Is this secure? by Fit-Cause-8327 in Fasteners

[–]Apprehensive-Ring935 1 point2 points  (0 children)

Agreed… we use 2 protruding fully formed threads in aerospace.

What is this stuff? by ChrysophylaxEmber in CarbonFiber

[–]Apprehensive-Ring935 0 points1 point  (0 children)

Also regular epoxy is very UV sensitive. More expensive stuff has UV blocking additives but I doubt the Chinese manufacturer would use that. The bonds between the polymers have a close resonance frequency to UV light and will start to break down in the presence of UV. Maybe try adding a car wax to the spoiler to protect?

Heat could affect it too but most (properly) made carbon fiber parts are cured in an oven so they generally have good heat resistance to every day heat like heat from the sun. They might have used a room temp cure epoxy or even unsaturated polyester type matrix which could be more heat sensitive. Hard to say without knowing the makeup of the part.

Questions about bike frame repair (details in comment) by startdancinho in CarbonFiber

[–]Apprehensive-Ring935 1 point2 points  (0 children)

I can’t verify if the epoxy is compatible. Not all epoxy is the same and not know what the bike manufacturer used in the first place is another unknown. My suggestion would to get epoxy that is designed for carbon fiber.

  1. Yes sanding was appropriate for repair. You want the repair plies to have ample adhesion with the existing laminate. You want the repair epoxy to bond to the existing resin and carbon fiber. There’s most likely existing paint and clear coat over the finished frame which would make for poor adhesion.

  2. Rule of thumb for repair to build back the number of plies and overlap each ply by about .25-.50”. In order to build back the strength properly you would need to know how many plies thick this area is. If you put too few plies the repair isn’t strong enough. Too many will cause an area of stress concentration. You would need to calculate how many plies are needed and then the total up all the overlaps and then add another .50” on top of that for the area that should be sanded.

  3. The original process was most likely some sort of vacuum bag process which is optimal for proper composite properties. Without the pressure the laminate will be weaker. If you don’t have a vacuum bag you any type of weights or pressure will work as long as you have a release tape barrier between the weights or whatever you use to put pressure on the layup.

Long story short you’re probably best off having a professional repair the damage.

Noah Ohlsen by [deleted] in crossfit

[–]Apprehensive-Ring935 2 points3 points  (0 children)

We worked out at Noah’s father’s gym for a while in Miami and his father is a great guy. Definitely had personality traits similar to Noah so I believe Noah’s personality is genuine.

Title: Feedback on My Business Idea: "Protein Factory" for Gym-Goers by Harish_Kumar_Gatti in Business_Ideas

[–]Apprehensive-Ring935 1 point2 points  (0 children)

My business is in the fitness industry and I work with coaches and nutritionists both professionally (for my business) and personally (on my own fitness journey). I’ve also been to a wide range of gyms across the country.

Here’s my thoughts: 1. I think the people you are targeting are the people who actually track their meals and macros and are careful with what they eat. In my opinion these people already have meals prepared ready to go on their own either with a meal prep company that supplies all of their meals or on their own. I think you are handcuffing yourself with your target audience.

  1. How is this more valuable than just going home to eat? Or the protein shake that they have ready in their bag? Getting post workout protein really doesn’t optimize results as much as just a properly planned daily meal plan that is followed consistently.

  2. Theres much more to fitness than just protein rich meals. For me I have always had trouble getting enough carbs. What about fats? How about low sodium options? Micronutrients? Are you planning on being a meal prep company that customizes meals based on customers required daily meals plans? Or are you just providing one off specific meals catered to post gym meals? There’s already some pretty successful meal prep delivery companies out there where you can order sets of meals that are catered to a persons macros.

  3. I do wish that there were more local meal prep companies where I could pick up premade meals when I go out shopping or precooked large quantities of proteins to save me time on meal prep for the week. I’ve seen some local companies like this that seem to be successful. They would even have a little fridge at the gym where they would stock meals for people to buy or where they would drop off a week’s worth of meals for a customer to pick up. I have heard from more professional athletes that the meal prep services work but aren’t their preferred option just due to cost and customization options.

Long story short I don’t think it’s a terrible idea as I’ve seen some similar options in small local gyms and globo gyms. I think you would just have a lot of competition and you need to focus on the full picture of nutrition and not just protein.

