Thanks!
Do you think a "P" insert (11¡ã) would help? It's only 6¡ã but better than the 2 I have now.
cnc sales <gcode.fi@...> wrote:
?
Hi Ryan !
For good results, boring holes are typically limited to about
1.5-2x boring bar diameter.
As such, a 3/8 boring bar is only good to about 1/2 inches.
After this it will chatter with variable results.
All lathe tools work well only upto about 1-3x their size.
Ie a 1/2 inch tool will only work well to 1-1.5 inches deep.
However..
Alu is easy.
Your problem is rake.
CCMT is 7 degrees positive and you need to maintain this,
*especially* when doing deep bores.
With a -5 degrees boring bar, you are losing the benefits of the
insert, and greatly increasing the problems of the overly long,
slim, thin bar.
It *can* be done with a 3/8 in alu but not well, imo.
You need to have at least 7 degrees rake, even? a bit more.
If you can make (buy) another bar (any steel) of near .7 inches,
and have the bit be at zero-1 degree rake, it will go vastly
better.
For alu, at .75 inches or about 18 mm, I would recommend about
1000 rpm, 0.1 - 0.06 mm cuts.
?
Hi group!
I recently bought a 3/8 indexable boring bar that uses
CCMT inserts. The bar has 5¡ã negative built in. I'm using
CCGT high polish 21.51 inserts and have a huge amount of
chatter. I'm doing a 3/4 inch diameter hole just over 3"
deep in 6161 aluminum.
I've tried the bar above center and on center. Above seems
to chatter a bit less but I still can't get a nice cut.
Wrong insert, bad setup? Do I need a different bar? Just
too deep of a hole and I'm going to have to live with it?
Any tips, tricks, hints, etc will be greatly appreciated!
Ryan
--
-hanermo
