On 2010-04-28, Jon Danniken wrote:
DoN. Nichols wrote:
Hmm ... what kind of reamer? Single size reamers are really
[ ... ]
Or -- if you are talking about a tapered reamer, that (under
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Well, I hadn't exactly completely throught through that part of the process.
I also have no experience in actually using a reamer, so you could say I am
eager to get my hands on one to learn from it.
The first rule with any reamer is *never* turn it backwards. It
chips the hardened cutting edge.
I think that the step drill would still be the best bet for
this, if you are going to pilot drill through. It will make smooth
round holes.
For the straight reamers, there are two styles -- the ones with
the square on the end for a tap wrench which are made for hand use.
They have along chamfer on the end to help getting it started cutting,
assuming that your pilot hole is close to size.
The other has a long round shank and is called a "chucking
reamer", intended to be used under power -- often in a turret in a lathe
for taking a hole to finish size just after the previous station drilled
it a little undersized. It has a very short chamfer and is pretty
useless under hand power. And often a bad idea in a drill press too.
[ ... ]
Do you use the chuck key in all three positions? This makes for
a somewhat better grip.
Until today, I had never come across that pearl. Whatever I take away from
my recent expeditions, this will remain the most valuable. 
Something which I learned as a teen, back in the late 1950s.
If you have a milling machine and a spin indexer, you could
machine your own flats on the shank if it turns out to not have them.
A few years ago I tried to "roll my own" flats on a spade bit without using
the above mentioned tools. You can probably guess as to how that experiment
worked out.
Well -- you could do it with a file while holding the shank in a
vise, but the trick is getting the three flats equally spaced around the
shank.
Thanks for the suggestion, Don. I must admit that I really like
water because it is cheap and is easy to flow at a volume sufficient
to cool the bit and workpiece.
You use it outdoors? Indoors makes a real mess since you don't
have a way to capture and recycle the coolant. If you did, I would
suggest you use it with a soluble oil in the water -- made for steel
cutting.
I used it indoors at the sink for drilling 1/8" holes through the center of
1.5" long sections of 3/8" threaded rod. I had to go pretty slow once I got
in, and also had to pull the bit out frequently to clear the debris, but it
did work (ignoring the half-dozen mulligans). Mess was contained by setting
the drill press into a plastic-sheet lined basin near the sink, so the water
flowed into the drain.
O.K. I hope that your drill press frame was well grounded
through the power cord -- or that the outlet was equipped with a ground
fault interrupter. Otherwise, you are in serious danger.
Here is a picture of one of the completed units in it's assembly for you to
guess out the
purpose: http://img15.imageshack.us/img15/7540/jonpart.jpg
Hmmm ... mounted in a piece of plexiglass with a curved edge
which looks as though it may form a complete circle.
3/8" rod -- the hole you say is only 1/8". It might be the size
of the center insulation of a coax cable just a bit smaller than RG-58.
I think that I see the impressions of the braid in the OD. It is not
precisely enough made to be a proper gas-tight seal. It looks as
though you have flats filed near the end for a wrench which suggests
that you are trying to adjust the extension. Perhaps some kind of spark
gap, sparking against something not visible in this view.
If there were metal extending beyond the insulation I would
consider it an electrical feedthrough, especially since I seem to see a
ghostly image of the same projection on the other side.
Hmm ... perhaps the Plexiglas is a full circle, and the whole
device is intended to carry a spark between electrodes spaced on either
side of the Plexiglas as it rotates?
BTW -- this (drilling though the center) is the kind of task which a
lathe with the bit in a tailstock chuck would have been better at. Yes,
keep backing the bit out (peck drilling) to clear the chips.
The sulfur in the high sulfur cutting oil both lubricates the
chips (a high pressure lubricant) and reduces the strength of the
metal in shear where you are cutting.
Thanks Don, I will be picking up some proper cutting fluid for this job; big
drill bits aren't cheap!
Indeed so.
Good Luck,
DoN.
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