Please recommend an epoxy

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#1

I am developing an ultralight bicycle saddle, something like this.

http://www.tnc-hamburg.com/TNC-Shop/product_info.php/info/p11763_Selle-Italia-CX-Zero-Carbon-Saettel.html

I appreciate the research, development and production that goes into such a product, but I am not interested in paying $500 for $10 worth of carbon fiber and epoxy. Besides, building one sounds like a very interesting project. I have made a few saddles in the past with vacuum bagging so I am not completely new to the challenges involved. This saddle will be made with a cavity mold and pressurized bladder. I have already built a rudimentary mold just to test out the process.

I have always used West System resin and epoxy for the obvious reason that it is inexpensive and readily available. For this project I want something that is very strong and very flexible, but still easy to source. I would appreciate any recommendations for a high quality commercial epoxy, available in small quantities.

Is West System good enough for this application, or do I need something more exotic?

#2

West will fit the job, but the heat distortion temperature is a bit low.

Contact MAS Epoxy, and see if they can recommend something for you. Unfortunately I am not too familiar with what is available over there, but I know for sure that MAS has something for you.

#3

You should have a look at the MGS product line, the spec sheets can be found on the MGS website. Very good stuff. And the North American distributor isn’t too far from you - Airheart Incorporated in Ontario.

To achieve higher strengths some post curing is necessary but would be pretty easy as you have fairly small parts.

#4

Resin Services HTR212/386-99. It’s listed as a flexible laminating epoxy. I tested a panel made with this resin against Boeing spec prepreg with a Gardner drop tester and found it to be much more impact resistant. RS sells directly to the public-- I think I paid $90/gal.

#5

Hey H8, Have you ever tested any of the temperature properties of the 212? I seem to remember an article where they mentioned a version of this resin having a very high Tg (+200 F) with a room temperature cure. I think the article was about Penske using it in their composites shop.

#6

Since posting this thread I have looked into both MGS and Pro-Set. I was initially very impressed by what I read about MGS. I spoke with the distributor(Composites Canada) and was told that Pro-Set(by the same people who make West System)is almost as good. I compared the specifications for both and found that they are indeed very similar in terms of tensile and compressive strength, elongation, and other parameters. They both have low viscosity, and are good for closed mold, heat cured, vacuum bagged processes, so from a manufacturing point of view they are also very close.

I would still prefer MGS, but I may begin with Pro-Set as it is available in smaller quantities. I have to buy a minimum of one gallon of MGS, but Pro-Set is available in quarts. A bicycle saddle requires a very small amount of resin, and the gallon would not get used for a very long time, even if I go through many prototypes.

I have basically narrowed it down to one of these choices, since they are both readily available in Canada. Has anyone used both Pro-Set and MGS? I would like to know how they compare.

#7

OK, you have Martin Scheufler (MGS) resins. (after that labeled Bakelite, Hexion and now Momentive, but still with the MGS as second name).

I am their distributor in NL.

You could look into their L285 or 385 series, with the latter equiped with hardeners which are non-toxic. These are great hand laminating systems, loved by many people in sports, sailplane and modelling business.

For infusion I suggest the RIM235 series.

Keep in mind that all these epoxies like to have some heat. A working temperature of some 20-22 degrees C helps quality a lot.

For Pro-Set: I have used their systems, but that was long, long time ago. Much has changed since then (in formulation), so I guess my recommendations would make no sense.

Being able to buy smaller quantities is something that is important for many customers, and it is what I make a living from. (although we supply up till truck loads, I guess the combination makes it all worthwhile)

#8

This is what I use everyday in my bike frame repair service. Works great at room temp. but better if heated to 60°C for 12 -24 h.

Cheers
DB

#9

212 is RT cure. The rep says it’s HDT is 325F. I’d imagine that is with some kind of post bake though. I’ve personally taken it to 120C with no problems. I bet a lot of people let it post bake in service.

They also make HTR250, which requires an unsupported post bake. HDT for that one is 375F if memory serves.

Any of you guys using Applied Poleramic resins?

#10

Thanks for the info H8 - I’m going to have to give them a call to get all the details. I wish they had better spec sheets listed on their site.

Never heard of that one. I’ll have a look.

#11

I think consumers think of carbon fiber as something that can be comparable to buying an aluminum fabricated part. Most everyone doesn’t understand or know how much, engineering, material costs, labor, skill etc goes into a final product. I can see a cf seat costing that much because it is probably a limited run production, a mold tool that probably costed tens of thousands of dollars, made by technicians who get paid very good $ for their highly skilled labor.

Even if a person saw the cf part and said " I can make that myself" and they have little or no experience in making cf parts; that person will still spend hundreds of dollars to make the same part and not get as good of results.

But if it is out of interest or hobby of making the cf part then that’s cool. Or even if you want to learn to make them to sell.

There’s very valid reasons cf parts cost so much :slight_smile:

#12

It is good resin from what i hear. i have used it, i didn’t like it’s working properties but if you work with it at room temp 75F - 80F it flows better and traps less air. It is 325F tg without post cure. This was the reason i tried it out. You can ask the rep if post cure is ok, but according to Resin Services it is not necessary.

For vacuum infusion i like Huntsman 8604 epoxy… very strong stuff, infuses like a dream.