I was going to add this to the AL336D lathe crash started by CC555 - http://ift.tt/19nghs2 but that would be taking that further off topic, so a new thread is perhaps more appropriate.
The comment was made that leadscrew covers are actually a safety device - now read on...
http://ift.tt/18NO64k
Page 5.
We bought some secondhand machines at work and one of the engineers immediately got quotes for refitting them so they were "safe". Of course, as soon as the "S" word was mentioned no one could argue how silly what was proposed was. I spoke to a dealer the other day who said that most of their machinery stock could only be sold to backyarders and hobbiests as even though machine tools have been used in that form for over a hundred years, these days they are not considered good enough with respect to guarding.
When I did failure mode assessments some years ago we were told to base it on what is likely or better yet, base occurances on real numbers. Risk assessments these days seem to be based on the idea that if there is even the slightest possibility of something happening you should prevent it.
I have never heard of anyone being pulled into a leadscrew and if you think about the millions of hours of lathe operations accumulated each year, the accident rate for this would be extremely low - yet it is regarded as likely to happen and hence has to be guarded against. The most common issue I've seen with lathes is the chuck key being left in when the lathe is started. Now the easiest way to prevent that if you want to be technical about it is to have a holder for the key with an interlock on that will not allow the motor to power up without the key being in the socket. Never seen it done. Instead a swing down chuck guard is required.
Having had that rant, there is some worthwhile stuff in that PDF although I think has been written by people who don't use lathes.
Michael
The comment was made that leadscrew covers are actually a safety device - now read on...
Quote:
Originally Posted by nearnexus ![View Post]()
http://ift.tt/18NO64k
Page 5.
We bought some secondhand machines at work and one of the engineers immediately got quotes for refitting them so they were "safe". Of course, as soon as the "S" word was mentioned no one could argue how silly what was proposed was. I spoke to a dealer the other day who said that most of their machinery stock could only be sold to backyarders and hobbiests as even though machine tools have been used in that form for over a hundred years, these days they are not considered good enough with respect to guarding.
When I did failure mode assessments some years ago we were told to base it on what is likely or better yet, base occurances on real numbers. Risk assessments these days seem to be based on the idea that if there is even the slightest possibility of something happening you should prevent it.
I have never heard of anyone being pulled into a leadscrew and if you think about the millions of hours of lathe operations accumulated each year, the accident rate for this would be extremely low - yet it is regarded as likely to happen and hence has to be guarded against. The most common issue I've seen with lathes is the chuck key being left in when the lathe is started. Now the easiest way to prevent that if you want to be technical about it is to have a holder for the key with an interlock on that will not allow the motor to power up without the key being in the socket. Never seen it done. Instead a swing down chuck guard is required.
Having had that rant, there is some worthwhile stuff in that PDF although I think has been written by people who don't use lathes.
Michael
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