Jet 9X20 lead screw ?
 

I just got around to noticing a table for using the threading
indicator. The table
is the usual listing of indicator readings versus thread pitch.

However I just noticed that the thread pitch column is labeled TPI and
the threads
listed are all imperial threads.. I have reason to believe that the lead
screw is metric.

So my question is, where is the error? Is my lead screw wrong and I
should have
a Imperial or is the label wrong and no 9X20 was ever shipped with a
imperial
lead screw.

Confused
Bill K7NOM

"Bill Janssen" wrote in message
...

I have reason to believe that the lead screw is metric.

Based on what?

Btw, it might help if you told us the vendor of your particular 9x20.


So my question is, where is the error? Is my lead screw wrong and I should
have a Imperial or is the label wrong and no 9X20 was ever
shipped with a imperial lead screw.

I have yet to come across a 9x20 with anything but Imperial leadscrew &
threading dial (at least in the US market). I would love to have a true
metric leadscrew (and metric threading dials) on my 9x20 lathe. If you
really do have a metric set-up, perhaps we could trade parts?

Regards,
Michael

"DeepDiver" wrote in message
...
"Bill Janssen" wrote in message
...

I have reason to believe that the lead screw is metric.

Based on what?

Btw, it might help if you told us the vendor of your particular 9x20.


Oops, I guess I get the "reading-impaired award" for the day. Missed the
brand name "Jet" in the subject line.

Jet 9x20 lathes definitely have Imperial leadscrews & threading dials.

- Michael

"Bill Janssen" wrote in message
...
I just got around to noticing a table for using the threading
indicator. The table
is the usual listing of indicator readings versus thread pitch.

However I just noticed that the thread pitch column is labeled TPI and
the threads
listed are all imperial threads.. I have reason to believe that the lead
screw is metric.

So my question is, where is the error? Is my lead screw wrong and I
should have
a Imperial or is the label wrong and no 9X20 was ever shipped with a
imperial
lead screw.

Confused
Bill K7NOM

I have one that is called a CT-918 it may be the same as your 920. My manual
provides tables to allow cutting of both imperial and metric threads by
making some gear changes. Metric threads are from 0.5 to 3 mm, inch are from
8 to 56 threads per inch. Do you have a manual and the change gears?

Jack

It isn't too hard, Bill. You hold up a ruler next to your lead screw
and count the threads per inch and see if you get e.g. 8 for 1" 16 for 2",
96 for 12" .. GWE

Bill Janssen wrote:

I just got around to noticing a table for using the threading
indicator. The table
is the usual listing of indicator readings versus thread pitch.

However I just noticed that the thread pitch column is labeled TPI and
the threads
listed are all imperial threads.. I have reason to believe that the lead
screw is metric.

So my question is, where is the error? Is my lead screw wrong and I
should have
a Imperial or is the label wrong and no 9X20 was ever shipped with a
imperial
lead screw.

Confused
Bill K7NOM

According to the manual the model BD-920N has a 9/16" x 16 TPI leadscrew.
Usually though there is a metric/inch change gear, or on fancy machines just
a selector. I believe the magic gear is a 127 tooth gear (25.4*5 = 127 =
zero conversion error).
I have used Russian made all metric machines that cut beautiful inch pitch
threads, and vice versa. It doesn't really matter whether the lead screw is
inch or metric as long as the gear ratio is correct you can cut any pitch
you want. - where it matters is in the cross slide, if you have a metric
dial that sucks.

"Bill Janssen" wrote in message
...
I just got around to noticing a table for using the threading indicator.
The table
is the usual listing of indicator readings versus thread pitch.

However I just noticed that the thread pitch column is labeled TPI and the
threads
listed are all imperial threads.. I have reason to believe that the lead
screw is metric.

So my question is, where is the error? Is my lead screw wrong and I should
have
a Imperial or is the label wrong and no 9X20 was ever shipped with a
imperial
lead screw.

Confused
Bill K7NOM

Dean wrote:
According to the manual the model BD-920N has a 9/16" x 16 TPI leadscrew.
Usually though there is a metric/inch change gear, or on fancy machines just
a selector. I believe the magic gear is a 127 tooth gear (25.4*5 = 127 =
zero conversion error).
I have used Russian made all metric machines that cut beautiful inch pitch
threads, and vice versa. It doesn't really matter whether the lead screw is
inch or metric as long as the gear ratio is correct you can cut any pitch
you want. - where it matters is in the cross slide, if you have a metric
dial that sucks.

