%%%%%%%%%%%% INSTALLATION %%%%%%%%%%%%%%
Part 1 - Mount the Split Nut:
Drilling
the only hole required to mount the Knaell Threading attachment.
A drill press is more accurate but I have done it by hand.
Use a #21 drill and tap #10-32TPI.
Drilling the #21 tap hole for the pivot-screw with the carriage and drillguide near the tailstock end ensures that the split nuts will align with the leadscrew. The headstock bearing, tailstock bearing, and mounted split nuts then become a "matched triple" since the headstock and tailstock bearings are already a matched pair. The rack should be removed from its mount and the #10-32TPI locknut (if there is one) locking the setscrew holding the eccentric bushing should be removed. The setscrew should protrude from the carriage casting so that it engages the slot made for it in the aluminum drill guide. The drillguide and carriage should be positioned lightly touching each other and be close to the tailstock leadscrew bearing (as mentioned)for drilling. The leadscrew should be threaded through the threaded hole in the drill guide. Drilling this hole parallel to the lathe ways and the leadscrew is not so critical that the operation must absolutely be machine mounted but one should have some confidence in holding a hand held drill. The aluminum drills very nicely and I have used a rather low powered 7.2 volt battery powered hand drill on several occasions. Positioning a mirror or having a helper judge the angle of the drill bit that is not easily seen by viewing from the operators direction may be helpful. Some electric handdrills have a spirit level that is useful for this.
Some alignment correction can also be applied in the following tapping operation if needed by guiding the tap in a slightly corrected direction but note that taps tend to bind after some turns if not started inline with their tap-hole. Using a mirror or second observer as in drilling is recommended here also. Slow and easy is the rule. The only result of a misaligned hole is that clamping down on the split nuts may feel a little spongy. The action of the split nut mechanism improves considerably with repeated operation with liberal application of the hypoid-high-pressure gear oil listed in the recommended accessories. Give this mechanism time to settle in.
Note that this operation can be redone if the first mounting attempt seems unsatisfactory. An aluminum #10-32TPI screw can be glued into the first hole using Loctite, cyanoacrylic, or epoxy, the protuding screw top removed and filed flat and the whole drilling process repeated. There are of course limits to how many time one wants to repeat this process. The best way is to do it right the first time of course. We can mail you a short length of #10-32TPI aluminum threaded stock if you have trouble locating an aluminum screw locally.
Mounting and adjustment of the split-nut plate involves
adjusting two of the three #6-32TPI setscrews to "level"
the plate in a manner similar to which a camera or surveyers
tripod would be leveled by adjusting only two of its three legs.
To judge the proper alignment, the double-ended-pointer-rod is
clamped near its center in the split-nut and the two setscrews
and #10-32TPI mounting screw (pivot-screw) are tightened against
the carriage casting. These screws are repeatedly adjusted until
the headstock bearing, tailstock bearing and split-nut are in
alignment as judged by the positions of both ends of the pointer-rod.
Note that when the pointer-rod is squeezed between the split
nuts, these can still be rotated as a pair about the pivot-screw
before they are clamped. The adjustment process therefore
involves simultaneous adjustment of two #6-32TPI setscrews, the
pivot-screw, and the position of the clamped down split-nut pair.
These settings are judged by the positions of the ends of the
pointer-rod relative to the lead-screw bearings. The bearing
blocks must both therefore be in position when this is done. Note
also that the bottom #6-32TPI setscrew (with the red paint)
should not be backed out in this adjustment since it must remain
below the surface of the nut-plate to clear the lower split-nut
lever. This adjustment is therefore similar to leveling a tripod
by adjusting only two of its three legs. In our case we must pull
the tripod against the casting with the pivot-screw instead of
letting gravity hold the tripod down. Note also that it is useful
to finally tap the setscrews lightly with a small hammer to let
them create a slight seat in the soft aluminum casting for the
nut-plate next time it is removed. The setscrews will then fit
into their previous seats and the split-nut algnment will not
have to be repeated if the nut-plate is removed again. A small
nail-set, center-punch, or large nail may aid in hitting the
setscrews with the hammer. The top edge of the nut-plate should
be made reasonably parallel with the top face of the carriage
casting.
Part 2 - Modify the handwheel for "Snap Out" operation:
The long reach grooving tool and the initial cuts. The tool is .020" wide at the tip and it is plunged .030" deep to make the grooves.
