[GeckoSub]

Hi,

(...)You need to do the momentum calculation, anything less is a pure guess, and that's not good enough when spending big money.(...)
(...)You need to do the inertia calculation to avoid walking into an impossible tuning situation.(...)

Craig

Craig, I almost have the full band gathered now.
There are a handful of people I have been seen popping up in threads over the years that I was hopping would stop by here and you are certainly one of them.

It's early morning out here though and I am on my way to the ocean for a freediving session so will respond to your comments when I am back.

But for now, you have convinced me to do the math to check the servo power so thanks for the formula

[Cadlach]

Hello i have mazak qtn250 M
I looking order
Please contakt [email protected]

[joeavaerage]

Hi,

Question - Z Counterweight, Gas Struts, Springs or Motor Brake...?
As the title says
Is motor brake easy enough to implement?
How does it actually work? The brake clamps locked when power is cut...?

Do yourself a favour, If you are of the opinion that you need a Z axis brake due to the mass of the Z axis, buy a servo with a built in electromagnetic brake. The Z axis 750W Delta B2 servo
pictured above has such a brake. Its magnificent and so easy. Its natural state, ie un-powered is 'brake engaged'......so you might say its fail-safe. Non braked 750W Delta B2's cost me $438USD each (new,
and the braked 750W Delta B2 cost me $542USD (new), so an extra $104USD, money well spent in my opinion.

No counterweights, no gas struts, no nothing, don't need it. The mass of the Z axis approx 50kg, requires 50/125=0.4Nm of torque from the Z axis servo to hold it up, and the servo is rated for 2.4Nm, so only
a small fraction of the available torque is required. This is one distinct advantage of 5mm pitch screws, great mechanical advantage, ie high thrust for minimal torque.

Craig

[joeavaerage]

Hi,

I was hoping to home to the zero pulse of the servos - and actually even the Leadshine CL steppers I have in mind have zero pulse - but it seems UCCNC does not offer that feature(?).

I use Mach4 and have done for eight years (light years ahead of Mach3). It does have 'Index Homing', and was my intent years ago to use it. I use Omron roller plunger snap action microswitches for Homes and Limits.
As it turns out with them I can get 0.02mm repeatability while homing......and that is good enough, or at least the extra work and wiring required to use Index Homing is not high on my list of things to do.
I rather suspect that with good roller plunger microswitches you too could get 0.02mm or better, and in which case Index Homing is not really required.

https://nz.element14.com/omron-indus...15a/dp/1500340

I do rather suspect that I will use index homing for both the trunnion and fifth axis previously pictured. I'll want very accurate and repeatable way to zero the fourth and fifth axes.
I'm hoping that if I can zero them well and repeatably that I can still use the mill as three axis, with the vise still sitting atop the fifth axis. The majority of the parts I make a small and
mostly brass, aluminum and plastics. If the parts are small enough I would not have to remove the trunnion off the bed of the mill.....and that would be a major time saver.

Craig

[GeckoSub]

Hi,



I use Mach4 and have done for eight years (light years ahead of Mach3). It does have 'Index Homing', and was my intent years ago to use it. I use Omron roller plunger snap action microswitches for Homes and Limits.
As it turns out with them I can get 0.02mm repeatability while homing......and that is good enough, or at least the extra work and wiring required to use Index Homing is not high on my list of things to do.
I rather suspect that with good roller plunger microswitches you too could get 0.02mm or better, and in which case Index Homing is not really required.

https://nz.element14.com/omron-indus...15a/dp/1500340

I do rather suspect that I will use index homing for both the trunnion and fifth axis previously pictured. I'll want very accurate and repeatable way to zero the fourth and fifth axes.
I'm hoping that if I can zero them well and repeatably that I can still use the mill as three axis, with the vise still sitting atop the fifth axis. The majority of the parts I make a small and
mostly brass, aluminum and plastics. If the parts are small enough I would not have to remove the trunnion off the bed of the mill.....and that would be a major time saver.