"Bill Janssen" wrote in message

My Grizzly G0516 is listed as having a 3/4"x10 tpi leadscrew but it is
20mm and 12 tpi. So much for the manual. I had to sort this out so I can
build a thread dial for it.

dp

That reminds me,
There is one flaky thing about using a metric pitch machine cutting inch
threads (at least the Russian lathes) & it is that the half nut, on some
pitches, can only be engaged on the exact same unique point on the thread
dial or you might not be in sync with the previous cut. They make it tricky
though by marking the dial like an inch machine so you think you can just
drop it in whenever your number comes by. A colleague of mine ruined a
leadscrew nut for a 5" HBM made from a cu$tom bronze ca$ting due to this.

"Dennis Peterson" wrote in message
...
Dean wrote:
According to the manual the model BD-920N has a 9/16" x 16 TPI leadscrew.
Usually though there is a metric/inch change gear, or on fancy machines
just a selector. I believe the magic gear is a 127 tooth gear (25.4*5 =
127 = zero conversion error).
I have used Russian made all metric machines that cut beautiful inch
pitch threads, and vice versa. It doesn't really matter whether the lead
screw is inch or metric as long as the gear ratio is correct you can cut
any pitch you want. - where it matters is in the cross slide, if you have
a metric dial that sucks.

"Bill Janssen" wrote in message

My Grizzly G0516 is listed as having a 3/4"x10 tpi leadscrew but it is
20mm and 12 tpi. So much for the manual. I had to sort this out so I can
build a thread dial for it.

dp

"Dean" wrote in message
...

I have used Russian made all metric machines that cut beautiful inch
pitch threads, and vice versa. It doesn't really matter whether the
lead screw is inch or metric as long as the gear ratio is correct you
can cut any pitch you want. - where it matters is in the cross slide,
if you have a metric dial that sucks.

That last statement is a matter of personal perspective, is it not? For me,
I work almost exclusively in metric, so having an Imperial cross slide (and
compound, and leadscrew/threading dial) is what sucks for me.

- Michael

As has been pointed out in this group before, same goes for doing metric on
an imperial machine.
When you have the 127 gear on (or it's counterpart on a metric machine doing
inch work) there is only ONE place you can engage the nut. Google the
archives and you'll find a few tricks to *try* and make it eaaser but in the
long run they are all a PITA.

Dave


"Dean" wrote in message
...
That reminds me,
There is one flaky thing about using a metric pitch machine cutting inch
threads (at least the Russian lathes) & it is that the half nut, on some
pitches, can only be engaged on the exact same unique point on the thread
dial or you might not be in sync with the previous cut. They make it
tricky though by marking the dial like an inch machine so you think you
can just drop it in whenever your number comes by. A colleague of mine
ruined a leadscrew nut for a 5" HBM made from a cu$tom bronze ca$ting due
to this.

DeepDiver wrote:

"Bill Janssen" wrote in message
...


I have reason to believe that the lead screw is metric.



Based on what?

Btw, it might help if you told us the vendor of your particular 9x20.




So my question is, where is the error? Is my lead screw wrong and I should
have a Imperial or is the label wrong and no 9X20 was ever
shipped with a imperial lead screw.



I have yet to come across a 9x20 with anything but Imperial leadscrew &
threading dial (at least in the US market). I would love to have a true
metric leadscrew (and metric threading dials) on my 9x20 lathe. If you
really do have a metric set-up, perhaps we could trade parts?

Regards,
Michael




I tried cutting a 8 TPI thread using the 1 on the dial and got three
diferent start positions.
Just counted the threads and it 16 or nearlu 16 per inch

Bill K7NOM

Grant Erwin wrote:

It isn't too hard, Bill. You hold up a ruler next to your lead screw
and count the threads per inch and see if you get e.g. 8 for 1" 16 for
2",
96 for 12" .. GWE


Ok I get 16 or so for one inch.

Bill k7NOM


Bill Janssen wrote:

I just got around to noticing a table for using the threading
indicator. The table
is the usual listing of indicator readings versus thread pitch.

However I just noticed that the thread pitch column is labeled TPI
and the threads
listed are all imperial threads.. I have reason to believe that the
lead screw is metric.

So my question is, where is the error? Is my lead screw wrong and I
should have
a Imperial or is the label wrong and no 9X20 was ever shipped with a
imperial
lead screw.

