This is a valuable tip: I have 3 die filers. All of them,including the MLA(which I have seen at Cabin Fever running) run WAY too fast. They destroy files by running too fast,and pinch your fingertips when they grab your small parts and snap them back down before you can react. I put a little 1/2 H.P. motor with a speed control box on my Butterfly. I slow it way down. It still removes metal quite well. It made all the difference in the World. MUCH more pleasant to run. PLUS,I have had 01 steel suddenly surface harden from filing too fast,and ruin the teeth on the file. Had this happen even when hand filing,so take this seriously if you value your expensive machine files.
I most often have used a 6" half round coarse cut Nicholson file with the tang sticking UP. Grind that tang off before you put an eye out!! REALLY!! I have to grind off a bit on each side of the file to get it into the chuck,but it works fine. Where the file emerges from the table,up to the tang,it is parallel.
Now that Nicholson has gone to Mexico,and their files are soft as butter,you'll have to find another brand. Grobet USA files are MADE IN INDIA!! and are getting increasingly poorly made. Bahco's are still good files. Vallorbe's are still Swiss made. The World is going to Hell in a hand basket as far as decent files are concerned. I'm afraid the file situation will only get worse. If you find some decent ones,buy a supply.
Even with 3 die filers,I still bought the MLA kit. I don't need it,but can't resist Andy's nicely made designs. I have the Loopy chuck though I already have a Hardinge HLVH with all the collets. I'll only use it on my 16" lathe. Those kits are just too cool!