Craig

Yes, there's a good video on home switches for hobby machines by JBWorxStudio on youtube and his findings are very much aligned with yours. He really liked the small Panasonic optical switch, too.
I am taking the liberty of attaching a screenshot here from his website that shows his results a bit more clearly than the video:


The reason I was thinking of the Metrols was because in the Philippines where I am now, we sometimes have power cuts so was thinking it would be great to have amazing home sensor accuracy to restart or continue a job, but I guess in reality I would just re-probe, re-zero from the vise corners or something like that. Though to square the gantry with the two Y-motors it would still be great to have some really precise sensors.

[GeckoSub]

How To Home A Rotary/4th Axis?

Hi,
(...)
I do rather suspect that I will use index homing for both the trunnion and fifth axis previously pictured. I'll want very accurate and repeatable way to zero the fourth and fifth axes.
I'm hoping that if I can zero them well and repeatably that I can still use the mill as three axis, with the vise still sitting atop the fifth axis. The majority of the parts I make a small and
mostly brass, aluminum and plastics. If the parts are small enough I would not have to remove the trunnion off the bed of the mill.....and that would be a major time saver.

Craig

This stirred my mind, thanks And a rotary does sound like a pretty near perfect candidate for zero pulse homing.

I had originally planned on having the rotary come way down the road, perhaps 6-9 months after the machine was up and running. But that might be changing. First of all, for the sake of getting the base right you guys urged me to really think the table layout and Z-height of the base through (thanks!). Also, I have found myself thinking about specialty tools, workholding, 2nd, 3rd ops, etc, at all sort of weird times a day already. I guess the bane of a (hobby) machinist in spe. Haha.
All this has firmed up the idea that the rotary will be incredibly helpful for the particular parts/product I want to make. So, now I am thinking the rotary might come as soon as I have an OK grip on the machine.
But how to home it?

If I stick to UCCNC, which I think I will, I see 2-3 options.
1). Indicate the part/rotary vise each time which I'd rather not do.

2). Use a switch, but I wonder how that works because I guess it would trip once per revolution, at least. Is it easy enough to tell enable it for homing/indexing and then disable it again right after? Or is that the sort of things macros are for? I have a feeling, just setting up UCCNC and wiring the machine will take plenty out of me and if this needs a macro, not sure how good I would be at that.

3). I think it may be possible to have the Delta A series do a zero pulse homing routine in the drive. I may be wrong, but I think that's one of the differences between the B and A-series. So, let's say the A series can do that, how would you trigger that from the software side. Is that another "dreaded" macro...? (I can get Delta A2 used too. A bit less than double what the B2 are, but still not too bad).

I may have left something obvious out

Also, I mentioned early in this thread that I had a 2 week, self-imposed deadline to send the base drawings off to the factory. The beauty of self imposed deadlines is that the guy who set it, wont hold it against me when they are moved....
And there's a cashflow issue, too. Haha. But as mentioned things are looking brighter on that front with the assignment I am about to fly out on. So, now the deadline for getting the base started and parts shopping spree is when the payment has come in + some days to finalize the base design if not done already by that time. In other words, no immidiate hurry. Maybe something like 3-4 weeks.

[joeavaerage]

Hi,
homing is a realtime operation, it has to be. The machine needs to respond to a home switch event within micro seconds. But UCCNC is running
on a Windows platform which is NOT realtime, ergo a home switch event being reported to UCCNC could take many milliseconds, then the PC/UCCNC has to make a decision and that
gets propagated to the motion buffer which could easily be several hundreds of milliseconds long. The around the loop delay could be several hundred milliseconds, way WAY WAY too slow
for Homing. No, UCCNC is not realtime and so cannot do homing. It is the hardware motion controller that does homing. Sure it does it with data from UCCNC but the motion controller
has to home autonomously. Thus there is no secret macro that will make this happen as the macro is within UCCNC and cannot enable realtime behaviour.