Confused
Bill K7NOM

On Fri, 13 May 2005 22:04:30 GMT, "Dave August"
wrote:

As has been pointed out in this group before, same goes for doing metric on
an imperial machine.
When you have the 127 gear on (or it's counterpart on a metric machine doing
inch work) there is only ONE place you can engage the nut. Google the
archives and you'll find a few tricks to *try* and make it eaaser but in the
long run they are all a PITA.

Dave
SNIP
Greetings Dave,
I've been trying to figure out how to do this threading
electronically. I looked at the Frog? controllers and they say you can
do threading with them but they only drive steppers AND they only have
one pulse per chuck revolution. The threading I do needs to be more
accurate than that. I do have Gecko drives that take step and
direction input and drive servo motors with encoder feedback. But I
can't find software that's cheap enough. I do have BIG CNC lathes (21
inch swing) but for one or two parts it's usually faster to put that
damn 127 tooth gear in place. If I can find the right software I'll
put a ballscrew in the lathe and use it for all my threading.
Eric

Dean wrote:

According to the manual the model BD-920N has a 9/16" x 16 TPI leadscrew.
Usually though there is a metric/inch change gear, or on fancy machines just
a selector. I believe the magic gear is a 127 tooth gear (25.4*5 = 127 =
zero conversion error).
I have used Russian made all metric machines that cut beautiful inch pitch
threads, and vice versa. It doesn't really matter whether the lead screw is
inch or metric as long as the gear ratio is correct you can cut any pitch
you want. - where it matters is in the cross slide, if you have a metric
dial that sucks.


Ok then the trouble I had must be the wrong change gear arrangement. I
cut a 8 TPI
thread and after having trouble I kept the nut engaged in the same place
and cut my thread.
It works but may be off slightly but not enough to not work.

Bill k7NOM

"Bill Janssen" wrote in message
...


I just got around to noticing a table for using the threading indicator.
The table
is the usual listing of indicator readings versus thread pitch.

However I just noticed that the thread pitch column is labeled TPI and the
threads
listed are all imperial threads.. I have reason to believe that the lead
screw is metric.

So my question is, where is the error? Is my lead screw wrong and I should
have
a Imperial or is the label wrong and no 9X20 was ever shipped with a
imperial
lead screw.

Confused
Bill K7NOM

"Bill Janssen" wrote in message
...

I tried cutting a 8 TPI thread using the 1 on the dial and got
three diferent start positions. Just counted the threads and it
16 or nearlu 16 per inch


Without seeing or knowing what you are actually doing (and without knowing
your background or experience), it is hard to tell what the problem is. But
I suspect it's a procedural error. If I'm wrong, I apologize.

I have an Enco 9x20, which is essentially identical to the Jet in every way
except for the spindle nose threads (for mounting chucks) and the paint
scheme. While I rarely cut Imperial threads, I have done so successfully by
disengaging the halfnuts and using the threading dial. It worked exactly as
advertised.

Regards,
Michael

I tried cutting a 8 TPI thread using the 1 on the dial and got three
diferent start positions.
Just counted the threads and it 16 or nearlu 16 per inch

I have a JET 9x20 and I successfully threaded a new back plate on it for a
4-jaw chuck without any problems. The spindle is 1 1/2 x 8TPI.

Have you checked to be sure the gear on the end of the thread dial is snug
up against the lead screw? It could be skipping if it's loose.

Best Regards,
Keith Marshall


"I'm not grown up enough to be so old!"

Thanks for all the comments. I must have used the wrong combination of
gears even
though my threads were close enough to be usable. So I will try again
but this time
I will double check the gear combination.

Bill k7NOM

Keith Marshall wrote:

I tried cutting a 8 TPI thread using the 1 on the dial and got three
diferent start positions.
Just counted the threads and it 16 or nearlu 16 per inch



I have a JET 9x20 and I successfully threaded a new back plate on it for a
4-jaw chuck without any problems. The spindle is 1 1/2 x 8TPI.

Have you checked to be sure the gear on the end of the thread dial is snug
up against the lead screw? It could be skipping if it's loose.

Best Regards,
Keith Marshall


"I'm not grown up enough to be so old!"

In article ,
DeepDiver wrote:
"Bill Janssen" wrote in message
...

I have reason to believe that the lead screw is metric.

Based on what?

Btw, it might help if you told us the vendor of your particular 9x20.

He did -- but only in the "Subject: " header, not in the body.
I know that it is typically quite a while between the time I select
subjects to read and the time a given article pops up, so I sometimes
have to remember to look back at the headers.

As for the original question -- others know the machines better
than I -- but I think that all in the US have Imperial leadscrews -- at
least the longitudinal one used for threading.

