How to turn a Groove

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outsider347

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I have been practicing tool grinding with reasonable success.
So far ground R & L turning & facing tools & a general purpose turning tools. All worked well with reading my books & corrected grinding

Having spent the day & several new HHS bits attempting a round groove, the result always the same....
lots of chatter & howling.
Obviously missing something

Suggestion appreciated
Tks
 
Although I'm no expert on grinding tooling depending on what your trying to accomplish for example an o-ring groove I have had success with using a parting blade or threading tool. Probably not the "proper" way but it works for me.

Your mileage may vary
GT
 
Im new to the forum,. but not the machining game. A few suggestions for you. I dont know what kind of material you are cutting, but you have to slow the RPM down for grooving, lubricartion is also important when cutting steel. Not watery lub either but a nice thick threading type oil that lubricates rather than cools. Also, if the groove is wide with lots of tool contact, you might have to grind the tool narrower and rough out the groove in sections. Also, rigidity is imptant. Keep eevrything as short and rigid as possible. And that includes tightening up the gibb key on the compound. Sometimes when you get chatter, you can get it ourt by putting the machine in neutral and carefully rotating the chuck by hand while feeding in the tool carefully.
Also when you grind the tool make sure it is cleraranced properly with the sides narrower at the back than the front . And on the top watch how you grind the chip breaker . I like to hold the top of the tool on the face of the grinding wheel to get a nice large radius as a short steep one ofter causes the tool to dig in.
It is all practice.
Grooving and parting are two of the most frustrating operations on a lathe. It never alsways goes according to plan.Good luck.
 
More (setup) info

I am turning 1" aluminum, on centers to .875. The groove ( relief for threading) is .625 from the tail stock. Groove depth is .600.

While I was turning the work to the proper .875 I had a bit of chatter. Looked up turning aluminum in my Atlas operations book, &followed the suggestion to add more top rake 35deg. Nicely fixed that problem

when I added some lube (Tapmagic) the cutter stopped cutting . Just seemed to ride in the groove til the lube wore away, then took a gouge in the work. Pretty sure I have plenty of clearance. I'l recheck today. Haven't tried to part yet. Looks like that will be an adventure as well

I am using a QC tool holder, minimal tool extension seems rigid to me....then again, I'm pretty "noob" to all this

Thanks again Gents
 
If all you are doing is relieving a thread, just use a parting tool to cut the groove. With considerably less contact area, the parting tool will be much less apt to chatter. The Atlas is notorious for lack of rigidity, so chatter will always be an issue. Just make sure your set-up is as rigid as possible. That means minimal tool overhang, work overhang (cut your groove near the headstock instead of the tailstock), and compound overhang.

Tom
 
WHAT LATHE are you using,and is it worn badly? P.S.: I just checked your profile. A small Atlas is a very unsubstantial lathe. Turning a groove is NO TROUBLE. By the way,describe the WIDTH of the groove. Wide form tools CAN be a problem,if you're cutting a real wide groove .

As suggested,you might do it in steps. Then,I'd suggest using a round file to finish off the groove if your lathe can't cut it.
 
tom makes a good point about the compound, I'm new at this and i was having a lot of trouble and it was because i had left the compound out too far and the gibs were a little to loose. everything needs to be as close in as possible to the tool post mounting center that you can safely do.
one of the guys i watched on youtube said always start your setup with ridgidity in mind and you will end with a better finish. it really helped me with my 9x20 hf.
steve
 
outsider347 said:
More (setup) info

when I added some lube (Tapmagic) the cutter stopped cutting . Just seemed to ride in the groove til the lube wore away, then took a gouge in the work. Pretty sure I have plenty of clearance. I'l recheck today.
Click to expand...


That sounds like the toolbit is not on center. If the toolbit is above or below the lathe centerline for parting and grooving you can have a lot of problems.

Also try running the lathe about 75% slower than you did for turning. Speed can have a big impact when parting or grooving.

Hope this helps.

Sandro Di Filippo
 
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