[Jim27]

Doing some work in 4140PH and need to ream some holes. I found carbide tipped reamers for the holes around 0.25 and larger no problem. Not finding them for around 0.125". I am finding solid carbide. I will be doing these on a cnc mill with reaming immediately after starting with a spot drill and drilling so alignment should be very good. As I understand it carbide tipped tolerate more shaft flex and one of the main reasons to go with them. What are my options at the small size and precautions if I go with solid carbide?

[metalmayhem]

the key thing with carbide is to have it dialed in perfectly , otherwise you'll be looking at oversized holes or a broken reamer . For small holes like that I'd use cutting oil rather than coolant , or undiluted cutting fluid which will wash out with a blast of coolant .
another option is cobalt