Will be boring some brass tubing (to about .75" diameter 5" deep) on a smaller machine. 1 hp - max boring bar of .5" shank. I was thinking of getting a 6" boring bar - zoro has a few from dorian but I am not sure which to go for. Positive rake CCMT was where I was leaning but I am happy to hear suggestions.
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Looking for boring bar suggestion
- Thread starter Abeship
- Start date
- Replies 9
- Views 1,978
Terry Keeley
Titanium
- Joined
- Oct 18, 2005
- Location
- Toronto, Canada eh!
I just got one of these Dorian boring bars and was finally able to do some good work on my under powered, less than rigid little Clausing mill:
Dorian Boring Bar, TPBN8-2, RH, .59 In 733115566 | Zoro.com
I used some "super positive" rake inserts for the gummy 1018:
ISCAR Cutting Tools - Metal Working Tools - TPGT-SP
Not positive but think you want zero rake for brass tho...
Dorian Boring Bar, TPBN8-2, RH, .59 In 733115566 | Zoro.com
I used some "super positive" rake inserts for the gummy 1018:
ISCAR Cutting Tools - Metal Working Tools - TPGT-SP
Not positive but think you want zero rake for brass tho...
sfriedberg
Diamond
- Joined
- Oct 14, 2010
- Location
- Oregon, USA
If you are going 10X diameter deep, spend the money for a carbide bar. (The bar itself, not the inserts.) It will be much more expensive than a steel bar, but also much more rigid. Going 5" deep with an 0.5" diameter bar, you need all the help you can muster. Even with a stiff carbide bar, you should probably choose one with a very low lead angle on the cutting edge (0 degrees or no more than 5 degrees) to minimize deflecting forces.
And as Terry Keeley correctly says, you will want zero rake inserts for brass, not shiny sharp positive rake inserts. Reason: brass is very grabby and will suck your cutter right in.
And as Terry Keeley correctly says, you will want zero rake inserts for brass, not shiny sharp positive rake inserts. Reason: brass is very grabby and will suck your cutter right in.
Mike C.
Diamond
- Joined
- Nov 25, 2004
- Location
- Birmingham, AL
If they have a bar longer than 6", you might want to go that route, since a 5" deep hole will leave you less than an inch in the tool holder.
Panza
Stainless
- Joined
- Oct 23, 2005
- Location
- Lillehammer, Norway
Iscar have some boring bars with triangular inserts that have very little radial stickout, so the bar can be almost as big as the hole. Boring bars for CCMT insert usually have a larger radial stickout. The drawback of low stickout is off course clearance for chips. But sometimes rigidity is more important.
Limy Sami
Diamond
- Joined
- Jan 7, 2007
- Location
- Norfolk, UK
You don't say qty, but few just a few I'd brew my own, a bit of 1/8'' dia HSS (aka broken centre drill) in the end of a piece of 5/8 bright steel bar, and mill a couple of flats if it won't fit in the toolpost.
Properly centred a 5/8 bar will fit down a 3/4 bore easily, and a small radius zero rake SHARP/I](as in oil stoned) will cut brass to a good finish with zero vibration problems.
Easy peasy, an hour or so's time, and next to zero $$
Properly centred a 5/8 bar will fit down a 3/4 bore easily, and a small radius zero rake SHARP/I](as in oil stoned) will cut brass to a good finish with zero vibration problems.
Easy peasy, an hour or so's time, and next to zero $$
Onepass
Hot Rolled
- Joined
- Jun 2, 2014
- Location
- Kansas City
+ for Sammi. I'd go with a 5/8" bar over 1/2 for that depth. Hell, even an 11/16" diameter with just the end turned down. I imagine you are going to drill out the majority of the stock and taking only a finish cut or two- not much chip production to get in the way
AlfaGTA
Diamond
- Joined
- Dec 13, 2002
- Location
- Benicia California USA
I second Sammy's post above with the additional note...Going that deep per diameter the largest problem is chatter.
long bars vibrate that is why Carbide bars work better...
If doing a home brew bar as Sammy describes i would add the feature of tapering the bar...Max diameter where the bar gets to the tool holder,(flats if needed to hold) then tapered to the end where the tool bit is clamped..
A tapered bar resists chatter better than a straight bar owing to the changing section along its length.
Cheers Ross
long bars vibrate that is why Carbide bars work better...
If doing a home brew bar as Sammy describes i would add the feature of tapering the bar...Max diameter where the bar gets to the tool holder,(flats if needed to hold) then tapered to the end where the tool bit is clamped..
A tapered bar resists chatter better than a straight bar owing to the changing section along its length.
Cheers Ross
PackardV8
Hot Rolled
- Joined
- Jun 4, 2006
- Location
- Spokane, WA
And bronze is even worse. I needed a custom bushing to pilot a reamer (installing oversize lifters in a Studebaker Champion engine) and thought a bronze valve guide would be perfect. It needed to be 1/2" ID and 5/8" OD. We didn't have a boring bar that small, so spent an hour trying to drill and ream the ID. It grabbed the drills, dulled and grabbed the reamer; some of the worst stuff to work with I ever tried. Next time, cast iron or aluminum or plastic, but not bronze.
jack vines
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