This lathe is advertised as being able to cut english and metric
threads. I have had no problems making english threads.

According to the manual, in order to do metric threads you must do the
following:

Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears
and run one on the 120 main gear and run the lower on the 127 gear
(machine has 120/127 double main gear for converting to metric).

Select the proper combination of levers - i.e L,T,A,C according to the
chart printed on the front of the lathe.

Disengage feed selector to the "O" posotion.

Now, when cutting english you use the dial indicator and
engage/disengage the half-nut lever. On metric, the manual says to
engage the half-nut lever and leave it engaged during the whole process
of cutting the thread.

However, the manual fails to tell you how to stop the machine at the
end of the cut so that you can reset the depth on the cross-feed. You
cannot reverse the direction of lead screw travel as suggested by an
authorized jet technician for three reasons. One, there's a large
warning on the front of the machine telling you not to do this. Two,
it doesn't work since you are temporarily changing gear teeth when
moving the selector know, therefore you are off when reversing and
coming back into the cut. Third, changing the lead screw direction
goes from cutting right-handed to left-handed threads when changing
directions.

It seems that the procedure involves leaving all gears continually
engaged. Then you cut the forward/reverse lever on the apron section
to the neutral position to cut power to the travel. The head continues
to rotate due to momentum until it comes to a rest and the magnetic
latches release on the motor. Then you back out the cross feed, jog
the machine backwards using the jog button, reset your depth and do
another cut. This appears to work, but what do you do to stop the
drift after stopping? If you need to thread a half inch piece that has
a 1/4" relief and then projects into a 60 degree bevel towards the
chuck, you risk crashing the tool into the part when trying to guess
where the momentum will stop the carriage. This machine does not come
with a brake and jogging the machine backwards immediately after
disengaging the feed start lever does not work since the motor does not
disengage the latches until it comes to a complete stop.

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC

In article .com,
says...

It seems that the procedure involves leaving all gears continually
engaged.

Yep. You cannot thread to a shoulder on a setup like this.

Short of running the spindle by hand, with a crank (some folks
*do* this) will have to have enough runout room to account for the
spin-down time of the drive train.

My approach is to use a 3 phase motor, and plug-reverse it when
the tool approaches the shoulder. A rotary converter supplies
the 3 phase power.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

Quoting from "Moltrecht":

"When cutting a thread with a split nut continuously engaged, the spindle
speed must be slow enough to allow the operator to have complete control
over all of the lathe movements at all times. Thus, the spindle speed used
depends upon the judgment of the operator. He should consider his
experience in cutting metric threads on inch lead-screw machines, his
experience on a particular machine, the ease with which a particular machine
can be manipulated, and the size and type of thread being cut. All other
machine settings made in preparation for cutting threads are the same as
before, except that the 127-tooth translating gear must be used in the gear
train."

One good way to maintain necessary control is to rotate the spindle
manually. I do this with a crank on the outboard end of the spindle.
Another way would be to turn off power to the spindle with enough room left
for it to coast to a stop. Then when almost stopped continue to turn the
chuck by hand. The moral to this is - metric threads aren't as easy to cut
on "English" machines as English threads are. Leave the gears disengaged
from the motor when turning the spindle by hand. Cranking back by hand is a
lot easier to do if you aren't dragging the motor along.

Bob Swinney
wrote in message
oups.com...
This lathe is advertised as being able to cut english and metric
threads. I have had no problems making english threads.

According to the manual, in order to do metric threads you must do the
following:

Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears
and run one on the 120 main gear and run the lower on the 127 gear
(machine has 120/127 double main gear for converting to metric).

Select the proper combination of levers - i.e L,T,A,C according to the
chart printed on the front of the lathe.

Disengage feed selector to the "O" posotion.

Now, when cutting english you use the dial indicator and
engage/disengage the half-nut lever. On metric, the manual says to
engage the half-nut lever and leave it engaged during the whole process
of cutting the thread.