At this point take some time and grind the long reach grooving
tool. Granted that it requires some grinding but it will have
utility in the future as well. The grooves that it must cut are
only .030" deep so only minimal clearance on its sides is
required. The width of the tip is .020" or about half the
width of the hairpin clip. A little greater than .020" will
not hurt and the edges of the tip do not have to be absolutely
square. The tool can be ground on both lateral sides to save some
grinding but the one shown is ground only on one side so that its
untouched face can easily be judged perpendicular to the
rotational axis of the shaft. The requirement is to cut the
groove in a position which is as close to the jaws of the chuck
as possible to eliminate vibration. Unfortunately the heavy
handwheel hanging on the end of the shaft is an open invitation
to a vibration problem. Grooving should be done with plenty of
oil and at as low a speed as one can set up.
The grooving tool is assymetrical to get close to the chuck.
The resulting grooves are therefore assymetrical however
the critical square edge is on the face needed to prevent the
handwheel from being pulled all the way out of the carriage.
Care must be taken not to mar this square edge when
forming the football shaped area between the grooves as shown in
the pictures.
The first groove cut is the one nearest the hand wheel and is
lined up with the slot in the eccentric bushing supplied in the
kit. The groove should align with the slot in the bushing when
the bushing is sitting on the inner face of the handwheel as
shown in the pictures. Note that the slot in the bushing is
closest to the end sitting on the handwheel. The second groove is
1/4" away from the first in the direction away from the
handwheel toward the pinion. When the hairpin spring is lying at
this second groove position then the handwheel shaft has been
pulled back into the bushing from its normal operating position
and no longer engages the gear rack on the lathe body. In order
to be able to slide the shaft between these two positions, the
sides of the grooves facing each other must be given a slope so
that the hairpin spring can ride up on this slope. It turns out
that slopeing this intermediate space up to its original diameter
in a football shape gives a suitable snapping action without
requiring too much force. This also does not allow the pinion to
slide into engagement with the rack unintentionally.
The tolerances and dimensions required are not highly critical.
When the two grooves are modified into the sloped surface which
appears like a football, (a prolate spheroid is the technical
term) care should be taken that the the side of the second groove
facing the pinion is not abraded too much and made into a non-square
edge. This edge hits against the hairpin spring when the
handwheel is pulled out and prevents it from being pulled all the
way out of the carriage. For this reason a file with a "safe"
edge should be used to smooth the cuts made by the grooving tool
into a smooth surface. A "safe" edge on a file is a
side that has no teeth to remove metal. Some jewelers files are
made this way purposely - otherwise the teeth should be ground
off of a regular triangular or rectangular file to make this
"football" shaped surface. An old triangular file is
ideal.
Helpful Hint: Creating the football shaped surface can be
aided by plunging stepped grooves to eliminate some of the
material that must be removed by the file. The result of this is
shown in the roughly profiled surface below. Working inward from
the two outer grooves will keep the backlash in the leadscrew
tight and prevent movement of the grooving tool back into the
grooves already cut. The six additional grooves (three on each
side) are cut by stepping in and then plunging to the following
depths. First set the grooving tool in the groove already cut and
take up the backlash in the leadscrew feeding toward the other
groove. Then back the tool out and feed the carriage by means of
the leadscrew an increment of .025"(1/2 turn of the
leadscrew) and then plunge the tool .024" after touch of the
tool to the surface. Then back the tool out and increment the
carriage position another 1/2 turn but this time plunge the tool
only .016". Finally back the tool out and increment the
carriage the last 1/2 turn and plunge the tool only .008".
This completes the grooving on on side of the football so the
process is repeated coming in from the other original groove.
Making a profile drawing of this process or practicing on a piece
of scrap material should give one a bit more confidence before
actually cutting into the real workpiece. The long reach grooving
tool has earned its keep and the trouble to make it at this point
and will have many uses in the future.
Profiling and smoothing the convex shape between the grooves finalizes the "Snap Out Handwheel"
Another Hint: When you have the stepped V-belt drive pulley off
of the lathe spindle take some time to file a small flat on the
spindle where the setscrew tightens down. This will keep the
burrs inevitably made by the setscrew from rasping into the
pulley bore every time the pulley is moved or adjusted. If you
can clamp this part of the spindle in a milling machine vise then
you can take off about .020" after touch and it will look
nice. If you are steady with a Dremel Tool this can work too.
