Measuring Chuck Clamping Force

[Nerdlinger]

Opposing jaw clamping forces do not sum.

Think if only one jaw were fitted, opposing an infinite resistance. The proverbial "brick wall". Still only 5k.

NOT 5K plus a brick wall.

I think you're right, even though most of my brain still says, "but 5+5=10"

 

[Nerdlinger]

Quick update - since cleaning the chuck resulted in NO change in clamping force I had Takisawa come in and service the hydraulic draw bar cylinder. After they swapped it out we still measured no change in clamping force. BUT parts are coming out noticeably better now! I believe we have made enough parts to confirm that they truly ARE better but we will monitor it for a bit to make sure. I don't know what would have changed. They also recommend we change the hydraulic fluid, which we haven't done in years. It looks clean in the sight glass but I guess the viscosity can change so we'll try that too. Thank you for your help and I will record 1) if I ever figure out exactly why changing that actuator would help if the clamping force did not change and 2) if I every get my mind wrapped around the force measuring paradox.

 

[Billy_C]

Manufacturers' recommended change intervals for hydraulic fluid always seem a little extreme but I'm no chemist. I doubt it will make a difference either way. As a counter point, the fluid looking clean in the sight glass means nothing. Viscosity, water absorption, and extremely fine dust contamination are the main reasons to keep up with some sort of change interval.

 

[Billy_C]

Yeah, the drawbar cylinder has the surface area marked on it, so I multiplied the hydraulic PRESSURE by the cylinder SURFACE AREA to get the drawbar FORCE. From there I used the info on the face of the chuck to determine what the clamping force should be. My problem is I'm not entirely certain on how to go about measuring that. It looks like I forgot the mythbusters where they crashed two cars into each other.

This is what I thought but I'm not really the boots on the ground anymore turning parts. It's been a while since I was actually hands-on doing setup in the machine. As an even less experienced "machinist" doing the setup I never really thought too much about it while only working on a few Haas lathes. Just cranked it up let er rip.

 

[Homeshopblob]

I think you're right, even though most of my brain still says, "but 5+5=10"

The opposing jaw is pushing back with 5000 lbs. If it was a fixed jaw fixed in place it would still be pushing back (resisting) with 5000 lbs.