Solid carbide boring bar in the 3/4"-1" range question

I've been working on the castings I mentioned a few weeks ago. Bought a Mit bore gauge and it works well. My 1" steel boring bar with sharp CCMT/CCGT inserts (forget which) worked fine for the outer and inner bearing pockets but there's a seal pocket deeper still that it was wanting to sing a bit on.

Looking real quick at Maritool they go up to a 3/4" solid carbide boring bar that uses those inserts and rate it at 10x extension even in steel. These castings are aluminum. I'm taking light cuts. Extension will be right around that 10x range. My question is, should I find an even stouter carbide bar- my Aloris will take up to a 1" bar of normal construction, I.E. with flats- or is the 3/4" bar really "all of that".

My only experience with carbide bars is really small ones I've used- and love- for gunsmith type work or other small boring jobs. The small one I have is indeed MUCH more rigid than the similar steel version I also have.

Thanks guys.

At the bigger sizes, IME the rest of the toolholding setup and the machine itself matter as much or even more than the bar itself. IOW, a 3/4" carbide boring bar can simply transmit its vibrations into the toolholder, turret, carriage, etc.. 1/2" boring bar is less likely to do that.

End result is that a 3/4" carbide bar, even though stiffer than a 1" steel bar, might not work any better.

I have a 3/4" carbide bar, and in my Mori Seiki SL-2, it works about as well as a 1" steel bar, same inserts, same extension, same holder, same F&S.

Regards.

Mike

When ever I do such operation, I set the tool up and do a face cut on a sacrificial stock and confirm that cutting tip is just below center. Being sure the tool is extended and mounted as will be used to bore. Disclosure: I am a redneck.

Long Tom said:

Looking real quick at Maritool they go up to a 3/4" solid carbide boring bar that uses those inserts and rate it at 10x extension even in steel. These castings are aluminum. I'm taking light cuts. Extension will be right around that 10x range. My question is, should I find an even stouter carbide bar- my Aloris will take up to a 1" bar of normal construction, I.E. with flats- or is the 3/4" bar really "all of that".

Click to expand...

Is the 1" upper limit because of bore size or your tool post?
I'd consider "customized" boring bar or some alternative means of mounting the boring bar if bore size allows 1.5 or 2" steel bar.

In those sizes the Silent tools from Sandvik might be the thing.

+1 on the Sandvik "silent" boring bars.....But you have to be running a job that pays...those bars are $$$$$$$
Can find them on E-bay at savings if you are lucky.

Cheers Ross