However, the manual fails to tell you how to stop the machine at the
end of the cut so that you can reset the depth on the cross-feed. You
cannot reverse the direction of lead screw travel as suggested by an
authorized jet technician for three reasons. One, there's a large
warning on the front of the machine telling you not to do this. Two,
it doesn't work since you are temporarily changing gear teeth when
moving the selector know, therefore you are off when reversing and
coming back into the cut. Third, changing the lead screw direction
goes from cutting right-handed to left-handed threads when changing
directions.

It seems that the procedure involves leaving all gears continually
engaged. Then you cut the forward/reverse lever on the apron section
to the neutral position to cut power to the travel. The head continues
to rotate due to momentum until it comes to a rest and the magnetic
latches release on the motor. Then you back out the cross feed, jog
the machine backwards using the jog button, reset your depth and do
another cut. This appears to work, but what do you do to stop the
drift after stopping? If you need to thread a half inch piece that has
a 1/4" relief and then projects into a 60 degree bevel towards the
chuck, you risk crashing the tool into the part when trying to guess
where the momentum will stop the carriage. This machine does not come
with a brake and jogging the machine backwards immediately after
disengaging the feed start lever does not work since the motor does not
disengage the latches until it comes to a complete stop.

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC

I made a hand crank for my EMCO lathe for the same reason. Slower, but
can thread to a sholder.

Be sure to back out the tool before cranking back to the beginning.

Paul

Robert Swinney wrote:
Quoting from "Moltrecht":

"When cutting a thread with a split nut continuously engaged, the spindle
speed must be slow enough to allow the operator to have complete control
over all of the lathe movements at all times. Thus, the spindle speed used
depends upon the judgment of the operator. He should consider his
experience in cutting metric threads on inch lead-screw machines, his
experience on a particular machine, the ease with which a particular machine
can be manipulated, and the size and type of thread being cut. All other
machine settings made in preparation for cutting threads are the same as
before, except that the 127-tooth translating gear must be used in the gear
train."

One good way to maintain necessary control is to rotate the spindle
manually. I do this with a crank on the outboard end of the spindle.
Another way would be to turn off power to the spindle with enough room left
for it to coast to a stop. Then when almost stopped continue to turn the
chuck by hand. The moral to this is - metric threads aren't as easy to cut
on "English" machines as English threads are. Leave the gears disengaged
from the motor when turning the spindle by hand. Cranking back by hand is a
lot easier to do if you aren't dragging the motor along.

Bob Swinney
wrote in message
oups.com...
This lathe is advertised as being able to cut english and metric
threads. I have had no problems making english threads.

According to the manual, in order to do metric threads you must do the
following:

Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears
and run one on the 120 main gear and run the lower on the 127 gear
(machine has 120/127 double main gear for converting to metric).

Select the proper combination of levers - i.e L,T,A,C according to the
chart printed on the front of the lathe.

Disengage feed selector to the "O" posotion.

Now, when cutting english you use the dial indicator and
engage/disengage the half-nut lever. On metric, the manual says to
engage the half-nut lever and leave it engaged during the whole process
of cutting the thread.

However, the manual fails to tell you how to stop the machine at the
end of the cut so that you can reset the depth on the cross-feed. You
cannot reverse the direction of lead screw travel as suggested by an
authorized jet technician for three reasons. One, there's a large
warning on the front of the machine telling you not to do this. Two,
it doesn't work since you are temporarily changing gear teeth when
moving the selector know, therefore you are off when reversing and
coming back into the cut. Third, changing the lead screw direction
goes from cutting right-handed to left-handed threads when changing
directions.

It seems that the procedure involves leaving all gears continually
engaged. Then you cut the forward/reverse lever on the apron section
to the neutral position to cut power to the travel. The head continues
to rotate due to momentum until it comes to a rest and the magnetic
latches release on the motor. Then you back out the cross feed, jog
the machine backwards using the jog button, reset your depth and do
another cut. This appears to work, but what do you do to stop the
drift after stopping? If you need to thread a half inch piece that has
a 1/4" relief and then projects into a 60 degree bevel towards the
chuck, you risk crashing the tool into the part when trying to guess
where the momentum will stop the carriage. This machine does not come
with a brake and jogging the machine backwards immediately after
disengaging the feed start lever does not work since the motor does not
disengage the latches until it comes to a complete stop.

