[SEL] OT lathe tooling for copper facing.

[John Hall]

We don't cut a lot of copper but when I do, I use a positive rake insert 
with a ground cutting edge. These inserts work great on plastic and 
aluminum. The brand I use is Vardex (VNE corp). I believe the prefix is 
CCGT. We have 2 styles--with and without chipbreaker--just depending on what 
you are doing.  These are pretty much an 80 deg insert but there is only 2 
cutting edges---they will not fit in holders for CNMG inserts. Sometimes the 
manual machinists even use these on steel when the matl. is soft, gummy, or 
they just can't get enough SFM for regular inserts. I know these inserts are 
available as a 3/8IC so you should be able to get a holder for your lathe. I 
just ordered one for our little lathe acouple weeks ago--I think it was a 
1/2" shank---but thats what milling machines are for.


In the CNC lathes we run a semi-synthetic coolant. On the manuals we would 
use oil,or kerosene. I would think diesel or WD-40 may also work. Many years 
ago we had an old timer that used bacon grese for threading copper. He kept 
it in a coffee cup so he could easily heat it up for applying.

You probably want to stay away from "yellow" inserts--thae material will 
probably just build up on them rapidly. There are all sorts of coatings 
available---some of them may help.


John Hall
----- Original Message ----- 
From: "Curt" <curt at imc-group.com>
To: "SEL" <sel at lists.stationary-engine.com>; "SEL (Oldengine.org)" 
<stationary-engine at oldengine.org>
Sent: Friday, January 12, 2007 10:22 AM
Subject: [SEL] OT lathe tooling for copper facing.


> Fellow machinists, a lathe tooling question for you.....
>
> When using carbide insert tool holders, how does one determine when to use 
> negative rake vs. positive rake tool holders?
> Are triangled inserts the best for facing? Or would round be better? Or 
> some other shape?
>
> MSC doesn't have a lot of small clamp style indexable tools. The shank 
> will need to be 7/16 square with an overall length of 3".
>
> Will be facing copper samples in our lab here at work. Want the smoothest, 
> brightest surface possible to lessen hand polishing after turning.....
> Curt Holland
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