If you want index homing then you have to use a motion controller that supports it. By-in-large motion controller behaviour is not user programmable....so if it does not have a feature you can't put it there.
You could alternately use LinuxCNC which is realtime, and thus you could program index homing if its not already there

You maybe correct about the A2 series servos being able to home themselves.

The B2 series has digital inputs which can be assigned certain properties. There is one called CCLR (page 7-96 of the ASDA B2 manual) that clears the pulse counter. Presumably you could trigger this from the Z signal
of the encoder. I suspect with some care you and clever programming of UCCNC you could make a B2 series servo home itself to an Index pulse.

To be honest I think you are making a real challenge for yourself. If you require Index Homing get a CNC software/motion control system that provides that feature. Mach4 has it for example.

Craig

[GeckoSub]

Hi,
homing is a realtime operation, it has to be. The machine needs to respond to a home switch event within micro seconds. But UCCNC is running
on a Windows platform which is NOT realtime, ergo a home switch event being reported to UCCNC could take many milliseconds, then the PC/UCCNC has to make a decision and that
gets propagated to the motion buffer which could easily be several hundreds of milliseconds long. The around the loop delay could be several hundred milliseconds, way WAY WAY too slow
for Homing. No, UCCNC is not realtime and so cannot do homing. It is the hardware motion controller that does homing. Sure it does it with data from UCCNC but the motion controller
has to home autonomously. Thus there is no secret macro that will make this happen as the macro is within UCCNC and cannot enable realtime behaviour.

If you want index homing then you have to use a motion controller that supports it. By-in-large motion controller behaviour is not user programmable....so if it does not have a feature you can't put it there.
You could alternately use LinuxCNC which is realtime, and thus you could program index homing if its not already there

You maybe correct about the A2 series servos being able to home themselves.

The B2 series has digital inputs which can be assigned certain properties. There is one called CCLR (page 7-96 of the ASDA B2 manual) that clears the pulse counter. Presumably you could trigger this from the Z signal
of the encoder. I suspect with some care you and clever programming of UCCNC you could make a B2 series servo home itself to an Index pulse.

To be honest I think you are making a real challenge for yourself. If you require Index Homing get a CNC software/motion control system that provides that feature. Mach4 has it for example.

Craig

Sorry, def still making rookie mistakes. Yes, the controller, not the software, runs the homing!
I do like the ProbeBasic screenset for LinuxCNC, which basically looks "heavily inspired" by Pathpilot but maybe there's a bit of poetic justice in there as Tormach runs on Linux. Anyhow, not sure of the ins and outs, history and morality/legality of all this. I just liked that it looked "modern". But then I started reading and watching tutorials and LinuxCNC is a bit more than I am willing to dig into right now.
The controller for UCCNC does Mach(4?), too so it's not completely out of the question. I think Engineers Anonymous made a screenset that looks nice (there's a video on YT with a lot of crap talking). And yes, looks shouldn't matter, but if I have the choice, I vastly prefer a pleasant looking UI most other things being equal.

Anyways, back to homing. I don't mind at all a simple switch. Just wondering if it's easy enough to set up? I mean it would trigger once every revolution, right? So, is it easy to enable it for homing and then disable it again for the machining?

[joeavaerage]

Hi,
IF you are using servos, then B2's are rated to 3000rpm but have a maximum of 5000rpm.

With 5mm pitch screws that means 25m/min rapids. At rated torque my machine can accelerate all axes at 0.27g (rated) and 0.75g(overload).
That is what I set my machine to initially....but its too God-damned scary fast. I have detuned it to 15m/min rapids and 0.15g accels...and that's entirely enough.

If you used 10mm pitch you could go faster and potentially even accelerate quicker.....but personal experience tells me that would be just over the top for a hobby machine.
If you stick to 5mm pitch with servos it will be fast enough and you get better thrust.

If you are using steppers and they perforce go much slower then 10mm pitch screws make sense.

Craig

[GeckoSub]

Hi,
IF you are using servos, then B2's are rated to 3000rpm but have a maximum of 5000rpm.

