Ebay Boring bar - Good deal or waste of money?

[Tekno_Cowboy]

Noticed an indexable 3/8" boring bar for about $20 on ebay today, wondering if it's worth the money, or if I'd be alot better off just saving up for something else.

Here's the link, let me know what you think...

 

[precisionworks]

That's not a bad price on the bar, and the inserts aren't expensive either.

Also, if you need a larger diameter bar, look at the ones from Mesa Tool. Imported, but decent quality, fast shipping, etc. I bought three of their 3/4" diameter bars for my 3" boring head.

http://shop.ebay.com/merchant/mesa-tool

 

[Tekno_Cowboy]

Thanks, I'll probably pick one up sometime soon.

Do you have any recommendations for an affordable indexable internal threading tool?

 

[Anglepoise]

Noticed an indexable 3/8" boring bar for about $20 on ebay today, wondering if it's worth the money, or if I'd be alot better off just saving up for something else.

Lots of differing opinions, but I would strongly suggest you pass.

Quality American,Japanese or European ( Sandvik) tooling is really worth it.

And they don't have to be new, but give some thought as to what you are going to be using your lathe to build.

If its flashlight related, then I would recommend a triangular, positive insert so you have 3 tips as opposed to 2.
Triangle shape works well for boring and turning so the same insert can be used in both tool holders. Under no circumstances get negative inserts. Positive only for light machines, to cut down on lack of power, vibrations and the fact that you might ( flashlights) be dealing with thin walls.

Also top rake insert geometry is so important. For aluminum, Sandvik recomend 20° at the tip and 25° further down. They call this geometry AL.

Also for aluminum, get a ground super sharp finish by specifying 'H10'
that is uncoated carbide that is perfect for Aluminum and as it just happens is also very good for Ti and SS ( small finishing cuts in Ti and SS only, due to AL geometry. Expect to pay retail $10 per insert and $100 for a holder, boring or turning. If your toolpost can handle 1/2" square shank, get this. Prices on ebay will be less.


So TCGX 2(1.5)1-AL H10 would be my sugestion as a superb all around insert that will be worth every penny.

NOTE:

The above sugestion is bases on the presumption that your depth of cut
will be low. Then I think this one insert, with its 7° positive front rake will work for boring as well as turning. If you were to take large cuts when boring , 11° would be prefered so the second letter would be 'P'

EXAMPLE TP** *****-**

Hope I have not confused you too much........

 

[Tekno_Cowboy]

While I understand that quality tooling is much better, I have a very limited budget at the moment. I just noticed that LMS carries these bars for about the same price, when you figure in shipping.

I guess I'll have to think about it for now, and concentrate on improving my skills first.

 

[jhanko]

I don't mean to be cruel, but that boring bar is junk. Poor quality steel that will flex & sing. There are many tools that you can get away with lower quality, but a boring bar isn't one of them. For instance, a cheapo turning or facing tool can do a great job, as there very little overhang, and the steel quality will play little or no role. Especially on a mini-lathe. A boring bar on the other hand has to deal with large overhangs, and to make matters worse, you can't see what the cutters doing. Quality steel will really show it's worth while boring. The first thing you will probably learn on the lathe is what not to do. The second will be how to make due with the tools you have. The third will be figuring out which tools just won't cut it and end up in the trash, replaced by the tool you should have bought in the first place...

Jeff

 

[Tekno_Cowboy]

Thinking back, I can remember more than a couple times that that has been true for me.

Looks like there's no getting around getting the right tool sometimes...

 

[precisionworks]

that boring bar is junk. Poor quality steel that will flex & sing

If you figure that any steel shank bar has a maximum extension of 5D (five diameters), a bar .375" diameter will be extended no more than 1.875" ... call it 2" maximum extension to keep things simple. It's nearly impossible to find a bad bar in smaller sizes, as long as the insert pocket is a good fit for the insert. If you get a warm, fuzzy feeling because your bar is marked Valenite, Iscar, or Sandvik, that's good - because they perform no better in the smaller diameters than the less expensive bars (1/2" and under).

At 3/4" diameter, where extensions can reach nearly 4", better bars have the edge. That said, the bars from Mesa Tool have produced accurate holes when used in my boring head.

If you need to bore deeper than 5D, solid carbide shanks allow great extension. Up to 10D is possible if the setup is dead nuts rigid & all the parameters are correct.

for aluminum, get a ground super sharp finish

+1

If you haven't started using aluminum specific inserts for turning, facing & boring, you don't know what you're missing. My most used tooling holds a CNMG-432, which is a negative rake insert. The manufacturers take that shape and mold a high positive rake face with sharp (no land) edge. LatheInserts.com sells them for $54 per ten pack, which is dirt cheap. http://www.latheinserts.com/main.sc

 

[precisionworks]

10" South Bend, 1.750" boring bar (Pafana brand). Nice for larger ID jobs

 

[jhanko]

If you figure that any steel shank bar has a maximum extension of 5D (five diameters), a bar .375" diameter will be extended no more than 1.875" ... call it 2" maximum extension to keep things simple. It's nearly impossible to find a bad bar in smaller sizes, as long as the insert pocket is a good fit for the insert. If you get a warm, fuzzy feeling because your bar is marked Valenite, Iscar, or Sandvik, that's good - because they perform no better in the smaller diameters than the less expensive bars (1/2" and under).

