Boring bar problems

I recently purchased (received 11 Dec 06) a R8 boring bar and head set
(model 800-5945) from H&H Industrial Products:
The head works quite well. However, the boring bars are no so
fortunate. The brazing of carbide inserts to bar is quite sloppy, with
little bits of braze metal in the wrong places, such as on the face and
edges of the carbide insert, and the nearby surfaces of the steel bar,
and the braze-metal surfaces looking pebbled or bubbled, as if
overheated during brazing.
But the brazes do look strong enough, so perhaps this is cosmetic only,
and I attempted to bore a ~1.00" diameter hole in a piece of 0.250"
thick 5025 aluminum plate, starting with a 7/8" rough hole, taking
~0.020" diameter passes, using the smallest boring bar provided, 3/8"
shank by 2.25" overall length.
Total failure. The tip of the boring bar is not correctly shaped,
allowing the heel of the carbide insert to drag on the walls of the
hole, preventing the cutting edge from touching the wall, so the bar was
totally unable to cut, and was instead trying to force its way through
the metal. Much drama, but fortunately I was able to stop it in time,
and nothing was damaged. The advantages of a manual machine.
I substituted a used Criterion boring bar (SBT-375A) of similar size
(OAL is ~3.20", tip is slightly smaller), and everything went well, so
the head is not the issue. In fact, the head appears to work perfectly.
Now, in the catalog description of 800-5945, it claims a minimum boring
diameter of 0.197", which is one fifth of the 1.00" that didn't work, so
the smallest boring bar should have worked, but cannot. Actually, the
tip of the boring bar is about 0.36" in diameter, and so 0.197" would
be impossible even if the heel didn't drag.
So, there are two problems. The product is not quite as described, and
the provided boring bars are not suited for their intended function.
My guess is that the final grind-to-shape step was omitted during
manufacture of the boring bars.
H&H Customer Service replied on Monday 18 Dec 06 to my query of the
prior evening with an email saying that their guy that knows about this
product will investigate. Stay tuned.
Joe Gwinn
Reply to
Joseph Gwinn
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How much did you pay for those imported bad boys, Joe, about six bucks? Sometimes you just simply get what you pay for. I think hhip is a pretty chancy vendor myself.
Reply to
Grant Erwin
The "import" boring heads are fine - I use one for a number of year w/o issues. The brazed-on carbide boring bars are of much lesser quality. I recommend buying indexable bars, decent ones can be had fairly cheap (McMaster etc).
You can play with rake and releif angles of boring bar by turning it inside of the boring head's mounting hole. Takes a few tries to get the proper angle set.
In general, up to 3/4 ID should be reamed, if possible. Some holes, in some stock :), can be bored on a lathe, mounted on a face plate or 4 jaw chuck. Boring on a lathe might be more accurate as the tool won't flex _outward due to centrifugal forces. Or course, there's always flex due to cutting pressure, but that one is directed _inward.
If you want to bore smaller ID holes, consider buying indexable _solid carbide_ bars . Those can get very expensive (MSC/Enco sells Tigons for something like $90 in a set), but they flex the least.
When boring on a lathe, you can angle the bar "in" a bit, where the bar's tip is closer to the operator compared to the butt, it improves stifness.
Grant Erw>
Reply to
I got a similar made-in-India set along with a Criterion boring head as a package from MSC many years ago. The shanks on the bars are about the softest steel I've ever seen, and the brazing is also pretty sloppy. I figured I'd toss them as I got fed up, but I'm still filing off the setscrew gouges and resharpening them as required. They don't inspire any pride of ownership, but cut as well as anything else in the shop.
Ned Simmons
Reply to
Ned Simmons
It was $240 for the set. Go to the above URL to see a picture, and specs. The equivalent thing bought new from Criterion would end up close to $1,000.
The bar steel is quite hard near the tips, and the tips have carbide inserts brazed in. If the tips were correctly shaped, I think that there would be no problem.
We'll see how HHIP handles this.
Joe Gwinn
Reply to
Joseph Gwinn
Looks to me that their warrantee would cover it if you want to reject the goods
Mark Rand RTFM
Reply to
Mark Rand
Yes. We'll see what they propose.
Joe Gwinn
Reply to
Joseph Gwinn
Henry is a good guy, but he is light on knowlegable machinists on his support staff - I'd be really surprised if you have a problem with him.
Reply to
William Noble
I assume that Henry is one of the "H"s in "H&H". I have not communicated with a Henry yet.
Unless the manufacturer went downhill after getting the order, the buyer at H&H cannot be an experienced machinist. One look at those boring bars would have raised fatal suspicions. The tips look crude. As I said before, it looks like the final grind-to-shape step was omitted.
The catalog says that the manufacturer is in Taiwan, although the boring head and its box don't say. The cardboard box is marked in both Chinese and English.
Joe Gwinn
Reply to
Joseph Gwinn
hh = henry hiep
he imports a lot of stuff, and also seems to acquire the overstock and returns from places like Grizzley - I got a nice 8 inch 6 jaw chuck from him, via e-bay for $125 - buying the backing plate cost me almost as much as the chuck.....
anyway, henry knows stuff, he has one knowlegable staff person (suzzy) who knows the stock but is not a machinist,and the rest know little (and speak almost no english)
Reply to
William Noble
Hmm. Me, myself, and I?
Sounds like a Chinese or Vietnamese name. No surprise.
Well, this boring bar set was made for H&H - the name is etched into the side of the head.
I think I talked to Suzy when I ordered the set. Their website flamed out when I tried to order, so I had to call.
My email complaining that the website flamed out was answered by a Chris, who seems to be perfectly adept at English.
This same Chris answered my email complaining about the boring bits. No word so far. I need to ping them.
Joe Gwinn
Reply to
Joseph Gwinn

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