How fast is too fast?

I think I can disregard the decal on the machine.

Just remember ignoring safety decals are a good way of becoming immortalized in an internet meme. ;)


Do you really want to be associated with these people?

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When it comes to lathes; the limitations start with what is attached to the spindle. Jawed chucks have cast iron or semi-steel bodies. Cast iron is definitely lower RPM being of lower molecular integrity. They may have balancing performed at the factory but not outside a limited speed range. Another issue for jawed chucks are those with self centering; the scroll subject to inertia beyond a rated RPM, and SFPM for it's size.
Don't overrun tooling. Machines too are restricted by design and weight bearing components; chiefly at the spindle where factory 'X' cannot control what a user attaches. Like why your little Clausing hasn't a D1-6 spindle, or my Pacemaker a D1-8.
My favorite appraisal of lathe design rigidity is length of headstock, representing distance between main bearings. IMNSHO a good ratio is 3-4 times swing for heavy duty and real nice toolroom, about 1.5-2.0 for an average engine lathe.
 
Thanks for all the valuable input. I enjoyed the over-the-top use of an excavator on the lift. Someone actually did that??

In my case, I'm pretty level headed and not felony stupid (just normal stupid sometimes). If I was that dumb, I wouldn't have asked the question in the first place and would have just cranked the thing up to max and "give her a go" with predictable results. I learned a bit about my chucks' ratings so that will be some guidance. Great point about the potential next owner. If I do anything, I can set the upper limits of the VFD temporarily and then back to the normal 1800 RPM limit.

I believe that this lathe was not designed so that at 1801 RPM things start flying apart, especially with a small chuck/part mounted. The trick is "staying well inside that envelope" and not pushing it. I think centrifugal force increases with RPM^2 so a 10% RPM increase is about 20% more force. So, if I do anything at all, after considering it, I'll likely keep it to at most 110% of nameplate.
 
Just remember that metal fatique is an accumulated long term non linear thing.
You might be just fine at 10% over the rating for 20 years or more.
but move that up to 20 or 25% over and it might only last for 2 years of service before something gives out.
 
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