When is an M45x3 not a 1.75x8 thread?
Louis Ohland
be 1.75x8
I bought a Kalamazoo Chuck Micro Set chuck and a 1.75x8 mounting
plate. The plate screws on about 4 threads, then stops. It does this
from either direction. My suspicions are that I'm dealing with a metric
thread.
Anyone have a seller of M45x3 nuts so I can check the spindle nose?
There are NO points for Grainger or McMaster.
Bob AZ
> There are NO points for Grainger or McMaster.
Louis
The 1.75" X 8 tpi are off too much for M45X3 to be a consideration.
Have you measured the Grizzly spindle thread to determine it actual
dimensions?
Bob AZ
Don Foreman
wrote:
You could measure it.
Put a sharp V threading bit in the toolholder and stick a DI on the
bed with a magnet or whatever. Visually align the point of the bit
with the crest (or the edge of a crest) of a spindle thread using a
10X loupe. Zero the DI that's tracking the carriage. Advance one
thread, optically aligning the point of the bit with the next crest.
Read the DI. You should now know the pitch to within a couple of
thou. You can measure the OD with a mike and the pitch dia with three
wires and a mike.
Jim Wilkins
> ...
> You could measure it.
>
> Put a sharp V threading bit in the toolholder and stick a DI on the
Or mount the DI in the toolpost, set the lathe to thread and see if it
tracks the spindle thread pitch. I would unplug the power cord first.
When you have it set to follow the spindle thread, clean up the
backplate thread. It may be correct but tight. I have an old South
Bend chuck that won't quite screw all the way onto my lathe.
jsw
Doug Miller
>> Anyone have a seller of M45x3 nuts so I can check the spindle nose?
>> There are NO points for Grainger or McMaster.
>
>Louis
>
>The 1.75" X 8 tpi are off too much for M45X3 to be a consideration.
Not that far off: 1.75" = 44.45mm; 8 tpi = 3.175mm.
Ed Huntress
"Doug Miller" <spam...@milmac.com> wrote in message
news:hmlmqh$rur$5...@news.eternal-september.org...
You probably could get the threads to engage, but the load wouldn't be
distributed among the threads. You'd probably have less than a full thread
in actual contact. That's the real weakness in having "almost" the right
thread.
--
Ed Huntress
Louis Ohland
> Put a sharp V threading bit in the toolholder and stick a DI on the
> bed with a magnet or whatever. Visually align the point of the bit
> with the crest (or the edge of a crest) of a spindle thread using a
> 10X loupe. Zero the DI that's tracking the carriage. Advance one
> thread, optically aligning the point of the bit with the next crest.
> Read the DI. You should now know the pitch to within a couple of
> thou. You can measure the OD with a mike and the pitch dia with three
> wires and a mike.
Don, you were helpful. Better quit that before you get into trouble...
Didn't think of measuring the crest to crest distance that way. I do
have a Mighty Mag not doing anything... Never used my Pee Dee thread
wires since shop operations 1 back in 96... Tried thread triangles last
night, and it didn't come up with a reasonable result.
OD has been determined with a digital caliper, multiple times.
To do list:
Measure crest to crest distance
Dust off thread wires and determine pitch diameter
Last step is drink heavily...
Grizzly answered back, they are researching it...
Jim Wilkins
> ...
>
> When you have it set to follow the spindle thread, ...
One of my first projects was a stub copy of the lathe's spindle to
take on treasure hunts. Mine is 2" Sched 40 water pipe. The thread
roots break into the ID in a few places but it's good enough to check
fits by hand. For yours a Sched 80 1-1/2" pipe nipple is 1.9" OD and
1.5" ID.
Perhaps you could turn a piece of wood to jam into the MT4 spindle
bore taper, then pound the pipe nipple onto it and lock the assembly
together with threaded rod through the spindle. Support it with the
tailstock center so it doesn't depend on a perfect taper fit. Then you
would have the spindle thread available to compare the maximum and
three-wire diameters while you threaded the pipe. Also copy the
unthreaded (register) diameter and the lengths.
If you don't mind spending a little more instead of carving wood you
could buy this and a 3-4 sleeve:
http://grizzly.com/products/MT3-Stub-Milling-Machine-Arbor-1-/G9308
The 1" shank is 2.0" long, the thread is 1"-14 left-handed. The drive
key on mine removes easily by clamping it in the milling vise.
jsw
Louis Ohland
Major diameter is 1.749 (D)
Pee Dee thread wire for use with 8tpi is .072", Constant for .072" wires
is .10775 (C)
Diameter over wires is 1.768" (M)
Formula to determine pitch diameter is E= M - Constant
E= 1.768 - .10775
E= 1.66025
Looking in Machinery's Handbook, pg 1668, Table 4:
1 3/4-8 UN Class 2A
Maj Dia Pitch dia
1.7477 Max 1.7327 Min 1.6665 Max 1.6590 Min
1 3/4-8 UN Class 3A
Maj Dia Pitch dia
1.7500 Max 1.7350 Min 1.6688 Max 1.6632 Min
If PD is 1.66025, it fits in Class 2A, but the Major diameter is 1.749
which is roughly 1.5 thou over. BUT... the adapter threads on about four
threads before it stops. I'm thinking the Major Diameter is not all that
critical.
