# Which material for a tennis grommet?

I am noodling around with the idea of creating a model to 3D print a specific set of out-of-production tennis racquet grommets for my tennis racquet. At this point, it’s just a vanity project to kill time, but it’s also really to test the difficulty of mapping the design, as well as the viability of a 3D printed product.

According to this article, https://3dprintingindustry.com/news/3d-printing-personalizing-tennis-37441/, Head used 3D print materials to prototype a new grommet system. I would like to prototype a simple old grommet system, reproduced from measurements I made on a 30+ year old tennis racquet. Anyway, after going to the hub, I was totally blown away by all the choices of materials. One thread from a few weeks ago discussed making string dampeners and the material PLA++ came up. The only labs on 3Dhubs with that material are far from me. I’d like to get suggestions of other materials that might be suited to this application.

The application calls for a smooth, non-abrasive surface with a minimal friction coefficient, some flexibility – for example during installation, enough flex in the strip to get the thing into the racquet – but also be rigid enough not to collapse under 50-60 pounds of string tension. I’m totally guessing, because I only learned what a hardness scale is today, but probably they need to be about a Shore A 85-90. I’d love someone who is familiar with tennis grommets are here to confirm that based on actual materials knowledge…

Also, for each recommended material, if I were to try to eventually purchase a printer myself that could handle that material without persistent issues, what model of printer would be recommended (for a small scale, household type operation)? This will help me decide whether there is any point to doing this long term for other people, since spending  is not in the cards…

Thank you very much for your help!

The main thing the grommet does is hold the string - that’s pretty much it. It has to be low friction / smooth, in order to pass the string through without damaging the string and causing premature breakage, and to pull tension through with minimal loss to allow proper tensioning of the racquet. Any other functional demands, like absorbing vibration, boosting the trampoline effect of strings, or acting like pulleys, is beyond this application, as is anything ridiculously complex like grommet surfaces that mimic shark skin or sand snake scales. Yes, the big companies market that stuff, but I’m looking for a low tech way to make the simplest grommets as a starting point.

Nylon looks promising. Standard injection molded grommets are made from nylon I believe. And when you have to fix a broken grommet that can tear your strings, you can use a nylon tubing. Another material used like that is something called teflon tubing, but I don’t know what it’s made out of… probably nylon with teflon mixed in… ? These suggestions of nylon type materials are very helpful.

I think a softness of 55 is going to be low. There are other things you might be thinking of that have to be that kind of softness, like a shock trap, or power pads. The grommets only need to be flexible enough to curve to the hoop of the racquet. You can get an idea from this video: https://www.youtube.com/watch?v=FlH4dXQEOHQ The strip, not the grommets, do most of the flexing. Although some of the longer grommets at the throat need to bend to follow a curved pattern near the yoke.

I dont think any PLA based material would be good. Forget your racket in the car on a hot day now your part is melted. Check out the nylon variety from http://taulman3d.com/index.html they list the hardness and tension info

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Nylon, polycarbonate, or even one of the PET based materials would probably work.

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Tennis racquet grommets needs to be in Polypropylene (PP). It is also very unlikely that you will be able to print these with a small, household type operational 3D printer. Printing these grommets will be a very precision job. You will need high end printer for it.

I would suggest that you used a flexible filament like ninja flex or similar. Rigid Ink also do a very good flexible PLA that may work, great for prototyping. If you were to go into production I would suggest making a multi-part mould and pouring them with an elastomer material.

Taulman Alloy 910 would be my choice. Shore hardness 85D, low friction (Nylon based), and just enough flexibility to allow it to be fitted into the racket. It can also be colour dyed with Dylon or Rit if you want nice colours.

It does need a much higher temperature to print than most standard desktop printers can safely deliver, but a full metal hotend upgrade would sort that problem.

Will wait for the OP to give comment but it is my understanding that these grommets are to absorb the resonance of the strings after a shot is taken, therefore a very soft material would be best, probably around 55 or below.

What would be the relative advantage of using polycarbonate over nylon?

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Why should it be Polypropylene? I believe nylon is the standard material for commercial grommets.

Have you actually had a successful print of them using PP on 3dHubs?