On Friday 04 August 2017 12:48:31 Gene Heskett wrote:
> On Friday 04 August 2017 09:45:14 Jon Elson wrote:
> > On 08/03/2017 09:52 AM, Gene Heskett wrote:
> > > On Thursday 03 August 2017 06:54:02 andy pugh wrote:
> > >> You probably want CBN (or conventional abrasive) for HSS. Diamond
> > >> is Carbon. Carbon dissolves in steel.
> > >
> > > At room temps?
> > The local temperature where the diamond hits the metal is likely NOT
> > to be room temp.
> This is no doubt true.
> > Unless you grind at low speed under water, there
> > will be some damage to the diamond.
> Not under water, but an old fashioned kerosene lamp wick, stuck in a
> tomato can of K2 with the other end laying on the rotating disk, which
> is diamond side up, and a small piece of scrap alu laying on top of it
> for additional contact weight, keeps the disk wet with k2. There is
> a "pile" of k2 against the leading face of the tool about 1/8" high.
> K2 of course is also a hydrocarbon, and possibly saturated enough to
> lower the diamond damage rate? Something never studied at length
> I left it running last night, taking nominally .180" off the bottom of
> the tools last 5/16", and will measure that to see how much more I
> need to take off to get a tool .0505" wide, which should give enough
> clearance it won't gall the SS and seize it in the action.
Which did not work, the diamond surface failing and leaving me with an
obviously tapered tool. So I put a carbide tool in the vice and trimmed
about 5/16" off the outer edge. Then I took the hss tool over to a
grizzly wet grinder, which has a white cupped wheel on the end, and keeo
it cool by dipping it in water, reformed the single tooth. It is just
barely tapered yet on the right, trailing face, and I have now made a
properly threaded stub on the end of a piece of 1.25" hot roll that will
screw into the action, however the thread OD is a few thou small.
But one thing bothers me. On close examination with a projector lens for
a magnifying glass, the left face of the thread has "torn away" places
that has caused me to stop the clear cut down to thread OD size about 10
thou early, then do the thread portion, then finish off with a slow
right to left sweep at the thread od to clean up the majority of the
tearout. This is a 10 tpi thread, and my tool is narrow, so the code
makes 2 passes at each diameter decrement, but with a .0045 offset one
way on one pass, and a .0045 offset the other way on the second pass.
I should observe that the drawings I have with measurements, are at odds
with what is on the old barrel. Thread OD is speced at 1.125" but I have
to turn to 1.111" else the top of the thread is cut into by the action
if I force it a turn with wrenches. Likewise, the ID of the thread is
stated as 1,085" but a caliper in the action bore says its 1.061", and
if threaded to that depth, the magnifying glass shows the action is
cutting into the bottoms of the threads in my test piece so I go in
another 2 thou and it fits. So much for interchangeability of parts in
the late 191*'s then this action was made.
To top that off, its an Eddystone made action that cannot be cut or
drilled without SHARP carbide tools. Ditto taps, the only carbide tap I
own is now 50 yo, a 6-48 for scope screws.
I can't get calipers into the action to measure the thread width there,
but the barrel I took out has threads .0525" for groove width. I tried
at .0049 on the scrap hot roll, jams tight in less than 1/2 turn, so I
added the wobble to my code and widened it .0005" per run till it fit.
But whats causing the tearout on the right side of the tool advanceing to
the left at 10 tpi? I figured the tools motion to the left was rake
angle enough, and the tool needs every atom of steel for strength.
> I have a 70 yo drawing of the barrel butt, with dimensions, from a
> smithing book of the era, but 100 years ago I suspect they were
> treated as guidelines, because the barrels of the day, and the action
> I have, miss those measurements by as much as 22 thou! (according to
> my measuring tools) So I'm going to machine to fit. That also means I
> will need to re-sharpen the flat (with rake angle) end face several
> times. So before I start, I will make a stickout gauge so I can
> restore that as I sharpen, and shorten, the tool. I'll see if I can
> locate some layout blue to help me see where the interference is as I
> approach the fit. Or borrow one of the better halves candles for
> sooting it.
> But first, take another thou, maybe 2 out of the front spindle bearing
> cap, I have a low frequency chatter that is coming from the headstock,
> which goes away for a few minutes after I dribble about 20 drops of
> 10w into each oil cap. There was nearly 20 thou of shims in the rear
> bearing when I loaded on the cargo van, and that slop was visible! All
> shims gone there, so any further tightening till have to be done my
> lapping the cap. About 4 thou left in the front cap yet. At 1500 revs,
> the caps will get up to 115 degrees, but that seems to be wearing in
> now that the rear cap is about right. But IMO 10W is too thick, and
> much of the heat is oil viscosity related, so the 10W is about to be
> replaced by 0W20 synthetic.
I noted that there was a dimple stick up on one edge of the front cap. I
scraped that away, and took a piece of paper out of the back side,
leaving only a 4 thou under the front ear. Turns hard, and heats to
around 115F during the 250 rpm initial turn to thread size. Hopefully
the next time I take it apart, I'll have another shiny spot to shave.
These bushings look at have been scraped to fit, lots of lengthwise
I also took the cap off the rear, put it in the mills vice and leveled it
to the table, then polished on the ears enough to flatten them some, and
the polished area surrounds the bolt hole. Those ears look to have been
worked over at some point with a file cut in a crosshatch pattern. The
low ends of the ears are eyeball visible, but since I can't pry it
around with a long bar more than .0001" on a sensitive dial, I didn't
take any more off the ears. Up front, the pry it distance is .002" or
so even with it heating. So we'll keep checking for high spots about
every hundred spinning hours. The worst part of the checking is
loosening the clamp rings that lock it so a fast reverse won't unscrew
it, then turning the chuck about 2 turns loose to gain room for the
bushing flange to clear the clamps.
But that didn't fix the chatter. So the wobble is accompanied by a change
in rpms, 100 or 110. Which still doesn't fix the chatter. I may have to
add a siggen and enable it to wobble the speed faster and
non-synchronous to the turning.
And I need to get back top the weed eating, I've got stuff 3 feet high in
places I can't get the rider to without tire chains. I envy you folks
with flat, level yards. But you have to make them in WV by hiring an
expert dozer operator at a few hundred an hour. :(
> > Jon
> Thanks Jon.
> > --------------------------------------------------------------------
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> Cheers, Gene Heskett
Cheers, Gene Heskett
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