Delta Stage Movement is Diagonal?


I have just completed a build of the Delta Stage. I have calibrated it and done the stage mapping and now the stage will move in the diagonal, this can be countermeasured by moving in the neighbor direction (eg, right and down will move true down while right only does right and down directions).

I am just curious if this is normal, I can grow accustomed to it no problem. Thanks in advance!

@golgothas it is great to hear that you have built a Delta Stage. A little more information will help to understand the problems. Are you using it as a microscope system with an optics module and the Openflexure web app? Are you able to post a photo, particularly of the optics module if you are using that.

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Apologies and thank you for responding so quickly!

I am using it with the ‘low cost’ raspberry pi camera until my doublet lens comes in and I upgrade to objectives.
I am also using the web app and Openflexure Connect on various devices.
I have to press both Left and Down to get the camera to move straight down. The Z Focus works, from what I can tell, normally.

That picture confirms my first thought. In Delta Stage mode the web app moves the stage in two axes which are aligned forward-back and side to side when you have the Delta orientated so that the illumination is away from you. This makes it intuitive to mount the sample on the stage.
The camera then should be aligned straight to the illumination mount.

The Microscope version of the stage has motion with one knob per axis, so to allow intuitive manual control the camera is aligned with those axes, which are at 45 degrees to the illumination mount.

These together mean that the optics modules for the Delta Stage and the Microscope are different. They are optically identical, but the dovetail for mounting is in a different orientation. I see that the Delta instructions don’t have the low cost optics instructions, so you cannot get the correct STL from there. The STL for the camera mount should be in the full source bundle at I cannot open the zip here to check. The black lens spacer you already have then goes on top of the new camera mount.

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Yes currently the mount for the low cost (RPi camera lens) has not been implemented yet for the Delta Stage. If there’s now a demand for it, I can add it.

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It’s also worth asking if you’ve tried calibrating the camera-stage mapping? That won’t change what happens when you push the arrow keys, but it will make click-to-move work properly.


As @samuelmcdermott says, the camera mount for the low cost optics module is not implemented in the Delta Stage, so the full zip that I linked to does not contain the part that you would need as it is not generated.

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Awesome! That would completely explain why everything is functional yet slightly off-kilter.

Knowing this, I can throw together a design to fix this issue, I will be upgrading the optics module to use a 40x planar objective within the month so this is just to mess about until the real gear ships in from Shenzhen.

Thanks for the great info, y’all!

Yes sir, I have. Yet the gpu preview confuscates my cursor and I have no control over that part of the screen even after calibration. I plan a full re-write of the SD card if the issue is not fixed by my installing an adjusted optics module to fix the skewed movement

The delta stage specific optics module rotates the camera relative to the stage, so it should fix your problem. It’s worth mentioning that the GPU preview means that click-to-move doesn’t work, so if you turn it off (in settings you should be able to un-tick “disable web stream” and “enable GPU preview”) you should be able to click to move on the Pi, just as you would if you connect from another computer.

Given that Pi 3/4 seems to be able to handle the JPEG stream, I’m very tempted to do this by default in the future, the GPU preview is a bit of a headache…


@golgothas I tried to implement the simple optics in the Delta stage, but it is complicated in that code base. Instead I have made a rotated camera platform STL from the Microscope code base to see whether it works. The STL looks OK, but I have not tried it. It should be the right angle, but may be the wrong height for the Delta. Let me know if you are able to try it.
camera_platform_45deg_test.stl (42.2 KB)