Different Epoxy for Different purpose??

Discussions about techniques for rocket building. Leave your tips and tricks to making the perfect rocket.

Moderator: Moderators

User avatar
NewtonsLaws
Parachute Packer
Parachute Packer
Posts: 24
Joined: Fri Feb 10, 2017 4:15 pm

Different Epoxy for Different purpose??

Postby NewtonsLaws » Sat Mar 18, 2017 5:15 pm

Hi New to HPR.
Aiming for L1 cert next rocket in April.

Was told to use JB Weld for attaching motor retainer to motor mount tube for temperature.
But not to use JB Weld for fillets as too brittle.

Ok got that.

BUT should I use JB Weld for
centring rings to motor mount tube?
centring rings to body tube?
shock cord to motor tube?

Or stick with fillet epoxy?

and is 5 min epoxy ok or do I need to use 15min epoxy?
QRS #184
AMRS #134 L2 RSO / LCO

User avatar
SpaceManMat
Astronaut
Astronaut
Posts: 1735
Joined: Mon Dec 15, 2008 9:56 pm
Location: Brisbane

Re: Different Epoxy for Different purpose??

Postby SpaceManMat » Sat Mar 18, 2017 6:27 pm

Really only the retainer needs JB, even then for a 38mm motor any decent expoxy would probably do.

Some people do use JB for fin fillets, but only normally when they have a black fibreglass rocket that they don't want to paint.

Either 5 or 15 minute expoxy is fine it more about what you are comfortable using.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 10,849 feet
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

User avatar
OverTheTop
It's only money...
It's only money...
Posts: 2337
Joined: Sat Jul 21, 2007 2:20 pm
Location: Melbourne, Australia

Re: Different Epoxy for Different purpose??

Postby OverTheTop » Sat Mar 18, 2017 6:43 pm

Hmm. Glue threads are always contentious. Many opinions.

Data sheet is king. Know the specs and what you want to achieve.

Having said that, there are rules of thumb.

Personally I would use JB for anything in contact with the motor casing. Its higher temperature rating helps it keep its specifications under the increased temperature there.

I use West Systems 105/206 (slow set) for everything else. It is what I have so it is what I use. Never let me down along the way to L3 or Mach 1.8 yet. There are some other epoxies that are slightly stronger but harder to source, so I stick with WS (no pun intended). It is a bit slow sometimes, but working the joint in hot weather with faster hardeners can be stressful.

Generally the quicker the set the less strength the joint has. It is a bit of a generalisation, but generally right. As I said earlier, the data sheet is king in this area. Remember you need to mix them correctly to achieve the specifications. I mix by weight exclusively.

This is only one opinion :)
TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

Kryten
Astronaut
Astronaut
Posts: 1945
Joined: Wed Oct 24, 2007 11:06 am
Location: Sydney

Re: Different Epoxy for Different purpose??

Postby Kryten » Sun Mar 19, 2017 10:58 am

I concur with the comments by OTT.
5 minute epoxy will work, but generally speaking, epoxies with longer set times are usually better - primarily due to the different hardener (the part "B") and the resulting structure of the cross-linked polymer.
I believe 5 minute Araldite becomes more brittle over time, so I would avoid it (although I did use it in one of my mid-power rockets for convenience)
"Pub, ah yes. A meeting place where people attempt to achieve advanced states of mental incompetence by the repeated consumption of fermented vegetable drinks" (“Timeslides”)

User avatar
OverTheTop
It's only money...
It's only money...
Posts: 2337
Joined: Sat Jul 21, 2007 2:20 pm
Location: Melbourne, Australia

Re: Different Epoxy for Different purpose??

Postby OverTheTop » Sun Mar 19, 2017 11:46 am

5 minute Araldite


Avoid it like the plague...
TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

User avatar
NewtonsLaws
Parachute Packer
Parachute Packer
Posts: 24
Joined: Fri Feb 10, 2017 4:15 pm

Re: Different Epoxy for Different purpose??

Postby NewtonsLaws » Mon Mar 20, 2017 5:37 pm

Thanks everyone!

I was looking at Loctite epoxy spec sheet.
it seems to have a higher termparater rating (150 deg C) and strength than Selleys araldite.

Any thoughts?

And where does one get this other magic stuff?
It does not seem to be in the common bunnings etc.
QRS #184
AMRS #134 L2 RSO / LCO

User avatar
OverTheTop
It's only money...
It's only money...
Posts: 2337
Joined: Sat Jul 21, 2007 2:20 pm
Location: Melbourne, Australia

Re: Different Epoxy for Different purpose??

Postby OverTheTop » Mon Mar 20, 2017 8:44 pm

I usually buy West Systems at Carbatec (http://www.carbatec.com.au) but they don't have a large range of hardeners or sizes. They do suit what I buy though. Probably worth a look.

You local boat-building place can probably help too, although if you mention the word "marine" the price will likely go up :) . Make sure you go through the data before purchasing.

Just Google and you should be able to find it.

JB can be purchased at Australian Rocketry and many other places.

