Increase XY travel range

I have samples that I would like to map and stitch with brightfield (for now, fluorescence or polarization later perhaps) but the full scan size would need to be larger, possibly 15 x 15 mm. My plan is to use the epi-collection design.

If we change the dimensions on the flexures should it be possible to achieve this increase with either the OFM or the Delta stage? Would be very excited to see how robust this approach is.

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This is also on another recent thread. I can’t see it just now.
In principle longer legs give more movement, but there are limits. The other thread has something about that.

Thanks @WilliamW. I wasn’t able to find anything but I may have missed it. I understand the principle of extending the legs to push the useable travel range, but I was curious about the limitations of that approach. I had reached out to @r.w.bowman who suggested I start this thread so we can hopefully try to sort this out as a community. Suggestions are appreciated!

This was the post I meant. Which is from RWB, and not a solution more a comment.

The parameter to play with is sample_z which sets the overall height of the main body. The effective lever length of the legs is 5mm shorter than sample_z, i.e. the default has sample_z=65 which gives a 60mm lever. My design assumption is that the legs bend through 6 degrees, meaning you get lateral travel that is about \pm10\% of the lever length, i.e. \pm6 mm or 12mm in total.

The number you need to change is in microscope_parameters.scad line 44, I don’t think this gets overwritten by the build script. You can then compile the modified main body by opening main_body.scad.

I’ve not tested this recently with anything other than the default value - but increasing it to, say, 85mm ought to work. I think the only other thing you might then need to adjust is the illumination mount, though it might adjust automatically if I was really on the ball when I wrote that code…

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I should mention you’d also need to adjust the optics module, as the default one will be the wrong size…

Hi everyone,
I am wondering how far the travel range has been pushed by increasing the lever length since this has been posted?

I am hoping to maximize the travel to 20 mm to cover a good portion of a petrographic thin section (20x30 mm thin sections from rock samples, 10x objective). To do that I would need to increase the lever length to 100 mm.

This is my first Open Flexure build and I am going for an upright design - my understanding is that I might need to adjust the spacer on the optic module and maybe tweak the illuminator module.

Could someone correct me if I am going off track?

I don’t know of people reporting on using longer legs. It should work.
If this is your first build, I would recommend making a standard travel microscope first, so that you can test it and get a feeling for the build and operation. Then you will be able to tell better whether longer legs is behaving as expected.

As I have said on other threads, If you are building a microscope right now I would recommend using the current master version, rather than the v7.0.0-beta1 release that is linked from the web site. I would not usually recommend a development version, but there are a large number of bug fixes and improvements since beta1. We are approaching the next beta release so there will not be breaking changes in the current master until that beta2 is released (unless there is some mistake :slight_smile:). Edit 2024-5-17: Beta 2 is now released, so this no longer applies.

Thanks William,
I am following your advice and building the default version from the master first.
As a follow up, I did render a version of the body with sample_z=105 mm and compared it to the default version one to assess where I would run into problems. The lower Z-axis dovetail is sitting at the default height which will create various issues depending of the configuration (low optics or low illumination). I will report when I get around to building it.

That looks great. The position of the optics should work itself out automatically if you run the optics module code.

There could be a problem with the high resolution optics module as the camera is expected to be below the body, but with the taller legs it would end up alongside the mounting dovetail. The low-cost optics modules should work, as the camera is already above the dovetail. It could be that the latest refactoring of the lens spacers and camera platforms for the low cost optics is needed, which is not yet merged to the main branch.

edit:
I had a try with the RMS optics modules, and indeed it fails for a leg height of 105mm, with the camera placed inside the dovetail mounting part. However the rms_infinity optics are slightly longer and that does work for a leg height of 95mm, so if you have infinity corrected objectives and make the legs a little less tall it will need less fiddling with the code.