Trying to bore on a lathe with very little experience on the subject

[Sebaste]

Hi all, first post here.

I've been programing and operating VMCs for the past decade. I recently moved to another job as a programer/machinist. The workload now is mostly on the lathe (about 75%) wich I have very little experience with. I haven't had much difficulty with the lathe until now, there's this one operation on a job we are having problem with. I have to bore thru(11.132in in length) a stainless 304 bar to an ID of .768in with a nice finish. We have tried ordinary drills, HSS reamers, ISCAR SUMOCHAM drills and more recently we bought 1/2in kennametal solid carbide boring bar with a length of 8in. None of what we tried (especially the boring bar as it seem to flex too much with a stickout of 5.625in ) gave us the result we want. The most effective is the ISCAR SUMOCHAM drill where we do a 1'' pilot hole with a stub length and then drill to half the length of the part with a longer drill with the same insert,we then flip the part and run the same operation to have our thru hole. The problem we have with this is the finish of the ID wich is very far from what we want it to be. Anyway advice on how we could do that bore and have the finish we want ? The machine we have is an old 2004 HAAS SL20. Thank you very much

 

[magneticanomaly]

Sounds like an ideal job for a gun drill..Have you talked to Iscar about tweaking the process with their drill?

 

[kenton]

Drill from both ends, extended reamer from one end and dingleberry hone for the finish?

McMaster-Carr

 

[PackardV8]

The problem we have with this is the finish of the ID is very far from what we want it to be. Anyway advice on how we could do that bore and have the finish we want?

Drill from both ends, extended reamer from one end and dingleberry hone for the finish?

If volume supports it, Sunnen makes hones which will give any desired finish and to your exact diameter quickly and easily. Call them and explain the application. They have great tech support.

jack vines

 

[Gobo]

I have been amazed at the great finishes we get drilling using a spade drill. AMEC makes a great product, and you will have thru the tool coolant. But you must be certain that the drill is parallel and concentric with your spindle centerline. A little bit of error when using a long drill will cause you grief.

 

[TeachMePlease]

Talk to these guys. Assuming you can get high pressure coolant through your tool, their drills will make your size and finish no problem, and no drilling from both ends (What's the Z stroke on your machine?)

Drill Masters Eldorado Tool | DMETool.com

 

[doug8cat]

I agree call your tooling supplier + 1 or 2 others and make them do the leg work. You have enough other things to do I am sure.