Micro100 boring bar, which coating? If any.

Amazon prices by some sellers are inflated to look like you're getting a big discount., sometimes.
Also, be sure you're buying the correct type of boring bar. The models that start with BB, are used w/o a holder. Others use a Micro100 tool holder. QBT.
 
Mikey, it was the "smoking deal on a TiN coated bar" that made me ask. Bought it last night on Amazon for $14.92. This morning it's back up to $70. No idea why it was cheap yesterday, but I don't really care. When it shows up on Monday I'll give it as good an examination as I can, but being Amazon I can always return it.

Brian

That is a fair price, Brian, and that bar will work fine. Micro 100 uses a proprietary formulation for their carbide bars that is tougher than most. I've dropped several of my bars on a concrete floor with no sign of damage but that is not the case for most carbide tooling - drop a carbide end mill and it can crack into pieces. Their bars are easily sharpened on a diamond stone so their useful life in a hobby shop is quite good. Of course, your coating will be gone after you sharpen it but that won't impair it's function.

Personally, I think Micro 100 makes the finest small diameter boring bars you can buy. You still have to pay attention to your extension limits but those bars will go every bit of the 10:1 extension ratio and hold their accuracy. You may also want to look at their small internal thread relief and threading bars; these are just as accurate and will allow you to internally thread that special project where you need a small threaded hole with a high accuracy class. My smallest inserted carbide bar is 3/16" so anything I have to thread under 1/4" is done with a Micro 100 bar. Just really superb tooling, in my opinion.
 
Just purchased the Micro100 BB that I needed for $7.53, Amazon Prime, Add-On Item.
Price went up to $35 after purchase.
We shall see. Sold and Ships from Amazon.com Free two day shipping. 3/16" shank, bright.
 
Thanks for that hint on Micro 100 tooling on Amazon! Like Mikey said, Micro 100 stuff is top shelf and I was able to get a really good deal on some nice tooling. The little boring bar I have now has been really usefully on a few occasions.
 
Mikey; How are you using the Micro100 bars on your lathe? I'll have to use the lathe at work for now, until I can buy one.
I am completely green on boring on a lathe.
 
I’m a hobby machinist, NO production. So, the word “coating” to me is just another way of saying you are going to pay more money for nothing meaningful. Do you really want a tiny Carbide boring bar? Would HSS do? Your machine and YOU need the proper finesse to handle tiny Carbide boring bars or you will just end up with broken bars. You did not say how tiny? I work with boring 0.025” holes all the time and I break them even with a good machine and finesse…Dave
 
I have sleeves that fit my boring bar holder for my QCTP and they hold the small shanks of these bars very solidly. I suggest you use them with zero radial rake; that means the flat on top of the cutting head should parallel the ground. I also suggest you align the bar in line with the spindle axis.

Stick out or extension on a solid bar like this is not like that of an inserted tip bar; your extension is dictated by the length of the shank (between the cutting edge and the round part that is held in the tool holder) so it cannot be varied. When buying solid bars, keep this extension thing in mind. A carbide bar can go about 10 times its diameter and hold its accuracy. For example, a 1/8" diameter shank can go 0.125" X 10 = 1.25" deep, which is considerable in view of the size of the bar. In most cases, Micro 100 bars will take this into account and a 1/8" bar will usually allow this depth of bore; the shank will be around 1.5" long and the part that is held in the holder will be about 1" long or so. Of course, this varies with the size of the bar but you get the idea.

In use, remember that a carbide bar does not like slamming into the bottom of a bore. As tough as a Micro 100 bar is, it won't tolerate bottoming for long. Therefore, I suggest you always use a carriage stop with these bars when boring a blind/flat bottomed bore.

Coolant is optional but I almost always use it because it alters the chip (tends to produce coiled chips that eject easily from the bore) favorably, while also enhancing finishes and reduces the incidence of a built up edge.

Speeds are calculated as usual. Feeds are adjusted to produce coiled chips, not strings; this feed rate will be faster than you think. Depths of cut varies based on the diameter of your bar; smaller bars require smaller cuts. For a 1/8" diameter shank, I would keep my cuts at 0.010" max for roughing and you can dial in your finishing cuts based on how the tool likes to cut for you. For example, say you dial in a 0.004" finishing cut and it produces a 0.0075" change in ID, then you can rough until you are 0.0075" away from final size and dial in that 0.004" cut and you should come in on size. So, you need to know how your bar likes to cut for both roughing and finishing cuts so you can close into your finishing cut.

There is a lot to this boring stuff. Fortunately, using a solid bar is easier than using an inserted bar and I'm sure you'll sort it out quickly.
 
Do you run hundreds of parts per day? If not the coating will gain you little if nothing at all.

I often use Accupro uncoated solid bars for bores smaller then 1/2" diameter X 1/2" depth, one may bore thousands of parts without issue, solid carbide tooling is very fragile however, I have broken several just banging them on the next tool holder in line. Excellent tools overall.
https://www.mscdirect.com/browse/tn...archterm=accupro+boring+bars&navid=4287923968
 
I have sleeves that fit my boring bar holder for my QCTP and they hold the small shanks of these bars very solidly. I suggest you use them with zero radial rake; that means the flat on top of the cutting head should parallel the ground. I also suggest you align the bar in line with the spindle axis.
There is a lot to this boring stuff. Fortunately, using a solid bar is easier than using an inserted bar and I'm sure you'll sort it out quickly.

Thanks. That's a lot of information to digest. May I ask about these sleeves? Are they the Micro100 BB holders or something else?
Could you post an image? This sounds a bit more complicated than I thought. Do have a part # for the Micro100 bars you are using?
 
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