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC

wrote in message
oups.com...
This lathe is advertised as being able to cut english and metric
threads. I have had no problems making english threads.

According to the manual, in order to do metric threads you must do the
following:

Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears
and run one on the 120 main gear and run the lower on the 127 gear
(machine has 120/127 double main gear for converting to metric).

Select the proper combination of levers - i.e L,T,A,C according to the
chart printed on the front of the lathe.

Disengage feed selector to the "O" posotion.

Now, when cutting english you use the dial indicator and
engage/disengage the half-nut lever. On metric, the manual says to
engage the half-nut lever and leave it engaged during the whole process
of cutting the thread.

However, the manual fails to tell you how to stop the machine at the
end of the cut so that you can reset the depth on the cross-feed. You
cannot reverse the direction of lead screw travel as suggested by an
authorized jet technician for three reasons. One, there's a large
warning on the front of the machine telling you not to do this. Two,
it doesn't work since you are temporarily changing gear teeth when
moving the selector know, therefore you are off when reversing and
coming back into the cut. Third, changing the lead screw direction
goes from cutting right-handed to left-handed threads when changing
directions.

It seems that the procedure involves leaving all gears continually
engaged. Then you cut the forward/reverse lever on the apron section
to the neutral position to cut power to the travel. The head continues
to rotate due to momentum until it comes to a rest and the magnetic
latches release on the motor. Then you back out the cross feed, jog
the machine backwards using the jog button, reset your depth and do
another cut. This appears to work, but what do you do to stop the
drift after stopping? If you need to thread a half inch piece that has
a 1/4" relief and then projects into a 60 degree bevel towards the
chuck, you risk crashing the tool into the part when trying to guess
where the momentum will stop the carriage. This machine does not come
with a brake and jogging the machine backwards immediately after
disengaging the feed start lever does not work since the motor does not
disengage the latches until it comes to a complete stop.

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC


Simply make a dry run with the threading tool clear of the workpiece. Cut
power when you think it is far enough along and see how far it coasts.
Adjust the switch point accordingly. If it coasts more than 1/4", reduce
the spindle rpm. You will always be safe because it will not coast as far
with the tool engaged in a cut.

Randy

Thanks for the suggestions.

One issue I have with the coast method is that even using the slowest
rpm (70), and dry running to figure amount of drift (1/2" in this
case), it may not consistently coast that 1/2 an inch. With only a
small relief area being allowed, this runs a good chance of damaging
the part and tool. The hand crank method suggested by others seems
like viable option given the short distance required to be threaded.

Will check tonight on the reliability of consistent drift or try and
make a manual crank for the outboard section.

These responses are greatly appreciated.

Doug

On 4 Oct 2005 09:13:52 -0700, wrote:

(snip)

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC

I'd suggest contriving a foot-actuated brake that can kill power and
stop the spindle instantly. My lathe came with such a brake, and it
is very handy when cutting threads close to a shoulder. At low
speeds I can always stop within considerably less than 1/4 revolution.
I usually make a relief groove about .050 wide next to the shoulder
for the bit to stop in.

Thought about this also. Not sure where it would attach, but I believe
it could be done as you suggest. Wish it had one already, simply for
the fact that it makes using the lathe a lot easier (in my opinion).

I made a spindle brake and cutoff switch for my GHB1340 Jet. With the
loowest speed being 70 its way to high and close in a lot of
situations, and it always made me uncommfortable, expecially when
working close to the jaws or a shoulder or in a blind hole when
threading.

I used a small drum type brake and expanding shoes from a honda ATV,
that is actuated by a foot treadle just like on the lathes that offer
such a foot brake. A flexible cable in a housing (brake cable assembly
from a ATV is what connects foot brake treadle to the brake assembly
which is mounted on the geartrain under the fiberglass cover on head
end. The switch is just a plunger type switch with a roller on it
that I had laying around from the old F-4 Phantom days and was used
on the BLC system. It breaks power to a relay, which in turn cuts
power to regular stop swtich assembly. The relay is a manuala engage
so after stopping it with foot peddle it mst be reset manually with
another switch, which is mounted in the control panel on the top of
the lathe in the space next to the power on green indicator light.