With 5mm pitch screws that means 25m/min rapids. At rated torque my machine can accelerate all axes at 0.27g (rated) and 0.75g(overload).
That is what I set my machine to initially....but its too God-damned scary fast. I have detuned it to 15m/min rapids and 0.15g accels...and that's entirely enough.

If you used 10mm pitch you could go faster and potentially even accelerate quicker.....but personal experience tells me that would be just over the top for a hobby machine.
If you stick to 5mm pitch with servos it will be fast enough and you get better thrust.

If you are using steppers and they perforce go much slower then 10mm pitch screws make sense.

Craig

Quick question to clear something up. Do I understand it correctly that the 3000rpm is where the motor has "all" the torque which would be sufficient in cutting scenarios (with a well matched motor) and then for rapids you can make use of the 5000rpm?

I just grabbed some numbers from a Haas SuperSpeed and a Syil X5 and they rapid at 36 and 30m/min respectively and have max cutting feeds of 21m/min and 10m/min. Given that my machine is just a rather glorified hobby router, I do think the speeds I can get from 5mm sounds alright.

[joeavaerage]

Hi,
I have made repeated purchases from this company in Korea. They specialise in CNC motion parts. I bought the 32mm screws I used in my machine. They were second hand, but when they turned up I'd swear they had never been
fitted, and even had matching serial number THK measurement certs, perfect in every regard. I paid $1000USD for three including six FK25 support bearings and three day Fedex to New Zealand, exceptional buying.
It made my new build possible, I just could not have afforded these quality parts new.

https://www.ebay.com/str/industrialp....m47492.l74602

This is a 20mm diameter C5, 5mm pitch by THK, five of them available:
https://www.ebay.com/itm/19448004260...cAAOSwWLphflwu

This is about the same price as a new C7 rolled screw....and a genuine ground C5 is sooooo much better.

Craig

[GeckoSub]

Thanks for the links Craig,
Looks like some good deals.
I have seen you mention that shop in other posts but I have the fortune of being able to dig into Chinese-only secondhand trading apps where the price is even a tad better (I don't speak Chinese but I have friends who are helping me with this). But selection and track record is of course not as solid as your Korean shop. Still, I think I can find a vendor or two that I can trust. Especially if I find a machininist who can do a good job of modifying them to length.
That said, I am aiming for C5 at least but keeping my eye open if a great deal on some C3 turns up.

[joeavaerage]

Hi,
there are a number of Chinese suppliers claiming C5 and C3 but at prices little more than rolled C7's. Total BS. If you can find some suppliers that you can trust to supply
genuine C5's or C3's, but quite frankly China is not the best place for high end ballscrews.

Do I understand it correctly that the 3000rpm is where the motor has "all" the torque which would be sufficient in cutting scenarios (with a well matched motor) and then for rapids you can make use of the 5000rpm?

Yes. Many AC servos have that feature. It is a quirk of Feild Oriented Control motors, its called Feild Weakening. In the case of Delta B2s servos they retain rated torque up to rated speed. In the specific case of
my 750W B2's, 2.4Nm at 3000rpm. Beyond 3000 rpm and up to 5000rpm it has lineraly reducing torque.

Torque at 5000rpm =2.4 X(3000/5000)
=1.44Nm

That would be enough for a rapid traverse (g0), but probably not have the thrust for regular cutting (g1) I would say my machine has max rapids of 25m/min but max cutting of 15m/min.
Its somewhat academic as I very seldom ever use the highest speeds and accelerations my machine is capable of...its just too scary.

For a small to medium sized hobby machines I would say 10m/min to 15m/min is fast enough and accelerations of 0.1g to 0.2g will ensure good toolpath following.

For production machines these would be considered tool slow and anemic, where 50m/min to 90m/min and 1g and higher is considered normal. Mind you those
machines weigh many tons and cost hundreds of thousands if not millions of dollars.

