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Reverse engineering USP for 3D printed frame

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3d printing cad usp10 usp40 usp45
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12K views 36 replies 26 participants last post by  Thebiochemist  
#1 ·
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I just finished doing this for the FiveSeven so I figured I should be able to make it work for a USP. I bought a cheap USP parts kit from EveryGunPart, and I'm reverse engineering the parts to make CAD files. My cousin is supposed to loan me a USP45 to measure, but my kit is a USP40, so I'm hoping you guys can fill in the blanks. I've reverse engineered a p2000sk before, and from what I can tell there are a lot of similarities such as frame rails and trigger mechanism, the USP40 slide will even slide onto the P2000sk frame. The main thing I need is distance between the 4 pins (hammer, sear, trigger, slide stop), and some overall frame measurements like height, width, and length. Also, I know the 45 frame is bigger than the 9/40, but how much bigger? Hopefully I can get my hands on some other frames and post the measurement differences in this thread.
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The way I normally do this is to fully reverse engineer the parts as is, then start modifying some things to be 3D printer friendly (beef up some thin parts, etc), so I'll have CAD files of both available when this project is finished. Also, the printed frame doesn't necessarily have to be a straight USP frame, I can remix it with some newer features like P2000 or P30 backstraps, so if you have any ideas for improvements let me know. Another thing I'm considering is building this kit as a 10mm, since the frame I have access to is the larger USP45 frame there should be room for the cartridge length, it's just a factor of finding a magazine that fits and tweaking the mag catch design/location.
Normally I sell these CAD models, but if I get some community support on this they'll be free for you guys.
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If you guys don't mind taking some measurements for me, the best way to do it is to drift the pins out slightly and then measure with calipers outside-to-outside, then inside-to-inside edges of the pins, then measure the pin diameter. It's easier to infer the correct center-to-center measurement this way. If you do this from each pin to the 3 other pins, I can triangulate their positions on the frame.
A = hammer axle
B = sear pin
C = trigger pin
D = slide stop pin
So A to B/C/D, B to A/C/D, C to A/B/D, & D to A/B/C.
 
#4 · (Edited)
Ignoring copyright/trademark issues, It's federally legal to manufacture your own firearms in the US, despite the recent pearl clutching rhetoric about gHosT gUns from politicians & media. Some states and cities have passed feel-good-do-nothing laws banning 'ghost guns' AKA unserialized firearms and 80% kits with misdemeanor penalities. Not legal to sell without an FFL afaik

For printed frames it's possible to add rails during the print process or use premade drop-in rails, depends on the model.

GiterDunn said:
If you guys don't mind taking some measurements for me
Click to expand...
I can help gather measurements for a USP 9/40 frame (LEM/v7) if you want, drop me a PM
 
#7 ·
I don't have enough post to PM yet, I'd appreciate if you guys could post measurements in the thread, I'm going to make them public anyway when the files are published. But you can also reach me at airsoftfarmer@gmail.com if you want.

I usually use PLA+, the 5-7 has some epoxied in polycarbonate reinforcements, but for the USP I might do all PC. I was also thinking about changing the inset steel rails design to a monolithic folded steel chassis like a Sig P320. With the 5-7 I used polycarbonate for the front slide rails, if that holds up in testing I may also do that with the USP.

I'm imaging a lot of possibilities too lol, a UCP would be awesome. I like the idea of the P2000 grip, I never liked the P30 spider webs. Another concept I've been playing with is modular mag wells. The base frame would be compact length, so it can accept the widest variety of magazines. This excludes SK mags, but I'd rather have the extra room for the hammer spring. Then there would be a jet funnel like mag well module, maybe integrated with the hammer spring housing like on 1911s. It would extend the grip to full size mag length, or you could run it without the magwell and use X-grips. I'd also appreciate if you guys could measure some magazines too, so I can check for compatibility.
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The modeling is going smoothly, almost done with the slide. I've imported some game models and stuff found on grabcad to compare to, my stuff is the colored models. Using video game models speeds up things like grip textures and complex curves, I can just scale them to actual size and add these features to my model.
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T
#9 ·
Not a 3D printing expert (only have done PLA and resin), but your typical consumer FDM printers will do PLA, ABS, and PETG. With upgrades (filament humidity control, heated enclosures, hardened nozzles, upgraded hotends and beds, etc), people can do nylon, polycarbonate, and fiber reinforced materials.

