On 11/17/2011 5:21 AM, Mark Wendt wrote: > On 11/16/2011 01:28 PM, Dave wrote: > >> Looks like most of the Datron mills actually have solid granite bases - >> most of them are not a composite polymer-granite dust mix. >> >> I have bought some epoxy resin to repair boat hulls and the best price I >> can find for non-blushing epoxy resin is about $75 per gallon including >> the hardener with shipping. >> So a gravel/epoxy composite or granite dust/expoxy composite frame is >> going to be a lot more expensive than basic concrete which is going for >> about $150 per cubic yard around here delivered in a mix truck. >> >> Making an epoxy/gravel composite would also take some experimenting as >> epoxy tends to self heat as it is sets and it can get very hot. I >> have no idea how they control curing in thicker structures with >> epoxy. I have had a cup of mixed epoxy get so hot, that I was not able >> to hold onto to it. (too much activator in the mix). The hotter it >> gets during a cure, the faster it sets so it can become a tail chasing >> exercise on thicker parts. >> That is why most boat hulls are laid up in thin layers - usually less >> than 1/8th inch per layer. >> >> Andy.... I think we got these old imperial measurements from you >> guys! Apparently we are rather resistant to change. But I'm still >> waiting for the UK to adopt the Euro...any day now .. right?? ;-) >> >> Dave >> >> > Dave, > > There are application epoxies that are designed to cure in bulk, and do > not exhibit the high heat generation that a typical laminating epoxy > does when mixed up and kept in a container in large amounts. The epoxy > I used to use to make molds and plugs was a greenish color and had metal > dust and a few other additives in it to make the final product strong. > Had a very slow cure rate, something like 48 hours for the initial cure, > and then you had to finish with a heat cure to get to the final > hardness. Prior to the heat cure, the epoxy never got much warmer than > a human's body heat. > > Laminating epoxies, like the ones you mentioned above, have much shorter > cure times, because they use the exothermic heat generated by the > chemical reaction to hasten the cure, moreso than the much, much slower > curing molding epoxy like I use. Of course, there are laminating > epoxies that don't quite fit that mold (no pun intended), like the Epon > epoxy I use to glue up the bamboo rods that I make. That epoxy has a 7 > day cure at 65 degrees F, though you can, and I do, heat cure it. > > Mark > >
Very interesting.... I am always learning things from this list. :-) Thanks, Dave ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-novd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
