Case back opener dimensions

[Garnix]

Hello all

I’m a professional CAD jockey and would like to print some case openers. I have found this model

Enicar Seapearl Case Back Tool by SFoskett

This is a tool to open the unusual scalloped watch case backs used by Enicar for their Sea Pearl watches, including their Supercompressor and Ultra-Compressors. I printed it with PLA so it would not mar the case, since it's so soft.This thing was made with Tinkercad. Edit it online...

www.thingiverse.com

But I understand that it will only work on 36mm cases. I would like to make a 40mm opener, and if there are other size tools people would like, it should only take me a few seconds to adapt a model. I’ll be happy to release the tools for public use if someone could help me get some dimensional data. I could take a caliper to my ops (and will do so to confirm), but if OEM specs exist, I’d prefer to start there.

 

[mc1]

I've just sold one of those smaller ones you've pictured for $25 plus postage. I'd be keen on a sherpa graph opener which are 14 sided and 34mm across on the flat sides and 34.7 mm edge to edge. Steve Harris had some metal ones made awhile back so he might have some better data

@SteveHarris

 

[Ronniebutler]

I’m keen to have a Sherpa Graph one.

 

[Garnix]

@SteveHarris

If Steve has a number of dimensions, that makes this easiest, but if anyone wants to take a caliper to a 14 sided case back and report that width with the reference, I can use those dimensions and share a link to a shapeways model here. I plan to make some models this week to order, so I’ll be measuring my Jets, Ops, and Garnix for those.

I’ll order some of my models first to make sure the tolerances are right and the material I select works, then share the models for any other references for which I have collected data.

 

[Garnix]

I have taken a caliper to all my Enicar compressors and found that they all follow a similar pattern, and all the watches I have use the same tool.

The corner to corner measurement ranges from 31.37 to 31.64mm

Using two corners as a flat, the flat to flat measurement ranges from 30.67 to 31.06mm

HOWEVER

Using the tangent circle to the inside edge of the 14 arcs, all of these watches have a 30mm tangent circle diameter (each watch measured between 29.93 to 29.95mm). Using a radius gauge, the arcs are all very close to 12mm. The arcs are too short to get a perfect measurement, but 12mm is very close. I got to 12.77mm from a CAD drawing using this tangent circle and a 30.8mm point to point estimate (the actual features don’t have sharp corners), so 12mm should work.

My design is a laser cut piece of brass from SendCutSend, and looks like this. The handles are for those of you that may not have a bench top case back tool, the 2mm holes are for those that do.


I am ordering 4 prototypes with the following parameters:
1. 30mm nominal tangent circle, 3.2mm thk
2. 30.1mm nominal tangent circle, 3.2mm thk
3. 30.2mm nominal tangent circle, 3.2mm thk
4. 30.1mm nominal tangent circle, 4.7mm thk

I’ll keep you all posted on the results.


If anyone wants a different size, I’ll be happy to post a model, but I’ll need three dimensions, as defined above:

Corner to corner, flat to flat, and tangent circle

 

[Garnix]

I got them in and tried them out. As expected, the 30.1mm was the best tool. The 30mm fit, but was difficult to get on, and stubborn. The 30.1 was perfect, but the 30.2 worked just as well tbh. 3.2mm thick is more than enough - 4.7mm is overkill.

The ergonomics of the tool need to be improved. The diameter is large enough that it almost hits the lugs, and the symmetric handles limit how it can be oriented, so here is the next revision.

I expect this one should work, so if it does, I’ll share the model, and any other sizes if they’re requested.


Incidentally, does the 34x34.7mm case back have flats or radii? If they are flats, I can model that and release it alongside this tool, once I prove this one. The case diameter of that watch would be necessary information, though, as the OD of the tool has proven important to its ergonomics.

Since SendCutSend has minimum order value, ordering 5 was going to be $4 more than ordering 1, so I’ll have 4 spares if anyone wants to buy one once I’m satisfied that they work.

 

[JimJupiter]

love your effort! Fortunately I have some original openers, but these rebuild ones are needed in the community!

Thanks , Nico

 

[Garnix]

love your effort! Fortunately I have some original openers, but these rebuild ones are needed in the community!

Thanks , Nico

Thanks!

If you have any data you can share on the originals, I would love to use it to model more of these if they would be of use to anyone.

 

[JimJupiter]

Where are you from? If not so far away, I would lend my openers of course

Nico

Edit: you can just write me a PM

 

[mc1]

I got them in and tried them out. As expected, the 30.1mm was the best tool. The 30mm fit, but was difficult to get on, and stubborn. The 30.1 was perfect, but the 30.2 worked just as well tbh. 3.2mm thick is more than enough - 4.7mm is overkill.

