Hi All,

For those who remember, I designed a 3D printed PVS-14 some time ago, but it was a bit rough, and even with flattering angles, had problems. Also I struggled with thread pitches higher than 24 tpi, so ended up modifying to use 24tpi where critical, and 32 tpi only where it wasn't possible to do otherwise.

Well, I got a new printer, one of the new generation of FDM models, and threw this in as a test print, as I had a model that was closer to the original spec, including 40tpi around the ocular. It printed up pretty nice, and without any finishing, the threads came out quite serviceable - well, better than most threads after someone has a few attempts at screwing in an ocular.

So I thought I'd share the pic - I think it came out pretty well - Note, this was the first time I took a photo head-on with the threads, in direct sunlight. Also, magnified images of the threads showing clean and accurate thread formation in both 32tpi and 40tpi.
So it seems that the technology is now sufficient to allow high detail and even milspec NV housings...



Those threads at the back are really fine - and I think it really pushed the printer in making them, but from the pic, they appear to have formed well. That's about 0.6mm between threads in metric terms ( 0.625 exactly )

David.

Hmmmm. My friend owns a 3d printing buisness. Are you selling the print files? Id give it a shot.

my largest issue with trying to print the housing was delamination with way the stresses were placed on the housing mostly in the thin threaded areas.  It wasn't horrible, but it didn't hold up to my needs. It would be fine and then someone would try to over adjust an ocular and would spin the whole lens right off the housing - threads and all. lol.

I assume you cant change the design due to the inside dimensions need to be a certain size?

That's correct - there's some very tight tolerances around the upper, and they are all close to the bad points on ABS, though a little trial and error can often address them - I'm just working out the difference due to shrinkage for the model - that is, the ABS shrinks as it cools, so some allowance must be made there. It also shrinks different amounts in X and Y axis to Z axis.

But the new printer doesn't seem to have problems with pulling threads away and I design my threads so that they increase the strength of the section rather than decreasing it... Then I'm going with 99% fill.

So I don't think it will pull away - I just need to get the tolerances right to make it easier to assemble. Too loose and you can rip the ocular off or make it skip threads when tightening. Too tight and it either won't fit or is difficult to turn...

Though I am also thinking of 3D printing some dies to recut the threads after printing to make them cleaner still.

David.

Sorry, it's still controlled, though at some point, when it's clear the patent has expired without any possible exceptions, I'll ask again to put the designs into the public domain.

David

OK, just tried, and that probably would have happened with my old printer, but the new one gives about 1mm of clear ABS wall before the threads start, with no "V" for the threads, but a gradual climb up to a rounded tip so there's no clear weak spot, and there's 2mm of solid plastic at the top of the thread, so the wall is thicker than it might seem.

I guess it would be possible to break, but I just tried to rip it off with my hands, and failed... Mind you, I'm not the strongest person, but I doubt even my most hamfisted friend would have succeeded in doing it accidentally.

Then I had to go and find a spanner, because I got it on so tight and bottomed it out against the ocular and I overdid it a bit... Still, only took a small turn to crack it and then it unscrewed beautifully and no damage to the threads either.

I had hoped for that, and it seems it's performing. I can print it in Carbon Fiber Amphora if I need more than that, but I wouldn't want to rub it against a normal ANVIS ocular, because it's just so abrasive... Maybe if I made both parts though.

This printer is a commercial FDM model though. It's the desktop version of an automated production line model so it's actually pretty good. I tried making a tube retaining ring with my old printer, and it pretty much failed... Tube kept slipping with any knocks. Just printed a new one in ABS and it absolutely holds the tube in tight.

So I'd say that the era when we can reliably 3D print the housings has emerged. I used to struggle with interference fits between threads, but now at 100 micron with a reliable printer that's designed for it, I can get six layers or more per 0.625mm thread, which still works as a bit of an interference pattern, but it means I'll have up to 70% to 100% optimal thread depth everywhere across the thread. That's better than I managed with a 200 micron system which went from 0% to 100% but made the outer thread way too thick.

David

My printer is a Creator Pro dual extruder that is probably getting a little dated and I was printing in ABS at 80% fill (which was about as solid as I could get without crazy expanding/shrinking issues). It works and was functional, but it wasn't worth it in the end for me. I opted for just building a battery box that could mate to Anvis pods and just wiring that up since there were a surplus of used anvis optics floating around at the time.

I would love to get a newer FDM printer, but I don't use it enough to justify that.

Mine was about 2013 vintage - very reliable and good print quality, but limited capability to go beyond 200 micron. I did hack it to get down to 100 micron once, but the quality wasn't much better than 200 micron. A lot of it was also the tolerances of the printer to lay down fine tracks repeatable.

The old printer weighs about 2 kg, the new one is about 50kg. Heavy metal and very solid. The workpiece doesn't move at all - just the head. And it prints cleanly at reliably at 100 micron. The different on many models isn't huge, but the difference when I am working with thin threads is chalk and cheese. For me, it's about moving from being close to able to print a fully functional NVD sometimes to actually being able to print a fully functional NVD reliably and repeatably.

But it was a big investment and I had to give up a few other projects to get there. I ended up getting a Tiertime UP300. It doesn't have dual-head capability or anything, yet, but they really have gotten the quality down pretty well.

Now it's time to revisit all my old projects. I also have a resin printer (DLP) and a CNC machine now, well, I always had a CNC, but now it works... So I can make PCBs and also cut carbon fiber plate and the likes. Now my kids are growing up and leaving home, I got some space back - :) Though I kind of wish they just stayed here....

David.

Makes sense, I understand. Was just interested in trying it out. I think 3d printers will change the future of small parts prototyping.
3d printing dies to cut threads on a 3d printed part. What a world we live in.

Are you sure the PVS-14 patent hasn't expired? It was adopted in 2000 and surely the patent was filed at least two years before then.

i dont know much about these things but its interesting - does the printer also scan the item so that it can make another or do you have to buy a seperate scanner to do this ?

Scanners worth using cost 20k. Designing a 3D file like an STL with design software is how its usually done.

Patents are only 20 years... https://en.wikipedia.org/wiki/Term_of_patent

It's this patent - https://patents.google.com/patent/US5943174A/en

It's expired.

Correct. I didn't copy the PVS-14 - I made a functional variant using CorelCAD that is interchangeable with the original when printed.

David.

You ever make a decent mx-11769 boot print file?

I was just wondering about this a week ago >.>

I wouldn't call it decent, but it does work if you're making it from scratch... It's on Shapeways and it is free to download - I think quite a few people have used it though. I think it was the second thing I ever designed.

https://www.shapeways.com/product/W4JH5QRXK/mx10160-boot

Don't order it though - You can download it for free and print it at home.

David