Hi, I am looking for my first boring bar and evaluating options. Lathe is a Logan 200, 10" swing.
First the material... any concerns running carbide on a lathe with top speed of 1450 RPM? Most of my bores are likely 1/4" to 1.5" range, but might have occasional needs to go larger.
Then to pick a manufacturer: (tool and any inserts must be USA made)
- Micro100 - solid carbide - looks nice, but seem to be consumable in the long run without inserts?
- UltraDex with inserts - look nice, pricey.
- Ajax bars with inserts - I can't actually tell that they are American made - I don't see it listed. Anyone know? e.g. https://www.ajaxtoolsupply.com/ajst06inboba.html
- Other brands / options I may be missing?
As far as sizing / model:
- Looks like I'll need a bar fairly small relative to the bore size if I want to turn the bottom of the bore flat, given the bar diameter plus the offset of the cutting edge or insert face beyond the outside diameter of the bar.
- Am considering 3* or 5* lead angles, not sure if one is substantially better than the other, or something else?
- My only boring bar holder is an old Armstrong holder for a lantern tool post (I don't have a QC tool post), but I think I can make this work or build another holder as needed.
Thanks for any tips! There's a lot out there, and still trying to digest it all.
Materials: all carbide tooling tends to run much faster than HSS equivalents, and unless you are boring large diameters, your lathe's max speed will be a bit low. Carbide will still work but solid carbide bars like Micro 100 bars tend to cut very similar to HSS and that would be your best bet if you have to go deep. Otherwise, cobalt HSS would also be a good choice.
Insofar as the bore size range you listed, boring bars don't care about hole diameters; they care only about bore depth.
Then to pick a manufacturer: Micro 100 is a high quality bar and if you need a solid carbide bar, that is what I would suggest. Micro 100 bars can be sharpened by honing their flat tops on a diamond stone so they will far, far, far outlast any carbide insert. Most of my MIcro 100 bars are over a decade old and cut like new. They will also take micro-cuts so they are also more accurate than most inserted carbide bars. Plus, if you choose the right shank diameter, they are as stiff as any inserted carbide shanked bar so will be just as, if not more accurate than, an inserted bar.
Other brands / options I may be missing? Yes, thousands of them. I tend to favor Circle Machine.
As far as sizing / model: If you plan to bore to a blind bottom then you need a positive lead bar, preferably 5 deg. When choosing a bar, you need to make sure you can fit the bar in the hole and still get chips out. Much depends on the bore depth, tolerances and finish requirements, too.
The smallest inserted carbide bar I own is a Circle Machine CCBI 3/16" diameter bar. It will bore a hole 1/4" ID or larger, to a depth of over 1-3/4" deep. For holes smaller than 1/4", I go with Micro 100 solid carbide bars.
My only boring bar holder is an old Armstrong holder for a lantern tool post (I don't have a QC tool post), but I think I can make this work or build another holder as needed. You might consider switching to a QCTP sooner rather than later and buy/make a good boring bar holder. It is the most important boring component you can own because it anchors your bar. It may not be so important for boring a through hole but I can assure you that if you ever need to bore a precision hole then it can make all the difference.
I think I'll go with an Ulta Dex with TCMT 21.51 insert. And learn from there. Thanks for the input!
Regarding super small holes - I have letter, number, and standard/metric drills, which should work for most small holes... if I need something super precise I suppose I'll buy a reamer (or try a very small boring bar, at that time).
This bar uses the old style triangular inserts with a 3 deg lead angle. I've never used this bar so I can't comment on it. Any particular reason for choosing it?
If I were to recommend a smallish boring bar,
this is what I would suggest. This is a Circle Machine CCBI solid carbide boring bar that will fit in a 1/4" hole. This one comes with 10 inserts with a 0.007" nose radius but it will also take inserts with a 0.002" nose radius. It takes flat topped inserts without a chipbreaker and the insert has positive axial rake. This bar is easily one of the finest small boring bars I have ever used and I can recommend it if you need to go small. It can bore to a depth of just over 1.75" deep, to as large a diameter as your chuck can hold and it is very, very accurate.
Below 3/16" bars, I suggest you go with Micro 100 solid carbide bars.
