Linear Scales Implementation

[andremalenfant]

Hi, I am looking at implementing linear scales in H5. In looking at the code I realized that it is not straightforward as nanoels already tracks it's position via step counts (as one would expect). That means that the scales are of course not required when nanoels is in control.

However, I often times use the lathe manually, in which case nanoels cannot track the position.

Was there a design idea behind the scales implementation beyond the PCB headers? Was the intention to use the scales only when steppers are disabled or to use their position in lieu of the stepper position tracking internally?

I am starting this discussion just to steer my design so that if it gets done in the master branch, I don't end up too far off when rebasing :)

[GeckoSub]

This is exactly what I have needed, too. Except my use case is even simpler since I decided to only have a stepper on the Z and keep the X fully manual. (I was fortunate enough to pick up a mini-lathe sized CNC lathe around the same time I got into NanoELS, so personally, I wanted to keep my NanoELS lathe more manual).

I am very far from being able to code but and judging from your lingo, you actually do;). However, I have somehow with the help of AI(!) managed to put together a custom FW that has DRO on the X and I just got a scale installed on the Z, too so will get into the code again over the next few days to see how I can make that work.
I should say, that I have also had to design a custom UI to make this work.

Not having a motor on the X made the scale implementation much simpler as there's no conflict between the ELS stepper counts and the scale. But let's see what I can make happen with the Z. I am thinking to just a have button switch between DRO/ELS mode. That would hopefully do the trick.
On the other hand, I imagine sometimes switching back and forth between ELS and manual mode. And even when in manual mode, I will be using the Z-motor as a power feed but I don't want to give up my scale whilst doing that.
Also, since I still have a regular half nut on my Z and no MPG, unlocking it and whipping back with the carriage wheel is way faster than doing it via the ELS. But then on the same part I may want to cut a thread and then go back to something manual afterwards.
I guess it would be great if the scale could do a handover of its value to the ELS when switching into ELS use - that might be the key to making this work... Anyways, I am just spit balling here.

Back to what I already did: There's a long-a** thread about my endeavours here but if you scroll towards the end, you will see the fruit of the labour;)
That thread is honestly almost a full build-log but I have tried, not successfully, to keep the FW and screenset work more condensed in this other thread - but there will be some overlap.

If you are interested, you are more than welcome to take a look at my FW and see if any of it could work for you. That said, the DRO version of the FW is not shared in the threads above as it seems very few people need it and my threads are confusing enough as they are. Point being, just ask if you need it and I will send/share it.

And since I have the lathe just next to me, I just shot a little clip of the DRO in action:
https://www.youtube.com/watch?v=46lEAFPqUvA

BTW, you may want to start by figuring out if you will run into hardware limitations. I feel like I have read that the ESP "only" has four HW counters and I think they are used by the spindle encoder, any MPG hand wheels you may want - and the scales, too. So, maybe it wont actually be possible to have two scales, two handwheels and one spindle encoder all working at the same time? But this is speculation on my part.

[GeckoSub]

ELS AND DRO WORKING
I made a new video and babbled some more since I now have DRO on both the X and Z working.
Keep in mind, I am not using all of the ELS features since I don't have an X-motor but I don't see why it wouldn't play along with the "full" ELS.
For others reading this, a DRO with input from scales probably only makes sense if you have decided to keep your leadscrews. If you made the switch to ballscrews, then there's no need for scales.

https://www.youtube.com/watch?v=GxUhRWPWlb8

[andremalenfant]

ELS AND DRO WORKING

I made a new video and babbled some more since I now have DRO on both the X and Z working.

Keep in mind, I am not using all of the ELS features since I don't have an X-motor but I don't see why it wouldn't play along with the "full" ELS.

For others reading this, a DRO with input from scales probably only makes sense if you have decided to keep your leadscrews. If you made the switch to ballscrews, then there's no need for scales.

https://www.youtube.com/watch?v=GxUhRWPWlb8

Thanks, will check your video.

I implemented scales because I want to still continue using the lathe manually. I mounted my X axis motor in such a way that I am retaining the wheel. I just disable the motor and use the crosslide manually. For Y, I disengage the half nut.

I implemented the scales independently from the steppers. The scale value only show when the corresponding stepper is disabled. The count is continuous to not loose track between modes. This gives me a DRO for manual operation and the CNC functions don't read their values.

Maybe I'll go full CNC ballscewson day, but I enjoy the manual aspect on small parts.

You are right that by eliminating backlash and using CNC all the time, scales are irrelevant.

[GeckoSub]

Sounds exactly like what I did except, you do have the X-motor so my scale is the only value showing on X. But as you, on Z it ended up being either scale or ELS coordinates showing. No handover/communication between the two. It's brand new, only had the Z working for a few days, but so far so good.

And I agree, it's nice to still have full manual control, it can often be faster this way for simple parts.