I just went through a process of boring out 7 pulleys for a line shaft.
The original diameter of the bores was 1 7/16" and they had to be
bored out to 1 11/16". The depth of the holes varied from about 2 1/2"
to 4 1/4". I found that 1/2" diameter boring bars just aren't stiff
enough when sticking out much over 2 1/2". The tools seem to vibrate and
cause a rough finish (using Bridgeports at a night school). I have an
old vertical mill that has a B&S #9 spindle, so I can't easily get a
3/4" head, but I sure would if I could!
On the subject of imported boring BARS: I bought a set of those 9
cheapies from Enco. They must be some sort of soft carbide becuase they
dull very quickly. I can even sharpen them on an aluminum oxide wheel.

Pete Stanaitis
------------------------------------------------------


Dennis van Dam wrote:

In article , "Paul Thompson"
wrote:


I have a cheapo Enco mill with an import boring head that has been nothing
but wonderful to use.


Paul,

Thanks for the reply, I was beginning to think nobody here would have
anything to do with one who espoused the use of "import" machine
tools/accesories, I know it can be a hot button issue sometimes.

I'm a rookie machinist with an older Burke Millrite machine. I've had
occassion to use a 2" import (taiwan manufacture) boring head on this
machine and, as you say, it worked just fine. The only problem I
encountered occured when I took too big of a bite on the material perhaps
combined with feeding the spindle down to aggresively, resulting in a bent
boring bar like it was just so much taffee. That the bar got bent was
mostly my mistake but I'm not discounting the fact that an import boring
bar set may be softer (a lot softer?) than higher quality domestic boring
bars.

I no longer have access to this particular import head, but the action and
accuracy on it seemed just fine to me, certainly for my purposes. In the
meantime the need to replace this head has come to the fore front and I
can't help but notice the considerable range in selection of boring head
brands, sizes and types, both import and domestic. Attendant to the
range of selection is a pretty considerable range in price. I can score
a 2" import boring head set compete with boring bars and R8 mandrel on
eBay for as little as $50 -$60 or I can go in to the catalogues and go as
much as $600 for essentially the same set up.

Too many choices on the menu and I go hungry for lack of knowing what to
order. (-8

So looking in the MSC catalogue I see APT, Accupro, and Criterion as
domestic brands and then the import options. (Not 100% that Accupro
isn't an import.)

One option is to get an import head then spend some extra money on
domestic boring bars, but even with boring bars types/prices it's a
multiple choice dilema. At least on this I can buy the boring bars one
at a time as I need them and, by the time I buy them all, not really spend
anymore than a complete set costs.

And as long as I'm wasting all this time on detail considerations, I'm
wondering if the two inch head will do me or if I might not be better off
with a 3 inch head for heavier jobs that might come up. APT has a 2-1/2
inch head for either 1/2" bars or 5/8" bars that looks like it might split
the difference in capacity and price nicely.

Concurrent to researching the catalogue I'm tracking a dozen or so eBay
auctions on various boring heads.

Long story short (too late for that) I was getting tired of trying to
figure all the variables and when I came across a "Buy It Now" for a 3
inch Criterion complete with boring bar set and other accessories I
decided the higher price was worth it to be done with this quest.

I hit the button.

Looking forward to the boring head arriving today.


Dennis





"Dennis van Dam" wrote in message
...

Is there an appreciable difference in quality between the 2" import boring
head typically available on eBay $60 "Buy It Now" auctions and the 2"
import boring head set available from MSC for $160?

I'm guessing it depends where the head is imported from. The "buy it
now" is Chinese the MSC import is unknown.

My applications are home hobby general purpose infrequent use.

Also what are the considerations in choosing between M-35 cobalt and C-6
carbide boring bar sets?

Thanks to anybody who knows and cares to respond,

Dennis van Dam