The cross-feed and compound ones may be a near fit metric,
especially if you wind up with weird counts on the dial for a full turn,
like 127 or 63-1/2. Precise counts of 200 or 100 or 50 are more likely
to be true imperial screws.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
Bill Janssen wrote:
DeepDiver wrote:

I tried cutting a 8 TPI thread using the 1 on the dial and got three
diferent start positions.
Just counted the threads and it 16 or nearlu 16 per inch

Did you by any chance touch the reverse tumbler while doing the
thread? That has to remain engaged until the thread is done, or you get
as many different start positions as you have teeth in the tumbler
gears.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" wrote in message
...
In article ,
DeepDiver wrote:

Btw, it might help if you told us the vendor of your particular 9x20.

He did -- but only in the "Subject: " header, not in the body.

Yes Don, I caught that as soon as I posted the first response (and
acknowledged my error in an immediate follow-up post).

- Michael

"DoN. Nichols" wrote in message
...

Did you by any chance touch the reverse tumbler while doing
the thread?

Hi Don,

I know you're not familiar with the 9x20 lathe. FYI, it has no factory
tumbler reverse. (However, there are a number of people who have added their
own. It's on my list of things to do.)

- Michael

I have a Jet 12x36
IIRC, to cut metric threads, you have to change the "gears"
could your lathe have the "wrong" metric gears installed

PS Jet is very helpful for info about this kind of stuff

HTH
Otto
"Bill Janssen" wrote in message ...
Thanks for all the comments. I must have used the wrong combination of gears even
though my threads were close enough to be usable. So I will try again but this time
I will double check the gear combination.

Bill k7NOM

Keith Marshall wrote:
I tried cutting a 8 TPI thread using the 1 on the dial and got three
diferent start positions.
Just counted the threads and it 16 or nearlu 16 per inch


I have a JET 9x20 and I successfully threaded a new back plate on it for a
4-jaw chuck without any problems. The spindle is 1 1/2 x 8TPI.

Have you checked to be sure the gear on the end of the thread dial is snug
up against the lead screw? It could be skipping if it's loose.

Best Regards,
Keith Marshall


"I'm not grown up enough to be so old!"

"Dean" wrote in message
...
According to the manual the model BD-920N has a 9/16" x 16 TPI leadscrew.
Usually though there is a metric/inch change gear, or on fancy machines
just
a selector. I believe the magic gear is a 127 tooth gear (25.4*5 = 127 =
zero conversion error).


I have used Russian made all metric machines that cut beautiful inch pitch
threads, and vice versa.

my gawed!! don't ever let Gunner find out about this!!!!

Otto


It doesn't really matter whether the lead screw is
inch or metric as long as the gear ratio is correct you can cut any pitch
you want. - where it matters is in the cross slide, if you have a metric
dial that sucks.

"Bill Janssen" wrote in message
...
I just got around to noticing a table for using the threading
indicator.
The table
is the usual listing of indicator readings versus thread pitch.

However I just noticed that the thread pitch column is labeled TPI and
the
threads
listed are all imperial threads.. I have reason to believe that the lead
screw is metric.

So my question is, where is the error? Is my lead screw wrong and I
should
have
a Imperial or is the label wrong and no 9X20 was ever shipped with a
imperial
lead screw.

Confused
Bill K7NOM

In article ,
DeepDiver wrote:
"DoN. Nichols" wrote in message
...

Did you by any chance touch the reverse tumbler while doing
the thread?

Hi Don,

I know you're not familiar with the 9x20 lathe. FYI, it has no factory
tumbler reverse. (However, there are a number of people who have added their
own. It's on my list of things to do.)

O.K. Then it is not a possible mistake -- yet. :-)

Hopefully, one of the other suggestions will have led you to the
solution by now.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
DeepDiver wrote:
"DoN. Nichols" wrote in message
...
In article ,
DeepDiver wrote:

Btw, it might help if you told us the vendor of your particular 9x20.

He did -- but only in the "Subject: " header, not in the body.

Yes Don, I caught that as soon as I posted the first response (and
acknowledged my error in an immediate follow-up post).

Yes -- but one which I did not see until I posted mine.

But people really need to be careful to duplicate the
information in the "Subject: " header down in the body, so as to make
this sort of thing harder to stumble over.

Sorry,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Thanks was Jet 9X20 lead screw ?
 

replying to Bill Janssen, loren green wrote:
I want to thread a back plate as well, but I have not figured out the setting.
Can you send me the set up for my jet 920?
thanks

--
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