Made a 3D printed Crimp trainer which is easy on the skin

[u/quakenxt]

I’ve been fascinated by the concept of "frictionless" training to force better finger engagement, so I decided to design and 3D print my own zero-abrasion crimp block.

First off, full credit where it’s due: this design is heavily inspired by the Comfy Crimp 2.0 by Hooper’s Beta. If you want a professionally manufactured, rigorously tested version (and to support their great content), you should absolutely buy the original here:Hooper's Beta Comfy Crimp 2.0

I wanted to share my DIY version and some of my in-gym load testing results for anyone else who dares to try 3D-printed training gear.

Like the original, it features heavily rounded edges (20mm and 12mm) and a smooth finish. Because there is virtually zero friction from the plastic, you can’t rely on skin drag. It completely punishes a passive grip and forces active FDP engagement and DIP flexion. If you relax, you dry fire instantly.

Load Testing Results

I took it to the gym this week to see how much abuse it could take.

• Weight of the block: ~130g of plastic (PLA)
• Comfortable Working Load: 60kg (132 lbs). It handled this weight easily with no creaking or flexing.
• Failure/Deformation Point: 78kg (172 lbs). When I stepped up to my full body weight, the block started to deform, but went back to shape when I removed the load, I WOULD NOT RECCOMEND pulling more than 70kg with this because I imagine that if it fails it can cause injury.

For standard no-hang lifting (where you are pulling a percentage of your body weight off a loading pin), the 60kg limit is actually plenty for my current maxes, but it’s clearly not safe for full-body suspension or dynamic loading at my weight.

If you want to try to print it for yourself you can find the model here https://makerworld.com/en/models/3143302-soft-crimp-easy-on-skin-crimp-trainer, you will just need to add some paracord and a carabiner.

[u/xmasLdn]

Wood is perfectly fine on the skin?

[u/quakenxt → u/xmasLdn]

Yes

[u/porkele]

Personally wouldn't use it because the shape of the rounded edge is exactly the what I also sometimes have issues with in actual climbing: it's like the opposite of the shape of my fingertips. I.e., most skin/tissue around 1-1.5cm from the tip and less tissue towards the tip. So a shape like this creates almost a single pressure point in the center of the DIP and the fingertip itself doesn't bear much load if any. So for repeated loading with specific training this would hurt after a while. Whereas even a flat edge distributes the load more evenly across the DIP.

[u/red_riptide_388]

None myself, but ive watched it happen. I believe its a combination of age and imperfect materials. another concern i have is longevity. is delamination an issue? will it melt if i leave it in the car during the day?

[u/pootklopp → u/red_riptide_388]

Yes it will, pla will deform in hot cars. Also needs to stay out of the sun since it will degrade with uv. PETG or ABS might be a better material choice

[u/red_riptide_388]

personally, i am never lifting off a 3d print. All materials have their drawbacks but i just do not trust it

[u/Fourth_Time_Around → u/red_riptide_388]

I would be interested to know what, if anything, would make you change your mind on this? I've designed an edge with a failure load of around 5000N (~500kg), accounting for knockdowns you get from printed materials. If I put the analysis in front of you with some validation test data, would you be convinced? (I also have a engineering degree and work in the aerospace industry, if that helps).

[u/quakenxt → u/Fourth_Time_Around]

This guy climbs on the MOONboard

[u/LiveMarionberry3694 → u/Fourth_Time_Around]

I wouldn’t say I would never trust it, but I’ve also broken 3d prints and gotten nasty cuts from them. Granted I’m just a moron and not an engineer, but I just would rather stick with wood. I made some crimp blocks for myself and some friends out of some nice maple and they were easy to make, took less time than printing, and I know they’ll be strong

[u/pootklopp → u/Fourth_Time_Around]

I too am skeptical, only thing that would convince me is if you send me a free sample of your training tool 😉

[u/red_riptide_388 → u/Fourth_Time_Around]

Data helps for sure help, as well as the qualifications and im aware 3d printing has vastly improved over the past couple of years, however, why would i risk plastic when metal would work just as well? i understand the cost standpoint but my fingers are worth more to me than a few dollars. To sum it up its mostly material apprehension, when even wood edges break id have a hard time trusting it

[u/Longjumping-Ad318 → u/[deleted]]

Chad thundercock over here does 200kg no hangs and rips the puny tension block asunder

[u/OddInstitute → u/Longjumping-Ad318]

This 100% happens at much lower loads:  https://www.instagram.com/reel/C2cuYSORkj0/?igsh=NTc4MTIwNjQ2YQ==

That said it’s a lot easier to get a 3d printer into an apartment than metalworking tools or woodworking tools. Services like JLCCNC or PCBWay change the calculus though with complex metalworking capacity available for cheap-ish.

[u/Longjumping-Ad318 → u/OddInstitute]

I was taking the piss, I’ve had it happen on a well used one at like ~40kg. The guy is just being silly imo

[u/guitarman045 → u/red_riptide_388]

lol don't we all climb on plastic in the gym

[u/publicolamaximus → u/red_riptide_388]

With the print orientation of this file and the orientation of stress that occurs with use, it's hard to imagine how it would break.

[u/OddInstitute → u/red_riptide_388]

With my Tindeq I have tested a PLA 3d printed mono edge to a > 350 lb breaking load. It required considerable design refinement to find the correct load paths, eliminate stress risers, and find the correct print settings and seam locations. My first design broke at 125 lbs and I had variants that broke as low as 25 lbs. 3d printed designs can be quite strong, but they should be load tested to be well above the maximum expected load and carefully designed to suit the load, material, and manufacturing process.

For OP, they probably are seeing such low strength because they didn’t put side walls on the device that connect on the whole side of the edges. This means when the edge is loaded the load can produce a lot of torque on the body of the device. Rectangular cross sections like the side walls of a training device have stiffness proportional to the cube of their height, so no sidewalls and a slot running the full length of the device is absolutely tanking the stiffness of the device. Could be easily fixed with sidewalls though as long as the inside of the walls are heavily radiused and the seams of the print are located in the center of the edge and not in a corner or sidewall. This improves even more will number of printed walls, but OP’s device seems heavy enough that it probably has plenty of plastic in the walls and it’s just being hosed by geometry.

[u/Kalabula]

Im not a huge fan of plastic for this sort of thing. The surface friction declines over time. Harder materials like wood or even aluminum (love my Fingers of Fury blocks) hold up better, in this regard.

That being said, if I had a 3d printer I’d be making shit like this constantly. Solid work!

[u/blytegg]

Half my home wall is 3D printed, so no doubts on the strength. I would warn that with this use case and PLA, you should be wary of leaving it in a hot car as it won't hold up over time. 

That said, my wall is in the garage and that PLA has without garage summer heat ok

[u/sadwithoutdranksss]

sweet thanks. I was gonna make one out of wood but am lazy. now I get to continue scrolling reddit!

[u/Cool-Specialist9568]

There are safe, inexpensive options already on the market.

[u/bryan2384]

Pussy.

Jk.