Mix epoxy?

kavel_r

Well-Known Member
Joined
Jan 31, 2018
Messages
51
Reaction score
0
Is it possible to mix two different epoxies - for example, JB-Weld (4-6 hour set time) and JB-Kwikweld (5-6 minute set time) to get an intermediate set time? I just thought of this and was wondering if it would work.
 

Nytrunner

Pop lugs, not drugs
Joined
Oct 15, 2016
Messages
8,011
Reaction score
3,760
Location
Huntsville AL
Without it being specifically stated, I'd contact the manufacturer directly. Could do some funky chemical business when mixed.

Hopefully this isn't about bonding motor retainers? You want the regular JB at full strength for that purpose.
 

kavel_r

Well-Known Member
Joined
Jan 31, 2018
Messages
51
Reaction score
0
Without it being specifically stated, I'd contact the manufacturer directly. Could do some funky chemical business when mixed.

Hopefully this isn't about bonding motor retainers? You want the regular JB at full strength for that purpose.

Thanks for the reply! I guess I'll have to test it on some scrap material and see what happens.
I was thinking of doing this for fin fillets so I'd have slightly more time to work than with JB-Kwik but not have to wait so long for JB-Weld.
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
11,960
Reaction score
3,787
Location
Pasco, WA
Its not usually recommended to mix epoxies especially given that one is a slow set and one is a quick setting. The chemical makeups of the two epoxies may not be compatible hence Nytrunners chemical funkiness statement, they may cure or they may never cure. You could test the two on your own, but you have no way of validating what changes it makes to the bond strength of the combined epoxy.

You can get 30 minute epoxy from local hobby shops or even possibly Hobby Lobby, mixed with wood flour, cabosil/fumed silica, or microballoons it makes a good fillet epoxy for rockets.
 

Nytrunner

Pop lugs, not drugs
Joined
Oct 15, 2016
Messages
8,011
Reaction score
3,760
Location
Huntsville AL
(tangent question)
What type of rocket airframe/fin materials is it?

JB weld may be what you have on hand, but it's a pretty heavy adhesive (steel powder!) and there are likely other products at hand that would do just as good a job for your fins.
 

kavel_r

Well-Known Member
Joined
Jan 31, 2018
Messages
51
Reaction score
0
Thanks for the info. I'll do some research into 30 minute epoxies.
 

kavel_r

Well-Known Member
Joined
Jan 31, 2018
Messages
51
Reaction score
0
(tangent question)
What type of rocket airframe/fin materials is it?

JB weld may be what you have on hand, but it's a pretty heavy adhesive (steel powder!) and there are likely other products at hand that would do just as good a job for your fins.

I'm building a Madcow 4" Patriot that I'll be doing my Jr. Level 1 on. I for sure want to use JB-weld for critical parts like the motor mount, but I may use something else for the fins.
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
11,960
Reaction score
3,787
Location
Pasco, WA
Bob Smith is a common hobby brand, Red Baron may be another one (not sure if its still around or was re-branded Bob Smith). Many hobby shops sell Bob Smith epoxy and CA under a house label, I have the 5 and 15 minute sitting on my work bench now and its labelled Hobby Town but on the back it says www.bsi-inc.com
 

kavel_r

Well-Known Member
Joined
Jan 31, 2018
Messages
51
Reaction score
0
Bob Smith is a common hobby brand, Red Baron may be another one (not sure if its still around or was re-branded Bob Smith). Many hobby shops sell Bob Smith epoxy and CA under a house label, I have the 5 and 15 minute sitting on my work bench now and its labelled Hobby Town but on the back it says www.bsi-inc.com

How viscous is it compared to JB? I've only used JB-Weld and Kwikweld in the past, but I think something that flows easier might be useful for fin fillets.
 

Nytrunner

Pop lugs, not drugs
Joined
Oct 15, 2016
Messages
8,011
Reaction score
3,760
Location
Huntsville AL
Never used the 15. Generally, the longer the cure time, the stronger the cured bond strength.
That being said, Unless you're planning to fly transonic or beyond, any of them will work.

I use 5 and 30. I did my L1 rocket with 5min before I read anything about Hi-power construction techniques, and it's still trucking. 5 requires lots of small batches, but it stays where you put it! lol
 

Zeus-cat

Well-Known Member
Joined
Mar 14, 2009
Messages
4,870
Reaction score
1,194
I only use JB Weld when one or more parts involved is metal.
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
11,960
Reaction score
3,787
Location
Pasco, WA
How viscous is it compared to JB? I've only used JB-Weld and Kwikweld in the past, but I think something that flows easier might be useful for fin fillets.
JB is a paste, the BSI epoxies are like honey, and will require thickening with the previously mention cabosil, wood flour, micro ballons or talcum powder ( some baby powders are talcum, just make sure and read the ingredients, cornstarch baby powder will not work). Thicken to the consistency of peanut butter.
 

kavel_r

Well-Known Member
Joined
Jan 31, 2018
Messages
51
Reaction score
0
JB is a paste, the BSI epoxies are like honey, and will require thickening with the previously mention cabosil, wood flour, micro ballons or talcum powder ( some baby powders are talcum, just make sure and read the ingredients, cornstarch baby powder will not work). Thicken to the consistency of peanut butter.
Is thickening required or can it be used as is?

Sent from my FRD-L04 using Rocketry Forum mobile app
 
Top