Epoxy resin in tennis racquets

gbgTennis

New User
Hey guys,

is anyone of you good with epoxy resins?
I've been wondering what kind of resin would be the best fit for a tennis racquet, and what the racquet manufacturers are using. When building Ski I found a specific resin for that, but for tennis there doesn't seem to be any information out there, and I don't really know anything about the characteristics of different resins unfortunately.

Thanks for your input,

greetings
 
Hey guys,

is anyone of you good with epoxy resins?
I've been wondering what kind of resin would be the best fit for a tennis racquet, and what the racquet manufacturers are using. When building Ski I found a specific resin for that, but for tennis there doesn't seem to be any information out there, and I don't really know anything about the characteristics of different resins unfortunately.

Thanks for your input,

greetings
I’m not “good” with resins, but I know a little, specially since I just ordered some carbon fiber and resin to go with it.

So, yes, epoxy is generally regarded as the proper resin for use with Carbon fiber. There may be more advanced/specific resins used in the tennis industry, and I’m sure there are people here in the forum with better information, but here’s a start. I’ll post a couple links.

Are you looking to do repair? Or make your own new racquets?



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And here’s the video I was watching about resins. It’s from a manufacturer/reseller, so it’s really just about their products. But it may help.



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Kevo

Legend
I would imagine anything that would work on skis would be good for tennis. A lot of ski manufacturers have made racquets. Also you got to figure skis are taking similar kinds of stresses as racquets. Impacts and vibrations and all that.
 
I would imagine anything that would work on skis would be good for tennis. A lot of ski manufacturers have made racquets. Also you got to figure skis are taking similar kinds of stresses as racquets. Impacts and vibrations and all that.
Not exactly. Not sure about skis, but snowboards tend to use fiberglass rather than Carbon fiber. Polyester resin (the less expensive smelly stuff) is ok for fiberglass, but not for structural carbon fiber work.

Here’s a quick overview of the types of resin.

http://www.sollercomposites.com/EpoxyResinChoice.html


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Tennis racquet carbon fibre is pre preg, isn’t it?


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Yes, for sure! that’s why in the video the Carbon is sticky, and they have to worry about temperature.

Not sure if the manufacturers have proprietary systems going that we don’t have access to. But I bet they do.

I originally misread the question, didn’t realize it was about manufacturing.

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gbgTennis

New User
Thanks for all the replies sofar.
The carbonfibre larger manufacturers seem to be using is indeed prepregnated, though I'm pretty sure this just for ease of manufacturing. For recreational use it's not practical.
I've been doing some research and talked to some resin manufacturers. I just asked the companies that sell resin for ski, boats and gliders about the properties each resin product would have, and they were able to point me in the right direction. The required properties are very similar to ski however, and I doubt ski and tennis manufacturers use different products at all. For snowboard production, at least at higher quality, they use epoxy, and not polyester resin.

Anyway, I have my resin and fibres now, have the press set up soon, now all I need to build is some sort of mold.
Hopefully I'll have my first racquet before newyear :)

If any of you are interested in the resins I found, feel free the send me a pm. I don't want to advertise any companies on the forum.
 

teachingprotx

Hall of Fame
Thanks for all the replies sofar.
The carbonfibre larger manufacturers seem to be using is indeed prepregnated, though I'm pretty sure this just for ease of manufacturing. For recreational use it's not practical.
I've been doing some research and talked to some resin manufacturers. I just asked the companies that sell resin for ski, boats and gliders about the properties each resin product would have, and they were able to point me in the right direction. The required properties are very similar to ski however, and I doubt ski and tennis manufacturers use different products at all. For snowboard production, at least at higher quality, they use epoxy, and not polyester resin.

Anyway, I have my resin and fibres now, have the press set up soon, now all I need to build is some sort of mold.
Hopefully I'll have my first racquet before newyear :)

If any of you are interested in the resins I found, feel free the send me a pm. I don't want to advertise any companies on the forum.
What type of mold shape are you going with ? Round head , egg head , elongated head and what about the bridge shape round , v shape, inverted bridge shape? I would imagine this would be the most fun part
 
Thanks for all the replies sofar.

