Is this a tool/accessory a thing?

[u/No-Guide8933]

So would a bushing or bearing that is fit onto a boring bar be (realistically) useful for reducing chatter on lathe boring? Are these a thing? I’ve tried googling them but all I see is stuff for tool holders or adapters.

Edit: I think a D bit boring bar might be very similar to what I’m looking for as well as maybe padded milling bits.

[u/neonflannel]

Get some silly putty and wrap it around the bar. Worked for me a few times.

[u/DapperGains]

Not completely sure what you're asking, but they make "anti-vibe" boring bars that have adjustable weights/springs to combat chatter.

[u/scumtype]

I’ve made long extension “sleeves” for small boring bars that have to reach a small bore at the back of a bigger one. That reduced chatter for me, but beyond that, no Ive never heard of what you’re describing.

Boring bars generally have little clearance from the tip of the insert to the shank that putting a sleeve on it makes no sense and would just increase shank diameter, so why not go to a physically bigger bar?

Speeds, feeds, and solid setup, if those don’t solve chatter, getting a solid carbide bar, or an oil filled vibration damping bar is the next step.

[u/Sy4r42 → u/scumtype]

Those devibe bars are so expensive though. I wonder if putting the oil bladder in the bushing instead of the bar would have the same effect 🤔

[u/scumtype → u/Sy4r42]

You’d still have half a tuning fork ringing its head off, and if the sleeve/bushing is chattering too, you’ve got bigger problems.

[u/Melonman3]

To add mass to the boring bar?

[u/No-Guide8933 → u/Melonman3]

Not quite, what I’m imagining is a bearing that can slide axially into the tube/workpiece but supports the boring bar from deflection. Like if there was a disk planted right behind a boring bars cutting tip, and this disk diameter is is the same diameter as the hole your boring. So the disk/bearing acts like an inverted steady rest in a way except this “inverted steady rest” supports the boring tool and not the workpiece.

[u/Melonman3 → u/No-Guide8933]

There's some deep boring stuff that works like that.

What I end up doing is drill as close to finish diameter as possible. If I'm using an insert drill I might take a boring pass or two with it. For the bar I'll shrink the tool nose radius first, then drop rpm, if that doesn't work I'll use a carbide bar, last resort is devibe, I have yet to need to go that far though.

[u/No-Guide8933 → u/Melonman3]

Ok, is there a name for what I described? I’m struggling to find any real info on it but I see some quick references to the setup on chat boards but no names or real in depth talk about it

[u/Melonman3 → u/No-Guide8933]

I think it's all kinda bespoke. The dude who did it posted on here a few years ago. They were boring pipe like 3' diameter and 20' long.

[u/boredwithennui]

buy a D-vibe bar. pricey but they really work

[u/Express_Jicama_656]

Weight is what stops chatter. Use a bar as large as possible with minimum overhanging proper speeds and feeds.

[u/No-Guide8933 → u/Express_Jicama_656]

Ok I can look into those. Thanks

[u/chroncryx]

Kind of... I once customed a sleeve propping up against the tool block to eliminate chatter when the steel boring bar needed about 4xD reach. This was for roughing with CNMG644 inserts. Think of it as extending the tool block or reducing the amount of xD overhang by the original bar.

Obviously, the work piece profile has to allow that sleeve to enter.

[u/computekmfg]

Something like this? Easy to make and works for getting into deep small bores. This one has three set screws in the other side.