I rather doubt 60mm of granite (E=70GPa) could reasonably contain the forces associated with 1g accelerations, it's just as likely to fracture. In fact, I'm not at all sure that grey cast iron (E=110GPa) would be enough......
I'd be using a good grade of SG iron (E=170GPa) at least, or casting in genuine steel and be done with it. Steel is at least three times stiffer (E=205GPa) than granite and has tenfold-twentyfold the impact strength of granite.

No, shy away from really high speeds and accelerations, your budget just won't stand it and your choice of basic material is wrong for that sort of machine.

5mm pitch ballscrews and servos in the 200W to 750W class of 2000 rpm or more will give you plenty of speed and accelerations with thrust to accommodate cutting forces.

Craig

[GeckoSub]

Hi,
there are a number of Chinese suppliers claiming C5 and C3 but at prices little more than rolled C7's. Total BS. If you can find some suppliers that you can trust to supply
genuine C5's or C3's, but quite frankly China is not the best place for high end ballscrews.


Craig

Still reading up on your previous posts and reading spec sheets of servos, etc but just wanted to address this one

Thing is, I am indeed looking at used Japanese hardware just like you. At the very least, Taiwanese.
China is - for better or worse - the factory of the world so there is litterally tons of used gear around and a lot of that is proper Japanese hardware as a lot of the Chinese factories or their overseas owners had the money to buy German, Japanese or TW machines. So, the question is not one of whether it will be Chinese or Japanese or real C3/C5 or "Chinese C5", the real question is whether I can get some that have not been run into the ground.

Honestly, some years back, buying anyting used was not easy. I think there was a bit of modern, cultural bias towards always wanting the newest bling so what was on the used market seemed to pretty much have been "run until destruction".
But that has changed, there's no shame in buying secondhand now, it seems whether it's consumer eletronics, clothes or machine parts. And for the latter, certain industries are already moving to even cheaper places and with the slowdown in the economy leading to closures, I feel like that could be the reason I start seeing what appears to be more good quality used, hardly used gear and even a bit of NOS.

E.g. for the servos, I can get a set of B2 400w with driver and motor for about 100 bucks. The ones where the people disassembling didn't just snip the cables but actually kept them are a tad more but still nothing bad. This price makes sense as they have soooo many of them around. I even see some OK priced Panasonic and Yaskawa stuff, but no need for that for me. And then there's Estun which is 100% Chinese but seem slightly more expensive than Delta.
But I think, due to you, and the sheer numbers of them, I have settled on Deltas

[joeavaerage]

Hi,
I think you are misunderstanding how Home switches work.

When homing the machine will move in the programmed direction at the programmed speed UNTIL it encounters the Home switch, whereon it decelerates to a stop and then backs up UNTIL
the switch deactivates. The axis is Homed when the switch deactivates not when it activates. So the accuracy or repeatability is not how much the switch travels before activation, but how
repeatable the hysteresis is, ie the travel until the switch deactivates.

So your Metrol switches might be best if you need to precisely define an edge or similar, and that I would call absolute positioning, but for repeatable homing then a switch with defined and repeatable
hysteresis is what you want. Such a switch might cause the axis to define Home as 0.435mm from the switch activation point but because it has defined hysteresis it will be 0.435mm plus or minus 0.01mm every time.
the absolute position is not that critical, but having a repeatable switch deactivation point is critical.

Craig

[pippin88]

Hi,
I think you are misunderstanding how Home switches work.

When homing the machine will move in the programmed direction at the programmed speed UNTIL it encounters the Home switch, whereon it decelerates to a stop and then backs up UNTIL
the switch deactivates. The axis is Homed when the switch deactivates not when it activates. So the accuracy or repeatability is not how much the switch travels before activation, but how
repeatable the hysteresis is, ie the travel until the switch deactivates.

So your Metrol switches might be best if you need to precisely define an edge or similar, and that I would call absolute positioning, but for repeatable homing then a switch with defined and repeatable
hysteresis is what you want. Such a switch might cause the axis to define Home as 0.435mm from the switch activation point but because it has defined hysteresis it will be 0.435mm plus or minus 0.01mm every time.
the absolute position is not that critical, but having a repeatable switch deactivation point is critical.