Keep the grit pointed away from the bearing.
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%%%%%%%% TIPS ON USING THE THREADER %%%%%%%%%%
1) Use a headband magnifier or reading glasses to "see"
what is happening. As always ones eyes come first so make sure
there is protection between your eyes and where chips are flying
from. This is especially true when you are up close with
magnifying glasses.
2) Pulley set-ups may initially be made easier if the Left-hand-threading-adaptor
is removed from the pulley frame when not needed. When tightening
down the setscrews holding pulleys N2 and N3 to the idler shaft,
make sure that they do not force the pulleys tight against the
inside faces of the frame. The idler shaft with pulleys should
turn reasonably freely without excessive binding inside the frame.
Note that the end of the idler shaft should not extend beyond the
pulley frame bearing toward the headstock because it may rub on
the headstock body when the pulley frame is in certain positions.
Note that there is a tendency for the upper belt (between pulleys
N1 and N2) to be drawn tight when the pulley frame is pulled down
tight against the headstock. This is because there is a slight
tendency for the frame to rotate as it is drawn tight. This upper
belt should not be so tight that it causes undue friction in the
rotation of the pulley/belt train. Both belts should have about
the same tension. Grasping the stepped V-belt spindle pulley and
the leadscrew pulley in each hand and twisting them against each
other should show a just perceptable slackening and tightening of
the belts as the direction of twist is reversed. The pulley
setscrews must be tightened sufficiently that no rocking of the
pulleys on the shafts occurs with similar twisting. Note that if
the setscrew threads on a fiberglass reinforced pulley is ever
stripped, that a new hole can be drilled and tapped at another
angle. For this repair the original stripped hole can be filled
with epoxy and the 1/4" bore cleaned up with a reamer or
drill. Note that full length setscrews increase the force
handling capability of the tapped hole in the fiberglass
reinforced plastic.
3) When threading, slow the lathe down so that you have control
over what is happening. Some metals machine differently - and
usually not as nicely - when cut at slow speed so this has to be
done with regard to the type of metal being cut. Most metals that
can be catagorized as "gummy" like hot rolled steel and
the lightly alloyed aluminums ("hardware store aluminum")
machine poorly and thread even worse. They tend to stretch and
tear rather than separate cleanly at a cutting edge. They have
their place where elastic strength and formability are important
but can be machined best only at higher speeds with very sharp
tools set at optimal angles. Threading does not fall in this
category. Free machining steel, cold rolled steel, harder
aluminum, brass, and even some drill rod does not stretch and
tear like the gummy materials and is thus much more satisfactory
for machining and threading. Unfortunately most of what you can
get in the hardware stores except for the brass, and what is
therefore conveniently available, does not thread or machine well.
Don't be discouraged by it.
So, to slow the lathe down you need either a hand crank, a
variable speed motor drive, or a drive with an intermediate
pulley reduction system like larger lathes have. I have settled
for the hand crank and a DC permanent magnet motor drive. The
main reason is convenience but also it is probably not possible
to get the large amount of torque one might like under some
adverse conditions through the stepped pulley on the spindle.
This pulley is about 1/3 the size of the pulley on 10"-12"
swing lathes so one should think of cutting threads about 1/3 the
diameter and 1/3 the pitch one would cut on these larger lathes
when using the stepped pulley as the drive. Thus cutting a 1/4"diameter
by 32TPI pitch thread on the TAIG using the pulley drive is
equivalent to cutting a 3/4" diameter by 10TPI thread on a
10"-12" swing lathe - a fairly hefty and deep thread.
Fortunately the ruggedness of the TAIG allows one to do better
than this if one supplies the torque through a hand crank that is
locked into the spindle through-hole by means of an expanding
internal mandril as is shown in the photo. The cone angle is 10
degrees surface-to-axis or equivalently, 20 degrees total
included angle. The diameter of the through hole on the TAIG
spindle allows a 5/16" passage however the hole is larger
than this at the pulley end of the spindle. The surface of the
cylinder on the crank that locks into this larger section is
turned down from 3/8" bar stock to 0.350" diameter
before the saw slots are cut. The draw-bolt that pulls the
internal and external cones together uses a #10-32TPI thread. The
length of the 3/8" bar is 2" and the "throw"
of the crank is 1+3/4" on the example shown however
increasing the length of the 3/8" bar to 2+1/2" to
clear the pulley frame and the throw of the crank to 2" or 3"
will allow easier cranking if larger diameter threads are
routinely cut.
