Have just fitted my new Glanze boring bar into my new tool holder. After more years than I care to remember I am upgrading to Quickchange Indexble tooling.
Am I mad or is the Glanze boring bar really down turned by 15 degrees?
As it has flats machined on it I assume it goes into a normal toolholder. If it was rounf I would put in a vee grooved holder and set the rake as I wanted!
Me mucho confuso
See photo
you got it right, if you look at it from the end the cutting edge should be on the center line.
DA
(08-17-2014, 02:53 PM)dallen Wrote: [ -> ]you got it right, if you look at it from the end the cutting edge should be on the center line.
Cheers for the quick reply dallen
But 15 degrees negative rake seems a huge neg rake angle.
I am more used to HSS boring bars being a few degress positive for generale use!
its the way the bar is made, I think you will find that it will work just fine once you get used to it, by rotating the insert they don't have to under cut the rake under the insert,
DA
Rotating the insert also enables the bar to be used in a smaller diameter hole that would otherwise be required. The top geometry of the insert will also play a part.
(08-17-2014, 02:53 PM)dallen Wrote: [ -> ]you got it right, if you look at it from the end the cutting edge should be on the center line.
Cheers for the quick reply dallen
But 15 degrees negative rake seems a huge neg rake angle.
I am more used to HSS boring bars being a few degress positive for generale use!
to start with set it up on the center line take a few passes thru a part, depending on the insert that you have on the bar will determine if you need it a above or below the center line.
what type insert is on the bar.
DA
You can find "pos-neg" inserts for that boring bar. These inserts have a very high positive rake on the top form geometry (chipbreaker) to help counteract the need to tip the insert so much for clearance inside smaller bores.
Hard to see what style insert that is from the end view, but given the width of it I'd have to guess its a TNMG322 (ANSI designation) or TNMG160308 (ISO designation.) There are some inserts available for those type of bars that are made specifically for boring operations, as the cutting characteristics are so different than when turning an O.D.
(08-18-2014, 06:29 AM)PixMan Wrote: [ -> ]Hard to see what style insert that is from the end view, but given the width of it I'd have to guess its a TNMG322 (ANSI designation) or TNMG160308 (ISO designation.) There are some inserts available for those type of bars that are made specifically for boring operations, as the cutting characteristics are so different than when turning an O.D.
The inserts are ISO DCMT 070204
Used it today and it worked fine. However as it only 8 mm it is a bit springy (to be expected) but it will start off in a small hole!
Choking it up in the holder, so that only enough of the bar protrudes to just clear the rear of the bore (plus some wiggle room) will reduce flex. Also, once the bore is large enough, you can angle the bar away from the centre line, which will also reduce flex.