Craig

No, the controller dictates what it calls home

Some controllers (e.g. LinuxCNC) have different options for homing and whether it is switch activation or release etc...

[GeckoSub]

Hi,
I think you are misunderstanding how Home switches work.

When homing the machine will move in the programmed direction at the programmed speed UNTIL it encounters the Home switch, whereon it decelerates to a stop and then backs up UNTIL
the switch deactivates. The axis is Homed when the switch deactivates not when it activates. So the accuracy or repeatability is not how much the switch travels before activation, but how
repeatable the hysteresis is, ie the travel until the switch deactivates.

So your Metrol switches might be best if you need to precisely define an edge or similar, and that I would call absolute positioning, but for repeatable homing then a switch with defined and repeatable
hysteresis is what you want. Such a switch might cause the axis to define Home as 0.435mm from the switch activation point but because it has defined hysteresis it will be 0.435mm plus or minus 0.01mm every time.
the absolute position is not that critical, but having a repeatable switch deactivation point is critical.

Craig

Still, a Metrol does that same job but with a repeatability that is even better. But this is probably a case of me wanting more than I need in real life and not yet having realized that +/-0.01mm is enough.
I mentioned I was hoping to be able to home the machine after a power cut and pick up the code where it left. But yes, +/-0.01mm is likely more than OK for that.

[edit] Ah, I re-read it all and I think you are saying that even though a switch has good repeatabilty on "switching on" it may not be the case for when it switches off. Got it. I would assume the Metrol would be great in both instances but would need to check if I go that way. After all, we know what they say about assumptions as a mother...

Not going the Metrol way would have the benefit of being able to more easily source NC switches and those Panasonic optical ones look small and come in many different configs: Some are right angled, some left, some straight and so on making it easier to make a clean and neat installation.
I will get a used Metrol for a tool setter, I think. They have a lot of those at good prices.

Actually, I still don't know how squaring the gantry off of two switches would work. Would I have to physically move the position of the switches so they both trigger at the point where the gantry is perfectly perpendicular? Or do you set them up such that they are close and then you can add a small offset in the software to get it "perfect"?

[joeavaerage]

Hi,
no, optical ones are not the correct choice. Firstly they are optical, and when you get working there'll be chips and coolant all over the place an optical is bad in those circumstances.
Second issue is hysteresis. See if you can find a specification about how much an optical switch has to back off before you get reliable switch deactivation. The same applies with
Hall switches and proximity switches, you cant really tell when the switch is going to deactivate as the magnetic/ferrous target withdraws.

I use roller plunger mechanical switches. You see the the switch is mounted on slots and allows the switch to be slid back and forth a little. The roller is activated by a shallow ramp
that is attached to the axis. It too is slot mounted, but especially because of the shallow ramp angle the adjustment is quite fine. Another important feature is that if the axis over travels for whatever reason
the switch will not be wiped out or damaged as the ramp alone passes by without ever impacting the switch nor does the ramp cause the switch to overtravel and get damaged.

Actually, I still don't know how squaring the gantry off of two switches would work. Would I have to physically move the position of the switches so they both trigger at the point where the gantry is perfectly perpendicular? Or do you set them up such that they are close and then you can add a small offset in the software to get it "perfect"?

Yes, that is about it, adjust the switches to be as square as you can and use software for the last bit. Not sure how UCCNC handles that but I do know how Mach4 and the Ethernet SmoothStepper handle
it.

Mach4 has two programmable features to do with Homing, namely Offsets and Back-off. They are applied to each home switch. So with a gantry you'd have a master motor with its home switch, and a slave
motor with its own home switch. Both motors are home simultaneously but each will have (in addition to whatever slight mounting discrepancy between master and slave switches) but will have individual Offset and/or
Back-off applied for that last few um.