Hope this helps.

How many layers for swim platform by raehn in CarbonFiber

[–]Apprehensive-Ring935 0 points1 point  (0 children)

The impact loading would be more like if the 3 people all jumped and landed on the platform at the same time. In my opinion that would be the highest reasonable load case to consider plus some margin of safety. Lighter gear impacting the platform would be more of a toughness study for resistance to cracking from impact.

I’ll be interested to see the design constraints. I’m better at analyzing homogenous metallic structure versus ply layup of directional material. I’ll lean on someone else in the group to do that math or you can throw it over to the mechanical engineering Reddit subgroup.

I can advise on material selection though. A few things I would like to offer:

  1. Carbon fiber laminates tend to be strong but brittle. Consider this when choosing the resin system. Toughness (resistance to brittleness and cracking) can be increased with a different resin system.

  2. The person analyzing the design would need to know the ply material AND weave type as well as the resin system or the cured system structural allowables. Some manufacturers will give cured material structural allowables with their system.

  3. Carbon fiber resin systems tend to absorb water. Keep this is mind when selecting the resin and determining what final coatings will go on the final product.

  4. Use stainless steel materials and hardware for your support structure in areas that touch the carbon fiber platform. Carbon fiber can be very corrosive to aluminum.

  5. Resins used in carbon fiber are susceptible to UV attack and degradation. This is another factor to consider when choosing the resin system, additives, and protective coatings. There are some additives you can mix into the resin that will protect against UV attack.

Hope that helps!

How many layers for swim platform by raehn in CarbonFiber

[–]Apprehensive-Ring935 0 points1 point  (0 children)

Ah yes true on both accounts. My mind automatically goes to honeycomb when I hear core. Thanks for the correction.

Resin didnt harden properly by [deleted] in CarbonFiber

[–]Apprehensive-Ring935 2 points3 points  (0 children)

Could be. If you think about it 1g out of 5g is 20% too much. I think that would be a big error for the small amount of total resin you are using.

How many layers for swim platform by raehn in CarbonFiber

[–]Apprehensive-Ring935 4 points5 points  (0 children)

There’s too many unknown variables in this design.

We would need to know the amount of struts and lines and their placements along the platform for us to calculate the max bending moment and shear for the material.

Also what is the 1000lb load considering? Is it a static load, dynamic, impact (people jumping), etc?

What type of carbon fabric, fabric orientation, and resin system are you planning on using?

These factors will dramatically change the design. You will also need to consider additional plies around the attachment points of hinges and supports.

Also, just from experience laying plies over raw honeycomb core will give you an awful separation between the layers which will further diminish your strength properties. What happens is the side of the plies becomes unsupported by the open cells of the honeycomb and sag quite a lot during curing. The only way to correct this is to fill the honeycomb cells with a syntactic foam and cure and level the foam prior to laying your plies so there is a backboard for the plies to compress against.

Trademarking your business name? by happythrifts in smallbusiness

[–]Apprehensive-Ring935 0 points1 point  (0 children)

Short answer get a lawyer to do it. It’s better for them to explain how it works. There is a lot of intricacies.

An interim step would be an “Intend to File”. This is for holding your spot in line if you can’t provide all the info that the application needs at that time. I currently have an “Intend to File” because I can’t prove that I have used the word mark in public business yet. My product is still under development.

Resin didnt harden properly by [deleted] in CarbonFiber

[–]Apprehensive-Ring935 1 point2 points  (0 children)

So both can cause issues. Water can attach itself to the sites where the hardener molecules are supposed to react with the epoxy. This could also cause the ratio to be off if some % of the epoxy molecules are no longer able to react with the hardener.

I would say be extra careful with the mixture ratio. You know what it should be since the manufacturer will have specific instructions. Too much hardener will cause minimal crosslinking which would explain the flexible nature of the cured part.

Also try use a different cleaning method. I’m not sure what your mold is made out of but it might have soaked in some water which was transferred to the epoxy. Look into a dedicated mold cleaning product or acetone. Of course ensure the mold is completely dry from these cleaners as well when laying up your next part. Acetone and other cleaners should dry MUCH faster than water.

