On 11/16/2011 3:06 AM, Erik Christiansen wrote: > On 15.11.11 19:30, perotter wrote: > >> Some DATRON mills are polymer-concrete. I think they are concrete with >> a polymer used like rebar would be. I also think that all of the 1st >> ones were concrete, but some are now granite.These mill are for high >> speed milling. >> > When I visited ANCA, a couple of decades ago, they just called it > "cement-filled plastic", I think. (Or perhaps that's just as much as I > understood at the time.) But now their website also talks of > polymer-concrete. So it's been in use in the CNC machine tool industry > for at least 20 years, then. > > For us, it might be easier to build machines with a fabricated steel > exterior, filled with epoxy-granite. The effect should be similar, I > think. (The method seems to be popular with users of micro-mills, > especially poured down the column.) > > Epoxy has another use in machine building, e.g. for installing ballscrew > end bearings. The mounting holes can be bored oversize, the ballscrews > aligned, and epoxy used to fix the bearings, in a more modern > alternative to the babbit metal method used in the 1916 example in > Kirk's OP. (Building a solid but imprecise base, then adding precision > by later alignment, has a lot of appeal for a DIY machine.) > > Erik > >
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 ------------------------------------------------------------------------------ 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
