JMB cases and gen tubes?

[bobandshawn]

Hi guys,

I'm waiting for Justin to respond, but in the interim does anyone know if gen tubes fit the jmb 1016 cases without having to re-drill and tap?

 

Thanks,

Bob

[Drummania]

Need to recut threads for gen tube.


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[bobandshawn]

Thanks.

[automatico]

My JMB '1016' case came with a 6.0mm OD crown on a 5.3mm case tube like later model rlx watches...meaning a genuine spec 5.3 crown or 6mm crown made to fit a 5.3mm case tube will screw down on this particular case tube.

 

Not exactly 5.3mm spec on the end that screws into the case however.  I tried a genuine spec 5.3mm case tube in the JMB case but it did not want to screw into the case so I did not force it.  I did not run a tap through the case either because I was going to use all 6mm parts...this may have cleaned the threads out to accept the gen spec case tube.  There was glue on the case tube threads and the tube was pretty tight.

 

I measured the threads on the JMB case tube and they were a hair smaller than a genuine 5.3mm tube where it screws into the case.  Otoh the threads where the crown screw down are the same as genuine. 

The JMB case tube threads where the case tube screws into the case measure 2.4mm and a genuine case tube measured 2.45mm.  I do not know about the thread pitch in the case, it is probably the same as genuine but I'll never know.

I drilled and tapped the case to accept a regular 6.0mm case tube p/n 24-6020 and put a gen spec aftmkt 6mm crown on it.

 

A few catches when drilling cases:

1...Depending on manufacturing accuracy, the case back gasket groove may be close to the case tube hole and going from a 5.3mm case tube to a to a 6mm case tube can cut into the gasket groove.  Mine did not. 

I have seen a few new replicas where the case tube threads were cut into the gasket groove.

2...The new case tube hole has to be drilled straight.

3...The tap can get started crooked and break or foul up the threads.

 

Fwiw all 1016 had regular 6mm case tubes and 6mm crowns.