Hi,

Overtravel could be accommodated by spring mounting the switch

Agreed, at the cost of complexity, but entirely possible.

These (Honeywell/Omron) switches have a 'sensitive' version and a standard version. The standard version has
according to the spec I posted, a max operating force of 3.61N, equivalent to 361 gram force. The sensitive version
reduces that to about 100 gram force, still not feather weight.

Either 100g force or 360 g force is not going to upset a granite slab at all!

Craig

Hi,
this afternoon I downloaded the current latest development build of Mach4. It has the new surface mapping
feature and I've been experimenting with it. I haven't had anything like the time to work out all the quirks yet
but this could, in fact almost certainly, be a worthy alternative to the Autoleveller solution.

I have attached a picture of the Surface Mapping generating screen. Note that it is in Machine coordinates and may
require a certain amount of thought before banging in some parameters.

The up shot is you program the X and Y extents of the area to be mapped, the target resolution between the sample points,
the probing speed, the Z axis retract height and the vertical Z probe movement the hit <Map Surface> and Mach obediently
probes the entire area and saves that as a map file. The mapping generator is a Wizard....too easy!!

I have yet to work out how Mach handles the results of the file, but it looks like you select the surface map file
in the Surface Map plugin and thereafter the Z axis machine coordinate Z datum goes up and down automatically.
So unlike Autoleveller you do not have to modify the Gcode to accommodate an uneven surface the datum goes up
and down instead.......how bloody clever is that!!

You might like Mach3 but you are being left behind BIGTIME!, get with Mach4, go mad early and beat the rush! 

Craig

Hi,
just found the video that has just been released to show how it works.

https://www.youtube.com/watch?v=M4o6dfQrAo8

This looks to be perfect for OPs needs. It is Mach4 but it does the business.

Craig

Ok. So... Tomorrow I will go to a omron shop near my city, or maybe call them on the phone today to check price and availability. The switch will be found and bought, hopefully. I am getting the idea of what I need.  Low current, sensitive switch. After this I will make the mounting bracket. So the thing is that I have to decide what to use, and since the autoleveller is free I will try it. About Mach4, the feature that Craig linked a video, was the first thing that caught my eye, when I was searching for a solution to my problem. It looks nice and easy and just the thing for my need. But, I am using parallel version of Mach3 on win XP, and I have no idea if the transition from one to the other will be smooth. Otherwise I am ready to pay for Mach4 license and parallel port plugin - 225 USD in total. Just wasn't thinking of doing it now, but as Craig said maybe I will go mad and beat the rush
Again thanks to everybody for the will to help.

Peter

Hi,

Otherwise I am ready to pay for Mach4 license and parallel port plugin - 225 USD in total.

No, I think that is a mistake, the Darwin plugin/motion controller is 'to have a play' with Mach4. This is likely
to end in you having a difficult time making the transition and  lose paying work as a result.

If you are serious you need to go the whole way and get a good motion controller and ideally Mach4Industial.

Projected cost Mach4Hobby/ mid-range motion controller/BoB =$500-$600
Projected cost Mach4Industrial / mid-range motion controller/BoB = $1700-$1800

There are several reasons:
1) A vastly increased range of PC's which can be used
2) Hardware/firmware support direct from he manufacturer
3) Mach4Industrial gives you one on one phone support

These combine to mean you get the easiest transition to Mach4 and maximum gain in profitable functionality
for years to come.

If you required a repair to your work vehicle of $500-$600 or even $1700-$1800 would you pay it? I imagine
that you would be hard pressed to earn a living without a work vehicle. Does your engraving mill fall into
the same category?

Craig

A search of nz.element14.com found this switch. 2.7 mm overtravel.

https://nz.element14.com/omron-electronic-components/d2qw-c003h/microswitch-spst-no-0-1a-14vdc/dp/2113271

Hi,
another useful alternative for a switch.

I notice you searched the NZ website but Element14 is global so search results are identical to any other site around the world.
The NZ site quotes prices in NZD, including GST, it also estimates the delivery from our closest warehouse which is in Sydney
Australia.

If the part is in stock in Sydney, I can order it up till 3pm and have it the next day. If my order doesn't qualify for free
freight that will cost $14 +GST NZD or $10.80 USD. I can't complain about that service!

Craig

I searched the NZ site because it was used in a previous post. Element14 has many aliases, Farnell in the UK and Newark in the US. I favor Digi-key because their main location is only 300 miles away.

The surface mapping video shows some very rapid probing with what appears to be a rigid probe so I wouldn't worry too much about overtravel. It wouldn't take much experimenting using the MDI to find the amount of Z axis travel past the probe sensing point for various Z axis speeds. Then you could select a fast but safe speed.

Hi,

The surface mapping video shows some very rapid probing with what appears to be a rigid probe so I wouldn't worry too much about overtravel.

It was only done at that speed for the video. If you are not concerned about overtravel that's fine. I however have done a lot
of probing on PCBs and found that a probe which has overtravel saves crashes.

Craig

Hi,
I have given considerable thought to overtravel and have done my best to quantify it:

https://www.machsupport.com/forum/index.php?topic=38730.0

Craig