4) The crank arm is made from lengths 1/8" drill rod and
soldered to the 3/8" rod using "Plumber's-No-Lead-Solder"
which is 4 times stronger than lead-tin electrical solder. The
parts can be "pre-tinned" where the solder will flow
using plumber's "zinc-chloride" or "acid"
liquid flux to alleviate solder flow problems. This three joint
soldered assembly is very nicely accomplished by first soldering
the bent piece of drill rod to the 3/8" shaft - readjusting
to get the position right. Then the short brace is beveled to lie
in position correctly and the beveled joint where the two 1/8"
pieces join is soldered without melting the joint previously
soldered. A piece of wet cloth wrapped around the first joint and
plenty of heat applied quickly with a propane torch keeps the
first joint from melting. Finally the third joint (second joint
on the 3/8" rod) must be soldered. This will necessitate
remelting the first joint but not the second. Again plenty of
heat quickly applied with water on the second joint is required.
A comfortable place to rest ones elbows, the 3/8" rod
resting on a heat resisting surface, holding the 1/8" pieces
in visegrip pliers, and having small pieces of solder resting
above the joints with flux and gravity helping makes this a
challenging but not too difficult soldering accomplishment.
Preparation is everything - especially in soldering.
5) Threading does not have to be done using a compound slide set
at 30 degrees to track one face of the thread as usually
described. Taking shallow cuts allows metal to flow away from the
cut if the tool is fed directly square into the work. Taking
shallow cuts straight in has numerous advantages once this
procedure is adopted. Shallow cuts upset the metal less at the
original cylindrical surface of the thread allowing a cleaner
crest to be obtained. The direct cross feed also creates this
burr equally on both sides of the crest and continually cleans up
both faces of the thread equally so that they are of equal
quality and have equal finishes. Another advantage is that the
direct crossfeed does not apply a load to the carriage which
tends to force it along the ways against or ahead of the motion
of the leadscrew. This also gives a balanced and equivalent
quality to both sides of the cut. It is easier to grind a small
accurate "Vee" on the end of a threading tool if it is
symmetrical and does not have a rake angle that is taylored to
taking chips off to one side only. Keeping the edges equally
sharp on a symmetrical tool seems much easier. The compound slide
on the TAIG works very well but does take up room in the limited
space available around the work area in this small configuration.
The tool post mounted directly on the cross slide is much nicer
to use. These opinions are not those usually given for the
logical approach to thread cutting technique however they have
been offered in other forums in the past and in reality seem to
work very well especially for fine threads or heavy threads which
are cut in fine steps on a small machine. If you try it you will
like it.
By the way don't be dismayed if for some reason (this sometimes
happens - planned or unplanned) that the tracking between the
lathe tool and the thread groove already started is lost. This
can happen for many reasons. It is really a nice use of all the
precision that is available to reset the threading tool (or a
sharpened threading tool for example)into the groove. You need a
magnifier powerful enough to see the tool relative to the groove
and also the lathe should be rotating with the tool tracking the
groove but just away from touching the work, and then just
dragging on the work. This is where the compound slide would be
handy but you can do this job without the compound by adjusting
the tool post - it just is not as convenient.
6) The leadscrew should be clean and well lubricated where the
split nuts clamp down(Hypoid gear oil again). Having the
leadscrew "wet" with oil and having this oil reasonably
clean at least where the split nuts first clamp down is a
constant consideration on any lathe with an exposed lead screw. A
carefully directed source of compressed air onto the screw and
into the split nuts makes this job easier. Clamping the nuts down
while the screw is turning allows one to feel how clean these
surfaces are and let any debris work its way out. Traversing the
clamped down split nuts back and forth once or twice over the
section of lead screw that will actually be utilized while
cutting will allow these mating surfaces to settle into position
before the first cut is made. Again - preparation.
7) The headstock and tailstock leadscrew bearing blocks have
dovetails that are expanded out to grip the matching dovetail in
the TAIG lathe bed by the setscrews in the front of the blocks.
