Shaving a 5513 dial seat to use a 1680 dial

[e30m3]

Just to be sure I’m about to take metal off the right area (.25mm all around, for a total of .5mm), it’s this little lip that needs to be lathed right? Where the arrow lands?

[Dan71]

Seem correct to me, but you have also to enlarge the dial window (the rehaut ) otherwise the minute track indices will be partially cover ..

 

What do you use a professional lathe ? I have read that someone have made this wise by hand with sandpaper.

 

 

 

 

 

[e30m3]

I was debating sandpaper until I saw how narrow that ledge is. Thinking it might be easier (but not easy) on the lathe.

So, both surfaces (rehaut and seat) go down .25mm?

Thanks.

[Dan71]

I think the same misure for both !

 

RolexAddict make this work on my cartel watch so I don’t know exactly which tools he use ..

 

But your lathe is professional (big tool) or those little lathe for model building ?

 

 

 

[e30m3]

It's a professional lathe, yeah. Super heavy, doesn't budge. Maybe @Rolexaddict could be so kind as to chime in on the "shave what where" aspect?

[Dan71]

Rolexaddict is a modder,
I think was more active in the past on rwg.bz is always busy..or maybe prefer keep same job secret , I don’t know..

At the moment the jkf 1665 is the more easy work because the case accepts gen spec 26.5mm dial..

[automatico]

"But your lathe is professional (big tool) or those little lathe for model building?"

 

I have enlarged quite a few dial windows and dial seats with a small Sherline precision lathe with the case mounted in a three or four jaw chuck.  A three jaw chuck is more or less self centering but it still may be off a few hundredths mm or more.  A four jaw chuck is more of a hassle because the part to be machined has to be centered with a dial indicator or something similar.  For something like a dial window, I mount a pointer and adjust the jaws until the object is centered using the pointer to check runout...or just eyeball it.

A three jaw chuck is good for making something start to finish without removing it from the chuck.

A three jaw chuck will probably be Ok for enlarging dial seats and windows as long as you 'chuck it up' a few times to get it as true as possible before cutting.   

A four jaw chuck is more precise but a hassle to set up and you have to adjust it every time you r/r the project.

You might need to grind tool bits to make the cuts and this may take longer than the lathe work.

A friend has a machine shop but I find it easier to do close work like this on the Sherline lathe.  Big machinery can be a hassle to work around and many of the accessories are too big for watch cases etc.

 

Attach the case in the three or four jaw chuck by clamping it inside the case where the case back threads are when enlarging the dial window.  I clamp the case in the lathe using the 'case neck' where the crystal is mounted when enlarging the dial seat.  You have to be careful not to clamp the case too tight and scratch or distort the case neck.  I have clamped the case in the lathe with a (used) crystal mounted to prevent scratches on the case neck but usually not.

Sometimes the case back threads and dial window are not concentric.  It's rare but I have seen it and it was not enough to matter.

 

Off topic...also have seen some cases with uneven lugs that will rock back and forth on a level surface...a few were genuine vintage DJ.  The case backs screwed down Ok so they must not have been bent, maybe the lugs were finished differently on the bottom side.  Had a genuine Seamaster 300 that was 'egg shaped'...the case back would come off (with effort) but not screw back on.  Had to round it out in a small arbor press and run the case back on and off 15 or 20 times with fine automotive valve lapping compound on the threads.

 

If you can figure out a way to spin the case more or less precisely (and not too fast), you can probably enlarge the dial window with sandpaper.  The dial seat will be harder to sand to size.

Maybe try this...if you have a spare case back, drill a hole in the center and put a screw through the hole from the inside.  Tighten a nut against the case back on the outside.  Chuck the screw in an electric drill and sand the dial window while spinning the case in the drill.  You may need a helper...and a medic.  Ha!  

 

No matter how you do it, practice on a low $$ case first if possible.

[e30m3]

1 hour ago, automatico said:

"But your lathe is professional (big tool) or those little lathe for model building?"

 

I have enlarged quite a few dial windows and dial seats with a small Sherline precision lathe with the case mounted in a three or four jaw chuck.  A three jaw chuck is more or less self centering but it still may be off a few hundredths mm or more.  A four jaw chuck is more of a hassle because the part to be machined has to be centered with a dial indicator or something similar.  For something like a dial window, I mount a pointer and adjust the jaws until the object is centered using the pointer to check runout...or just eyeball it.

