School me on boring bars please

[WhoWhatNow]

I just picked up an Atlas 12’ lathe and have a few projects that will require a boring bar. I figured I would try one that used carbide insters so I went to the Kennametal site and downloaded their catalog to check out what they offered. That’s about when my head exploded. What the hell am I looking at? Can someone explain what insert clearance angle and lead angle are and why do I care? I know I will need a right hand tool because the Atlas has a threaded spindle but what else should I look for? I am not going to be using this every day for 12 hours but I would like a nice one when I do use it. I figured I could watch eBay and pick a good one up cheap. What insert shapes are good for general boring and are readily available? For a hobby user does the insert holding method matter?

 

[Jarhead0408]

Sorry I can't contribute.

I was just thinking of all the boring bars I went to in my early 20's.

No too many good ones around here.

 

[A_Pmech]

Welcome to the wonderful world of indexable tools!

I strongly suggest you download or buy a copy of Sandvik Coromant's "Metalcutting Technical Guide." It's the best (perhaps the only) book on insert tooling and it's application.

Running a light machine, you will be machine limited, not tool limited. That is to say, the machine will give up before any tool you can buy will. Keeping that in mind, I would stick with positive geometry finishing inserts with small nose radii. Avoid wiper inesrts, negative inserts and roughing geometry inserts.

 

[Tig Master]

Join the practical machinist forum and get the info from the front of the horse.They are the experts very little chance of getting the wrong info.That is what they do.

T

 

[gtermini]

My favorite small bar is a 6' long 1/2" dia Kennamatal with a TPG 221 insert on a 5 deg lead angle (5 deg off perpendicular to the bar shank). Just plain and simple and does everything reasonably well.

Greyson

 

[Shadowdog500]

Join the hobby machinist forum. Lots if info and are targeted for hobbyists.

Sorry, but My boring bars aren't indexable so I can't answer your question.

Chris

 

[Letsgobowhunting]

I love the comment about the boring bars when in the 20's and also the comment about the 6 foot 1/2" boring bar. I play with a lot of machine tools, i just bought another lathe today. I would not suggest you buy Kennametal or Sandvik unless you get it on fleabay. They are the most expensive because they are the top two manufacturers. I personally do not recommend a bar with TPG inserts. They are some of the oldest geometry available. I would recommend a CCMT inserted bar as it should reduce the cutting forces more than a lot of other bars. If you stick with an ISO standard with most geometries are than it doesn't matter who's bar you buy or who's insert you use. Fleabay if by far the best place to buy for the home shop DIYer. This is just my opinion. I do make a living on my opinion though.

 

[wyo george]

Sandvik tools are pricey, but they are well worth it in my opinion. I use them daily as a machinist working on oilfield equipment. Some days I turn parts that will fit in my shirt pocket and other days I'm spinning a 120" (yes, ten feet) chuck with 25,000lb parts in it. In the early days we tried cheaper tooling and the quality work was subpar as well as the life of the tooling.

FWIW, If you are shopping for used tooling, just make sure you can easily purchase inserts as some outdated styles have little options left.

 

[zach540]

Personally I have this model from The Little Machine Shop: http://littlemachineshop.com/products/product_view.php?ProductID=1721&category=

However, I haven't used it enough to compare it to other brands or types. Be sure to check what MSC, Grizzly and Enco has available while you are shopping around.

Zach