On Tue, 04 Oct 2005 13:33:38 -0500, Don Foreman
wrote:

===On 4 Oct 2005 09:13:52 -0700, wrote:
===
===(snip)
===
===I have read other scenarios about reversing with other machines, but
===this is designed to run 220V single phase. Any help would be
===appreciated.
===
===DC
===
===I'd suggest contriving a foot-actuated brake that can kill power and
===stop the spindle instantly. My lathe came with such a brake, and it
===is very handy when cutting threads close to a shoulder. At low
===speeds I can always stop within considerably less than 1/4 revolution.
===I usually make a relief groove about .050 wide next to the shoulder
===for the bit to stop in.


==============================================
Put some color in your cheeks...garden naked!
"The original frugal ponder"
~~~~ }((((o ~~~~~~ }{{{{o ~~~~~~~ }(((((o

Sounds like a very interesting modification. Do you have any pictures
or maybe a rough drawing of how the brake assembly is connected to the
gear train? If not, that's OK. Thanks for the detailed explanation of
the setup.

Doug

On 4 Oct 2005 09:13:52 -0700, wrote:

This lathe is advertised as being able to cut english and metric
threads. I have had no problems making english threads.

According to the manual, in order to do metric threads you must do the
following:

Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears
and run one on the 120 main gear and run the lower on the 127 gear
(machine has 120/127 double main gear for converting to metric).

Select the proper combination of levers - i.e L,T,A,C according to the
chart printed on the front of the lathe.

Disengage feed selector to the "O" posotion.

Now, when cutting english you use the dial indicator and
engage/disengage the half-nut lever. On metric, the manual says to
engage the half-nut lever and leave it engaged during the whole process
of cutting the thread.

However, the manual fails to tell you how to stop the machine at the
end of the cut so that you can reset the depth on the cross-feed. You
cannot reverse the direction of lead screw travel as suggested by an
authorized jet technician for three reasons. One, there's a large
warning on the front of the machine telling you not to do this. Two,
it doesn't work since you are temporarily changing gear teeth when
moving the selector know, therefore you are off when reversing and
coming back into the cut. Third, changing the lead screw direction
goes from cutting right-handed to left-handed threads when changing
directions.

It seems that the procedure involves leaving all gears continually
engaged. Then you cut the forward/reverse lever on the apron section
to the neutral position to cut power to the travel. The head continues
to rotate due to momentum until it comes to a rest and the magnetic
latches release on the motor. Then you back out the cross feed, jog
the machine backwards using the jog button, reset your depth and do
another cut. This appears to work, but what do you do to stop the
drift after stopping? If you need to thread a half inch piece that has
a 1/4" relief and then projects into a 60 degree bevel towards the
chuck, you risk crashing the tool into the part when trying to guess
where the momentum will stop the carriage. This machine does not come
with a brake and jogging the machine backwards immediately after
disengaging the feed start lever does not work since the motor does not
disengage the latches until it comes to a complete stop.

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC
Greetings DC,
Now's the time to consider a 3 phase motor and a foot brake if the
lathe doesn't have one. I'm not familiar with this lathe but if it's a
bench lathe then maybe an electric brake. At the very least get a
three phase motor. Using google to check previous threads on Rotary
Phase Converters (RPC) will provide you with a wealth of information.
Three phase motors are cheap and plentiful used. And you need two
three phase motors. One for the lathe and the other for the RPC. I
know this answer doesn't help you out much right now but others here
will tell you how to solve you immediate problem. The three phase
motor will allow you to instant reverse the lathe so if you are
careful you can withdraw the threading tool at the same time as you
reverse the spindle. Keeping the lathe running reverse until the tool
is past the part will allow you to cut metric threads pretty fast.
It's also real handy for power tapping. And some kind of brake can be
a real finger, chuck, tool, etc saver.
ERS

Don Foreman wrote:
I'd suggest contriving a foot-actuated brake that can kill power and
stop the spindle instantly. ...

I don't know if you're talking about a mechanical brake, but you can
brake ac motors electrically. I've not done it, but if I recall
