Beginner : Bar for boring head

[ccfl]

I'm pretty sure all the generic brazed carbide bars are as unusable as that one.

Not true. When they are made properly, the cutting edge will be on center, whether the tool requires sharpening, or not. The example shown clearly displays a blank made with the mounting surface on center, so the only way the tip can be on center (in a boring head that holds that size shank) is if the bar is rotated, creating excessive negative rake. All in all, not a good tool.

Are there any brazed carbide boring bars out there that have the correct geometry?

These are surprisingly affordable especially when compared to something comparable from Kennametal or etc.

That's not a fair comparison, as price is not a good reason to purchase a tool that is not capable of performing the required task. This is a classic example of a case whereby the buyer would be much better served to pay for a more expensive tool that is capable of proper performance.

Maybe one of us missed something here. Is there something wrong with the Mesa Tool indexable bars (other than their being indexable and therefore have no place in the home shop/hobby environment so on and whatever)?

[Harold_V]

Are there any brazed carbide boring bars out there that have the correct geometry?

Sure! Even imports. Here's an example: http://www.ebay.com/itm/3-Pcs-Cabide-Br ... 1997462676

Maybe one of us missed something here. Is there something wrong with the Mesa Tool indexable bars (other than their being indexable and therefore have no place in the home shop/hobby environment so on and whatever)?

The point I tried to make is that buying a cheap bar isn't a good idea if it doesn't serve the intended purpose. I may have misunderstood your thoughts, though, as I now think the link you provided was for an inexpensive bar, one that uses inserts. I got the impression that the brazed bars were what you referenced. In that case, I apologize.

The bar in the link appears to be made properly, but it is also intended for use with a lathe. That doesn't mean you couldn't use it with a boring head, assuming the shank was the proper size. The one real negative is you have no choice in over-all length. Boring bars intended for use with boring heads generally permit installation in random orientation, so you can tailor the tool to the purpose, to say nothing of being able to choose various lengths, which limits spring and chatter. The other issue, which can be important, is that you can't introduce the bar to the bore with additional clearance, as you would using it with a lathe. Chips become troublesome when the shank is too close to the bore, as it would be with that specific bar.

I rarely encourage the home shop to pursue carbide, be it insert or brazed. Unless one has a machine that truly benefits from its use, HSS will generally yield superior results. The exceptions are when machining highly abrasive or hard materials. Otherwise, you can beat carbide's performance by properly grinding HSS. For boring, where tool pressure is always a concern, carbide simply is not a great choice.

Harold

[hobgobbln]

Oh wow, those Mesa bars are pretty cheap. I'll give one of those a try. And A.R. Warner has some TCMW HSS inserts that might fit. Thanks!

[earlgo]

There were either 4 or 6 'free' brazed carbide bars in the Shar boring head set that I bought, and they all looked like the pics seen here in this thread. That is why I had to modify the one I did, so it was useable for a small hole. So far it is the only one I have modified or used for that matter.
Ugly stuff, indeed. One gets what one pays for...

--earlgo

[warmstrong1955]

Oh wow, those Mesa bars are pretty cheap. I'll give one of those a try. And A.R. Warner has some TCMW HSS inserts that might fit. Thanks!

I have a couple Mesa bars, a threading tool, as well as 3 of their boring attachments.
Good stuff.

Bill

[hobgobbln]

I like the idea of the bar with two posts. The setscrews are to use different length posts to make the "boring bar" longer?

[warmstrong1955]

I like the idea of the bar with two posts. The setscrews are to use different length posts to make the "boring bar" longer?

I've never done that. I have always slid them in flush. The two posts are short, as well as the bores in the boring heads. Not a lot of adjustment there, without sacrificing ridgidity.
Big advantage is ridgidity. I bought them when I had a much less than ridgid mill. (3 in 1)
If you are boring larger holes, that's where they really excel. The cutting tool is closer to the quill, as the boring head goes into the hole, not just the bar. Helps a lot.