Anyway, I have my resin and fibres now, have the press set up soon, now all I need to build is some sort of mold.
Hopefully I'll have my first racquet before newyear :)

If any of you are interested in the resins I found, feel free the send me a pm. I don't want to advertise any companies on the forum.
Ok, but without advertising or naming brands, can you tell us a little about what you’ve learned? Was epoxy recommended? Heat cure or room temperature? Anything? I thought this forum was supposed to be about sharing knowledge.


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gbgTennis

New User
Ok, but without advertising or naming brands, can you tell us a little about what you’ve learned? Was epoxy recommended? Heat cure or room temperature? Anything? I thought this forum was supposed to be about sharing knowledge.


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I just didn't want to name any companies. For most sport equipment, and tennisracquets in particular you want high dynamic stiffness, while static stiffness isn't very important - in comparison to gliders or boats for example. What works for ski should work well for tennis racquets aswell, although for ski too, you need more static stiffness.
Many of the expensive epoxies are so costly because they cure out very clear and transparent, because I don't care for that I could save some money.
Most epoxies can be cured heated, warm or at room temperature, sometimes you need to add a specific hardener for each. Heated curing usually yields the best results and as I've done it before and liked the results, that's what im going to be doing. The epoxy has to be cured at around 80C° for 4 hours, and should be flexible enough when it's done.
There are a couple of different kinds of epoxy resins in general. Products that are good for pouring, laminating, thick layers, etc. And there's resin for pressmolding, so that's what I chose.


What type of mold shape are you going with ? Round head , egg head , elongated head and what about the bridge shape round , v shape, inverted bridge shape? I would imagine this would be the most fun part
I'll probably just copy an old HEAD prestige I've got lying around for the first test. Copying a preexisting model will hopefully make drilling the holes easier. So that would be a rectangular beam and bridge shape
 

teachingprotx

Hall of Fame
I'm under no illusion this forum is about making people buy at Tennis Warehouse, brilliant move.
I know I do! And love these guys ! I bet it’s fun working there too! It would be a dream job if all u had to do was test new rackets strings grips shoes and apparel ! God bless I know that’s only probably like 20% of what anyone there does the other stuff being admin . But still I could not imagine part of my day would be going to the indoor court with a handful of new sticks and trying them out and report back to your supervisor. How awesome ! Anywho back to the point of this thread .
So ..gbg tennis? Are you building a personal stash or a company build ? Or both !:)
 

teachingprotx

Hall of Fame
I just didn't want to name any companies. For most sport equipment, and tennisracquets in particular you want high dynamic stiffness, while static stiffness isn't very important - in comparison to gliders or boats for example. What works for ski should work well for tennis racquets aswell, although for ski too, you need more static stiffness.
Many of the expensive epoxies are so costly because they cure out very clear and transparent, because I don't care for that I could save some money.
Most epoxies can be cured heated, warm or at room temperature, sometimes you need to add a specific hardener for each. Heated curing usually yields the best results and as I've done it before and liked the results, that's what im going to be doing. The epoxy has to be cured at around 80C° for 4 hours, and should be flexible enough when it's done.
There are a couple of different kinds of epoxy resins in general. Products that are good for pouring, laminating, thick layers, etc. And there's resin for pressmolding, so that's what I chose.




I'll probably just copy an old HEAD prestige I've got lying around for the first test. Copying a preexisting model will hopefully make drilling the holes easier. So that would be a rectangular beam and bridge shape
Man I’m excited dude this is one of the coolest post threads I’ve ever read on here’. I’m a layman when it comes to actually building a frame, so for me this is a dream come true. Thank you for sharing as you go thru this build . Super exciting stuff keep us posted and pics man pics!
 
Copying a preexisting model will hopefully make drilling the holes easier. So that would be a rectangular beam and bridge shape
Are you going to make a mold of an existing frame? Or use it as a guide to do a frame in CAD and have it machined?

Would you be using braided sleeve and air pressure to inflate it? Might be interesting to try a braided carbon/Kevlar sleeve like an OG Pro Staff.


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gbgTennis

New User
Man I’m excited dude this is one of the coolest post threads I’ve ever read on here’. I’m a layman when it comes to actually building a frame, so for me this is a dream come true. Thank you for sharing as you go thru this build . Super exciting stuff keep us posted and pics man pics!
I'm happy to hear people are enjoying this as much as I am :) Didn't realize there was demand for this so I haven't really done any documentation sofar, but I'll happily start doing so and share some pictures.


Are you going to make a mold of an existing frame? Or use it as a guide to do a frame in CAD and have it machined?