correctly, it's a matter of applying dc to the field winding. I'd think
that the only problem would be with how much current to apply.

Bob

On my 13 - 40 lathe, from MSC, the motor shaft has a brake disk mounted on
it. Automotive type master cylinder is hosed to a set of calipers and the
whole affair is actuated by a long treadle, within easy reach of any area in
front of the lathe. IMO, your time would be better spent learning to cut
metric threads with a hand crank, etc., than fiddling around with trying to
contrive a brake. Frustrations less; rewards more! You will feel better
about your new machine if you perfect certain difficult procedures first
rather than trying to modify it.

Bob Swinney
wrote in message
oups.com...
Sounds like a very interesting modification. Do you have any pictures
or maybe a rough drawing of how the brake assembly is connected to the
gear train? If not, that's OK. Thanks for the detailed explanation of
the setup.

Doug

In article , Eric R Snow says...

Now's the time to consider a 3 phase motor and a foot brake

If he has three phase, then he doesn't really need the foot brake.

It's a snap to plug reverse the motor to a dead stop, or better
yet throw it over into reverse as the tool is backed out, to
bring it away from the shoulder.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

jim rozen wrote:
In article , Eric R Snow
says...

Now's the time to consider a 3 phase motor and a foot brake

If he has three phase, then he doesn't really need the foot brake.

It's a snap to plug reverse the motor to a dead stop, or better
yet throw it over into reverse as the tool is backed out, to
bring it away from the shoulder.

Jim

If the thread is a short one consider setting up a hand-crank for the lathe.
If this is not possible/practical you will have to anticipate how long the
lathe will coast after power is turned off and 'pull the plug' in advance.
As the machine is slowing down have your hand on the cross slide ready to
rapidly back it off at the right moment.
Then reverse the lathe back to your starting point.
Be sure to have all the lash on the correct side of the tool before starting
into the cut.
Takes some practice and will supply a few moments of high drama but it gets
easy.

Ken.

wrote:

This lathe is advertised as being able to cut english and metric
threads. I have had no problems making english threads.

According to the manual, in order to do metric threads you must do the
following:

Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears
and run one on the 120 main gear and run the lower on the 127 gear
(machine has 120/127 double main gear for converting to metric).

Select the proper combination of levers - i.e L,T,A,C according to the
chart printed on the front of the lathe.

Disengage feed selector to the "O" posotion.

Now, when cutting english you use the dial indicator and
engage/disengage the half-nut lever. On metric, the manual says to
engage the half-nut lever and leave it engaged during the whole process
of cutting the thread.

However, the manual fails to tell you how to stop the machine at the
end of the cut so that you can reset the depth on the cross-feed. You
cannot reverse the direction of lead screw travel as suggested by an
authorized jet technician for three reasons. One, there's a large
warning on the front of the machine telling you not to do this. Two,
it doesn't work since you are temporarily changing gear teeth when
moving the selector know, therefore you are off when reversing and
coming back into the cut. Third, changing the lead screw direction
goes from cutting right-handed to left-handed threads when changing
directions.

It seems that the procedure involves leaving all gears continually
engaged. Then you cut the forward/reverse lever on the apron section
to the neutral position to cut power to the travel. The head continues
to rotate due to momentum until it comes to a rest and the magnetic
latches release on the motor. Then you back out the cross feed, jog
the machine backwards using the jog button, reset your depth and do
another cut. This appears to work, but what do you do to stop the
drift after stopping? If you need to thread a half inch piece that has
a 1/4" relief and then projects into a 60 degree bevel towards the
chuck, you risk crashing the tool into the part when trying to guess
where the momentum will stop the carriage. This machine does not come
with a brake and jogging the machine backwards immediately after
disengaging the feed start lever does not work since the motor does not
disengage the latches until it comes to a complete stop.

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC



Ok here is my suggestion

Use the thread dial but only use the 1 position

Take the first cut and when at the end disconnect the half nuts and
