Schaublin 125-CNC retrofit.

RotarySMP wrote:

I hope you find an undamaged one.
 

Thanks for the video.

Shame about the chuck master jaws being cracked.  However, I'm not sure that chuck was in a crash... Considering how tight the master jaws are in the body, there doesn't appear to have been a tool-to-part or jaw incident.  The jaws don't appear to be distorted or the slots 'wallowed' out or deformed.

Looks like the jaws are cracked in a way that suggests the force was along the radius of the chuck; that is, in the same direction as clamping or unclamping.  Specifically, the cracks appear to be at the corner of the jaw face where the bellcrank pushes the jaw during clamping.

There also might be a manufacturing defect at that corner.  Note the sharpish notch where the large main radius doesn't quite meet the other surface.  That notch isn't present on the other side of the jaw (surface used for retraction/unclamping).  Jaw #3 has the same geometry right where it's cracked.  It might be an intended geometry feature, but it doesn't look like it.  Looks more like the main bellcrank cross-slot was milled out, and then the face with the notch/crack was tweaked with a grinder to be a precise fit to the bellcrank.

With evidence of the chuck having a hard life, it's not beyond the pale that the drawtube closer air pressure was turned way up to overcome the lack of chuck lubrication in order to get decent holding force.

Now imagine that poor chuck, with a sharp(ish) notch at the corner of the two faces... with the air pressure turned up to 11... running interrupted cuts in a production shop for years.

Just thinking about it is fatiguing.

Maybe the manufacturer will warranty the defective chuck jaws and throw in some T-nuts as a gesture of goodwill?


PS - speaking of NDT/NDE... sharpie pens make a pretty good unofficial dye penetrant for fine cracks.  Clean the surface with ISO or acetone, then get a fat marker and saturate the suspect indication with marker ink - the more the better.  Wipe it off the surface before it dries and sprinkle/blow a fine dust (talc, cornstarch, etc.) over the indication and it'll draw the ink out.  More ink = deeper indication.  Beats paying $$$ for the good stuff.

I think that is probably a good diagnosis of what caused the crack initiation /  propagation. I contacted Gamet, with this unique business proposition, but they havent responded

RotarySMP wrote:

. I contacted Gamet, with this unique business proposition, but they havent responded
 

Which Gamet? 

I am a bit puzzled as to who this Gamet is. Gamet was a bearing manufacturer in Colchester, though I think that they have now been absorbed into Colchester lathes, moved to the Harrison works in Heckmondwike and now, apparently, based in Elland. 

There is also an Indian chuck manufacturer called "Gamets" -  www.gametschucks.com Which I suspect are unrelated...

I see references to "Pratt-Burnerd Gamet chuck"  on that eBay, so I think that you probably need to be talking to the 600 group.  www.colchester.co.uk/spares/

Hmm, but, also, I see Gamet boring heads, made in France..

And it seems that Gamet bearings are now part of HB bearings, in Holmfirth.

www.hb-bearings.com/

andypugh wrote:

Hmm, but, also, I see Gamet boring heads, made in France..

And this might, finally, be the right Gamet:  www.gam-tek.com/produits/

Hi Andy, correct, it is Gamet in France who made, makes and still supports the power chuck business. No idea if they were ever associated with Gamet the bearing manufacturer.

Mark