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View Full Version : Boring bars suck, use endmills instead



Elninio
05-06-2013, 07:17 PM
I noticed that I can't bore at all with chinese boring bars of all kinds; light cuts big bars. I can bore deep with chinese endmills, small diameter heavy cuts. This isn't my setup, but to give you an idea:
http://i141.photobucket.com/albums/r58/cucvzuz/P8081149.jpg
http://i.imgur.com/m2CrRIM.jpg
I just ordered a 3" long 1/4" solid carbide (made in canada, not chinese) on ebay, less than 10$ shipped.
Also available in extra lenght:
http://i.imgur.com/VeUYXmM.jpg
Often, there's the choice between TiAlN and uncoated:
The fundamental reasons why TiAlN coatings outperform pure TiN coatings are considered to be:
- Increased oxidation resistance at elevated temperatures due to the formation of a protective aluminium-oxide layer at the surface
- Increased hardness in the freshly deposited films due to micro-structure changes and solid solution hardening
- Age hardening of the coatings at temperatures typical for cutting tools operation due to spinodal decomposition of TiAlN into TiN and cubic AlN
5" bore, back in the day:
http://www.old-picture.com/american-legacy/012/pictures/Boring-Inch-Gun-5.jpg

Ron of Va
05-06-2013, 07:39 PM
I don’t know if your are buying an insert style boring bar, specialized for boring heads, or using a solid carbide endmill inserted into the head.

I have never seen the insert style you posted, but any flex in your setup and you will snap a regular “solid carbide” endmill like a dried twig.

(I have had good luck using Mesa boring bars in a Criterion head. They also make one a little beefier sold as a “boring head attachment”.) Made in the USA.
http://www.mesatool.com/products/boring-bars/

Elninio
05-06-2013, 07:44 PM
I don’t know if your are buying an insert style boring bar, specialized for boring heads, or using a solid carbide endmill inserted into the head.
I'm using solid carbide endmill, and I have some HSS endmills too that I use on the lathe and in a boring head. The 'dimple bar' boring bar is a boring bar by mitsubishi that shows better surface finishes because harmonics are reduced due to less mass in the end of the bar. The profile of that bar is important too, so that it is more rigid than a conventional boring bar. Those endmills aren't specialized for anything.

A.K. Boomer
05-06-2013, 07:46 PM
Never even gave it a thought - why not? I could see it being ideal in "certain" situations,,,

could also see it lifting a thin piece out of it's mount once you push it past the initial cutting area...

Elninio
05-06-2013, 08:22 PM
Never even gave it a thought - why not? I could see it being ideal in "certain" situations,,,

could also see it lifting a thin piece out of it's mount once you push it past the initial cutting area...

Lifting how? One thing you can do with these carbide bars is to bore the shank of a larger HSS endmill, and machine a stub down a steel bar, then shove them together and braze them for extra lenght.

A.K. Boomer
05-06-2013, 08:25 PM
Lifting how?

The spiral...

oxford
05-06-2013, 09:01 PM
I recently used one for a boring operation in the lathe. It may not be a total replacement for boring bars but I like using it.