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Is RTM all its cracked up to be !

Stevie BoyStevie Boy Posts: 1,736 ★★★Triple Panda Award Recipient ★★★
edited March 2011 in Skis Fins Bindings
Is RTM technology any better than other methods, not many other ski manafacturers seem to be giving it a go, they semm to be sticking with their try and tested methods of contruction.

" My Arms Keep Going Numb May Have To Use My Teeth”

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Comments

  • 6balls6balls Posts: 4,881 ★★★Triple Panda Award Recipient ★★★
    It may be an expensive risk to take for many companies, potentially w/out the promise of a marked increase in sales to justify it. I know the hype, but not enough about the actual engineering to say RTM offers huge tech advantage or not. Will see how the Razor works this spring...if the snow ever melts in MN.
    Dave Ross--die cancer die
  • HortonHorton Posts: 25,685 Administrator
    Bottom line is RTM is harder to do than other methods. Recutting a RTM mold is not cheap.
    On the other hand (theoretically) once you get going with a batch of skis it should be easy to make them all identical. There is some anecdotal evidence that RTM skis last a lot longer ….. the other factory’s will dispute that. The process I saw at Fischer last year was super impressive.
    There is a Razor on my ski rack right not. Just waiting for weather to start a formal review.

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  • MCskiFreakMCskiFreak Posts: 326 Baller
    From an engineering standpoint RTM has a lot of benefits and in my opinion they more than offset the costs. Because you have better resin to fiber ratios there is a more efficient use of materials (lighter weight), and the physical properties can be adjusted very easily. That being said all of my experience with RTM is with boat building where you can see huge weight savings, I cant speak on if there are significant weight savings or not with a ski; but without a doubt there is an increase in physical properties.
    Matt Welton - Resident boat nerd
  • HortonHorton Posts: 25,685 Administrator
    I'm not sure that the current RTM skis have a lower resin content. My understanding is that they have a more consistent resin content. More importantly they have more consistent laminate placement and orientation. If you are looking for pure optimization of resin to fiber content I think you have to go with pregreg. My speculation is that the only skis that utilize prepreg are Goode and SansRival. Of course this is only speculation.

    One of the differences between skis today and skis 15 years ago is the amount of air mixed into the resin. With RTM the resin is mechanically mixed and drawn through the mold under vacuum. Since I'm already speculating, I assume that all the factories have much better resin mixing procedures then what I saw at KD 10 years ago.

    Again this is speculation, when Eddie Roberts reads this he will call me and make fun of me for not knowing what the hell I'm talking about. that is part of the joy of being me

    Support BallOfSpray by supporting the companies that support BallOfSpray

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    MasterCraft / Masterline / MOB / O'Brien / Performance Ski and Surf / Reflex / Radar / Stokes

  • MCskiFreakMCskiFreak Posts: 326 Baller
    The weight savings doesn't come from using a different amount of resin per say, because the resin is drawn in under vacuum no excess resin is left in the part. Again this all comes from using closed molding processes in boats where we saw about a 300 lb reduction in weight, on a 25ft. boat, over a slop and mop boat due just to the fact that there was no excess resin used in the part.
    Matt Welton - Resident boat nerd
  • eddie_roberts_jreddie_roberts_jr Posts: 442 Water Ski Industry Professional
    John, where do you come up with this stuff?
  • eleeskieleeski Posts: 3,624 MM Trick Skier / Eccentric Person
    The best resin to weight material I used was an autoclave press cured unitdirectional sheet. Optimal resin mix, high temperature resin, pulled straight and reasonably priced. It came with peel ply on both sides so it laminated well with my wet layup. Using this style of material would probably result in the lightest ski.
    RTM or resin infusion would work well for large parts (like boats - is this the "new" MC hull?) because the resin is mechanically distributed efficiently. But for a ski where every bit of the ski can easily be handled by the layup person, I don't see such an advantage. I can squeegee my cloth to nearly optimal wetting on a ski layup. My skis are radically light so my low tech process can't be too far off.
    There is no air in my resin, John. If I get bubbles, it is a defect that I repair before finishing (with wallboard texture). Variables in the RTM process (temperature, pressure, dry fit, etc.) can change an RTM ski. I think Obrien's consistency is due to excellent QC proceedures at the factory as much as the technology. I could easily screw up RTM on my skis and have to cover up with wallboard texture still.
    Boron fibers rock! They are light and strong (in both compression and tension) and are easy to wet out. They are a bit difficult to Dremel cut when grinder mods are made to the ski!
    Eric
  • MCskiFreakMCskiFreak Posts: 326 Baller
    The boat that I was referring to was a boat that I worked on for a company called CAT 5 composites here in New Orleans. MC just has too many models to try and vacuum bag a few specific models since set up can be pretty time consuming using the vacuum bagging method.
    Matt Welton - Resident boat nerd
  • auskierauskier Posts: 448 Baller
    300lb of resin multiplied by X number of boats must add up after a while. I assume the material cost savings dont outweigh the cost of a unit/setup time though.

