(quoted from post at 20:06:03 01/28/15) For someone doing the type of machine work Lanse will be doing with this lathe, the carbide needs to be run dry. The only reason he would need to run coolant is if the part was getting too hot and the heat was causing the part to warp.
That said, carbide is designed to run 'hot' and still perform. In some cases, and with some coatings, it actually performs better when it is run hot due to the coating.
That's not to say carbide can't be run with coolant, it can. When coolant is used though it needs to be flooded on, not trickled on, brushed on, etc. This is necessary because of the thermal shock to the carbide caused by the coolant not actually keeping the whole bit cool, but rather cooling the cutting edge more than the rest of it. This shock will cause premature wear on the carbide, and with the cost of inserts, the longer the life you can get, the better.
Given that Lanse is just getting into the field of machining, and the fact his machine isn't set up with a coolant system, I'll stand by my statement. I also stand by it for the simple fact that I have been doing both lathe and mill in my shop, as well as portable line boring in the field for well over 15 years, and nearly always run carbide tooling dry unless I'm making extremely heavy cuts, or threading. Given the size of Lanse's machine I can't see him doing any cutting that I'd call heavy, but if you'll notice I did say to use lube when cutting threads.
Finally, yes, good tooling can be found on Ebay, CL, and many other places. However, even used tooling often fetches prices much higher than it's imported counterparts. So, if your on a budget, or don't do enough volume of work to justify spending $1000 on something to use twice, when you can spend $100 and do the same job, it's crazy to spend the money on a tool that won't offer you any returns for years to come. In my case I've got plenty of the name brand stuff to work with, but also have plenty of the import stuff that usually does just as good of a job as it's more expensive counterpart. I mean if your using a new lathe and trying to hold your tolerances in the .0001 range, then by all means spend the extra money. But, when you've got an old lathe that hasn't seen a .0001 tolerance in 30 years, it's kind of stupid to waste the money.
But in the end that's just my .02.....