Got a hankering to buy a 1" boring bar for general purpose to have on hand. By the way, I have an Aloris BXA 4-D boring bar holder.
Borrowed my son's Kennametal and it was very well made and has a high price tag to go with it. I am thinking for my needs something less expensive would be adequate.
What bar and insert style/size would you recommend for general purpose work. I have 1/2" and 3/4" bars now and want to put a 1" one in the tool box.
I have a Kennametal 1" MCLNR boring bar that I got for $100 brand new. If you're patient you can find one for a good price & it doesn't have to be Kennametal. It seems like 1" MCLNR boring bars are an industry standard size, almost all of them that I have seen (at the time when I was purchasing) ar 12" long.
I prefer the SCLCR boring bars that use CCMT inserts. I only use CCGT inserts in them. My 3 smallest indexable bars all use the same size insert, 21.5x. I choose that route so I could use the same insert in all of them. My next largest is a 3/4" SCLCR that uses 31.5x inserts. I use this size CCGT inserts for turning quite often so again convenient.
Now my 1" MCLNR uses CNMG inserts which is not needed on my 1236 but I use CNGG or CNMP positive & ground geometry inserts so it's much more free cutting.
Bigger/thicker isn't always better though. A couple of weeks ago I had to bore a 3.25" ID tube 6061 that was 12" long boring from both end. The 1" Kennametal steel boring bar chattered as it got close to the 6" depth. I switched to my 3/4" solid carbide bar with CCGT insert & it took care of it no problem even with a 1/32" nose radius (32.52) insert. Could barely tell where the 2 bores met each other.
These are all my current indexable boring bars, all but the Kennametal are solid carbide.
BTW, what's the depth for a 3/4" and 1/2" steel bar respectively?
That will vary on workpiece material & insert type. For example a boring bar using DCMT inserts will be much more free cutting than one that uses CCMT inserts. All my boring bars use 55° diamond inserts. All but one (the 1" Kennametal) uses CCMT inserts as noted & seen above. A smaller nose radius will cut even more freely when you need to bore deep.
My take on boring bars is buy the longest you can find and/or afford. Even if you think might not need the length or it might not work well you never know when that extra length will come in handy & might work for the situation.
There was a seller on ebay years ago that sold solid carbide boring bars quite often. They always varied in lengths so you had to pay attention to the listings. I'm very happy with my 3 smallest indexable boring bars that are seen above. Got them for $30 - $50 ea. I for get who the seller was but I suspected it was a secondary account & name for JTS machinery. Funny cause I inquired once about a specific size boring bar, they quoted me like $300. I waited & they ended up listing the size boring bar I was looking for but in an even longer length for $50. That was for the 1/2" boring bar.