    a 300lb saving of weight on a wakeboard boat seems pointless, when that 'saving' is going to go straight back in as ballast. All they would need to do is the prostar!
    Toby Daff
  • MCskiFreakMCskiFreak Posts: 326 Baller
    Depending on the application, or the number of boats the use of RTM makes sense. For the military contract that we were working on it made sense. The problem with doing it with only the prostar is that you would need another production line to make it work efficiently and they really dont have the room to do that sort of thing.
    Matt Welton - Resident boat nerd
  • eleeskieleeski Posts: 3,624 MM Trick Skier / Eccentric Person
    Larry Parker, a San Diego skier and composites guru (teaches and runs a fiberglass business) used resin infusion on a lifeboat he was contracted to build. Resin infusion sounds like RTM without the fancy molds and super high pressure. He used his old molds. I didn't personally get to see his operation - I wish I had. His lifeboats saved labor as well as material when they switched to resin infusion. He had a weight he had to meet so he had to add ballast to meet the weight spec from the resin he didn't waste. Ballast should be cheaper than resin and you can place it more strategically (especially in a wakeboard boat - and maybe get a good slalom set when empty).
    In skis, I wonder if the real value is in marketing. All production ski molds are expensive and expensive to change. Coupled with great QC, Obrien's Elite is a great ski. The RTM may justify a higher price.
    Darn MCskifreak, I just got back from New Orleans. I'd have bought you a hurricane on Bourbon Street if I knew a couple of days ago you lived there. Next time.
    Eric
  • MCskiFreakMCskiFreak Posts: 326 Baller
    Right infusion simply uses either a disposable or reusable "bag" instead of the extremly costly two part molds that are used to make a ski like the elite. Currently I know of only one boat company that uses true RTM, and they were part of genmar so who knows what happened to them.

    This is a link to a video from the factory. http://www.fincraftboats.com/vec-video.php
    Matt Welton - Resident boat nerd
  • BoneHeadBoneHead Posts: 5,897
    I have a handle that has put a hole in the top sheet of 3 different skis(RS1, Senate C, and Sixam SS). That same handle hasn't left so much as a scuff on the top of either of my Elite's. And it's hit just as hard or harder on the Elites.
    Shane "Crash" Hill

  • RichardDoaneRichardDoane Posts: 3,977 Mega Baller
    Shane - stop "popping" the handle !
    BallOfSpray Pacific Northwest Vice President of Event Management, aka "Zappy"
  • BoneHeadBoneHead Posts: 5,897
    It's not so much me as the handle. It's got these knife edged end caps.
    Shane "Crash" Hill

  • AdamCordAdamCord Posts: 601 Open or 55K Rated Skier
    Oh man I wish I had seen this thread earlier, I get to do shameless self promotion!!

    There were a lot of factors that drove us at Obrien to RTM. First off, Compression molding is a mess. You suit up head to toe in protective gear, you have to have big ventilation fans and you *should* wear a gas mask (not everyone does). When you're laying up the ski (by hand), everything sticks together in a big sloppy mess, and you have to try and get all the carbon/fiberglass/graphic layers to line up straight, not fold over, and also you have to keep everything from sticking to it. The best part is this layup process is a race, because you only have a few minutes to get it all together before the resin begins to harden. If you can't get it all together in time, you're toast. If you can get it all to stick together in time, you toss the whole messy glob into the mold, and close the press. As it closes, all the excess resin comes squeezing out the side, and inevitably, some of the carbon will come shooting out with it. Then 5 minutes later the mold opens, and out comes a big rectangular shaped thing with something that resembles a ski in the middle. Cut the ski out, file the edges, and viola, a ski is born.

    Here are the big issues with this process that we hoped to resolve when we started down the RTM path:
    Flex - ski flex (both length and torsion) vary all over the place
    Rocker - huge variations from ski to ski
    Weight - You guessed it, it's all over the map
    Strength - Here's the big one. Even though you get great core and laminate adhesion with Compression molding, you still have a MAJOR weak point. This point is at the Flash Line. Here you essentially have a "naked spot", where there is no carbon wrapping the core. This makes a huge difference in break strength
    Torsional Stiffness - You just can't get as torsionally stiff when you have that exposed flash line

    With RTM, everything is just so much more civilized. The ski is laid up completely dry. Because of this the layers don't stick together (and everything else), you can take as much time as you need, and you don't need all the protective gear. Once in the mold, none of the carbon sheets can move. These two factors are why we can keep flex/rocker so consistent. Also we can wrap carbon completely around the ski, including where the flash line is on compression skis. We monitor the amount of resin we put in each ski, which keeps the weight and the resin/carbon ratio at the optimal level. The ski is left in the mold for over an hour, not 5 minutes, so the epoxy has time to fully cure. (partially cured resin has a lot to do with why skis change over time!)

