Deep bore with mini boring bar

CMaier said:
Al,
'splain why ?
why can't you torque in place and then true ?
i am a big believer in torque wrenches for repeatability.
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If you have a precision fit torquing it may, "MAY" register itself back in line. When you assemble two parts foreign to each other and torque them they will create a fitup that they may repeat. But, unless they are of close tolerance each part torqued together will not take the same set.

Quote Originally Posted by CMaier View Post
i was under the impression the carbide wants high speed not slow speed.
i use a micro100 long small bar ...i try to turn the speed up when using it.
???
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Carbide has speed limits just as HSS does, it's just a higher sfpm, but you can over do the speed and burn the edge off of carbide. The biggest mistake most do when they use carbide is to spin the work too fast and not increase the feed and depth of cut. Carbide's sweet spot is .030-.050 finish dept with quality steel in lathe work.
 
Mitsubishi "Micro-Dex"

Get a Mitsubishi solid carbide SCLC type boring bar that takes the CGCT inserts: http://www.mitsubishicarbide.com/application/files/7214/4643/8970/b042g.pdf

You can go down to a 0.200" hole 2" deep with these boring bars with a 0.0025" feed at 1300 RPM and a 0.015" DOC. Get the inserts with a 0.007", or better yet a 0.004" nose radius. I regularly do interrupted cuts with this insert (TiN coated version) in muzzlebrakes. I can get 30-40 brakes before I have to index the insert on a manual lathe running dry. I typically bore 0.010 under final bore diameter and finish with a chucking reamer. Make sure the boring bar is set exactly on center, or if you still have trouble getting a good finish, set the bar 0.003" above center.
 
Greg Walley said:
Get a Mitsubishi solid carbide SCLC type boring bar that takes the CGCT inserts: http://www.mitsubishicarbide.com/application/files/7214/4643/8970/b042g.pdf

You can go down to a 0.200" hole 2" deep with these boring bars with a 0.0025" feed at 1300 RPM and a 0.015" DOC. Get the inserts with a 0.007", or better yet a 0.004" nose radius. I regularly do interrupted cuts with this insert (TiN coated version) in muzzlebrakes. I can get 30-40 brakes before I have to index the insert on a manual lathe running dry. I typically bore 0.010 under final bore diameter and finish with a chucking reamer. Make sure the boring bar is set exactly on center, or if you still have trouble getting a good finish, set the bar 0.003" above center.
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Plus a whole bunch on this.

Keep in mind, once you get a truly straight hole bored, a reamer will follow it. You can get small chucking reamers in .001 size increments at any large tool house.
 
thank you mike and richard, i had no luck also and was going
to ask the same question.
 
Thanks for all the tricks and advices. I came up with a solution that is working really well. As I said I was boring from the back after threading the brakes and my boring bar was hanging too far.

I made this boring bar holder that hold the bar all the way in the brake threaded area leaving just enough bar hanging for the boring. I gave the tool a slight negative angle and voila I was able to bore and had a nice mirror finish.

Don't mind the surface finish of the tool, I have a lot of 1018 on hand and did not take the time to get that nice shinny finish



GST
 
Rflshootr said:
In the meantime, try taking a piece of 3/8" or 1/2" round stock about the length of the spacing of 2 of the set screws on your tool block plus 1 1/4" and drilling a hole for the bar to side neatly into. Split the stock lengthwise on 1 side with a hacksaw so that when you clamp it the sleeve collapses around the bar. Hang the bar out of the sleeve the length you need to bore the small hole plus about 1/8".
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Hmmm imagine that ;) and you didn't have to spend any money. Good thinking:D
 
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Received a MSC sale catalog in the mail today. They have the Hertel F series 1/4" carbide bar with 10 inserts on sale as well as a 3/16" diameter carbide boring bar with 10 inserts on sale as well. The 3/16" bar is very similar in style to the Mitsubishi bar that Greg Walley had posted in this thread previously. A little larger in diameter than the 4mm diameter Mitsubishi.
 
Mike Bryant said:
Received a MSC sale catalog in the mail today. They have the Hertel F series 1/4" carbide bar with 10 inserts on sale as well as a 3/16" diameter carbide boring bar with 10 inserts on sale as well. The 3/16" bar is very similar in style to the Mitsubishi bar that Greg Walley had posted in this thread previously. A little larger in diameter than the 4mm diameter Mitsubishi.
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I just got one of those 3/16 carbide bar yesterday and it looks like it will do great
and takes the same inserts as my 1/4 carbide circle bar from widia.
 
CMaier said:
i was under the impression the carbide wants high speed not slow speed.
i use a micro100 long small bar ...i try to turn the speed up when using it.
???
Click to expand...

Carbide does not "want a high speed" it is just better at resisting the heat generated.

It is at its best in large cuts and higher speeds common in industrial settings repeating the same cut over and over.

It can pay for itself in down time for switching out cutters in demanding applications.

Solid carbide boring bars do have a decent stiffness that can be useful in some applications.

Just watch out for less than solid setups.
They do not tolerate flex well and simply crack.
 
I'm running a BXA sized Aloris tool post with an Aloris tool holder for a 5C collet. It works very well for holding the 1/4" or 3/16" diameter boring bars with the appropriate sized collet.
 
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