3D Printing M25 Threads for Objective Cases

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aidanmoore
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3D Printing M25 Threads for Objective Cases

Post by aidanmoore »

Does anyone have an accurate thread profile for the M25X0.75 thread used for Nikon and Leica Objectives?

After reviewing the cost of shipping Aliexpress M25 (Nikon) Objective cases from China, I am experimenting with designing and printing M25 Objective cases using Fusion 360.
cases.jpg
CLEAR copy.jpg
However, Fusion 360 does not include a M25x0.75 thread profile by default, so it's necessary to creat your own profile. I've used an online thread calculator to get the Major, Minor and Pitch diameters and the results are sort-of-good but there is room for improvement even after relaxing the threads using press/pull.
threads.png
profile copy.jpg
Thanks!
Custom Nikon/Thorlabs Microscope Nikon Z7ii ZCAM E4

Scarodactyl
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Re: 3D Printing M25 Threads for Objective Cases

Post by Scarodactyl »

If you are using an fdm printer internal threads probably won't print to nominal spec anyway, they will be a bit tight. Mine tend to be a quarter millimeter tighter in diameter than specced. It takes some experimentation to get it dialed in.

Smokedaddy
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Re: 3D Printing M25 Threads for Objective Cases

Post by Smokedaddy »

I'd like to know if you ever figure it out. Not that this answers your question but I found these two links.

https://all3dp.com/2/3d-printing-thread ... d-to-know/

https://dkprojects.net/openscad-threads/

-JW

Chris S.
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Re: 3D Printing M25 Threads for Objective Cases

Post by Chris S. »

Aidan,

I don't know if this is helpful, but I once photographed the profile of Nikon M26 (not M25) x 0.75 threads. The results are in the thread: Nikon and Mitutoyo objectives have different M26 threads

Similarly, if one had a Nikon M25x0.75 objective, it would be pretty easy to determine the profile photographically. (High NA objective for shallow DOF, evenly-distributed backlight; no need, in my experience in this case, for highly collimated light; shoot a stage micrometer at same magnification for measurement.)

--Chris S.

Smokedaddy
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Re: 3D Printing M25 Threads for Objective Cases

Post by Smokedaddy »

On another note, I bought one of these a couple of years ago but not from this particular seller. It worked fine too but then again I had machining equipment to begin with.

https://www.ebay.com/itm/113441957882

-JW:

aidanmoore
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Re: 3D Printing M25 Threads for Objective Cases

Post by aidanmoore »

Thanks for the suggestions!

I just looked at a few Nikon M25 X 0.75 objectives with my Wild M8 at 40X and it looks like I can pull the data I need using Chris's suggestion of superimposing a micrometer scale at the same magnification.

I'll update with some pics once I've photoshopped the compsite image.

Thanks again.
Custom Nikon/Thorlabs Microscope Nikon Z7ii ZCAM E4

physicsmajor
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Re: 3D Printing M25 Threads for Objective Cases

Post by physicsmajor »

If you would like someone to test, I have multiple very highly tuned enclosed printers and can print in PLA as well as ABS, ASA, and Polycarbonate. Throw some STLs my way.

My initial suggestion for such fine threads is that it should be possible to print but will require a well tuned printer and definitely need small layer heights to sufficiently approximate the thread profile. I have successfully mounted objectives on RMS threads printed at 0.12mm layer height. You'll want your layer height to match an integer multiple of your Z stepper motion's full step distance for ideal results (mine is 0.04mm; if yours is 0.05mm you'd go for 0.1mm layer height). "Blobby" materials like PETG likely will not work well, you need a clean surface.

Scarodactyl
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Re: 3D Printing M25 Threads for Objective Cases

Post by Scarodactyl »

Petg works fine for threads on my plain old ender. They don't need ultrafine tuning to work, but it may take some tweaking for the particular printer I suppose.

aidanmoore
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Re: 3D Printing M25 Threads for Objective Cases

Post by aidanmoore »

Well I finally am getting very good fit with the objective threads.
case2.jpg
case3_sm.jpg
I had to iteratively scale the case top to get an easy fit for the objectives as well as chamfer the start of the threads to allow an easy start to the rotation. I ended up using a 2% scaling factor and the objective fit easily and are snug with a 2% scale from the original M25 spec.
case1_sm.jpg
I used both PETG and PLA with good results. My only dissapointment is that no matter what the transparent PETG is always translucent at best. There is a way to partially print in "vase" or spiralize mode so I might give that a try next.

Otherwise these are functional storage cases even though you really need to mark the body as to what objective is inside.

The .stls are located here: https://www.thingiverse.com/thing:5395489
composite_M25.jpg
Custom Nikon/Thorlabs Microscope Nikon Z7ii ZCAM E4

physicsmajor
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Re: 3D Printing M25 Threads for Objective Cases

Post by physicsmajor »

If you want translucent, you want a bit of deliberate overextrusion and 100% infill (actually ideally 999 walls with 0% infill and gap fill enabled). Any gaps - infill or between layers - will be obvious and visible. However this has to be balanced with the need for the threads to work at the top of the part. Might have to manually change the flow up a few % during the main cylinder and reduce back to normal for the threads.

I'll give it a go with clear Polylite Polycarbonate once I get done upgrading my main printer.

aidanmoore
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Re: 3D Printing M25 Threads for Objective Cases

Post by aidanmoore »

Thanks for looking into this. I'm using Cura 5.0 and some of your sugestions do not translate into Cura-speak. But I will try based on your suggestions and update here.
Custom Nikon/Thorlabs Microscope Nikon Z7ii ZCAM E4

JKT
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Re: 3D Printing M25 Threads for Objective Cases

Post by JKT »

aidanmoore wrote:
Thu May 26, 2022 7:59 am
I used both PETG and PLA with good results. My only dissapointment is that no matter what the transparent PETG is always translucent at best.
My my. I happen to need neutral translucent for diffuser and this looks pretty good. What exactly was your material and the wall thickness?

aidanmoore
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Re: 3D Printing M25 Threads for Objective Cases

Post by aidanmoore »

Yes. I printed several translucent discs to check for transparency, but they are quite good diffusers. Overture transparent PETG printed at 2mm thick is a decent starting point for a diffusion element.

https://www.amazon.ca/gp/product/B0875J ... =UTF8&th=1
Custom Nikon/Thorlabs Microscope Nikon Z7ii ZCAM E4

JKT
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Re: 3D Printing M25 Threads for Objective Cases

Post by JKT »

aidanmoore wrote:
Thu May 26, 2022 2:26 pm
Yes. I printed several translucent discs to check for transparency, but they are quite good diffusers. Overture transparent PETG printed at 2mm thick is a decent starting point for a diffusion element.

https://www.amazon.ca/gp/product/B0875J ... =UTF8&th=1
Thanks! I'll have to try that.

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