Is RTM all its cracked up to be !

[Stevie Boy]

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.

[6balls]

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.

[Horton]

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.

 

[MCskiFreak]

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.

[Horton]

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

[MCskiFreak]

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.

[eddie_roberts_jr]

John, where do you come up with this stuff?

[eleeski]

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

[MCskiFreak]

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.

[auskier]

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!

[MCskiFreak]

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.

[eleeski]

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

[MCskiFreak]

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

[ForrestGump]

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.

[RichardDoane]

Shane - stop "popping" the handle !

[ForrestGump]

It's not so much me as the handle. It's got these knife edged end caps.

[AdamCord]

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!

[MattP]

Thanks Adam for all the great info! I was wondering if you were going to chime in here!

 

Loving my Elite!

[disland]

Interesting stuff, Quattro anyone/

[ForrestGump]

Adam, So you're not able to use a graphic topsheet with RTM? Or you just choose to not use one?

[AdamCord]

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_jr]

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

 

 

[Wish]

Where's the popcorn this just got good!! ;-)

[AdamCord]

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.... :)

[disland]

Hey do you guys use Nano carbon? Only kidding

[Jim Neely]

Eddie,

 

Can I get the numbers for my Strada? SN-1007

 

[sullyski]

What size is it?

[Jim Neely]

68"

[eddie_roberts_jr]

Jim, Did you get my email?

[Jim Neely]

Yes, Can you add a little definition

 

68" Strada #1007

72.5 - ?

109 - ?

142 - ?

169 - ?

3lb 6.5 oz

1.965" tail height - ?

 

[Gern Blanston]

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!

[Old MS Accout]

As stated in the Nano thread, check out the PBS special on building things stronger. After watching it I cant figure out how it gets applied to building a ski but Goode must have somthing figured out.

[Bud Man]

Jim,

To my understanding a ski’s flex is measured in 4 different locations from the tail of the ski. 17”, 25”, 33” and 41”. I have always wondered how they came up with the starting of point of 17” since the distances are all 8” apart, I would have thought 16” would have been a more logical start since it is two increments of 8.

 

So it would appear; 17” 72.5lbs, 25” 109lbs, 33” 142lbs and 41” 169lbs.

 

The 3lb 6.5 oz, sounds like the weight of the ski.

 

I could only guess that when the ski is on a flat surface the tail rise is 1.965” high. But I have never heard that measurement before. Is that guess right Eddie?

 

 

 

[Gern Blanston]

MS -

 

I don't think there's any question that the materials are superior (don't have an hour to watch that video). Pinarellos now use a 60kg fiber in a 1K weave on their top end bikes http://www.torayca.com/index2.html. We know this because it's a selling point for them. 60,000 KG per sq mm is unreal. A new nucler sub has steel/titanium/whatever that is something like 100 tons per sq in. And while we actually do want some flex in the bike otherwise it's too stiff, most people seem to neglect that fact and think "stronger is better" and it is - but it needs to be done "right" and thus we talk about the layup of the carbon. Carbon is unusually strong - but only in one dimension. So in bikes, they vary the angle, size and position. I would think that the stresses on a ski are pretty intense and this type of conversation would be relevant.

 

My question was more along the lines of why aren't they more of a differentiator in the marketing of new skis? We seem to focus on the design of the ski rather than it's makeup. It seems that both are important enough to bring to the discussion. Bicycling is just about the opposite - it's assumed the frame will do everything you want it to do, and won't do the things you don't want it to. I mean at this stage, lots of skiing comes down to marrying preferences and style with the technology. The Elite may work well for some, but not others, the Strada and Zst the same thing, etc. Goode seems to have acknowledged this and is marketing accordingly.

[eddie_roberts_jr]

Bud Man, For the most part you assume correctly. We deflect each ski .100" in these four locations and record how many pounds of force it took to do so. The weight is the blank, inserted ski w/o a fin. The rocker is measured from a machined, true flat surface to the top deck of the ski right in back of the fin slot. Jim - doe this answer your question. Gern, I'm not 100% sure what your question is but it sounds like you know what you're talking about and it seems as though an answer might be long and may contain some proprietary information as well.

[Jim Neely]

Eddie, When you say without a fin, I assume that means without a fin or fin block.

[lkb]

I'm convinced I was sold an RTM ski that had flex problems. I got no support from factory. No I didnt get it through a retailer but it was sold new to me as a first qual ski. It was a disappointing experience. So a potential ski buyer shouldn't automatically assume RTM is better. Ski them and then decide.

 

Eddie, good post on the previous page.

[lkb]

How do we do private messages now?

[MattP]

Click Inbox at the top of the forum in blue then select new conversation.

[lkb]

Thanks Matt. You are the BOS IT guy. You should get a raise.

[MattP]

HAHA yea I should send Horton a message and tell him that!

[Gern Blanston]

Eddie - more succinctly put, we don't know anything about the carbon that goes into pretty much everyone's ski but (apparently) the new Goode. I mean if Andy can put 1000 pounds of force on the rope, the forces acting with the ski should be (significantly?) greater. And thus the materials making up that ski could be a decided difference/edge of the performance or durability of the ski. I'm not asking for trade secrets here, just curious as to why no one seems to feel that the carbon used seems to be important enough to sort of market around it? e.g. Pinarello has an exclusive arrangment with Torayca so that they're the only manufacturer to get their 60hm1k fiber. Does that mean anything? Maybe not, but it's at least a "differentiator".

[Old MS Accout]

There is a reason that pros/represented skiers have good success with skis. They get to try 2 or 3 of the same make of ski and keep the best one. I would like to know if there are pros out there that dont have that option. I dont think that they go to a ski shop, buy a ski and like it. They get a few hand picked skis sent to them to try and take the ski that skis the best. My point is that you could get 2 or 3 skis with the exact same flex and you would be able to tell which one you like.