The setscrews do not need to bear against the lathe bed to hold
the blocks in place. Note that the tailstock bearing block is
probably more critical than the headstock block since it has only
one setscrew and it also takes the load when right hand threads
are cut in normal practice. One can get a feel for the amount of
torque required on the setscrews by first tightening them until
the dovetail just starts to drag in its slot. Then about double
the torque should seat the blocks securely. Force can be applied
to the blocks along the direction of the dovetails to gauge their
tightness. Note that slipping of the tailstock block in its
dovetail is the only safety valve in case the carriage ever gets
locked up while being driven by the leadscrew. This obviously
should not be used as a regular practice. Also note that one
should not tighten up one screw at a time in the headstock
bearing block to engage their dovetails since there is not enough
force available from a single setscrew to expand the whole block
without driving the setscrew completely through the hole. These
four setscrews should be tightened and untightened sequentially
to lessen the wear on the aluminum threads. Oiling with hypoid
gear oil or molebdynum disulfide or graphite grease occasionally
will help.
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%%%%%%%% THINGS NEEDED OR USEFUL %%%%%%%%%%
THINGS THAT WILL BE NEEDED TO INSTALL THE Knaell Threader. (Might
as well round them up before starting the installation)
1) USE EYE PROTECTION
2) A hand held Electric Drill or Drill Press and a #21 twistdrill.
Needed to drill the #21 hole (to be tapped #10-32TPI) to mount
the split nut assembly to the carriage.
3) A #10-32TPI Tap and Tap Wrench. Needed to tap the #21 hole to
mount the split nut assembly to the carriage.
4) A 1/4" square HIgh-Speed Lathe Tool Bit. Needed to make
the Long-Reach grooving tool for handwheel modification. (Note:
This and the following are needed to modify the handwheel for
"Snap-Out" operation. Don't wait too long to do this.)
5) A Bench Grinder. Needed to grind the Long-Reach grooving tool
to shape.
6) Calipers or Micrometers. Needed to measure the .020"
width of the tip of the long reach grooving tool. A microscope
with a graduated reticle can also be used to make this
measurement and reveal the detailed shape of the point at the
same time.
7) A Small Triangular File with one face having no teeth. Needed
to smooth the roughly contoured "football shaped" cam
machined into the handwheel shaft. The "safe edge" with
no teeth is needed to safeguard against "rounding over"
the sharply defined edges that have been machined into the shaft
in the earlier plunging steps. A "not new" file can be
used to make this using the bench grinder since the teeth do not
need to be in "like new" condition in order to smooth
down the ridges left in the "rough forming" steps.
THINGS THAT WILL BE USEFUL IN USING THE KNAELL THREADER. (These
are not absolutly essential but are highly recommended)
1) Since EYE PROTECTION IS A NECESSITY, this protection might as
well supply some magnifyng power for the small work that
constitutes operation of the TAIG. A magnifying visor with hood
large enough to fit over safety glasses is my choice. There are a
number of these available but I prefer ones with glass lenses
such as made by Optivisor. A set of magnifying reading glasses
should work here also but I have gotten used to the visor type of
magnifier.
2) A set of jewelers files. These are useful for further cleaning
up and smoothing the "football shaped" cam area
machined into the Handwheel shaft and other small jobs. Various
sets with course and fine teeth are useful.
3) A bottle of "Hypoid Gear Oil" from the auto store.
This "high pressure lubricant" is an excellent oil to
use to lubricate the split nut mechanism and lead screw on the
lathe. Also thinned down with "mineral spirit" based
paint thinner, it makes an excellent cutting oil, especially for
tapping.
4) A bottle of Automatic Transmission Fluid (ATF) from the auto
store. This lubricant is a great light weight oil to use on the
dovetail ways of the lathe and also to alternate with the hypoid
gear oil as a lubricant for the leadscrew. It is not as "penetrating"
as many other light oils and thus tends to "stay-put"
where it is needed. It may not have the "film strength"
that the hypoid oil does so I have found that mixing some hypoid
oil into the ATF fluid seems to produce some of the higher film
strength of the hypoid oil while still maintaining the fluidity
of the ATF.
5) Get a plumbers tool called a "Faucet Handel Puller".
This is equivalent to a two arm, light duty wheel puller and is
just right for pulling small wheels of the TAIG variety,
especially getting the original V-belt drive pulley off the
spindle. You will have to put a bar down through the spindle and
lock it with collet up front to give the puller something to push
on for this job.
6) Make a hand crank for the spindle.