Boring Bar recommendation

ranchak · Feb 16, 2017

I have to make some motor couplings out of 1018 with a 2 inch diameter bore, 4 inches deep. I have drilled the holes out to 1.75 inches. At the moment I am using a 1 inch boring bar that uses TCMT inserts. I am getting a poor finish and lots of squeal. Heavier/lighter feedrates, faster/slower speeds, nothing works. I have 5 inches of stickout which I can shorten, but I am thinking of going with a bigger bar. TMX makes a 1.5 inch bar that uses the same inserts. Am I wasting my time with this insert geometry? I really don't need an expensive high dollar bar in this diameter, any suggestions?

706jim · Feb 16, 2017

That 1" bar is pretty much at its limit at 5" overhang. For now, try shortening it to 4.1" just enough to prevent colliding with the part. But a 1.5" bar will be a lot stronger at either extension.

Mtndew · Feb 16, 2017

ranchak said:
I really don't need an expensive high dollar bar in this diameter, any suggestions?

It depends on what you consider to be high dollar, really.
A REALLY good bar would be a Sandvik 1-1/2" anti-vibe bar, and that would cost you upwards of $1,000. To me that's high dollar lol.

Are you just wanting a bar for finishing? Or for both roughing and finishing?
You can get the old standard CNMG 1-1/2" bar for a decent price. This can do both rough and finish. But you'll probably have to chop off a few inches from the 12-14" length it will come in.

ranchak · Feb 16, 2017

I'm looking for one bar to do both roughing and finishing. This is the bar I was looking at:

http://www.jtsmach.com/jtswebshop/CarbideTooling/CN948.asp

I'm not married to this insert geometry, I just don't have enough experience boring to know what works and doesn't

fmari --MariTool- · Feb 16, 2017

This will work just fine. It is 1.25 shank, if it hangs out 4.5 inches that is a 3.6 ratio. Nice and solid. Just $88. I never had much luck with TCMT inserts.

SOLID STEEL BORING BAR MariTool

Hazzert · Feb 16, 2017

fmari --MariTool- said:
This will work just fine. It is 1.25 shank, if it hangs out 4.5 inches that is a 3.6 ratio. Nice and solid. Just $88. I never had much luck with TCMT inserts.

SOLID STEEL BORING BAR MariTool

Agreed, I would at least switch to something in a CCMT/DCMT to decrease tip pressure and consider changing rads on the tool as well. Two out of three changes should get the squeal under control.

ranchak · Feb 16, 2017

Thanks Frank, what insert do you recommend?

fmari --MariTool- · Feb 16, 2017

Something like this but in a .015r. I just found out we dont have it so I am ordering a whole bunch. I think .031r may be a big big or a radius.

CCMT 8 deg diamond MariTool

Captdave · Feb 16, 2017

At the moment I am using a 1 inch boring bar that uses TCMT inserts. I am getting a poor finish and lots of squeal. Heavier/lighter feedrates, faster/slower speeds, nothing works.

TCMT inserts may work well in some applications, which one I have not found. CCMT are mostly what we use unless a taper is involved.
Good Luck!

alphonso · Feb 16, 2017

My first choice insert is WNMG for about 90% of my boring. The rest of the time I use DNMG or VNMG. Yeah, get a larger diameter bar.

gorrilla · Feb 16, 2017

Mtndew said:
It depends on what you consider to be high dollar, really.
A REALLY good bar would be a Sandvik 1-1/2" anti-vibe bar, and that would cost you upwards of $1,000. To me that's high dollar lol.

Are you just wanting a bar for finishing? Or for both roughing and finishing?
You can get the old standard CNMG 1-1/2" bar for a decent price. This can do both rough and finish. But you'll probably have to chop off a few inches from the 12-14" length it will come in.

WE have several different sizes of Sandvik De-Vibe bars. From 1 1/4" to 2". They are really good bars, but I wouldn't think necessary in this application. A WNMG bar, or a CNMG solid steel bar, in 1.5" should reach out far enough and be rigid enough to do this job. Personally, I like the WNMG the best, since we get 6 cutting edges to index to, rather than the 4 edges on the CNMG. Your going to use this bar again, later, so you might as well get the one that makes the most sense, and gives the best ROI.
You'll likely have to cut some of the tail off, as the bar is probably gonna come 12" long or so. With an 1.5" bar, you should hang out no further than 6".

ranchak · Feb 16, 2017

Thanks for all of the input. I went with the 1.25 inch bar from Mari Tool. The price was right and Frank was very helpful over the phone. When it arrives next week we'll see how well it performs, but I'm pretty sure I'm done with the TCMT inserts.

Captdave · Feb 17, 2017

Been buying Mari tools for years, you just can't go wrong shopping there. I have also found their a great source for custom ground tooling when the need arises.

dksoba · Feb 17, 2017

Frank's customer service is top notch. You CANNOT go wrong with maritool in my opinion.

ranchak · Mar 8, 2017

Well the boring bar arrived and worked flawlessly. Actually makes boring a pleasurable experience. I guess now I need to replace the other bars that I have with Frank's bars!

XD341 · Mar 8, 2017

I'm running a TCMT bar and insert from Widia right now in 316. I'm not hanging it out that much but I've been impressed.

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Boring Bar recommendation

ranchak

Cast Iron

706jim

Titanium

Mtndew

Diamond

ranchak

Cast Iron

fmari --MariTool-

Titanium

Hazzert

Stainless

ranchak

Cast Iron

fmari --MariTool-

Titanium

Captdave

Titanium

alphonso

Titanium

gorrilla

Stainless

ranchak

Cast Iron

Captdave

Titanium

dksoba

Hot Rolled

ranchak

Cast Iron

XD341

Hot Rolled

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