What is West Systems 404 High Density Filler?

[SeaJay]

Is there a generic equivilent? I need to bed my engine stringers against a composite hull and at the same time, create high strength epoxy fillets for future laminating. I have some 1/2" chopped strand, some 1/32" milled fiber, and cabo-sil but am curious as to what 404 actually is, as well as any other other recommended recipes.

Best Regards,

Sea Jay

[Herman]

West 404 is a mixture of calcium metasilicate (ground stone, basicly, but very alkaline) and silicium oxide (cab-o-sil). It is mainly used in coatings, for various reasons (cost, flow properties)

For glueing your engine girders, use a mixture of chopped strands and cab-o-sil.
For smooth, high strength fillets, use only cab-o-sil. Perhaps add some milled fiber.

Clean up the fillet before it completely sets. Sanding is a pig to do.

Simple trick for that: run a piece of aluminium tube (of the desired radius) along the corner to be filleted. The aluminium will leave 2 black stripes. apply tape along that line. Now apply your fillet material, and run the aluminium tube along it again. There is your fillet, and the excess material is on the tape...

[SeaJay]

Herman,

Thanks for the information and the trick about the fillet...very clever!

[GG]

Herman's idea is great and to tell you the truth i have worked at Thompson Boats , S 2 Yachts's , Power Quest , and over 12 years at Skater and the only thing we have ever used for filling the gaps in a stringer system or ( fillet) was Cabosil and to tell you the truth forget the chopped strands and make a putty out of cabosil using a hobby stick filling in the gap to make a nice radius to lay your fabric into with less chance of air .....because you will get your strength from your layup and to tell you the truth why would you want to make more work for yourself ,adding Mill fibers to your putty or (fillet) ? I have to say that a putty made with Cabosil is far more easier to work with then something with mill fibers added do it ............which the end results will be ... is a smooth radius filling in the gap on your stringers waiting for you to do your layup .

[SeaJay]

GG,

What ratio of CaboSil to epoxy do you recommend for high strength fillets?

Just mix it until it is thick. It is not very thixotropic until you use a lot of Cabosil. You can save a bit of expense by using some wood flour too.

Mix thoroughly A + B (slow), mix Cabosil until like mollassas in January, mix wood flour until thixotropic, apply (if it does not hold a well-formed peak, you will be sorry as it runs out from under the stringer. Don't get carried away or you simply have a dry, lumpy batter). I wudn't use long fibers here either. The fibers won't do anything for the structure and will make a lumpy radius.

[SeaJay]

thanks guys

[Herman]

If using woud flour, wait 30 seconds before determining the consistancy. It sometimes seems to get thicker after a couple of seconds.

Also, if mixing in a deep container, make sure you work the lower viscosity material that is deep in the container upwards, so the mix is consistent throughout the mixing container. This can be a pig if you overfill the container.

Everyone has his own "secret" mix. Do some experimentation, and you will get a feel for it.

Do not forget to pre-coat the wooden structures with neat resin, or you might end up with a bad bondline. For wood that likes a lot of resin, I usually soak it a couple of times, wait for the epoxy to stiffen up, and then make glue and fix the part. This way the bondline does not starve.