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 ------------------------------------------------------------------------------ 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
