 7axx case back plate, so adjusting the displacement of the 3 Jaxa tool prongs to the correct position should do the trick. I guess you have tried it already, and that is the usual method, but please confirm.

--

My personal Blog: www.onlyvintagewatches.com/blog

November 4, 2013 at 2:51 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

George. Please stop taking this thread . But I'll answer you this one last question ....

Yes, a Jaxa copy 3-prong tool will work, most of the time - after a fashion, to unscrew the case-back on a Yema Spationaute III ....

But, the P.C.D. of the Yema's 6 tool holes is only 24.5mm, compared to approx 32mm for the notches in a Seiko 7Axx case-back.

Hence to unscrew the Yema case-back, you need to apply more effort to achieve the torque required - thus increasing the risk of tool slippage. That apart, most Jaxa copy tools, including the one I bought years ago, don't come with the correct diameter (1.85mm) round pins to fit the holes. So that probably means using the oblong / rectangular pins which you'd normally use on a Seiko 7Axx case-back, which don't fit particularly well. That's what I used myself, until I had some correct diameter brass pins turned to fit my Jaxa copy tool.

November 4, 2013 at 4:12 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

O.K., time to get this thread back on track - and keep it that way. 

Today was going to be 'make or break' / 'crunch day' for Thomas of WatchmeHK's prototype Cartier Ferrari Formula case-back tool.

This is Nathan's other watch that is providing the (tough) challenge - also suffering from a missing pusher button (and a dinged one).



It has a few other issues besides, which I hope to be able to sort out in due course: a flat battery (normally the easiest thing to fix - IF you can get the case-back undone, that is) and scratched crystal. It's also badly fitted with a non-original after-market Rowi two-tone bracelet. This watch case, having the early style full width 12mm lug cut-out (and undrilled lugs) would originally have been supplied fitted with a notched leather strap. If I can figure out how to get the Rowi bracelet off, I may see if I can find something that fits better.




Here's a shot of that case-back, which had so far defeated my efforts to unscrew it. I'd tried a sticky ball (and using aerosol freezer, to make the threads contract, but wiping off the 'frost', before trying the sticky ball again). In fact I'd tried it a few times - all to no avail. :(

November 9, 2013 at 12:35 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

Knowing already that this case-back was screwed on absolutely solidly (God only knows how they'd put it back on that tightly, unless they had access to a proprietory Cartier case-back wrench), it was with some trepidation that I approached the task. Before I gave it any 'welly', I dropped the tool onto the case-back just to see how well it actually fitted. As I hinted before, there is some slight 'play'.


Rotated Clockwise:Rotated Anti-Clockwise:

November 9, 2013 at 1:02 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

That radial 'play' looks a lot worse than it actually is, but I'll expand on it at the end of this series of posts. ;)


I first tried holding the watch in a towel (my palm open), with the tool held and rotated between my  fingers, gripping it tightly. No way.

Then I tried holding it in a watch case vice (in the same towel) - again no go. Then again, giving it a quick squirt of aerosol freezer. :(


There was only one thing for it - the same set-up I use when unscrewing obstinate Seiko 7Axx case-backs (using a Jaxa copy tool) -

Mount the watch case vice in a bench-mounted aluminium jawed vice (a Stanley No. 702); Give it some freezer and a LOT of 'welly'. 




After a good l-o-n-g squirt of aerosol freezer (it looked like the Antarctic inside the case-back tool), and bearing down on the tool with both hands, to make sure it couldn't slip, I finally managed to persuade the case-back to unscrew. Perhaps it was because I didn't have the leverage you'd get when using a Jaxa 3-prong case-back tool, but it seemed like damned hard work for a minute or two. 



November 9, 2013 at 1:25 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

The prototype tool came away relatively unscathed after being given this 'ultimate test' - save for a couple of light marks on two facets:




The case-back (once it had de-frosted) looked none the worse for wear:



As a sanity check, I measured it across the flats and found that the smallest distance was 31.93mm (as shown by the vernier gauge).



