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Cab-O-Sil with Micro or Flox

D

Dorfie

Well Known Member
I have to build up the door frame over which the McMaster door seal will fit. I have to add thickness at places as well as build some extra length (Max 1/4 inch). Will Cab-O-Sil mixed with micro be strong enough, or should I use flox in place of Micro?
Thanks.
Johan
 
I'd go with the flox, it's for structural use, much stronger than the micro which is used for filling purposes.

Glenn Wilkinson
 
I had to do the same on my RV-10. I used strips of fiberglass to build up around the doors. The most challenging was the support between the door and rear window for the infamous flat spot on most cabin covers. I felt it would be stronger than just flox.

I also did the same around the interior of the door frame to build the edges up to ensure that the McMaster trim fit snug.
 
It's okay

You can mix in some micro as well to make it easier to work with. The flox will still retain its strength. Not a problem
 
Cab-O-Sil

Dorfie said:
I have to build up the door frame over which the McMaster door seal will fit. I have to add thickness at places as well as build some extra length (Max 1/4 inch). Will Cab-O-Sil mixed with micro be strong enough, or should I use flox in place of Micro?
Thanks.
Johan
Click to expand...

Cab-o-sil is merely a thixotropic additive to epoxy to thicken it and make it into a paste, if you need that property to stay in place and not sag, while it it's hardening. It adds no strength to your epoxy.
 
Now I'm confused..

I have purchased the McMaster-Carr seal and will have to modify and add material to make a full 1/4" thick mounting edge for the seal.

I used the cab-o-sil and epoxy to glue the two door halves together as directed.

Anyway, when I see the word "flox" used, I thought it was the epoxy/cab-o-sil mixture. So what is flox and where do I get it?
 
JackinMichigan said:
I have purchased the McMaster-Carr seal and will have to modify and add material to make a full 1/4" thick mounting edge for the seal.

I used the cab-o-sil and epoxy to glue the two door halves together as directed.

Anyway, when I see the word "flox" used, I thought it was the epoxy/cab-o-sil mixture. So what is flox and where do I get it?
Click to expand...

Flox is finely chopped cotton fibers and is a structural additive unlibe Cab-O-Sil. I personally would peel the door halves apart and redo them with an epoxy/flox mix. You can get flox at AS&S: http://www.aircraftspruce.com/catalog/cmpages/flockedcotton.php?clickkey=10409 or just about any composite supplier.
 
If you want to see the difference mix up a ball of epoxy with micro and cabosil and then make one with flox and cabosil. You can sand the micro ball but the flox ball will be like a rock.

You can blend in some micro to make it easier to work with when you are sanding down to shape things. But you want the flox in there for the basic shape and strength. Cabosil keeps it from running everywhere.

There are scientific words but you need to see Dan's posts for those......
 
Door bonding

Going out on a limb here but.....if I had to do our doors over, I would bond them with Lord adhesive from Aerosport. Much stronger bond and eliminates the peelability issue linked to epoxy. We used flox and epoxy to bond our doors.
 
DarylT said:
If you want to see the difference mix up a ball of epoxy with micro and cabosil and then make one with flox and cabosil. You can sand the micro ball but the flox ball will be like a rock.
Click to expand...

It would be interesting to hit each ball with a hammer too------I am pretty sure that the micro one will crush/shatter nicely.
 
Thanks for all the replies

I am now practicing with Resin, Cab-O-Sil and Flox. Also adding some Micro to the mix to see the difference in sanding. I have no good way to test the strength other than the "feel" of the different compounds.
Thanks again.
Johan
 
I talked with Don from the West Systems people a few days ago. He told me cabosil (their 406 product) is good to build up a vertical surface and for my needs, up to 3/8 tall, should require no supporting cloth on the sides. Then to fill in gaps use microspheres ( their product 407) as it is easier to sand. No need to mix 406 and 407; use one or the other depending on the intent. They saw no need to use flox or microfibers (their product 403). They refer to this as a wetting product, good for adhering structures to wood.
 
dspender said:
I talked with Don from the West Systems people a few days ago. He told me cabosil (their 406 product) is good to build up a vertical surface and for my needs, up to 3/8 tall, should require no supporting cloth on the sides. Then to fill in gaps use microspheres ( their product 407) as it is easier to sand. No need to mix 406 and 407; use one or the other depending on the intent. They saw no need to use flox or microfibers (their product 403). They refer to this as a wetting product, good for adhering structures to wood.
Click to expand...

Dennis, may I strongly suggest that you purchase a trusted guide to homebuilt composite aircraft work? Author is a guy named Rutan. Read it, and do the practice exercises.

http://www.aircraftspruce.com/pages/cm/books/moldless.php
 
Sanding Flox

I read on some post if you use flox, you can sand it when it is green and not fully cured! I tried it and lord have mercy, its the best tip ever! I don't worry about adding micro anymore ti help with sanding!
 
Composites!

Nothing wrong with adding some flox to the micro, you can mix in some of the virtues of both products. For your project, maybe 4:1 micro/flox. After building a Cozy MK IV, I have no idea why anyone would want to use cab-o-sil, unless you like sanding.
Tim
 
West Systems

One thing I was made aware of when building is some of the WS products,particularly 407 I believe, is not recommended in areas where heat could impact its cured state due to sun. Example on tarmac with sun on dark paint.
 
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