Obama, CIA, NSA, beaches, bitches… You’ve got a lot going on in your little corner of the world, don’t you?
As for your part dilemma, as Herman said, stiffness is more a function of the geometry and thickness than it is of the material modulus. Saertex provided me with a simple graphic that explains it quite well. I’ve attached it for you to look at.
I would suggest using some form of a rib through the center between your window cutouts. Maybe a structural foam hat section. It would increase stiffness without much of a weight penalty.
About your plans to turn the mold 5 times in an 8 hour shift along with a class A finish, good luck. It’s been my experience that speedy turns aren’t very conducive to high finish quality. It is hard enough getting class A out of an RTM part to begin with much less one with high cycle rates. Better to have more molds if finish is high on the list of priorities.
Herman also touched on a method for building up the part to create a surface for the counter mold. I agree with him. In fact, I’d go even further and say it is a better method than calibrated wax if you want a nice surface on the counter mold.
Ok this is good material below and above. I am looking at it now. That is good news about avoiding the Freeman wax.
Ok can sacrifice class A finish. I am also confused about gelcoat curing time.
There is good video on youtube of what I guess is a VARTM/LRTM mould. I love their system if I could pop them out like that -
https://www.youtube.com/watch?v=MWUxhC6-q0c
“This video shows a simple closed mould vacuum process, this technique is more beneficial to the GRP moulder if runs from 100+ are needed, expected life of tooling 3,000 - 5,000 lifts.
During an eight hour cycle 7 parts can be produced, depending upon complexity of moulding.”
Ok first thing I need to do is produce a new plug from the current mould.
Last time I laid up CSM450 directly over the gelcoat. Was 10 layers of CSM450 and then I used MDF strips for ribs, pasted down with bondo made from same resin mixed heavily with calcium carbonate filler pasted down with tonnes of it, then two more layers of CSM450. Well there is a little print-through (telegraphing)of these ribs on one flange corner and some other evidence of it. https://www.youtube.com/watch?v=kn7pg8icfSo
You can see the ribs there before I moulded the steel cradle structure to fit over the ribs as closely as possible and then siliconed the steel cradle to the mould and secured it with a dozen straps of fibreglass.
So, it is still good enough quality to make the counter-mould and for first production cycles to make product but I am concerned that telegraphing may continue and so will build a new plug (old one is buggered) and keep that as a back-up in case I have to build a new female for the RTM mould if the telegraphing worsens. I dont know how to install the cores while ensuring they wont telegraph later? Should I apply a heavier woven mat first after the 10 layers of 450CSM? Also the risk of apply 450CSM straight over the gelcoat have seen some telegraphing of the fibres in the lay-up products I have pulled from it.
One method I saw is to paint a 1mm of Vinyl-Ester barrier coat over the gelcoat? I am using polyester tooling gelcoat and resins.
Ok that is a good graph. If Class A finish costs that much in production time then forget it. I can accept lower finish.
Alright so stiffness is one important quality which I am concerned about.
But i was hoping just for anyone with experience to make a guess at what Build layers I would use for that poptop if Vaccuum bagging and/or LRTM. Just some example Buids would help. At the moment because I have done a few hand-layups I just used 450CSM with 4-5 layers. Indeed is a big different in stiffness I noticed with added layers.
That graph is quite misleading in tht the %-increase in stiffness gets less each 3mm thicker.
For example would be more interesting to look at the increase in stiffness every time you double thickness does the stiffness double? Would be a log scale showing straight line right?
And where the thickness is held the same and the modulus increase, well the graph is simply rising with modulus, by definition modulus IS stiffness. Its like saying, “What happens to stiffness if I increase stiffness?”
What that graph did if anything was reveal to me that MODULUS=STIFFNESS just like kilograms=pounds=weight.
Yes I do have some cores to put into the roof but the original didnt have any cores, just some steel plates inserted where hinges and load-bearing fixtures needed mounting points. Also the positions of the cores I need installed for functional reasons (water-piping, roof rack supports) are in locations where the inherant shape of the roof already has its greatest structural rigidity in those locations. Their added benefit to the roofs already existing rigidity will not be increase as it would had they been installed in weaker areas.
For this reason I want be comfortable with the Build layers chosen based on their rigidity alone without cores.
I have no idea how to utilise available materials that can be utilised when doing infusion, such as Rovicore. For all I know one grade of Rovicore is popular because it is a ready-mat to pad into the mould before closing the lid but it is equivalent functionally to have hand laid-up 5 layers of 450CSM. As far as I know trying to infuse 5x450CSM layers is difficult due to the lack of design with resin-channeling that is incorporated into the design of Rovicore…
I don’t think you quite understand what the graph and table are showing. The graph shows a plot of the table so you are right, the increase in stiffness of 3mm steps decreases as a percentage of overall stiffness, just as the 3mm increase in thickness decreases as a percentage of overall thickness. The graph and table are correct.
If you double thickness, the stiffness increases by about 8 (as can be seen in the table). Pick a thickness on the table and then look at it’s double. The stiffness will increase about 8 times. For instance, 3mm has a stiffness value of 11250. 6mm has a value of 90000. 90000/11250 = 8. You can test the rest of the table if you like.
The graph of modulus is also correct. If you increase the modulus but keep the thickness the same, this is what you get. I’ve explained this before that in simple terms, the top of the table would be the cheapest laminate, maybe E-glass and polyester resin and the bottom of the table would represent the most expensive laminate, something like carbon/epoxy.
The point of these tables and graphs is to show that stiffness increases with thickness at a far greater rate and lower cost than trying to increase stiffness through material selection.
As for you wanting an example of a laminate stack to use, not knowing much about your product (loading, duty, etc.), it is just a shot in the dark but I’d consider a couple of layers of 1.5 oz mat, 0.5-0.75" core where needed for stiffness, 1708 biax patches for local stress and maybe a 1208 over the whole unit (at least over the core).