The largest sides I measured were 31.98mm across. I then measured (best as one can) across the flats of the tool: 31.93 to 32.06mm.

So Thomas' machining tolerances are within +/- 0.06mm - which considering what he charges for these tools is quite respectable.  

One consideration in designing such a tool, is that it needs to be relatively easy to fit onto the case-back by an amateur user. 




The other issue is allowing for worn corners. Nathan's case-back still had reasonably sharp defined edges, but as with all of these, there's a slight taper to the edges - and that raised tetradecagonal area, which is all the tool has to act on, is less than 0.5mm high.


Where I would recommend this tool could be improved, is by considerably reducing the size of the corner drillings. As you can see from the tables in my second post, in 'a perfect world' the 14 inside faces of such a tool would measure 7.30mm. In Thomas' prototype tool, because of the over-sized drillings, the few sides I measured were only 5.0mm long. I believe by reducing size of the corner drillings, it should be possible to extend the inside faces to at least 6.0mm or maybe even 6.5mm, thereby giving the tool a better 'purchase'. ;)


November 9, 2013 at 2:03 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

When I originally gave this topic the title: Cartier Ferrari Formula case-back removal tool - coming soon !

Back in September last year .... I didn't actually say how soon, did I ? 

Well, perhaps I ought to change it to: Available Now ! 


http://www.ebay.com/itm/251433225527




Looks like Thomas took on board my recommendation about significantly reducing the size of the corner driilings too. 




January 24, 2014 at 11:10 AM Flag Quote & Reply

Sir Alan
Member
Posts: 451

Great news Paul.


Given the shipping charges are almost the same as the cost of the tool, perhaps we should be looking at a group buy?

January 24, 2014 at 12:50 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

Yes, perhaps the shipping charges are a bit excessive, Simon, but given the effort that Thomas had put into manufacturing the tool ....

I thought the least I could do was to order one myself - if only to see how it compares with his prototype tool. So I did. :P


It arrived yesterday. Here it is alongside the prototype. You can see the much reduced corner drillings / longer mating faces ....



The transition between the corner drillings and the flat edges of the mating surfaces is less well defined, but as best I could measure them, on the production tool they're each well over 6.0mm long - almost 6.5mm (as I'd suggested to Thomas in my last email).

As a result, there is absolutely ZERO evidence of radial play - compared to what I'd percieved on the prototype tool. :)




In fact, if there's any slight criticism to be made of Thomas's production version, the tool proved a very tight fit on this Ferrari Formula case-back I tried it on, as a test - I suspect partly due to the couple of extra thou' added by the lovely metallic red anodized coating.


February 15, 2014 at 9:42 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

Browsing the Italian Orologi & Passioni forum this morning, I came across this thread: http://orologi.forumfree.it/?t=67002127 

Two posters with Cartier Ferrari Formula case-back opening problems. :( Roughly translated (by google) from the original Italian:


.... I took it to a private watchmaker and he told me that he cannot change the battery .... maybe because the lock ring back is 'a bit special'.

 

I have a similar pattern, with red dial, you have to take it to a Cartier dealer.

They alone have the key to open the bottom with a specific shape. Not all dealers were also retailers Cartier Ferrari Formula, but I think the percentage was very high . My watchmaker has never opened my Ferrari Formula, sure he would definitely scratch it.

Mine is from 1990 and works perfectly and is still, for me, very nice.

PS never mind the fact that they ask you for 20 euros to change a battery that costs 1.5 euro ...

 

I've pointed them in the right direction, needless to say. 8)


March 8, 2014 at 5:09 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 9329

Sir Alan at January 24, 2014 at 12:50 PM

Great news Paul.


Given the shipping charges are almost the same as the cost of the tool, perhaps we should be looking at a group buy?


Or just wait till Thomas drops the price (and shipping charges) a bit. ;)


http://www.ebay.co.uk/itm/251471015294

March 13, 2014 at 4:00 PM Flag Quote & Reply

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