Shars boring bar issues.

[aametalmaster]

I really like this Shars 5/8" TPGB 322 boring bar. Well i did until i found off the shelf TPGB 322 inserts don't fit as was said they would. The screw on the BB is .153 in dia where the hole in the insert is only .125 which is standard. I wrote to them but don't expect anything back that i can use. So i have some jobs to do and prob will mig weld up the hole and redrill and tap to something i can use...Bob

[EdK]

Their web site seems to be screwed up. I can't seem to navigate to anything. Both IE and Firefox don't like it, although IE does a little better.

Ed

[aametalmaster]

(12-26-2012, 06:04 PM)EdK Wrote: Their web site seems to be screwed up. I can't seem to navigate to anything. Both IE and Firefox don't like it, although IE does a little better.

Ed

Yes their website is scrap. I did get the email address from it. I went back to the ebay listing and reread it and it "says takes standard TPGB inserts" Looks like the china factory put the wrong bolt in it. Maybe they will write back tomorrow...Bob

[the penguin]

The ones with the big holes look like the TCMT-322 inserts, I have at the house, that fit the 1/2" indexable lathe tools I bought from Grizzly.

[aametalmaster]

I did find the bar usable with the small hole inserts. It will get this job done and outta my shop. I used a 4-40 allen head bolt and nut thru the insert and bar. It worked until i get it welded up and retapped. Never heard anything from shars...Bob

[PixMan]

I've learned a lot about the boring bar (and turning tool) designs, inserts, and nomenclature over the years. Only in the past couple of years did I learn about TPGB & TPGH inserts on boring bars.

It was Circle Tool Company who started using those oddball inserts. They use standard I.C. sizes, but non-standard thicknesses, side clearance angles, and hole sizes so you can only get inserts from a very limited number of suppliers.

The thickness of the insert is as much of an issue as the screws here, so be aware. The inserts TPGB 322 are (theoretically) about 1/8" thick, while a TCMT or TCGT is usually a 32.5x size and would be closer to .156" thick. Also of note is that a TP is 11º side clearance angle, a TC is 7º. The I.C. size of an insert is measured at the top, at the cutting edge (the largest part) of the shape, so a thicker insert would actually be a bit loose in the pocket made for a thinner insert, even when the angles are the same.

I have an S08R-STFPR2, a steel 1/2" boring bar that takes a screw down TPMT/TPGT 21.5x size screw-down insert. It was when I had gotten some TCGT21.51 inserts that I learned you can fit a TPxT insert into a pocket made for TCxT inserts, but not the other way around. What the problem is, which you have found, is that there's no reall standards regarding the hole size in the inserts. I've found that as soon as you get away from a "T" or a "W" as the last letter of the 4, you risk getting odd size holes in the inserts. From my measurements, all TxxT and TxxW inserts of a "21.5x" size seem to have a .110" hole, and the larger 32.5x have a .173" hole. With the oddball TPGB & TPGH, all bets are off. I've not seen TCMT-322 inserts that Jack mentions, but they're real if he has them. ;)

My 1/2" bar is the one below and to the left, the top one is a solid carbide Valenite VCND7462 that takes the no-hole, no chipbreaker TPG inserts.


These kind of problems are why I won't buy new Chinese insertable tooling from Shars, CDCO, or even Tools4Cheap. I'd rather find quality tools from the bigger name brands and know I can use anyone's inserts. I get both new and used ones from eBay and Amazon, even flea market finds, and pay the same or less than deal with the oddbal Chinese import.

Best of luck to you Bob.

[aametalmaster]

Now that i have the job done with the boring bar i am going to fiddle with it. It worked fine with a 4-40 bolt and nut to hold the insert on the nut defeats the purpose sticking out the bottom. So i am going to bore out the old threads and weld up the hole and prob tap it 4-40. Should be an easy fix. But its cold and snowy outside so i will have to wait a week or so until i can get to my welder...Bob