View Full Version : Machining drill rod????

brian Rupnow
12-03-2010, 08:04 PM
Guys, I'm having valve seating issues with the small I.C. engine I have been building, and I want to machine a valve seat "truing" tool like the one in the picture, out of drill rod. This is small---the minor diameter is .093"---the major diameter is about 5/16". I have carbide lathe tooling to turn the diameters, but I only have HSS milling cutters. Can I make the 4 "plunge" cuts which form the cutting facets with an HSS end mill into the drill rod? I will harden the drill rod after the machining is finished.---Brian

12-03-2010, 08:16 PM
Yes, HSS end mills and lathe bits work fine on drill rod. I make things that way all the time. Keep the spindle speeds low so the drill rod doesn't heat up and you're good to go.

12-03-2010, 08:56 PM
Machine-ability of drill rod (A1 or O1) is poor if I recall. I think I checked earlier in the week and its about 40% in the table I looked at. I would agree based on my experiences. HSS will work fine.

12-03-2010, 09:15 PM
O1 machinability is pretty darn good. We use it for all sorts of stuff because it is cheaper than ground rod. You can use any cutter to cut the stuff.

12-03-2010, 09:25 PM
I will double check my book. I think I was using the black book. Its does not machine as nice as 12L14. At least not on my crappy machine. I will defer to the experts.

brian Rupnow
12-03-2010, 09:41 PM
Is it really worth making a tool to cut one valve seat!!! I'm torn here. I really don't want to take the head off this engine again after tomorrow. I will definitly make a new valve from drill rod , because the stem on the intake valve is undersize. I do have a container of Permatex valve lapping compound, and the seat (valve cage) is made of brass. I can do a heck of a lot of lapping in the time it would take me to make a valve seat cutting tool like George Britnells. I'm not sure I'm a total putz at filing and honing, but I'm light years away from Georges abilities. I think the plan will be #1---Make a new valve #2--Lap the valve. #3---Lap the valve some more. ---#4 Then lap it a bit more. #5--Put some permanet marker on it and do the concenticity test. #6---Pray----#7---Reassemble engine. Thanks for your answers, gentlemen.

12-03-2010, 09:51 PM
W-1 is the best machining I have found.

12-03-2010, 10:38 PM
Actually 0-6 is the freest machining tool steel. The common drill rod materials from cheap to expensive are W-1, 0-2, A-2, D-2, S-7. They can all be easily machined with HSS. Not as easy as low carbon, but not hard to do.