Out of curiosity, what CAD program are you using for this stuff... Also, the idea of scaling video game models into printable, editable stuff is really neat. I think it'd be cool to print a model of something you can't get here, and stuff a .22 kit or something into it.
 
#10 ·
I've been printing for about 10 years, I just did a writeup on it for American Gunsmith magazine. There have been some recent advancements in materials that allow you to print much stronger parts with the cheapest of machines. I run an Ender 3 bone stock inside a plexglass enclosure with a heat gun, and it will print PC blends and Nylons no problem. The strongest filament I've found yet is Polymaker PC-FR (fire retardant), followed by Priline CF-PC and Duramic PLA+. Spoolworks Edge PETG is also an excellent all around material, a little more heat resistance than PLA+. The nylons are strong but they all degrade with moisture and some have significant creep. I made a 5-7 extended mag base with Fiberlogy PA12-CF15, which had the best numbers of any filament I've ever tested, but leaving the mag loaded for a week caused the base lips to give, it exploded and spewed 5.7 rounds all over the room.

I use sketchup, I have an old version that's loaded with engineering plugins for things like motion simulation and finding a component's center of gravity. I can even do lens design with ray-tracing.
 
#11 ·
#13 ·
I can see that now that I have a complete USPc45 in front of me. I should be able to compare and modify to make the full size 40 slide fit. I see where the recoil spring guide needs room for the buffer spring's stroke, but I'm not sure what you mean by slide guides. Are you talking about the metal tabs it rides on? What is different about them, their lengthwise position? The height appears to be the same because I can slide the 40 slide onto the 45c frame.
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I got a little sidetracked with the modeling and did some research on magazines. I have a bunch of different types of 9mm mags on hand for my p2000sk, an 8rnd 45 mag with my cousin's loaner gun, and a 10rnd 40 mag I bought with the parts kit. I traded the FiveseveN CAD files for a USPc9 magazine CAD file, and tweaked this model to reflect the measurements taken from the mags I have on hand. From what I can tell they are all very similar even between calibers, with the 45 mags being 2.6mm deeper.
 

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#16 ·
Sure, just do me a favor and don't post this anywhere else, I'm trying to sell it. I've tested about all the filaments I can afford to so I'm starting a patreon to fund further testing. Patreon
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This test is designed to be weak enough to break them by hand so you can get a feel for how strong a filament is, but I use a push/pull force gauge for testing.

Just a reminder with the USP I need full size frame measurements, I have a compact to measure.
 

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#22 ·
I just started working on this project again. So far I've modeled the slide, RSA, barrel, and slide stop pin of a USP full size 40 and a compact 45. I'm working on modeling the 45c frame and internals now.
I got sidetracked from the USP because I got a good deal on some P2k/P30 series parts kits. It took about a year of work and 17 iterations to get a printed frame working on the P2000sk. Turns out the P2k CAD that I thought was mine was some I had bought and it was way off, so I had to start from scratch.
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But I've finally got it working, this version lasted 200rnds on a printed CF nylon ejector. That was just to test the fit of my ejector CAD, I'm getting some laser cut from 316SS from SendCutSend.
This gun is a graduation present for my sister, and a "resume" piece because I'm looking for gunsmith work. Cerakoted the mag catch, trigger, and slide crushed silver, jeweled all other exposed metal surfaces and all the trigger parts, gold filled the deeper engravings, printing the frame in Tiffany blue, and machining the sights from an iron/nickel meteorite, with rubies for sight dots.
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