I've had both. I started out with a chinese 3/8" bar and got frustrated with it fast. I later got a great deal on Ebay for a 3/8" Sandvik bar. There was a big difference between the two. I didn't get a warm, fuzzy feeling with the Sandvik, but I loved the fact that I had to do less finishing passes (due to less flex).

Jeff

 

[wquiles]

I have had "normal" boring bars, and then thanks to modamag got to try solid carbide bars (still very affordable on Ebay) - man, what a difference. Today, almost all boring that I do is with the solid carbide bars

I would pass at this one, and look for solid carbide bars on Ebay instead. I just sold two of these to darkzero - I think they were around $50 each on Ebay, of course I sold them even cheaper than that as mine had some minimal wear marks

Will

 

[jhanko]

I have had "normal" boring bars, and then thanks to modamag got to try solid carbide bars (still very affordable on Ebay) - man, what a difference.

+1. Carbide bars are an excellent investment. They may be costly, but are worth every penny. I just got a 1/2" carbide bar, and I'll be buying other sizes when great deals come along...

 

[old4570]

Tin coated inserts ????

Or titanium nitride coated inserts ... ??

 

[precisionworks]

Tin coated inserts ????

Or titanium nitride coated inserts ... ??

Yes & no

One of the earliest tool coatings is TiN (Titanium Nitride), which is a gold colored, ceramic coating. It was first applied to cemented carbide milling inserts in 1985. It is so inexpensive & so common that even HF uses it on their drills (although that may be just gold spray paint). You mostly see TiN on lower cost tooling & inserts. Hardness is 81 Rc, and CF (coefficient of friction) is .40, with a max temp of 1000 deg F.

A more popular coating today is TiAlN (Titanium Aluminum Nitride). The color is purple-black, and it's used in tougher materials that generate higher heat at the cutting edge. Max temp 1350 deg F.

AlTiN (Aluminum Titanium Nitride) is good up to 1450 deg F, and is normally run dry. AlTiN coated endmills should be run fast enough to generate sufficient heat to form a hard aluminum oxide layer at the cutting edge.

It all depends on your machine & the material being worked.

 

[darkzero]

I have had "normal" boring bars, and then thanks to modamag got to try solid carbide bars (still very affordable on Ebay) - man, what a difference. Today, almost all boring that I do is with the solid carbide bars

I would pass at this one, and look for solid carbide bars on Ebay instead. I just sold two of these to darkzero - I think they were around $50 each on Ebay, of course I sold them even cheaper than that as mine had some minimal wear marks

Will

Yup, big thanks to wquiles again! At $50 for both solid carbide bars plus extra inserts I am truely greatful! They've been working great! :thumbsup:

I purchased another 1/4" solid carbide bar from ebay for $50 shipped. Even uses the same size insert as my other two larger ones. The larger sizes cost a tad bit more but are still a great price for what I've seen them for online. I'm set for boring bars for a while I hope.

 

[Tekno_Cowboy]

Those the toolholders for the Lathemaster QCTP?

 

[darkzero]

Those the toolholders for the Lathemaster QCTP?

Yes, those are T250-102 with the V groove for holding round shanks. Wquiles has more info posted here.

 

[gadget_lover]

I (finally) got around to picking up some smaller solid carbide boring bars just like Darkzero. I was not in a hurry, since I have 4 sets of boring bars with shanks from 3/8 to 3/4 inch in both HSS and brazed carbide as well as a 7/8 inch steel with inserts. What I lacked was a tool to do those long narrow bores with some degree of accuracy.

The bars I just bought are both 6 inch long. They are 5/16 and 3/8 diameter and use cnmg inserts. I have to look up the exact insert sizes.

Just for fun, I turned a 1 inch long, .007 thick collar from a piece of 6061. It came out nice. I was quite pleased with the finish, though the photos did not look as good as it looks to the naked eye.

I paid a few extra bucks to get the longer bars , even though you should not extend carbide beyond 10 times (???) the diameter of the bar. So a 6 inch 3/8 bar with a 2.5 inch long holder still leaves an inch or two out the back.

Here's the question:
Is there a down side to doing something with that other end? I have diamond wheels available. How about grinding it for another insert? Or making it a grooving tool by grinding all but a small nub??? Or some other clever use?

It looks like the boring bars have steel heads brazed to the carbide. Is this normal?

And now the second question; The boring bars are held in 6061-t6 QCTP holders attached to an aluminum tool post that is on a 7x12 lathe. Is there any benefit to making steel holders? I suspect the answer is no.

Daniel

 

[darkzero]

Anyone want my old 1/2" solid carbide boring bar? I got it from Will. It was ground just a bit (reason unknown). I smoothened it out & dyed it black again. Absolutely nothing wrong with it, works perfectly fine. Pictured above in post #15 on top. I'd like SOLD $17 shipped for it. I'll include a couple of new 21.51 CCMT inserts as well.

 

[PEU]

if you give me one day to check with my sister in law who is vacationing in Orlando right now, Ill take it


Pablo