Would you be using braided sleeve and air pressure to inflate it? Might be interesting to try a braided carbon/Kevlar sleeve like an OG Pro Staff.
My plan is to inflate a tube inside the mould to around 5-10bar, while heating to ~80 C°. In industrial production temperatures and pressure will be higher, but that's typically just done to save time. The epoxy should cure the same way at lower temperature and pressure, just take longer - and time efficiency isn't really something I'm too worried about.
I'm not familiar with the OG Pro Staff and how it's constructed. What do you mean by braided carbon sleeve?


this is awesome, how difficult would it be for others to replicate your process and build their own frames?
I'll soon see how difficult the actual assembly is, but in theory none of this should be terribly difficult to replicate. You'll need decent carbon fibres, some good epoxy resin, an inflatable tube of some sort, a compressor, and a heattreating oven would be good, I don't think it's mandatory though.
The hardest part is probably building the mold. A CNC, or CAD machine would be helpful here, or at least a milling machine, but if you're not trying to build at industry levels of precision, you could probably manage without.



I'll build my mould the coming week, still not 100% sure what I will build it out of though. Aluminium would be ideal, I don't want to spend that much on a proof of concept though, so I will probably just use pressboard for the first one.
I have a CNC-machine so I will use it to mill out the outlines of a racquet that I will just draw by hand on the first try.


The one thing I'm not sure how to do yet is the racquet yolk. As the tube of a racquet is going through just the fram and handle, I don't yet know how to inflate the yolk at the same time as the racquet, and at a similar pressure to avoid deforming.
If any of you have an idea, I'd be glad to hear it. I've been thinking about putting a liquid in there that evaporizes at 80C°, but calculating the amount of pressure that would produce is really hard.
 

teachingprotx

Hall of Fame
Wow man Your really doing this this thing I’m excited and looking forward to more news as you go through the process . Sorry I am a layman on all this so I’m learning from you as you go and thank you for documenting this so we can share
 

teachingprotx

Hall of Fame
I was thinking last night how cool it would be if you could round out the drill holes in a way and at certain angles where you don’t even need ANY GROMMETS AT ALL ! Think of a max 200 g
 

Sanglier

Semi-Pro
The one thing I'm not sure how to do yet is the racquet yolk. As the tube of a racquet is going through just the fram and handle, I don't yet know how to inflate the yolk at the same time as the racquet, and at a similar pressure to avoid deforming.
If any of you have an idea, I'd be glad to hear it. I've been thinking about putting a liquid in there that evaporizes at 80C°, but calculating the amount of pressure that would produce is really hard.
The earliest composite racquet makers confronted the same questions you are asking and tried a lot of different approaches 40-50 years ago. Some of them experimented with yokeless/bridgeless designs, others used solid yokes/bridges that did not require internal inflation, still others molded the piece separately and either riveted or fused it to the rest of the frame after the molding step (like on many metal racquets). In the end, the approach that became most common was to use a preformed foam "dowel" in the shape of the yoke/bridge, around which they would wrap fibers or prepregs that are continuous with those of the adjacent shafts, before putting the whole assembly in the mold. The "dowel" is walled-in during the molding step and becomes the core of the yoke/bridge. This is why many otherwise hollow frames can be found with foam-filled yokes/bridges. As you can probably imagine, there is a lot of stress at these joints due to the abrupt change in flex characteristics, so these areas must be properly reinforced. However, reinforcements can easily alter the flex and balance of the frame, and shift the weak spots to somewhere else. Before there was CAD, there was a lot of guesswork and trial and error before the engineers got these joints right, even then, many of the earliest commercialized frames were known to prematurely fail there. I think this may be the one area that makes a tennis racquet substantially more difficult to engineer than a ski or snowboard. I know of no instance where the designers/engineers got their product right on the first try.

Since you are not a novice in this art and seem to have all the required equipment to do the job properly, you have the freedom to really experiment here, so why restrict yourself to the conventional shape and layout? Whatever comes out in the end is not going to behave like a Prestige anyway, since you are not using the same prepregs and won't be replicating the fiber composition and orientation used by Head. The frame shape on its own really doesn't matter in this context! The rest of your project costs so much more than the grommets that the latter cannot possibly be your primary concern! If you decide to give your frame a foam core, you can chamfer the holes to avoid using grommets altogether (as was done on the original Prince Graphite), or you can go with individual grommets, which were the norm on early composite frames.