immediately stop the
motor.

Notice how far the thread dial continued to turn.

Reverse the lathe and engage the half nut when the dial read 1

Stop the lathe and get set up for the next pass and leave the half nuts
engaged
and start the second cut.

Repeat as needed.

Hope this is clear and useful.

Good luck.
Bill K7NOM

"jim rozen" wrote in message
...
In article , Eric R Snow
says...

Now's the time to consider a 3 phase motor and a foot brake

If he has three phase, then he doesn't really need the foot brake.

It's a snap to plug reverse the motor to a dead stop, or better
yet throw it over into reverse as the tool is backed out, to
bring it away from the shoulder.

Jim
Yeah, that "snap" would be me breaking tools.

Bob Swinney

--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

In article , Robert Swinney says...

Yeah, that "snap" would be me breaking tools.

You'd be suprised, it's easy to get into the swing of
threading this way. I recently did a run of M8X1 fasteners
for my motorbike restoration, granted it's a fine thread
so the feed rate is slow, and if you make a mistake and
over-run the thread end there's not much danger.

But some of them were pretty short, so I was threading
right up to the collet, and nothing went wrong.

First few times doing this I would suggest using a
setup part with large relief runout area, and
getting used to the machine. But with the three phase
power, the spindle comes to a stop and reverses,
very predictably.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

I think the hand crank is probably my best option. Still would like to
install the brake as an option later (probably after warranty is up).
Setting up 3 phase is also a pretty good idea, but I'm not ready to
make the investment in rewiring and replacing motors.

Started making hand crank last night. Decided to design a model that
will do a clamp fit over the spindle shaft so no machine modifications
will be required (do not want to void warranty). Looks good so far.
Should have finished today and ready for testing by tonight.

Thanks for the help.

Doug



Robert Swinney wrote:
On my 13 - 40 lathe, from MSC, the motor shaft has a brake disk mounted on
it. Automotive type master cylinder is hosed to a set of calipers and the
whole affair is actuated by a long treadle, within easy reach of any area in
front of the lathe. IMO, your time would be better spent learning to cut
metric threads with a hand crank, etc., than fiddling around with trying to
contrive a brake. Frustrations less; rewards more! You will feel better
about your new machine if you perfect certain difficult procedures first
rather than trying to modify it.

Bob Swinney
wrote in message
oups.com...
Sounds like a very interesting modification. Do you have any pictures
or maybe a rough drawing of how the brake assembly is connected to the
gear train? If not, that's OK. Thanks for the detailed explanation of
the setup.

Doug

I made a rear tool post to hold the threading bit. Then I run the lathe in
reverse to cut the right hand thread. This way the direction is away from
the head stock. The return stroke then can be by hand with no chance of
hitting the chuck.

Jim

wrote in message
oups.com...
This lathe is advertised as being able to cut english and metric
threads. I have had no problems making english threads.

According to the manual, in order to do metric threads you must do the
following:

Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears
and run one on the 120 main gear and run the lower on the 127 gear
(machine has 120/127 double main gear for converting to metric).

Select the proper combination of levers - i.e L,T,A,C according to the
chart printed on the front of the lathe.

Disengage feed selector to the "O" posotion.

Now, when cutting english you use the dial indicator and
engage/disengage the half-nut lever. On metric, the manual says to
engage the half-nut lever and leave it engaged during the whole process
of cutting the thread.

However, the manual fails to tell you how to stop the machine at the
end of the cut so that you can reset the depth on the cross-feed. You
cannot reverse the direction of lead screw travel as suggested by an
authorized jet technician for three reasons. One, there's a large
warning on the front of the machine telling you not to do this. Two,
it doesn't work since you are temporarily changing gear teeth when
moving the selector know, therefore you are off when reversing and
coming back into the cut. Third, changing the lead screw direction
goes from cutting right-handed to left-handed threads when changing
directions.

It seems that the procedure involves leaving all gears continually
engaged. Then you cut the forward/reverse lever on the apron section
to the neutral position to cut power to the travel. The head continues