A three jaw chuck is good for making something start to finish without removing it from the chuck.

A three jaw chuck will probably be Ok for enlarging dial seats and windows as long as you 'chuck it up' a few times to get it as true as possible before cutting.   

A four jaw chuck is more precise but a hassle to set up and you have to adjust it every time you r/r the project.

You might need to grind tool bits to make the cuts and this may take longer than the lathe work.

A friend has a machine shop but I find it easier to do close work like this on the Sherline lathe.  Big machinery can be a hassle to work around and many of the accessories are too big for watch cases etc.

 

Attach the case in the three or four jaw chuck by clamping it inside the case where the case back threads are when enlarging the dial window.  I clamp the case in the lathe using the 'case neck' where the crystal is mounted when enlarging the dial seat.  You have to be careful not to clamp the case too tight and scratch or distort the case neck.  I have clamped the case in the lathe with a (used) crystal mounted to prevent scratches on the case neck but usually not.

Sometimes the case back threads and dial window are not concentric.  It's rare but I have seen it and it was not enough to matter.

 

Off topic...also have seen some cases with uneven lugs that will rock back and forth on a level surface...a few were genuine vintage DJ.  The case backs screwed down Ok so they must not have been bent, maybe the lugs were finished differently on the bottom side.  Had a genuine Seamaster 300 that was 'egg shaped'...the case back would come off (with effort) but not screw back on.  Had to round it out in a small arbor press and run the case back on and off 15 or 20 times with fine automotive valve lapping compound on the threads.

 

If you can figure out a way to spin the case more or less precisely (and not too fast), you can probably enlarge the dial window with sandpaper.  The dial seat will be harder to sand to size.

Maybe try this...if you have a spare case back, drill a hole in the center and put a screw through the hole from the inside.  Tighten a nut against the case back on the outside.  Chuck the screw in an electric drill and sand the dial window while spinning the case in the drill.  You may need a helper...and a medic.  Ha!  

 

No matter how you do it, practice on a low $$ case first if possible.

I'm half tempted to try your idea above - maybe even right on the lathe. I have an old caseback that doesn't have other plans... It'd be a matter of really nailing the center on the caseback, of course. But as you say, I could always check runout before screwing the case on if I'm using the lathe! As far as the two walls that need to come down .25mm, I have those right? Each one needs .25 off?

[Dan71]

[mention=5071]e30m3[/mention] here we have a lot of information from Automatico!

[mention=14711]Automatico[/mention] very kind how always!

Not simple translate all the technical detail but is clear that is not simple this work also with a lathe (little or big)

 

So Is not impossibile make the work with a dremel .. very useful the tip about the screw in the center throughout a hole on a spare caseback for enlarge the dial window!

for enlarge the diameter we can use sandpaper while the case spin , maybe we can use the same sandpaper with a tool like a pliers for the dial seat ?

But which sandpaper you suggest 600 and than 1200?

 

 

 

 

 

 

[automatico]

"As far as the two walls that need to come down .25mm, I have those right? Each one needs .25 off?"

 

Yes, you need to cut half of the total needed. 

 

"But which sandpaper you suggest 600 and than 1200?"

 

You may need a different grit to remove the material than what is used to finish up.  Match the grain on the reflector (rehaut), then go with a slightly rougher grit to remove the material to save time.  After it is almost sanded to size, finish up with the matching grit.  Be careful not to use paper that is too rough because the scratches left behind may be hard to sand away with the finer matching grit.  When spinning the case, material will be removed rapidly compared to hand sanding so measure the opening constantly.

It is hard to match the angle of the reflector (rehaut) so I usually sand or machine the excess material straight down at a 90 degree angle to the dial.  This will not be noticed and it prevents getting into the angle of the reflector (rehaut) and thinning the case neck down.

 

Sometimes the number on the paper does not match the grit.  I have some 'off brand' 1000 paper that is as rough as 320.  I would try 600 or 1000 to remove the material and see how it goes.  If you start with something rougher, 320 maybe, it might be hard to smooth it up.

I have had good luck with the 3M 'Wet or Dry' (Minnesota Milling & Manufacturing Co) sandpaper as it is always consistent.  If it is not available, go with another top quality brand.