If you are going to infuse or LRTM, you can use continuous filament mat to increase flow in the stack. Rovicore (and similar products), used in one of the videos you posted, is a great product and it can greatly increase efficiency but that comes at a price. You’d need to carefully examine material cost vs labor expense when using it.
Yes, for RTMlight, you need some sort of resin channel. Rovicore-like materials have this built in.
If you say 5mm would be sufficient, I would look for an infusion mat which has enough CSM on the outsides, and can fill the 5mm cavity. Such as a M900-M05-M900 from Scott&Fyfe. (Polymat)
Use a good gelcoat, apply sufficiently thick, and use a peroxide which allows a better cure. Perhaps an AAP catalyst.
For the resin, you could try with a filled resin, which limits shrinkage. This can bring your so desired Class A finish (and honestly, I would not deviate from that. Better to have 2 moulds doing the same to give the output wanted, than rework on the parts).
Make sure your inserts are near the inner side, which can have a slightly lower quality finish. A piece of Soric under the insert can help limit telegraphing to the outside.
Also, Soric can be a viable option to get lighter weight products. However, placement of the material is more critical.
“Use a good gelcoat, apply sufficiently thick, and use a peroxide which allows a better cure. Perhaps an AAP catalyst.”
Ok usually I feel more comfortable to require the gelcoat supplier specify the ideal catalyst. So I am not sure what you mean there because is alot of sophisticated testing involved when they recommend a catalyst and often they will ship them together.
About the gelcoat I am also confused how those guys in the video demo are getting 5-7 cycles per day and have a cycle time of 30 minutes.
On a hand layup job I am waiting 2-4 hours for the gelcoat to feel the safe tackiness quality to continue with the first layup of fibre.
Obviousy they are using a gelcoat that is different from this.
Any ideas? Is it because the mould must be heated?
If it is heating then I am going to be keen to find a few illustrated examples of installed heating systems.
About the Infusion Mat, those a good leads. And yes I am sure 5mm will be safe thickness. ANd you have given me some good leads to hunt down more understanding about selection and usage of them.
Make sure your inserts are near the inner side, which can have a slightly lower quality finish. A piece of Soric under the insert can help limit telegraphing to the outside.
Also, Soric can be a viable option to get lighter weight products. However, placement of the material is more critical.
Ok I am confused trying to visualise this. This is where I am happy to pay for someone to bother illustrate it.
I’ve got a project right now I’d kill to be able to make even 5 a day. I’ve got a contract for C7 Corvette Side Skirt and front splitters I’d love to close in a week instead of a month.
Can anyone walk me through how to set this up? My issue is in cure time. I can’t understand how to get more parts out of the same mold in under an hour. My current fiberglass tech is taking a full day to lay up 4 fiberglass molds, with only one part per day coming out of them.
If you need the most output from a mould per day, the press moulding is the way to go. You just need a heated press and moulds with their closures able to whithstand heat and pressure.
With this system a long time ago I’ve been able to make 1 roof per hour for Fiat vans.
So let me me pay you $500 per hour to know how. My female can withstand the pressure but she is not heated. I dont want to strip her to heat her. And if you know that much about press then you know enough to help me. $500/hr. get an account on Odesk and make yourself available like a java programmer. The world needs 3D-printers, it needs fibreglass experts, and it needs java programmers. None of us are experts, God is the only expert of everything.
SOmeone once said that God can see the future. The NSA are trying to see if they can see the future. The Jews believe in God. They think that they are his “Chosen” and He will always forgive them their trespasses. Get on Odesk I will pay you $500/hr and so will the next guys and the next guys.
My market is like this. People ask me why dont you make just ONE xxxxing prototype to show people the product and see if they will buy it?
I ask them, “are you stupid?”
I dont make one because then they will have ONE to copy it. I need to have a machine ready to make nobody ever think about copying it.
I mentioned above two of my degrees. My third degree was a Masters in Business Systems. How business succeed, how they fail, why they failed, what tools they used in the corporate world to make things move and make money…
i was smart, too smart, too smart because I took the degrees and education of the new world order and then went and told them to xxxx themselves I will not be a slave-master, I will not turn your engine of misery and slavery. I fear God and He is my best friend today manifested in my black labrador.
If anyone wants to put their hands on this project I got to warn you I live in the most sexy women capital of the world, Floripa. California is nothing compared to this. All the sexiest women in Brasil come to live in Floripa waiting for some rich guy to fall in love with them. Your eyes will leave your head I will have to slap you in the face 50 times per day if we drive anywhere it is like babe paradise I cant believe i am living here sometimes I even have to slap MYSELF!If you insist on smelling the gelcoat which smells like your ex-wife’s xxxxx, if you really need to smell around and cant use iphones in 3D to be here and you really need smell all the xxxxxxs, even the dog;s xxxxxxs and their sperm (you must know something I dont know about science if you really need to be here in person or unless you want to try and xxxx my wife)
It went nowhere because there was no links to any useful knowledge and everyone is working on carbon fibre and different technologies.
Press is expensive moulds. Its never just about the technology. Its about the market. The objective is never your product, the objective is profits. Lawyers, copyrights, patents, scammers, stupid businessmen who setup companies trying to offer consulting services for their expertise and then suddenly someone makes their expertise obsolete with a new way of doing it and then that person is stuck over invested in their consulting mould-production Old-RTM company selling resin injection machines they spent 5 years designing and building and their wife is threatening to leave them or simultaneously having an affair in their face with a “So you going to break the children’s hearts and let them know about this???” grin on her face.
The point is its almost never about the technology. IT IS ALWAYS ABOUT THE PROFIT$!
