According to :
Do you *really* need that much strength? The roll pin should be
plenty. I consider the dowel pin or the solid carbide pin to be
seriously extreme conditions.
There really is no way todetermine howmuch force thepin would be
subjected to, which is why I said I want to go with the stongest
corrosion resistant material that would stay in the hole.(If it fails,
I'll just have to try something else).
a) It is a joystick, right? And the pin (roll or dowel) will be in
shear only if someone is pulling up on the ball, right? Assume
the heaviest guy is say 300 pounds (as anyone heavier would
probably not be able to lift his own weight with even a
two-handed pull-up, let alone with a single-handed one.
Personally, I think that he could not shear the pin without
first breaking something else, such as the mounting of the whole
assembly.
b) If the whole game weighs 300 pounds, you probably don't *want*
someone to be able to lift it by the joystick ball, so it would
be better to use a pin which *would* shear first to protect the
rest of the machine.
c) The roll pin will be a spring grade steel, *not* a stainless,
so it would be vulnerable to corrosion anyway. (So would the
dowel pin, for that matter.) *Except* that it is not out where
it can be handled, and unless someone is going to be pouring
pints of sweat down the shaft, I see no problem.
Note that with a dowel pin, you would drill the hole through the
shaft slightly undersized, and use an undersized reamer to make it a
just *barely* undersized hole.
I've only seen bits and reamers in 1/8" size increments.
If you go to the industrial places (such as MSC, if you ever
succeed in getting the catalog), you will find that you can get
the sizes in just barely over the nominal size (probably
something like 0.0002" or so) to allow a slide fit on the dowel
pin, and also in just barely under the nominal size (by about
the same amount), so the dowel pin would be a press or drive
fit.
I have a Dremel. :-)
I see deburring bits and simular in the Dremel catalog. The various
Dremel tools have different bits for different operations on wood,
plastic, and metal(including stainless). I'll see if anyone at the
Dremel forum has any ideas.
The main problem is having a steady enough hand to control it as
you use it to open up the jagged slots.
SFM recommendations?
Material specification, first?
1) What material you are drilling? (IIRC, it was a stainless
steel, but don't expect me to remember which stainless steel.
303 stainless steel.
O.K. I think that I posted that as an example. When you get
your _Machinery's Handbook_, you can look it all up there.
2) Drill bit material? You've got the choices of Chinese or
Indian pseudo-HSS, a real US (or European) made HSS, a high
cobalt steel (and which percentage), or a solid carbide drill
for starters. Also, there are various coatings TiN, TiAlN, or
various others which affect the friction, and thus the proper
speed.
As a firm believer(victim) of Murphy's law I tend to lean towards
getting the best within reason, even it if is over-kill. Hence, my
penchant for "over-manufacturing". :-)
O.K. I would suggest going for cobalt steel bits with split
points, and unless you need the extra length, go for screw machine
length bits. They are shorter, and flex less as a result.
As for the drill bit. The most use I can get out of it for what I paid
is a priority(using 303 stainless steel and a common standard
lubricant). So the idea is to get a general idea of what the best bits
are.
You can contact the drill bit manufacturers and talk to someone
there to give you the best that *they* make, at least.
Buy the drill bits in envelopes of ten (I think that is the
standard package size for 1/8" drill bits and similar.
If it comes down to chosing the *right* SFM, I would pick up my
copy of _Machinery's Handbook_ (a recent edition), and look up
what the proper SFM would be for the combination. And I would
then probably use something a bit slower, as these are for
massive production, and are a speed selected to make the optimum
tradeoff between the time the job takes and the life of the
drill bit. And the time taken to change the bit counts for more
than the cost of the bit in this equation. You won't have
production capable machinery, so don't push it.
Ok. Since "time" is a complete non-factor for me, would a 20% drop in
the rated rpm and/or feed rate suffice?
Sure. Maybe even a 50% drop.
The chart on page 1030 of the 24th edition of _Machinery's
Handbook_, for 303 SS (among some others) suggests for HSS that
you use a SFM of 20 (Opt) or 40 (Avg), with a feed of
0.015" per revolution (Opt) or 0.007"/rev (Avg)
The other column for drilling assumes indexable insert drills,
which make no sense at the size were you are working.
I'm not sure how you are going to manage a known feed rate while
drilling in the lathe, unless you mount a drill chuck to the
toolpost and set the feed gearing to accomplish that.
?!? Mounting a drill chuck to the tool post is something I've not read
about before.(Back to the drawing board).
You can get quick-change tool holders -- at least for the AXA
size and larger) which have a Morse taper. Get one which matches the
taper in the tailstock -- or adaptor sleeves to reduce if necessary --
and you can mount the tailstock drill chuck in the toolpost, parallel to
the axis of the lathe spindle.
The major problem with it is that you have to be careful to both
adjust the height of the tool holder (only once), and you have to adjust
the position of the cross slide to be precisely in the middle of the
spindle's axis -- *every* time you go back to that after doing something
else with the lathe.
So -- make a copy of _Machinery's Handbook_ one of your
purchases. The answers to *many* of your questions can be found
there, and I will henceforth assume that you have one for such
questions.
I expect that when it arrives, it'll clear up some things.(I hope that
the 25th edition is late enough).
That is the latest that I have. I don't know what the later
editions may cover that the 25th does not. I would also suggest that
you look for a much older version, such as around the 15th or 16th, to
pick up some of the advice which has been dropped in the more recent
ones, in part thanks to the move from manual work to CNC work.
Should I also look for the guide that
is commonly advertised for use with these?
I have one for the 23rd edition, along with the main handbook,
and I've never used it. *You* may find it useful -- I don't know. My
copy came for free with the handbook -- both were a gift from someone
who was shutting down a machine shop.
BTW. UPS left a nameless notice at my address for three consecutive
days. Now since four of the eight family's in this partcular complex
live at the same address, if there is no name then no one would know
who is supposed to be getting a package. Anyway, I get a card in the
mail UPS stating that they made three attempts to deliver a package
from MSC... I could go on and on about my past problems with UPS(and
the neighborhood driver in particular), but... (Sigh).
This suggests that you need to find a *service* to receive things
for you, because MSC uses UPS for all their shipments which are not too
heavy. I suspect that it was your catalog.
Good Luck,
DoN.
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