Forgot to mention. You might be able to get some epoxy donated from some HPR flier(s) that have some to spare, if you don't need much.
TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

Lamp
Aged like a good scotch
Aged like a good scotch
Posts: 1098
Joined: Fri May 08, 2009 9:28 am
Location: Melbourne

Re: Different Epoxy for Different purpose??

Postby Lamp » Fri Mar 31, 2017 8:52 am

For an L1 rocket (unless you are doing a glass tip to tip or rolling your own tube) all you really need is "hobby" epoxy like BSI. Blake sells this in the Aus rocketry shop. I tend to use either the 15 min or 30 min stuff to make sure I have enough working time.

For higher strength requirements I also use West Systems but typically with 205 fast hardener (about 30min working time), generally with chopped CF (injected internal fillets) or Wests micro fibre filler (for external fin fillets).

JB weld is great for anything attached to the motor mount tube (retainer, CR) but to be honest, you could get away with not using it. A small HPR motor will not get hot enough for long enough for you to really need it...but having said that, I always use it for these applications :wink:
‘It takes sixty-five thousand errors before you are qualified to make a rocket.’ — Werhner von Braun
TRA 12286 L3
TAP member

joeman
Rocket Flyer
Rocket Flyer
Posts: 174
Joined: Fri Mar 06, 2015 9:05 am

Re: Different Epoxy for Different purpose??

Postby joeman » Mon Jul 03, 2017 5:29 pm

Hi,
Continuing this thread....(might help others)
RE: 4" Katana
I've just purchased some J-B Weld for the gluing of the fins (root of fins) to the Motor Mount. This seems like the most sensible decision based on the knowledge that the motor mount will increase in temperature some what. It should also be relatively easy to apply as well.

External Fillets
My decision on the external fillets is West Systems - 105/206/403. That seems like a widely used combination and I like the idea of the 'peanut butter consistency' ... to make the creation of the fillets easier.

Internal Fillets
For the internal Fillets, I was originally toying with idea of using just 24hr Araldite. But now I'm thinking I should just use West Systems instead.
In terms of creation of fillets, I wouldn't expect either to be harder to create.

So then it comes down to strength...It looks like there are a lot of different ways to 'measure' the strength of a material.... and it isn't just the strength of material, but the adhesive properties, the temperature of use, etc. Lap Shear strength seems to be a common way to measure the strength...but it is hard to validate and come to any sensible conclusion.

26MPa at 40degrees for Selleys 24hr Araldite - Bonding to Aluminium.
2346PSI (~17MPa) At room temp (so assume 25 degrees) for West Systems bonding to G10

I know that Araldite strength drops off considerably above 100 degrees C. Does that makes me wonder if West Systems 105/206 retains greater strength as temperatures increase. Searched in vain for something to help me compare to Araldite, but nothing solid.
Question: Does anyone have any information on West Systems strength at various temperatures?

Any other thoughts?

Cheers

Joe
p.s. I'm also aware that the surface preparation is KEY to the success of the joint and may significantly affect performance.
L1 - Callisto (H133) - 11-Jan-2016

User avatar
OverTheTop
It's only money...
It's only money...
Posts: 2337
Joined: Sat Jul 21, 2007 2:20 pm
Location: Melbourne, Australia

Re: Different Epoxy for Different purpose??

Postby OverTheTop » Mon Jul 03, 2017 7:50 pm

TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

drew
Southern fried goodness
Southern fried goodness
Posts: 677
Joined: Sat Aug 01, 2009 10:20 pm
Location: Perth

Re: Different Epoxy for Different purpose??

Postby drew » Tue Jul 04, 2017 2:06 pm

I figure it's worth chiming in as it seems everyone has their own preferred epoxy systems. For me, I routinely use 4 different types of adhesives for my builds. This has recently changed as well so it's good to document when changes occur.

1. JB Weld - for Motor Retainers/bonding metal to a motor mount. That's ALL I use it for. Motor retainers.
2. Araldite (5 minute) - I use this for tacking fins on as it's fast.
3. Epiglue - for fin fillets and any internal glue work. The consistency is so thick runs aren't a worry. Great stuff.
4. Araldite K3600 - I use this for rolling airframes, making fin stock, and doing layups on fins. Incredibly low viscosity so it's great for this type of work.

Historically I used Proline 4500 for fillets and internal work but I went through two quart sets and wanted to go local. I've got some RocketPoxy too but I've never really taken to it. I still have a large amount of Wests Systems but I prefer to use the Araldite K3600 kit given its superior capabilities when compared to Wests.
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015

Oldboy
Rocket Flyer
Rocket Flyer
Posts: 128
Joined: Sun Oct 28, 2012 10:51 am
Location: York WA

Re: Different Epoxy for Different purpose??

Postby Oldboy » Tue Jul 04, 2017 10:24 pm

Proline 4500 for me ,fillets and mechanical bonds (had a rocket driven over by DFWM agricultural vehicle last season ,fillets and bond held)
JB weld for retainer bonding ,and that's all it's good for ,my humble opinion.
And yeh as Drew said
WARS 005 AMRS 98
L1


Return to “How to's”

Who is online

Users browsing this forum: No registered users and 1 guest