RoyJ
tried some bluing to find where it is rubbbing?
Louis Ohland
spirit of McGyver, how can one measure the interior PD?
I'd like to verify the thread dimensions of this chuck adapter plate.
Louis Ohland
> If the thread crests are sharp, the OD will make a difference. Have you
> tried some bluing to find where it is rubbbing?
I have Dykem blue and the time to do it. Any hints on what wear in
certain areas if the thread means?
Louis Ohland
> On 3/3/2010 10:46, RoyJ wrote:
>> If the thread crests are sharp, the OD will make a difference. Have you
>> tried some bluing to find where it is rubbbing?
>
> I have Dykem blue and the time to do it. Any hints on what wear in
> certain areas if the thread means?
My first try shows the leading face has wear for about 1/8th of the
diameter. Reapplied the Dykem on that area, it's drying now.
/\/\/\/\ - Wear on this thread
|
|
\/\/\/\/
Louis Ohland
of the spindle close to the bore, then spiraling out to the thread crest
of the first full thread.
Jon Elson
maybe have an 8 TPI leaf on it. If not, use the 16 TPI leaf, and see if
the thread is 8 TPI (perfectly exact fit in the gauge) or 3 mm which
won't fit the gauge well.
It may just be an overly tight thread, too.
Jon
Louis Ohland
> Louis Ohland wrote:
>> I've got a suspicion that the Grizzly G9972Z spindle thread may not be
>> 1.75x8
> maybe have an 8 TPI leaf on it. If not, use the 16 TPI leaf, and see if
> the thread is 8 TPI (perfectly exact fit in the gauge) or 3 mm which
> won't fit the gauge well.
>
> It may just be an overly tight thread, too.
It was a spot on fit to an 8 tpi leaf, both the spindle and the adapter
plate...
Jon Elson
> If PD is 1.66025, it fits in Class 2A, but the Major diameter is 1.749
> which is roughly 1.5 thou over. BUT... the adapter threads on about four
> threads before it stops. I'm thinking the Major Diameter is not all that
> critical.
The major diameter is not SUPPOSED to be critical, but if the point on
the threading tool used to make the backplate was breaking down, the
major diameter in the plate would come up UNDERSIZE, ending in a tight
fit. I think it is time to use blue dye on the spindle and wring the
plate on, then inspect where the dye transfers in the plate, and where
it gets rubbed off from the spindle. I think a likely scenario is
either the plate is entirely undersize (not easy to measure without a
go-nogo gauge) or the major dia. is short, which is the most likely
situation. If you can get this thing mounted on your lathe somehow,
chase the thread lightly with a sharply-pointed threading tool and then
re-check the fit.
Jon
Jim Wilkins
> ...
What do you have now for chucks or faceplates that do fit the spindle?
jsw
Jon Elson
> Second try with Dykem shows a thin line of contact starting at the front
> of the spindle close to the bore, then spiraling out to the thread crest
> of the first full thread.
but a slightly bent one, if I understand your description. If they made
these things with a big tap instead of turning the thread on the lathe,
this is quite possible. Do you have anything that fits your lathe
spindle? You can always take the jaws off a chuck and C-clamp the plate
backwards onto the chuck body. You then have to center it very
carefully. Then, pick up the thread with an inside threading tool
(people have had good results grinding these from old Allen wrenches).
Unscrew the chuck from the spindle and turn around to check fit, if it
needs more, screw the chuck back on and take another pass.
It probably will only take a VERY small cut to fix this, maybe just a
couple thousandths of an inch.
Jon
Wes
> OK, finding the PD for an exterior thread was too easy. In the best
>spirit of McGyver, how can one measure the interior PD?
Cerrosafe?
http://www.brownells.com/.aspx/pid=384/Product/CERROSAFE_reg__CHAMBER_CASTING_ALLOY
Wes
Louis Ohland
> On 3/3/2010 17:13, Jon Elson wrote:
>> Louis Ohland wrote:
>>> I've got a suspicion that the Grizzly G9972Z spindle thread may not be
>>> 1.75x8
Response from Grizzly
After reviewing your callback, our records indicate that the correct
spindle thread for the G9972Z lathe is 1 3/4 x 8. Our back plates are
made with a shallow cut thread and may require machining to fit threads.
If we may be of any further assistance, please do not hesitate to
contact us. You are a valued customer, and we look forward to serving
your future woodworking and metalworking needs.