These switches are about $20USD depending on where you buy from and with care can get repeatability of 0.01mm, I regularly get 0.02mm. The Metrol switches you have proposed may result in better absolute accuracy,
but really who cares....what you want is repeatability and that can be had for less money.

Craig

[GeckoSub]

Hi,
no, optical ones are not the correct choice. Firstly they are optical, and when you get working there'll be chips and coolant all over the place an optical is bad in those circumstances.
Second issue is hysteresis. See if you can find a specification about how much an optical switch has to back off before you get reliable switch deactivation. The same applies with
Hall switches and proximity switches, you cant really tell when the switch is going to deactivate as the magnetic/ferrous target withdraws.

I use roller plunger mechanical switches. You see the the switch is mounted on slots and allows the switch to be slid back and forth a little. The roller is activated by a shallow ramp
that is attached to the axis. It too is slot mounted, but especially because of the shallow ramp angle the adjustment is quite fine. Another important feature is that if the axis over travels for whatever reason
the switch will not be wiped out or damaged as the ramp alone passes by without ever impacting the switch nor does the ramp cause the switch to overtravel and get damaged.



Yes, that is about it, adjust the switches to be as square as you can and use software for the last bit. Not sure how UCCNC handles that but I do know how Mach4 and the Ethernet SmoothStepper handle
it.

Mach4 has two programmable features to do with Homing, namely Offsets and Back-off. They are applied to each home switch. So with a gantry you'd have a master motor with its home switch, and a slave
motor with its own home switch. Both motors are home simultaneously but each will have (in addition to whatever slight mounting discrepancy between master and slave switches) but will have individual Offset and/or
Back-off applied for that last few um.

These switches are about $20USD depending on where you buy from and with care can get repeatability of 0.01mm, I regularly get 0.02mm. The Metrol switches you have proposed may result in better absolute accuracy,
but really who cares....what you want is repeatability and that can be had for less money.

Craig

Thanks so much for explaining the back-off feature and the pics of your switch and mount. Will put it on the list off what to check up on in relation to UCCNC before I buy into the system. I guess if it can be made to home to the "on" latching and not the "off" that widens my options. Will try to lock it down fairly fast though so I can incorporate the switch and mount into the design.
Already on the list: checking hysteris for switch options.

[GeckoSub]

Hi,
no, optical ones are not the correct choice. Firstly they are optical, and when you get working there'll be chips and coolant all over the place an optical is bad in those circumstances.
Second issue is hysteresis. See if you can find a specification about how much an optical switch has to back off before you get reliable switch deactivation. The same applies with
Hall switches and proximity switches, you cant really tell when the switch is going to deactivate as the magnetic/ferrous target withdraws.
(...)

Craig

Just wanted to tie a bow on this as other people might come across this thread later and I now have a bit more info.

In post #30, I linked to a youtube test of various, affordable switches: https://www.youtube.com/watch?v=7P6a_aWgm2E&t=75s&ab_channel=JBWorxStudio

Here's screenshot of the same results (from his website):


I like the channel. Well presented and good topics for novices.
Jorg(?) did an apprenticeship in machine building and a degree in manufacturing and his stated claim is to help people get into machining in an affordable way. So, he tested cheap switches (and one expensive one) and he really liked the optical one.
I have since asked him how his software is set up. He replied, that he uses EdingCNC and it also uses the release/off point of the switches, so I think we can say his results are trustworthy and directly relatable to Mach or UCCNC.

As for optical switches being the wrong choice, while others should probably avoid them depending on how shielded they are, coolant choice, etc, I guess for some they may still be a good choice.
He was asked/told the same thing in the comments about them being triggered by accident and he replied that he has had them for 9 months and wish he had changed years ago. He also doesn't have any issues with various levels of light affecting the switches.

What I did read in other places is that some of these non-mechanical switches can be very prone to temperature drift. Not sure if that's an issue with these brand name opticals, but supposedly some of the proximity switches can vary wildly. Fine, if your software can use a Zero Pulse. Not cool, if it can't.

Anyhow, your milage may vary, but since I asked him, I thought I might as well share the info.