Just go wherever your imagination takes you!

As for braiding, it requires a large braiding machine that is probably not in the cards for you unless you intend to turn this from a hobby project into a commercial venture.

Like others here, I'm curious to see your progress and wish you luck. You are about four decades late to the game to be able to come up with some trick that hadn't been tried before, but who would know for sure until it's tried?! At any rate, this is a far more ambitious and interesting project than playing with colors and graphics. Record your progress and post it on Youtube! :)
 

gbgTennis

New User
I've never held a Dunlop max 200g in hand and don't know anything about their drilling. If any of you have any pictures of the racquet in profile, I'd love to take a look at it. Interestingly the max 200g aparently has been produced my injection moulding, instead of compression moulding ( https://www.tennis-warehouse.com/Reviews/MW200G/MW200GReview.html ).
The main reason for me wanting to copy a racquet I own was so i could use it's grommets. Another option would be to use small plastic tubes, or 3d-print some. I also thought about drilling the holes in a way that wooden racquets used to be drilled. But the graphite's edges are probably going to be too sharp for that. But if I'm going to make myself a custom racquet I plan on using, I will definitely try to find a better solution than those pesky grommets.
Still looking for a solution for the racquet bridge.
 

gbgTennis

New User
The earliest composite racquet makers confronted the same questions you are asking and tried a lot of different approaches 40-50 years ago. Some of them experimented with yokeless/bridgeless designs, others used solid yokes/bridges that did not require internal inflation, still others molded the piece separately and either riveted or fused it to the rest of the frame after the molding step (like on many metal racquets). In the end, the approach that became most common was to use a preformed foam "dowel" in the shape of the yoke/bridge, around which they would wrap fibers or prepregs that are continuous with those of the adjacent shafts, before putting the whole assembly in the mold. The "dowel" is walled-in during the molding step and becomes the core of the yoke/bridge. This is why many otherwise hollow frames can be found with foam-filled yokes/bridges. As you can probably imagine, there is a lot of stress at these joints due to the abrupt change in flex characteristics, so these areas must be properly reinforced. However, reinforcements can easily alter the flex and balance of the frame, and shift the weak spots to somewhere else. Before there was CAD, there was a lot of guesswork and trial and error before the engineers got these joints right, even then, many of the earliest commercialized frames were known to prematurely fail there. I think this may be the one area that makes a tennis racquet substantially more difficult to engineer than a ski or snowboard. I know of no instance where the designers/engineers got their product right on the first try.

Since you are not a novice in this art and seem to have all the required equipment to do the job properly, you have the freedom to really experiment here, so why restrict yourself to the conventional shape and layout? Whatever comes out in the end is not going to behave like a Prestige anyway, since you are not using the same prepregs and won't be replicating the fiber composition and orientation used by Head. The frame shape on its own really doesn't matter in this context! The rest of your project costs so much more than the grommets that the latter cannot possibly be your primary concern! If you decide to give your frame a foam core, you can chamfer the holes to avoid using grommets altogether (as was done on the original Prince Graphite), or you can go with individual grommets, which were the norm on early composite frames.

Just go wherever your imagination takes you!

As for braiding, it requires a large braiding machine that is probably not in the cards for you unless you intend to turn this from a hobby project into a commercial venture.

Like others here, I'm curious to see your progress and wish you luck. You are about four decades late to the game to be able to come up with some trick that hadn't been tried before, but who would know for sure until it's tried?! At any rate, this is a far more ambitious and interesting project than playing with colors and graphics. Record your progress and post it on Youtube! :)

Thank you for your kind and extensive reply. The solution you describe is the one I thought best too, will just have to find the suitable materials.
As I alluded to earlier, the main reason I chose to copy a preexisting frame was to have an easier time getting the mold right and having a proof of concept without having to worry about the drilling on the first try. If this turns out well and it's enough fun for me to try again, I will definitely try other things, I've got a few ideas in mind.

