Mgs Epoxy System 335

[codensr]

Will be ordering the first apoxy kit next week for chapter 4. Does any one have any pro or con thought on the MGS system 335? I will be building in a year around temp controlled shop for the individual component, later I will need to use my garage for final assembly, non temp controlled. Just wanted to be sure to start with proper apoxy system.

[dust]

LOVE the stuff, have used nothing but. Keep it in a heated box, we use 2 light bulbs connected to a kerosene heater thermostat, no crystalization problems, when heated continiously and always ready to work with.

 

We are addicted to the sloooooooow set and don't put any fast hardener in, but, we only work 1 day a week and we don't care if the part takes 2 days to cure.

 

I use the west system in my other hobby, furniture building, only because of the pumps that attach to the containers, don't use it very often, it smells, it sets too fast for my preference.

 

Mixing in the fast hardener is a personal preference, john used it because he is a real airplane builder and works on his plane every day.

 

My advice, start with all slow and then carefully add the fast to get a cure time and a pot life you like to work with

[Richard Schubert]

I am using the MGS 285 system. MGS has an excellent english language web site from which you can view and download the specifications on their products. Before ordering your epoxy, I would compare the two systems. Also keep in mind that both these systems require that you post-cure.

 

I also keep my epoxy in a hot box. I tried 50-50 slow to fast ratio which was fine but a 66-33 slow to fast ratio gives me a little more working time. I bought a one gallon steel gas can and mix 2 slows to one fast. The containers should be sealed when not in use. I weigh epoxy with an electronic balance(personal preference)

 

It don't smell bad and I like the purty blue color

[John Slade]

>john used it because he is a real airplane builder and works on his plane every day.

 

A "real" airplane builder? Me? I don't have a clue what I'm doing half the time! (I try to do the important stuff during the other half). I use all fast these days, because I ran out of slow.

 

Yes, start with slow, then work up to a 50/50 mix. It depends on the working temp, the temp of the epoxy, the amount you're mixing and the complexity of the part. e.g. Mix 4 oz all fast at 85F and you get about 30 seconds to get it out of the pot and spread around. You'll get to know what works in what circumstances. You've got to experience an exotherm at least once, just for the fun of it.

 

Richard said:

>keep in mind that both these systems require that you post-cure

That's what MGS say, true. I think the German FAA make them require a post-cure for epoxy work in Germany. But keep in mind also that most of the longs, vars and Cozy's built so far were done without a post cure using epoxy with MUCH lower tg's at room temp cure. The only post cure my plane got was to sit the wings in the Florida sun for a few days.

[Richard Schubert]

There is a long discussion about the pros and cons of post curing at http://www.cozybuilders.org/mail_list/topics99/post_cure.txt

[HM Andersen]

While I was working offshore on the oil installations in the north sea we started to use fibercast pipes from Amron for seawater service.

In this line of business Quality is rated very high.After assambling pipes with epoxy, Heat treatment was a must before pressure test could be performed.There were no time limit between doing the assambly and the heat treatement.

There were never problems with the quality.I believe when in doubt do the heat thing.My entire plane will be heated

Helge

[John Slade]

>when in doubt do the heat thing...

Perhaps, but there's no doubt that most canards flying today were not post cured, and were built with epoxy with a much lower "melt point". There are a lot of issues like this in airplane building. Someone says something would be better, and all of a sudden it's exaggerated into a life or death issue, even though all those who went before survived quite well without it.

 

Be sure to follow the staged temperature directions carefully when post curing to avoid over doing it and ending up with downward curved wings.

[mplafleur]

I was thinking I might be able to post cure my parts in the thermochambers at work. At what temp and how long?

[Dave Clifford]

I do believe that the times and temps are listed on the containers of MGS. If not, I do have the spec sheets from the manufacturer with all the technical data at home and can get you some copies.

[mplafleur]

It looks like the literature uses a post cure of 15 hours at 55 deg C.

[John Slade]

I just had an opportunity to compare the usage properties of MGS 335 (which I used for my whole airplane) and 285 which I used this weekend to help Jim Sower repair his Velocity gull wing door. (Ask him - it's a facinating story )

 

ANyway, we used 285 50% mix hard & slow for four days and 20 or so layups and for making flox & micro. As usual I kept the epoxy pump in a hot box at about 110F. On the first couple of layups I was concerned that the stuff might be too old (Jim had owned it for a few months) or something because it didnt seem to be going off when I expected it to from my experience with 335. After about 3.5 hours it was rock hard. I've come to the conclusion that 285 starts curing (ie gels) quite a bit later than 335, then goes off more quickly, ending up a bit harder than 335 after say 4 hours. I get the feeling that a similar mix of 335 at the same temperature reaches say 85% of full cure in 4 hours, then gets to 100% over the next 3 days or so. By contrast, 285 seems to get to the 95% stage after 4 hours.

 

The above might be a bit hard to follow, so let me summarize by saying that I LIKE 285 a little better than 335. Yes, it's more expensive, but it seems to be a little more manageable, and it does have a higher tg without post cure than 335. Since both products are have significantly better tg than the old SmellyPoxy of yesteryear this issue may not be very significant. Over the course of building a whole airplane you might spend an extra $100 on 285 over 335. My guess would be that its worth the difference.

 

By the way - as an aside - if comparing the price of various brands, be sure to include the volume of MIXED epoxy you get for the money, and then consider how much of each you use for a particular task. I'd venture that you'll use significantly less mgs than you will other more viscous brands.

 

Just my thought for the day.