I'd like to bore a hole approx 2.75", I have a boring head from APT
which will do it, but cranking the slide over far enough to use either
of the vertical bar mounts leads to significant vibration on my Sieg X3.
Can I use a horizontally mounted boring bar in order to reduce the
rotating offset mass? .500 inch round shanks in a 2.5" head.
I recently cut some panel meter holes that way, after roughing them
out with the nearest undersized hole saw. The feed outward was 0.010
per pass, more than that caused trouble. Speed was 180 RPM, the
slowest pulley setting, and still somewhat too fast.
>> Machine shakes, RPM is past 500.
>> Pete C. wrote:
>>> Louis Ohland wrote:
>>>> I'd like to bore a hole approx 2.75", I have a boring head from APT
>>>> which will do it, but cranking the slide over far enough to use either
>>>> of the vertical bar mounts leads to significant vibration on my Sieg X3. >>>>
>>>> Can I use a horizontally mounted boring bar in order to reduce the
>>>> rotating offset mass? .500 inch round shanks in a 2.5" head.
>>> The vibration is more likely from tool chatter / rigidity issues than
>>> from the off balance boring head, unless your are running it excessively >>> fast.
> Same shake when not actually cutting? I run my boring head
Not sure I understand the question. Your boring head looks like the
Harbor Freight model 33562-0VGA L? With two holes that are vertical
and one hole that is horizontal? And you are asking if you can use
the horizontal hole?
I have not read anything about how to use a boring head, but I would
assume the horizontal hole is put there to use.
Have you calculated what the RPM ought to be when boring a 2.75 inch
hole? I have not, but 500 rpm sounds pretty high to me.
I happen to have a calculator handy. At 500 rpm the SFM is 360. Okay
for brass or aluminum.
Second, when using a boring bar you want the cutting edge slightly
above center. That is so any deflection of the cutting edge reduces
The same principle as having the cutting edge slightly below center
when making a cut on the OD.
That's your problem, the machine doesn't have a back gear,
When you get up to larger diameters, you need to slow down.
500 RPM at 2.75" diameter is 360 SFPM. Not insanely high
for Aluminum, definitely a problem for steel.