Ever body has to start somewhere

[Boucher]

What does this mean?



That was the question that I was pondering after I got my lathe home and started trying to decipher the controls.

The guy that worked for me took one look and saw that it was a four jaw in the picture. To me it was just a chuck with a speed limit. When he mentioned that it was a four jaw I understood that it was a speed limit for the out of balance condition found when using a four jaw.

I smile when I think back to how little I knew starting out.

[bollie7]

I would have read that to mean the max speed for the chuck supplied with the machine. In balance. In other words, its not a high speed chuck.

bollie7

[oldtiffie]

Chuck rated speed

Does the chuck have a maximum rated speed marked on it?

What does the manual (if you have one) say?

[RB211]

Depends how big this chuck is. If it is a 12" 4 jaw, I don't think I would want to run it faster than 300rpm out of balance!

[macona]

Max RPM while you are threading. Thats why its above the thread controls.

[bborr01]

Max RPM while you are threading. Thats why its above the thread controls.

X2 on that

Brian

[A.K. Boomer]

if it was for the chuck it would be just a chuck rpm and not if its being run out of balance --- deductive reasoning tells me that they cannot give a proper RPM for the chuck in an out of balance state -- for one it would require them to know how big a chunk of out of balance material you have in it...


The threading sounds more like it.

[huntinguy]

It means....

Maximum RPM for the 4 jaw chuck supplied with the machine is 315 RPM. It has nothing to do with an out of balance condition. Out of balance would most likely be much ... MUCH... lower.

Chucks, depending on the material they are made out of, flex at RPM... IE. Centrifugal force and can release a part or tear themselves apart.

The machine we used to have at work had a key you set to the chuck maximum RPM to prevent such issues. Once an operator did not set it correctly and tossed a part out of the machines.

[lazlo]

Maximum RPM for the 4 jaw chuck supplied with the machine is 315 RPM. It has nothing to do with an out of balance condition. Out of balance would most likely be much ... MUCH... lower.

...and the max RPM would be highly dependent on the degree of out of balance

[gda]

Max RPM for invisible parts.

[jeremy13]

I would have to say it is the max RPM for the 4jaw. My lathe has a similar picture and one of a face plate with a lower RPM rating than the 4jaw.

[chipmaker4130]

Or, maybe it's a limit with the jaws set for outside like in the picture? That puts a lot of mass way out there in 'the zone', although I really can't see a configuration-specific limitation on a home shop machine.

[oldtiffie]

Keep it slow

The 4-jaw chuck and the face-plates of many lathes have quite large masses and inertia - whether concentric/balanced - or not.

It will take quite a bit of power to rev them up when starting but if the lathe has a screwed nose and if the lathe brakes hard, the mass and inertia of the heavy 4-jaw chuck or face-plate may cause them to overtake the head-stock spindle and actually unscrew the chuck etc. from the screwed spindle.

Then you may not only have a problem but you may become (painfully??) aware of the reason for the warning.

[darryl]

The most sensible meaning I can derive from that is it's for the chuck with the jaws wide as shown. Seems odd that it's printed on the lathe, since you could use any chuck you wanted to and are not limited to the one supplied with the machine. Of course, the machine and accessories would have been supplied together, so they would have expected that chuck to be used- so it does become an apt warning.

My lathe manual details the maximum chuck speeds along with many other things to know, and it's not printed on the lathe anywhere. I've never seen that anywhere actually. The info that is printed on the lathe is confusing enough-

I would take that as a warning though, and heed it. That speed does seem a bit low, but look at what speeds you normally use, and for what diameters of workpiece. Maybe the warning is to remind you, just in case you previously turned a brass needle at 2000 rpm, and now you go to mount a 6 inch diameter of lumpy cast iron- you definitely wouldn't want to spin it up that high by accident-

[Mcgyver]

that's an odd one, I don't suppose there's a manual?

The lathe doesn't know the chuck diameter you mount on it, that's a warning the chuck maker should give (and it would have to be a massive chuck to top out at 315 for fear of it coming apart).

The lathe doesn't know how out of balance something is - 315 could be waaaaay toooo fast

Why would the lathe care if you threaded at say 500?

The only guess i have (because the jaws are shown turned around for large work) is don't run the lathe faster than 315 when you're running close to it maximum swing....but its still lame