They are still my boring tool of choice, with my BP clone, for any holes or applications where they will fit.

Bill

[ccfl]

I have tried everything I can think of, and I am unable to make the carbide inserts not work like the old wives' tale says. I must be doing something wrong.

[Harold_V]

I have tried everything I can think of, and I am unable to make the carbide inserts not work like the old wives' tale says. I must be doing something wrong.

Blink! Blink!

Well, now I'm confused. If you're unable to make them not work, you must have achieved success.

Did you?

Harold

[Richard_W]

These cobalt boring bars are better than the brazed carbide bars in my opinion.


http://www.travers.com/premium-cobalt-b ... 0bar%20set

Reason being is the brazed carbide don't use a good quality steel to put the carbide on. Unless you pay the bucks for a quality name brand brazed carbide boring bar.

[pete]

I'd sure agree with Harold about using HSS while boring if the material is within it's capabilities. One of my UK published books also pointed out something along the lines of "it's impossible to get a better surface finish than the tools cutting surface condition" or something much like that and it's always stuck with me. The author was 100% right once I tried it out. A rough, dull cutting tool surface always equals a rougher surface finish.And HSS will cut with a lot less force than standard carbide does.Like many I first bought one of those boring heads that included the 9 pc boring bars and they finally soured me on any more off shore cheap cutting tools. After more money than I'd care to add up there's no such thing as cheap and good in the cutting tool world. There's lots of good braized and indexable boring bars around by more than a few manufacturers. And those A.J. Warner HSS tips will drop right into the correct seats if you buy the right bar first. That combination isn't cheap but do you want to bore the hole or rub the metal off in a somewhat round straight hole. More than a few others around, but for braized I finally bought Criterion bars. If anyone knows boring they sure do. And they worked just like there supposed to right out of the little blue boxes. But there's also lot's of others who make just as good to possibly better.

There's more than a few YouTube videos around showing exactly how poor those cheap bars are and why they can't bore. They could be improved a lot with a green silicon carbide wheel to rough them in and even a cheap diamond wheel spun up in a drill press to put a better edge on them. My Criterion bars were a fast, easy, not exactly cheap method that finally fixed the frustration level. Right out of the box those off shore boring heads aren't the easiest to get set to a measured bore diameter either. But there's also a few YT videos showing a few tweaks to improve them. Ignoring the dial and measuring the tools offset when adjusting it with dial indicator for large movements and a test indicator for the small ones was the best method I found until I finally replaced it as well. They can be made to work ok, but there's lots of used good condition 202's on Ebay for the same or less money. Almost $300 for a new one hurt but I'd still do the same again for the difference in results. There boring bars and heads do what they say they will.

I've had an argument on YT about the proper use of these boring heads and the off shore copies. Contrary to what a lot of people think only the center screw is used to lock the head in position after an adjustment. Criterion themselves say that in the instructions no one seems to read.The outer two are rarely used to only make gib adjustments after a lot of use. Oxtools on YT is no moron and he's found after years of usage that locking the head isn't even needed after adjusting a good head. I'm far less experienced so I still lock it just because it makes me more confident in the setting. It's tough enough to bore to an exact size and those cheap bars make it just about impossible. Good, sharp and correct cutting tools make everything much easier in my opinion. And there more than worth what they cost.

[Richard_W]

I have tried everything I can think of, and I am unable to make the carbide inserts not work like the old wives' tale says. I must be doing something wrong.

Blink! Blink!

Well, now I'm confused. If you're unable to make them not work, you must have achieved success.

Did you?

Harold

Using a good insert boring bar to start with really helps. I have been using a heavy metal 1/2" boring bar with no problem. Even running as fast as 2,000 RPM. Would have tried faster but the out of balance would start to shake the machine. The bar uses CCMT2151 inserts. Some of the imports insert boring bars must be made out of the wrong material or improper HT.

Richard W.