Re: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications

And I must reply while hoping it doesn't result in a slanging match.

What I wrote was my opinion and was meant to show there is another way used
to establish a datum start point/home position other than having limit/home
switches. I made the comments taking into account that it is unlightly the
post was coming from someone who was intending to CNC a 20 hp machine. I
should have made it clear that table-top machines, used in the home shop by
competent machists, do not need the safety features found on industrial
machines where the users have got to be treated like morons because of their
propensity to do something stupid and sue.

In all my years, and it is considerable, of using and repairing machine
tools I have never seem or heard of a CNC machine running away because it is
faulty, they stop. I have seen and repaired the results of bad programming
but never on a machine which had an on-screen display of what the program is
going to machine. I have never and would not remove safety switches from a
machine that was being used in industry or by other people.

I have an 11" swing lathe and the only thing that happened, on the one
occasion I did run the tool into the chuck, was a loud bang and a bent
boring bar. Just as would have happened had it been a manual machine without
all the switches. Since this incident I do not allow others into my home
shop while I am machining.

Regards,

Terry



| Sorry, but I have to jump in on this one.
|
| You may consider you have the intelligence to avoid this but,
| we all at times make mistakes.
|
| It is also known that now and again a CNC machine can run away
| through a fault or a programming error.
|
| On the financial side you will have removed any form of compensation
| if anything does go wrong.
|
| I have seen more industrial injuries and deaths than I care to remember
| because someone decided to disable a safety device as it was inconvenient.
|
| To suggest this to someone who has declared themselves as a newbie is the
| height of irresponsibility.
|
| Dave M
|
|

|
|
| > Hi,
|
| ---snipped---
| >
| > I do all my programming from this point and have no use for limit or
| > homing
| > switches. In fact my lathe came with all the health and safety switches
| > required to make it almost idiot proof but I found them so annoying they
| > have all be removed or wired out. I have enough intelligence to know I
| > can't
| > moved a slide into the chuck without some serious bit of flying metal.
| >
| > The only time limit switches come into their own is when jogging the
| > slides
| > outside of program control and holding a conversation at the same time.
| > Something I avoid.
| >
| > Regards,
| >
| > Terry
| >
| >
| > | I'm new to CNC
| > |
| > | I understand that the tool has to be homed to get a physical
| > | reference to the m/c in relation to which the tool will be moved.
| > |
| > | Is this done with a switch to which the tool has to be moved, and
| > | the when the switch closes, the tool is stopped & the position
| > | becomes the home position ?
| > |
| > | If the above is true , then what is the accuracy / repeat accuracy
| > | possible with home switches ? Are there any special switches
| > | available for this purpose ?
| > |
| > | Is there any other method for homing ?
| > |
| > | Are there any sites / books where I can get my basics of CNC -- like
| > | the question above ?
| > |
| > | Any help from all you so knowledgable people is welcome ?
| > |
| > | Biswanath