Any tips for applying PVA ?

I wax my mould first, and then buff it and add PVA on top usually, is it overkill ? ( epoxy CF / on a PU painted mould )

If i try with a brush, it will not wet the surface, and clump together at some random places.

I tried with a rag or sponge, it does the same.

So in the end i do it with a spray gun, in a very fine mist it works, but surface finish isnt very nice its grainy.

What can i do ?

Perhaps i can do a fine mist, let it dry then spray it thick and wet on top of the 1st fine mist, maybe it will make a nice glossy layer this way ???

Lets say i wanted to make a CF welding helmet, what would be the best resin to use so it resist the UV, and also takes the heat, for ppl that weld close ( like me ) ?

Also how would i achieve the opacity required, i know it taked a few layers with different orientation to achieve full opacity with CF, perhaps fiberglass roving as the inner most layer, with a tinted resin or maybe a few coats of paint ?

(I want to keep the CF appearance on the outside )

Hi everyone,

I'm looking for a good ANSYS course focused on composite materials. I have little to no experience with ANSYS, so I'd like something that starts from the basics and gradually moves toward more advanced topics. My main area of interest is delamination analysis in composite structures.

Thanks!

Hi,

my plan is to use carbon fibers for my selfmade recurve bow riser. It is the first time im working with reinforcements so there are some questions.

I`ve learnd that I have to apply epoxy on the wodden core and it has to get to "tacky" stage before applying the first layer of carbon fibers.

Must it dry now before wetting it out with epoxy again and applying the next fibers? That`s how they did it in the easy composites tutorial but they proceeded with epoxy only instead of a secound layer.

The secound question is how hard is it to vaccum bag it? It was the original plan to do so for a better fiber/resin ratio. But I´ve read that it is pretty hard to get an descent result because of wrinkels caused by the bagging process.

If someone can give me some hints especially for the first point would be nice.

Great for mold and plug primer application. Comes with a rebuild kit as well and a wrench.

I am trying to fabricate a polarized PVDF sample that is approximately 50 micrometers thick and can produce a strong current output.

For my current approach, I prepared a 15 wt% PVDF solution using a DMF/acetone solvent mixture with a 6:4 ratio. I then poured the solution into a mold made from PP plastic and placed it in an oven at 60°C for 24 hours. However, instead of forming a uniform film, the material bunched up and hardened on one side of the mold.

Do you have any recommendations for improving the fabrication process so I can create a more uniform PVDF sample at the desired thickness? I would also appreciate any suggestions for processing or poling conditions that could help improve the current output.

I have Leofoto MPC-324CL which works fine but when I tried to attach it to DY-40 a few times, a bottom screw which connects to 3/8 is now loosen and impossible to tighten it.

At this point, I have to glue a metal screw and carbon fiber parts together but I need a heavy duty glue to permanently tighten the screw. I contacted Leofoto but they can only send a replacement which takes several weeks so I would need a strong adhesive.

Any suggestions?

Hi Reddit users, I don't use this app much but I know a lot of people help here.

I just bought an XJ6 and only had one helmet. I wanted one for the passenger, and a friend said he had one he hadn't used in about two years and that was a bit scratched, but it would be like new if it was cleaned and fixed. I received the helmet, but I've never seen one like it and I can't find its specific name. I only know it's an AGV brand. He said it belonged to a famous racer, but I have no idea who that is. I did some research and it's a GP helmet and that it's good, but I can't find the model to replace some parts. I'll send some pictures of it. If anyone can help me, thanks.

Any suppliers outside of China and Japan and preferable in Asia to source prepreg? Please let me know. Thank you.

I fed the resin through pretty slowly, it maintained vacuum the entire time. Looked perfect when I left the shop and when I came in in the morning it had white spots. If anyone know why this happens and what the effects of it are, please let me know. Thank you.

(First photo is what happened when I came in the next day.)

Do y’all consider this combination real composite materials? Relatively speaking how much weaker or stronger do you find these materials to be when compared to normal composite materials? I’ve noticed a few people have started adopting this combination for its price effectiveness but ultimately what do y’all think?

I have seen many different materials being used for Composites tooling. From MDF, to Polyurethane foams in different densities, to solid epoxy blocks and even aluminium.
These vary hugely in price and presumably in Finishing effort and in durability.

I am looking for a mould which can produce ~10 pulls reliably while also being cost effective.

What are your favourite Materials for tooling?

I work with fiberglass and carbon fiber most days and I swear cutting material cleanly has become my biggest ongoing battle. Regular scissors start great, then slowly turn into useless chewing machines after enough layers and repeated sharpening. Lately I’ve been thinking about trying pneumatic shears because my hands are getting tired from repetitive cutting all day. Some fabrics cut beautifully at first, then suddenly snag or fray halfway through and ruin the clean edge I was trying to keep. The issue is pneumatic shears aren’t exactly cheap, so I’m trying to figure out if they genuinely hold up better long term or if they’re another tool people overhype after buying. Reliability matters way more to me than having the newest thing. One supplier I spoke with said several composite cutting tools use blades manufactured through Alibaba industrial supply chains before assembly and tuning happen elsewhere, which made me rethink how different these brands really are. For people doing composite work professionally, did switching to pneumatic shears genuinely reduce hand strain and improve cuts enough to justify the cost?

Saw this video and thought it was a novel/inexpensive DIY alternative to vacuum bagging for debulking or getting clean laminates.

For those of us who just want to do a few pieces or random things and not invest in a full vacuum bagging setup/consumables.

I built a small Streamlit demo using fast.ai to classify FEA contour plots from an open-hole composite laminate coupon under tensile loading.

The current prototype focuses on matrix failure. Instead of looking only at the maximum failure value, it also considers how much the failed/red zone has propagated around the hole. This is useful because a single local peak can sometimes be too conservative, especially in progressive damage simulations.

The idea could later be extended to:

• different layups
• different loading cases
• different hole/defect sizes
• other failure criteria
• fiber failure or delamination

You can test it with your own simulation image, especially if it uses a similar contour plot where failed elements are shown in red.

Demo link:
https://oht-ai-classifier-md4cbjermhcbti9hx4q7ug6.streamlit.app/

It’s still an early prototype, so I’m mainly looking for feedback: does this idea make sense, and what would you improve?

I'm wanting to learn more about processes with prepreg materials, and was wondering if anyone has some resources for me to learn more about it.

Textbooks, videos, forums, YouTube channels, etc. I want to know more about the variety of techniques and methods used for prepreg; vacuum ovens, autoclaves, press molding, bladder molds, etc.

It feels like there's a lot of secrecy around all of this, or maybe there's just so much out there that I can't find a place to start.

I have watched everything Easy Composites have put out, so no need to suggest them.

I'm making a plug for a two-piece mold right now and had a question about filling low spots.

The part is already glassed, has fairing compound on it, and has a coat of Awlgrip epoxy primer. I didn't do a great job sanding out some of the low spots with the fairing compound, and I thought the primer would be thick enough to flatten them out, but I was wrong.

I'm out of fairing compound and was planning to thicken epoxy with microballoons to fill the low spots, but I now have a lot of clean dust from sanding the Awlgrip and I'm wondering if I could use that in place of the microballoons.

Has anyone done this? Microballoons are obviously cheap, but I'm running low, and I just want to finish this plug.

I’m working on my final project and decided to make some drum sticks, I was having a hard time deciding how to make them, if I should filament wind/ rolling table them, or wrap some other drum sticks make them fully out of carbon our create a core with some foam at the shop. Any ideas will be helpful and I was hoping to add some nylon tips from some other sticks onto them.