The joints between the frame and the bridge are indeed going to be subject to a lot stress, and I will definitely reinforce them with additional fibres. I'm really curious to see if it will hold up :) Pretty sure I will be using much better quality basematerials than retailers, so I hope that will count for something.
 

vsbabolat

G.O.A.T.
I've never held a Dunlop max 200g in hand and don't know anything about their drilling. If any of you have any pictures of the racquet in profile, I'd love to take a look at it. Interestingly the max 200g aparently has been produced my injection moulding, instead of compression moulding ( https://www.tennis-warehouse.com/Reviews/MW200G/MW200GReview.html ).
The main reason for me wanting to copy a racquet I own was so i could use it's grommets. Another option would be to use small plastic tubes, or 3d-print some. I also thought about drilling the holes in a way that wooden racquets used to be drilled. But the graphite's edges are probably going to be too sharp for that. But if I'm going to make myself a custom racquet I plan on using, I will definitely try to find a better solution than those pesky grommets.
Still looking for a solution for the racquet bridge.
There are no holes drilled in an injection molded Max200G.
Here are sections cut from the Max 200G to show the internal pillars that you can only have with a Injection Molded Frame.








A real piece of art how Dunlop manufactured these racquets. Here is a layman's explanation of the Injection Molded Process works. First there is a casting of a low melting point alloy core. The alloy core is then put in the injection molding machine. A Compound of GRAPHITE and NYLON is Melted and then injected around the alloy core. Once the graphite and Nylon is cooled the Alloy core is heated up so it melts and then poured out of the frame. This leaves individual string holes that have pillars inside the frame. There are no holes drilled in these injection molded frames by Dunlop.
 
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I think to start, CNCing MDF OR “pressboard” is a good first step rather than investing in aluminum. I would consider infusing it or painting it with water-thin cyanoacrylate - aka superglue, to give it a durable hard surface.

You can buy braided carbon,carbon/Kevlar, or carbon/fibefglass sleeve in a roll or by the yard/foot/meter. I think we’re thinking of the same thing. What you call tube, I call sleeve.



The Wilson Original Pro Staff 6.0 from the 80’s was renowned for its feel, in large part due to its continuous braided carbon/Kevlar construction. As seen in the video I posted earlier, modern racquets are made with a custom layup of smaller pieces in custom directions, but the methods and materials used in the 80’s were sound.

While it’s smart to try to reuse an existing and available grommet set, I agree that you can try other approaches. Individual grommets made from tubing would be easiest to start. I’ve considered custom 3D printed grommets before, but most printers use a less flexible plastic (PLA), so unless you have a printer that can handle nylon, think about making a grommet in several shorter sections that don’t have to bend so much. I think the upcoming Wilson Clash will be doing a multi-piece grommet.

The yoke is definitely the trickiest part. I think Dunlop (and maybe others) May have used an elastomer core for the yoke of my 200g hotmelt, which would have the secondary effect of dampening shock.

Another 21st century approach may be to 3D print a bridge/yoke. There is a printer that fuses a continuous thread of carbon into the filament, so it actually has performance characteristics




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There are no holes drilled in an injection molded Max200G.

A real piece of art how Dunlop manufactured these racquets.


This IS amazing, I’ve never seen a cutaway of the Max 200G, but may be impractical for a small shop setup.

The downside of that injection approach i believe, is that the carbon was limited to short chopped fibers, so it’s not as strong as longer pieces or continuous braid.



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gbgTennis

New User
I think to start, CNCing MDF OR “pressboard” is a good first step rather than investing in aluminum. I would consider infusing it or painting it with water-thin cyanoacrylate - aka superglue, to give it a durable hard surface.

You can buy braided carbon,carbon/Kevlar, or carbon/fibefglass sleeve in a roll or by the yard/foot/meter. I think we’re thinking of the same thing. What you call tube, I call sleeve.



The Wilson Original Pro Staff 6.0 from the 80’s was renowned for its feel, in large part due to its continuous braided carbon/Kevlar construction. As seen in the video I posted earlier, modern racquets are made with a custom layup of smaller pieces in custom directions, but the methods and materials used in the 80’s were sound.

While it’s smart to try to reuse an existing and available grommet set, I agree that you can try other approaches. Individual grommets made from tubing would be easiest to start. I’ve considered custom 3D printed grommets before, but most printers use a less flexible plastic (PLA), so unless you have a printer that can handle nylon, think about making a grommet in several shorter sections that don’t have to bend so much. I think the upcoming Wilson Clash will be doing a multi-piece grommet.

The yoke is definitely the trickiest part. I think Dunlop (and maybe others) May have used an elastomer core for the yoke of my 200g hotmelt, which would have the secondary effect of dampening shock.