The ergonomics of the tool need to be improved. The diameter is large enough that it almost hits the lugs, and the symmetric handles limit how it can be oriented, so here is the next revision.
View attachment 7195
I expect this one should work, so if it does, I’ll share the model, and any other sizes if they’re requested.


Incidentally, does the 34x34.7mm case back have flats or radii? If they are flats, I can model that and release it alongside this tool, once I prove this one. The case diameter of that watch would be necessary information, though, as the OD of the tool has proven important to its ergonomics.

Since SendCutSend has minimum order value, ordering 5 was going to be $4 more than ordering 1, so I’ll have 4 spares if anyone wants to buy one once I’m satisfied that they work.

The sherpa graph has flat sides

 

[Garnix]

@mc1 @Ronniebutler

Here is a model that should work for a Sherpa Graph.

Free CAD Designs, Files & 3D Models | The GrabCAD Community Library

The GrabCAD Library offers millions of free CAD designs, CAD files, and 3D models. Join the GrabCAD Community today to gain access and download!

grabcad.com

I don’t own a Sherpa Graph, so I can’t test it, but if you’re willing to try it and share some feedback, I’m pretty confident it should work. I made it 34.1mm flat to flat, so it should fit just like the one I made for my Jet.

Sendcutsend.com has a minimum order price, but not quantity, so 4 or 5 of these should cost basically the same as 1. If a few people want these, a group buy might be efficient. It was only $33.50 for the order I placed for the 5x 30mm tools. I probably have a discount through my company, so I’d be happy to facilitate as needed

I wrote some instructions in the description for the model.

 

[Garnix]

I ordered 4x of the Sherpa Graph openers. It was $35 for all 4, so if anyone else wants one, pm me and I’ll figure out how much shipping costs. I expect $20 should cover my costs including shipping anywhere on earth, but probably less CONUS. The same applies for the Jet openers.

 

[mc1]

It's very generous of you to do this

 

[Joe_A]

Once upon a time a couple years ago, I sent my first Sherpa Graph to RGM, Roland Murphy, in Mt. Joy, Pa. for service and he did not have an opener. He does a fair amount of CNC milling work, so he made one of these for himself and one for me:



The holes were drilled to be used with the Bergeon case opening press/tool.

I have a small manual SX-2 milling machine and 7x16 lathe and made the attachments so it can be used by hand.

I am located in New York. I'd be happy to try the new tool on my Graphs if that will help.

I too appreciate your generosity and good work.

Cheers,

Joe

 

[Watchyouwant]

I ordered 4x of the Sherpa Graph openers. It was $35 for all 4, so if anyone else wants one, pm me and I’ll figure out how much shipping costs. I expect $20 should cover my costs including shipping anywhere on earth, but probably less CONUS. The same applies for the Jet openers.

Whatever you do, i take one opener as well. Will ask my watchmaker; he might need one as well. Kind regards. Achim

 

[Garnix]

Great success!

Sorry for the long silence. I’ve been trying a lot of these, and decided to wait until I had results to share. Here are the iterations I’ve tried:

From bottom to top:

This was the first version, I’ve already shared it here, so I won’t elaborate

This is the sherpa graph version. I don’t have a sherpa graph, but I expect it to work very much like the next one

This is the wrench style sherpa jet opener. This style definitely grips the case well, and the brass doesnt scratch the steel at all. I found it very difficult to grip the case solidly enough to use this style tool, though it is probably the best that can be done without a bench top case opener.

The next three are different versions intended to be used on a bench top opener. The middle one was intended to be used if the top didn’t work. The second from top was an experiment that I never tried because the top one worked perfectly.

The top caseback opener was my best case scenario. I was concerned that the small amount of metal between the 2mm hole and the outer edge would simply burn, and that thin wall might not support the torque. There was some burn through on the outer edge, but it doesnt seem to matter. These openers are perfectly sized (you can see they have a loose friction fit with the case back pattern). My bench top tool makes opening these easy. The only challenge was that my first test watches were polished (which is why I tested on them first), so the alignment marks were not visible.

I have a few of the wrench styles I would be happy to sell, and if people would like the bench top style, I can order a small production run.

I would like to see how my wrench pattern fits a sherpa graph before I order more of them in the other pattern.

 

[Joe_A]

PM sent.

Happy to test on the S.G.

~ Joe