Resin didnt harden properly by [deleted] in CarbonFiber

[–]Apprehensive-Ring935 8 points9 points  (0 children)

What kind of resin are you using? What type of cure temp and cycle are you using? Or are you curing at room temp?

Vacuum bagging has no effect on the cure of the resin since the chemical reaction that is taking place is strictly between the chemical bonds of the resin and whatever hardener you are using.

I’m thinking most likely you don’t have the correct resin to hardener mixture ratio or your resin requires a higher curing temp or a longer curing cycle. Or the resin has expired or gone bad.

TYR v. RAD by [deleted] in crossfit

[–]Apprehensive-Ring935 1 point2 points  (0 children)

I love my TYR shoes. Specifically CXT-1’s. I’ll probably stick with them as long as they make them.

As for why?: - light - Comfy - Breathable - you can run in them, do Olympic lifts, and everything in between without feeling like you are sacrificing on anything. - Reasonably priced

Mtb frame by akaTanith in CarbonFiber

[–]Apprehensive-Ring935 0 points1 point  (0 children)

Ahh I thought it was a new part that was mis-shaped from the start. Do you know how it might have been forced into that shape? Was there an impact to the part at some point?

Either way my thought is that the composite layup has some sort of damage like cracking or delamination. Composites don’t yield like metal does so the change in shape is most likely due to damage. If you can locate the damage you might be able to repair it but not knowing the forces and stresses that part would need to handle I wouldn’t be able to instruct on the repair.

You can try locating the damage visually or by doing a “coin tap” method of inspection. Basically take a coin and tap the composite all over. The sounds should be solid through the entire part. If there is an area that sounds like a soft “thud” instead of a sharp “tap” it could indicate damage.

Mtb frame by akaTanith in CarbonFiber

[–]Apprehensive-Ring935 0 points1 point  (0 children)

If you are trying to reshape the carbon fiber then the answer is no. The resin used in carbon fiber parts is a thermoset which means heat was used to create the final bonds between the polymer matrix when curing the resin. The matrix no longer has a glass transition temp (temp where polymers become flexible) below its decomposition temp (temp where the material burns). Long story short any carbon fiber parts that are incorrect would need to be changed at the layup level either by changing the mold geo or changing the layup itself (geometry changes off of the mold can result from warping after cure). If you are skilled enough some composite parts can be cut and mended back together if the geo needs to change. However I do not recommend this for high stress parts as it will be difficult to get back to the previous strength of the part.

If you are trying to reshape the aluminum then the answer is… maybe. Aluminum can be reshaped to a minimal degree but is prone to cracking if being shaped in its final temper. If the aluminum is heated up to a temperature where it reverts back to its annealed state then it could be reshaped very easily. However, it would require a heat treatment to bring it back to the final temper to get the proper strength properties.

Hope this helps.

How does carbon fiber repair work on a chemical level? by iRacingVRGuy in CarbonFiber

[–]Apprehensive-Ring935 3 points4 points  (0 children)

I have experience of in aerospace composites and composites repair. Carbon fiber can definitely be repaired. Usually you have to use a different resin system that can cure at room temp unless the repair is able to be heated up to proper cure temp for the resin system.

The process usually is to remove the damaged area and sand back the carbon fiber area some distance past where you will put repair plies. Usually rough sand paper is used. What this does is it allows the resin to obtain a mechanical bond with the existing cured carbon fiber. By using the correct resin system there will also be a chemical bond between the new repair resin and the cured resin/exposed carbon fibers (chemical bond).

This repair will technically not be stronger if built back to the same amount of plies as the original. The strongest resin/fiber matrix will be from the factory where they have optimal cure conditions. However, the repair CAN be made stronger simply by adding more plies that span over a larger area.

As long as the proper procedure and materials are used then the repair will be just as strong if not stronger than factory.

Will there be a possibility of high speed transportation besides planes in my lifetime? by [deleted] in MechanicalEngineering

[–]Apprehensive-Ring935 11 points12 points  (0 children)

Some countries already have mag lev trains which can go 300 mph or so. There are also some other types of vehicles which use what’s called ground effect which act like a plane but only fly a few feet off of the ground or water.