    In the end, here's what this all means for the customer:
    Your ski has the exact flex, rocker, and weight that it was designed to have. Compression molded skis have an "acceptable range", and that range is usually pretty big.
    Your ski won't break* (Ok anything can break, but I can honestly say that after 3 years and hundreds of RTM skis sold, we have had one customer breakage. ONE!)
    Your ski won't break down - Break down is caused by several things: Polymer break down - exacerbated by air in the epoxy. Poor core adhesion - something that is prevalent in prepreg skis. And resin that is not fully cured.
    Torsional stiffness - This makes the ski feel much snappier through the edge change/rollout, making the ski cast out much better, and this is allows us to run a softer ski without losing speed, meaning the ski is forgiving and easy to ride.
    Consistent top edge - The top edge of a ski has a MASSIVE effect on the way it skis! Sharp top edge = fast, consistent ski.

    To be fair, RTM also has some down sides:
    It requires expensive machinery
    It is very slow compared to compression molding (making it more expensive)
    It requires A LOT of attention to detail by the operator
    It was very very hard to figure out. In the beginning we discovered a lot of ways to build scrap skis.
    The ski is "naked" meaning, any flaw or defect is visible and not hidden by a graphic sheet (this keeps us honest!)


    NOTE- I'm sorry for the long rant, I drank way too much coffee this morning!
  • MattPMattP Posts: 5,973 Mega Baller
    Thanks Adam for all the great info! I was wondering if you were going to chime in here!

    Loving my Elite!
  • dislanddisland Posts: 1,212 Crazy Baller
    Interesting stuff, Quattro anyone/
    Dave Island- Princeton Lakes
  • BoneHeadBoneHead Posts: 5,897
    Adam, So you're not able to use a graphic topsheet with RTM? Or you just choose to not use one?
    Shane "Crash" Hill

  • AdamCordAdamCord Posts: 601 Open or 55K Rated Skier
    The graphic sheets don't really work out so well with RTM. We tried a few things that came out ok, but honestly the carbon looks so good I don't really see why we would want to cover it up.
  • eddie_roberts_jreddie_roberts_jr Posts: 442 Water Ski Industry Professional
    Interesting stuff Adam. If that was the way you made your compression molded skis it's easy to see why you had all those problems..Five minutes? I guess you like to pull them out green and let them cure some kind of random rocker huh? Our skis are in over twice as long as that. Ski flex? We monitor each and every ski and record that flex and keep a data base so we can refer to the serial # we put on each and every ski. They are very, very close. Rocker and weight? Oh, that's right we record those measurements as well and they also go into the data base. Yeah and sorry to pop your bubble but our skis are wrapped with carbon and we also check the torsional stiffness as well so you won't find any "nudity" in Radar skis. I'll compare overall quality with you any day and if the skis you brought to Nationals last August are any indication of what you call quality, well then I guess that's why you were selling your top of the line ski for 800.00. Isn't retail something like 2,500.00? You'll have to come out to the barn sometime and we'll flex test a few of your skis that you say are "dead nuts on". Oh, and we have absolutely NO air in the expensive resin we use that was developed especially for us for use in high performance products.

    Have a nice day,

    Eddie

  • WishWish Posts: 7,317 ★★★Triple Panda Award Recipient ★★★
    Where's the popcorn this just got good!! ;-)
    >>> 11.25..a different kettle of fish. <<<
  • AdamCordAdamCord Posts: 601 Open or 55K Rated Skier
    Nah, I have a ton of respect for Eddie and definitely won't get into an internet debate! I've never been to the "Barn" and seen how their skis are built, for all I know their skis are built with unobtanium. I was just explaining our reasons for switching to an RTM product and why we think it's superior. Move along, nothing to see here.... :)
  • dislanddisland Posts: 1,212 Crazy Baller
    Hey do you guys use Nano carbon? Only kidding
    Dave Island- Princeton Lakes
  • Jim NeelyJim Neely Posts: 291 Baller
    Eddie,

    Can I get the numbers for my Strada? SN-1007
    68" Vapor
  • sullyskisullyski Posts: 7 Baller
    What size is it?
  • Jim NeelyJim Neely Posts: 291 Baller
    68"
    68" Vapor
  • eddie_roberts_jreddie_roberts_jr Posts: 442 Water Ski Industry Professional
    Jim, Did you get my email?
  • Jim NeelyJim Neely Posts: 291 Baller
    Yes, Can you add a little definition

    68" Strada #1007
    72.5 - ?
    109 - ?
    142 - ?
    169 - ?
    3lb 6.5 oz
    1.965" tail height - ?
    68" Vapor
  • As long as Eddie and Adam are viewing this thread, I have a question as it relates to ski construction. In the world of bicycles, much ado is made about the brand of carbon being used, the strength of the carbon, and the layup used in the manufacturing process. In contrast, very little marketing goes towards suggesting why the frame design of one manufacturer is superior. Trek talks about OCLV - their open compaction, low void exclusive process to remove the gaps in the fiber strands and thus improve consistency and strength. Pinarello talks about their asymetric layup due to the fact that the cranks and hub are on the right side of the frame. I could go on, but I think you get the point.

    in skiing, we seem to be focused on the rocker, bevels, etc. We seem to regard all carbon as more less the same. Goode is now talking about Nano carbon, and whether that's the beginning of what I'm referring to as a means of differentiation, or whether there's some truth to it is really the basis of my long winded question. Thanks, guys!
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