Supporting > Tooling & Machines
No limits CNC
Vixen:
The discussion regarding end stops, limit switches and 'home' switches has been moved here from the Mercedes W165 build thread.
It's quite an important subject and definitely one that needs it's own topic which members can refer to, read and perhaps contribute too.
Different machinists have conflicting views on the use of limit switches and stops, the discussion has been examining the pros and cons and the possible consequences.
My much modified Emco VMC, has a table movement of 200 x 100. I do not use limit switches, so I impose a soft limit of 190 x 90 instead. I see no sense in tap dancing on the limit switches or end stops. If you run into either, the job cannot be completed and is probably ruined. 190 x 90 is more than enough movement for most of the parts I need to make.
Mike
kvom:
--- Quote ---I do not use limit switches
--- End quote ---
Same here; soft limits work fine.
internal_fire:
I don't "use" limit switches, but I have them installed and functional. Hit one on rare occasions when something goes really wrong. Not sure anything would break, since the motors are not oversized, but it provides added safety.
Gene
dieselpilot:
--- Quote from: Vixen on September 08, 2021, 12:29:54 PM ---My much modified Emco VMC, has a table movement of 200 x 100. I do not use limit switches, so I impose a soft limit of 190 x 90 instead. There is no sense in tap dancing on the limit switches or end stops. If you hit either, the job cannot be completed and is probably ruined.
--- End quote ---
Do you not use home switches? Or are they not accurate enough to restart a job?
Vixen:
Hello All,
I do not have, or use, any limit switches or 'Home' switches on my machines. They can be a source of unreliability and EMF interference. Any limit or home switch needs to be hermetically sealed to prevent the ingress of fine metal dust particles, otherwise they have the potential to cause nuisance tripping or failure to trip. :zap: My philosophy has always been to keep it a clean and simple as possible.
So what do I do about 'Homing'?
Well, I do not use 'Home' switches to define a fixed point on the mill's table. Instead I use a digital touch probe (similar to a Renishaw) to find a corner, or a center, or a defined position, such as a toolmakers button, on the piece of material to be machined. That position on the material becomes my Zero (Home??) point. My CAD CAM uses the same position to calculate the tool paths. It certainly simplifies tool offsets... there are none. :wallbang:
This may not be how they do it in a professional machine shop: but it has worked well for me for the last twenty years.
Mike
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