[Mstcnc]

I think you miss understand, your machine is homing even though you don't know or see it move, yes there are a lot of machines / controls that do this, that don't have Home switches, it is in the posts above, the different methods machines use, Okuma being one of the best at doing this, and the first to ever use this technology to it fullest

What you are experiencing when you can't reach the hard limits /end of stroke, is called soft limits, all machines have this, even hobby home built machines, this can be setup in the software like Mach3 and UNCNC and most other Hobby control software

Which way is the best is up to the users thinking, physical homing, or moving the machine around, helps the machine move the lubrication around before you start to run, at high speed, Spindle run warmup cycle is a must on any machine, if you don't do this your machines life will be less, so over all you gain nothing from your machine having this type of technology, 3 Axes Homing only takes about 20 seconds , on an average size machine

Again nope

I think you use "home" as some other meaning than setting machine reference / home location.

Machine warm up or machine safe location do not have nothing to do with "machine homing". And I am not talking mach or other "toys" only commercial machines, hobby machines I realy do not think are worth to use absolute measurement devices because increased costs.

I do not know how many commercial machine you have setup or designed but there are so many different ways to do either incremental or absolute measurement feedback system in cnc that at least I do not have time to go thru here.
Shortly: using incremental measurement system there is need home machine.
With absolute system homing operation is not needed.

Yes Okuma introduced their absolute measurement system 1963.
Depending machine model usually okuma machine coordinate zero point is outside work area, some machines even several meters. Some okuma models have fixed "safe or home" location eg lathe for tool change. Some models that location can be modifield by user some not.
That location either have nothing to do with machine homing or coordination system setting.

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[Al_The_Man]

With absolute system homing operation is not needed.

Also typically Robotic applications have traditionally used absolute positioning to avoid referencing a home position on power up.
As to encoder resolution, one of the world leaders in CNC (Fanuc) have used 1000 - 2500 p/rev encoders for many decades now.
As have many other major manuf.
With many of these machines still in use across the world today.
Al.

[PCW_MESA]

Also typically Robotic applications have traditionally used absolute positioning to avoid referencing a home position on power up.
As to encoder resolution, one of the world leaders in CNC (Fanuc) have used 1000 - 2500 p/rev encoders for many decades now.
As have many other major manuf.
With many of these machines still in use across the world today.
Al.

There are also some interesting resolution tradeoffs with absolute encoders and serial interfaced encoders vs quadrature
encoders related to velocity estimation, which affects low speed smoothness. Quadrature encoder counters can do
delta_count/delta_time velocity estimation but absolute and serially interfaced encoders typically cannot, since they do not
provide the count linked timestamp information (time between counts) that incremental encoder counters can.

What this means is that you need about 2 to 5 times the resolution in an absolute encoder to get equivalent
velocity estimation resolution to a quadrature encoder.

For high end machines this is not an issue anymore since most use 1 million or more count/turn encoders (up to 32M/T last time I looked)

[mactec54]

Also typically Robotic applications have traditionally used absolute positioning to avoid referencing a home position on power up.
As to encoder resolution, one of the world leaders in CNC (Fanuc) have used 1000 - 2500 p/rev encoders for many decades now.
As have many other major manuf.
With many of these machines still in use across the world today.
Al.

Yes Robots are a good example of using absolute encoders

For the last 10 years I don't think any manufacturer has used Encoders that low on there CNC machines, the minimum today is 20Bit which is over 1 Million PPR

Fanuc the leader in high resolution Encoders, for there machine controls, have options of 10 Million 16 Million and 32 Million PPR these are there standard range

Fanuc also have other resolution Encoders 23 Bit= 8 plus Million and 27 Bit

Yaskawa also are at the 24 Bit as there standard Encoders they offer for every day general use, Mitsubishi also are up there as well

[Al_The_Man]

I am in agreement with Mike here:

https://www.mmsonline.com/columns/re...ncrement-value
Quote: "Today’s CNCs boast amazing resolution. Internal to the CNC drive system, resolution is often stated in nanometers (billionths of a meter).
Even so, most applications for CNC, especially those related to turning and milling, do not require (nor can they achieve) this level of accuracy."

I have used Galil Motion cards that have encoder response time of 12Mhz and can position to 2µm, I am not sure what else you would need for the average turning/milling application.
Many of my machine shop operator customers are suppliers to Boeing and the Aerospace Industry customers, and the only asset I have seen with some of the latest machines is that very high speed positioning, but the actual machining process is comparable to the older machines.
Al.

[mactec54]

I am in agreement with Mike here:

https://www.mmsonline.com/columns/re...ncrement-value
Quote: "Today’s CNCs boast amazing resolution. Internal to the CNC drive system, resolution is often stated in nanometers (billionths of a meter).
Even so, most applications for CNC, especially those related to turning and milling, do not require (nor can they achieve) this level of accuracy."

I have used Galil Motion cards that have encoder response time of 12Mhz and can position to 2µm, I am not sure what else you would need for the average turning/milling application.
Many of my machine shop operator customers are suppliers to Boeing and the Aerospace Industry customers, and the only asset I have seen with some of the latest machines is that very high speed positioning, but the actual machining process is comparable to the older machines.
Al.

This is how Fanuc do it and it is for lathes and mills, this is there standard and has been for a few years, this is only one company that is doing this all the other major manufactures are ding the same

It has very little to do with how well they can position, a 500 PPR Encoder can get to a commanded position, it's all about how fast and how smooth they can run, and large count Encoders achieve this

High speed 3D 5 Axes machining uses every bit of resolution you can get, you can never have to much Note the finish on this part it is as machined, you can not achieve this on an old machine with low count encoders