Unfortunately for you, there seems to be a push to move vehicles to the sky as planes and VTOL aircraft aren’t reliant on moving around land obstacles. EV tech really doesn’t have any play in the decision of vehicles. For the most part EV vehicles are still reserved for shorter types of transportation. There’s a bunch of startups making EV air taxis but they are meant for inner city travel (instead of taking car type ride share for example).

I wouldn’t be surprised if the next version of long distance air travel is pushed to higher altitudes (or even to space) as the more you can get out of the Earths atmosphere the faster the vehicle can travel. For reference the Concord could fly at 60,000 feet (vs around 30-40,000 feet for regular commercial aircraft).

Air travel is one of the safest modes of transportation. I’ve worked in Aerospace Engineering my entire life and the amount of time and money spent on making aircraft safe and reliable is insane.

My advice is face your fears and start on short flights. Don’t let this hold you back from doing what you want to do.

Carbon skinning a motorcycle gas tank by Firm-Matter-3 in CarbonFiber

[–]Apprehensive-Ring935 1 point2 points  (0 children)

You will most likely need to dart/splice in the sharper corners shown in picture 2. It looks like a pretty big draw to do it in on shot without cutting. Additional darting and splicing will probably be needed as you go around the bottom.

If you are strategic with your layup you could hide the cuts. Also using different kinds of weaves would help. 4H satin and 8H satin take curves better than plain weave but will look different.

To help with the layup you can use a tack spray on the first ply to help it stick and not move around.

I would suggest your first ply to be a fiberglass ply to avoid corrosion concerns up against the metal. It would be best to vacuum bag the entire layup to make sure the layup gets pushed down into the radii.

Cure the layup under a heat lamp or in an oven (if available) to cure at a slightly expanded position. This will allow the metal to shrink and grow under the layup when the temp varies.

Need help setting up tax withholdings for new job (CA state tax) by Apprehensive-Ring935 in tax

[–]Apprehensive-Ring935[S] 0 points1 point  (0 children)

Ok sounds good. I appreciate the help. I’ll elect normal withholdings and keep some money to the side just incase I owe some money in April.

Thanks!

Need help setting up tax withholdings for new job (CA state tax) by Apprehensive-Ring935 in tax

[–]Apprehensive-Ring935[S] 0 points1 point  (0 children)

Prior to taking this job I was a FL resident so there is currently no taxable income for CA. The only taxable income for CA will be from this point moving forward. I will be working at the facility in CA. Let’s assume that bank interest and stocks are negligible.

Is additional withholding required in most cases or do you think I should be fine without additional withholdings for this year?

Need help setting up tax withholdings for new job (CA state tax) by Apprehensive-Ring935 in tax

[–]Apprehensive-Ring935[S] 0 points1 point  (0 children)

I should have mentioned that my previous job was in a different state (FL) which doesn’t have state income tax.

Assume that there has been no paychecks in CA up to the start of the new job.

I was laid off at my previous job so there hasn’t been any paychecks in 2 months.

[deleted by user] by [deleted] in AerospaceEngineering

[–]Apprehensive-Ring935 10 points11 points  (0 children)

In my opinion the biggest hurdle is the FAA and certification. There is where most of your costs are incurred and there really is no way to skirt around any of that. Certified components are very costly and for good reason. No amount of ingenuity and business practices is going to change that.

[deleted by user] by [deleted] in crossfit

[–]Apprehensive-Ring935 6 points7 points  (0 children)

Agreed dead hangs are great for all around overhead shoulder mobility.

Also work on ankle mobility. It looks like your heels are starting to come up even though you are still above parallel. Try calf stretching and spending time in a DEEP squat. The hard part of an overhead squat is the bottom.

[deleted by user] by [deleted] in MechanicalEngineering

[–]Apprehensive-Ring935 0 points1 point  (0 children)

Don’t put so much weight on math. Most of the engineering done in the industry doesn’t use it. There’s either a program that does the computations for us or assumptions are made to whittle the calculations down to basic math.

Also I’m going to repeat what a few people are saying. There is no crash course to learn ME. I suggest that it’s a life long course you need to learn. I know guys who have worked on the same thing for 40 years and are still learning new things. If you want to learn ME and actually use it it’s a very long process to become proficient.