Interrupted cut tool

[randyjaco]

I keep hearing on this forum that one can't do interrupted cuts with a carbide insert. That maybe true with most inserts. Long ago I got started with diamond shaped inserts. It always bugged me that I got only 2 useful cutting sides. So I made a tool holder that made use of the useless obtuse angle sides. I found that this tool holder was great for roughing cuts. It works well on hard surfaces like welds and gas torch cutoff surfaces. It also has an amazingly ability to withstand the impacts of interrupted cuts. Just take it easy on the feed. One warning, my tool holder makes lousy finish cuts B-)
Try it, you'll like it.

 

[kd4gij]

I hear the same claim. I must be doing something wrong as I have never chipped an insert turning interrupted cuts.

 

[JimDawson]

I've never had a problem doing interrupted cuts with a carbide insert or brazed carbide tool. I guess I didn't know it couldn't be done

 

[Wreck™Wreck]

I find the trigon WNMG inserts excellent for roughing flame/plasma /laser cut material as well as interrupted cuts, have blown up several hundred corners on these inserts in the last several years but I tend to run everything way to fast with large DOC's. Also they are not mine which is a nice thing, my employer is not concerned about $6.00 inserts if I am banging out the parts as fast as possible.

In plain carbon steel there is no reason not to run them at 300 SFM at 1/8" DOC if the machine will do it. Have been running a job in 6061 round bars for the last several days, I shoot for 750-1000 SFM , the lathe would do it but the work holding became problematic and annoying.

 

[682bear]

We use carbide inserts 99% of the time at work and a lot of what we machine is interrupted surfaces... not a problem if you pay attention to your feeds and speeds. I typically use Kennametal VPGR 331/332 KC730 inserts.

-Beat

 

[Dabbler]

We have a group of hobby machinists here in my city, and we get together for coffee regularly. this came up at a meeting recently and about 6 of us pounced on it to dispell the misconception. Of the dispellers, 4 of them are full time machinists. The urban myth needs to be corrected to "carbide tools will shatter on interrupted cuts if you aren't careful!"

I use Kinnemetal triagular inserts (the design is from long before ISO and ANSI standardizations, so no insert #) on interrupted cuts all the time - by being very, very careful! Haven't broken one yet (jinx).

 

[Suzuki4evr]

Never had a problem with interrupted cuts or welding,but it does not like the surface that has been cut with a cutting torch. I try to go slow on those till I am through the hardest.

 

[Mitch Alsup]

I have both the 80º CNMG tool holder (sharper) and the 100º CNMG tool holder (obliquer) in order to use all the cutting points.