Another 21st century approach may be to 3D print a bridge/yoke. There is a printer that fuses a continuous thread of carbon into the filament, so it actually has performance characteristics




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I don't think the carbonfibre in tubeform is useable here, I don't see how i could stack multiple layers with them. What i meant by the tube was something under the carbonfibre, something that is airtight so I can inflate it when pressmoulding.

Haha, is it called "yoke"? I've been calling it "yolk" all the time :X3: :D
I doubt the 3d-printer I have access to is capable of weaving filaments, and a printer would probably have to be extremely state-of-the-art to print something sturdy enough. Also there would be the problem of connecting it to the frame again.
My approach will be to get a PU-foam and build the bridge around it, the foam should expand when heated and will hopefully put enough internal pressure on it so it won't collapse from the outside. We will see how it works.



About the grommets I've been thinking. I feel like I'm remembering some colourless grommets that were inserted individually in woodracquets. Maybe some of you know what I'm talking about. Otherwise I don't see how I could use another frames grommets for my own racquet design, but maybe I can cut them into individual parts.
 

gbgTennis

New User
There are no holes drilled in an injection molded Max200G.
Here are sections cut from the Max 200G to show the internal pillars that you can only have with a Injection Molded Frame.








A real piece of art how Dunlop manufactured these racquets. Here is a layman's explanation of the Injection Molded Process works. First there is a casting of a low melting point alloy core. The alloy core is then put in the injection molding machine. A Compound of GRAPHITE and NYLON is Melted and then injected around the alloy core. Once the graphite and Nylon is cooled the Alloy core is heated up so it melts and then poured out of the frame. This leaves individual string holes that have pillars inside the frame. There are no holes drilled in these injection molded frames by Dunlop.


Great photos, thank you very much!!
 

Sanglier

Semi-Pro
I don't think the carbonfibre in tubeform is useable here, I don't see how i could stack multiple layers with them. What i meant by the tube was something under the carbonfibre, something that is airtight so I can inflate it when pressmoulding.
Those braided tubes/sleeves are pretty simple to use if they are dimensionally suited for your frame size. It's like putting on multiple sweaters - just slip the first one (the inner-most layer) over a rigid rod, then put on additional fiber tows or more sleeves in accordance with your design and fix them in place relative to one another. Once finished, remove the rod and insert your air bladder, and into the mold the whole thing goes!

Braiding was initially implemented to keep the cuts in the fiber (namely where the string holes are drilled) from developing into cracks. The radially oriented fibers don't provide as much strength to the frame as do unidirectional fibers, nor do they allow the designer to fine-tune the flex of the frame the way a conventionally laid frame does, so the truly successful designs were actually a hybrid of both braided sleeves and uni-directionally-laid fiber tows or prepregs. However, fans of legendary braided racquets like the Wilson Ultra and ProStaff liked the playing characteristics of these frames so much that this type of construction became a marketable feature in its own right.

Making custom braided sleeves requires expensive and complex machinery, a capital investment that is probably out of reach for all but the largest of the manufacturers (the earliest maker of braided racquets was in the nuclear reactor parts business, so they had no problem in the tooling department), but if you can get exactly what you need in terms of performance specs and overall dimension in a ready-made form from a third party supplier, then it's an option you could certainly look into and study further. While braided sleeves are naturally seamless (a very desirable characteristic in composites, as you undoubtedly know already), one thing to be very careful about with this approach is to keep any type of fold or void from forming in between the inner and outer "sweaters" during compression, as they would almost certainly create weak spots in unpredictable places, so whatever sleeves you choose for your project must fit the dimension of your mold very well (it might even be simpler to base your mold dimension on those of the sleeves, should you decide to go in this direction).

Lastly, all of this stuff was patented ages ago, and most of those patents have long since expired. If you don't want to go into this project blind (you seem to be experienced in making composite objects, but not quite familiar with the history of tennis racquet development), you could spend some time going through the old patents and see if you could recycle some of the old ideas, or even improve on them. A lot of the "new" innovations we see today are only new to those who weren't around back then, at least this seems to be the case with all the good ideas. :)
 

Kevo

Legend
You can get Fittex grommets from TW. They are individual grommets designed for use when repairing damaged grommets on frames that no longer have available grommet sets. I think that would be ideal for your use case initially at least.
 
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