to rotate due to momentum until it comes to a rest and the magnetic
latches release on the motor. Then you back out the cross feed, jog
the machine backwards using the jog button, reset your depth and do
another cut. This appears to work, but what do you do to stop the
drift after stopping? If you need to thread a half inch piece that has
a 1/4" relief and then projects into a 60 degree bevel towards the
chuck, you risk crashing the tool into the part when trying to guess
where the momentum will stop the carriage. This machine does not come
with a brake and jogging the machine backwards immediately after
disengaging the feed start lever does not work since the motor does not
disengage the latches until it comes to a complete stop.

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC




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Re. hand crank: I used a tail pipe expander from HF as the axel part for
the hand crank. I made 2 of these, one for the rear of the spindle and a
smaller one for the 5-C collet tube when it is in the spindle.

Bob Swinney
"Jim and Jackie Instone" wrote in message
...
I made a rear tool post to hold the threading bit. Then I run the lathe in
reverse to cut the right hand thread. This way the direction is away from
the head stock. The return stroke then can be by hand with no chance of
hitting the chuck.

Jim

wrote in message
oups.com...
This lathe is advertised as being able to cut english and metric
threads. I have had no problems making english threads.

According to the manual, in order to do metric threads you must do the
following:

Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears
and run one on the 120 main gear and run the lower on the 127 gear
(machine has 120/127 double main gear for converting to metric).

Select the proper combination of levers - i.e L,T,A,C according to the
chart printed on the front of the lathe.

Disengage feed selector to the "O" posotion.

Now, when cutting english you use the dial indicator and
engage/disengage the half-nut lever. On metric, the manual says to
engage the half-nut lever and leave it engaged during the whole process
of cutting the thread.

However, the manual fails to tell you how to stop the machine at the
end of the cut so that you can reset the depth on the cross-feed. You
cannot reverse the direction of lead screw travel as suggested by an
authorized jet technician for three reasons. One, there's a large
warning on the front of the machine telling you not to do this. Two,
it doesn't work since you are temporarily changing gear teeth when
moving the selector know, therefore you are off when reversing and
coming back into the cut. Third, changing the lead screw direction
goes from cutting right-handed to left-handed threads when changing
directions.

It seems that the procedure involves leaving all gears continually
engaged. Then you cut the forward/reverse lever on the apron section
to the neutral position to cut power to the travel. The head continues
to rotate due to momentum until it comes to a rest and the magnetic
latches release on the motor. Then you back out the cross feed, jog
the machine backwards using the jog button, reset your depth and do
another cut. This appears to work, but what do you do to stop the
drift after stopping? If you need to thread a half inch piece that has
a 1/4" relief and then projects into a 60 degree bevel towards the
chuck, you risk crashing the tool into the part when trying to guess
where the momentum will stop the carriage. This machine does not come
with a brake and jogging the machine backwards immediately after
disengaging the feed start lever does not work since the motor does not
disengage the latches until it comes to a complete stop.

I have read other scenarios about reversing with other machines, but
this is designed to run 220V single phase. Any help would be
appreciated.

DC




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News==----
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Newsgroups
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On 4 Oct 2005 15:08:22 -0700, jim rozen
wrote:

In article , Eric R Snow says...

Now's the time to consider a 3 phase motor and a foot brake

If he has three phase, then he doesn't really need the foot brake.

It's a snap to plug reverse the motor to a dead stop, or better
yet throw it over into reverse as the tool is backed out, to
bring it away from the shoulder.

Jim
Jim,
The main reason for a brake is to stop the machine in an emergency. It
sure has saved my butt a few times.
Eric

On Tue, 4 Oct 2005 15:08:49 -0500, "Robert Swinney"
wrote:

Bob,
Since I make my living on my machines I tend to see thing in a daily
use production mode. For just occasional use a hand crank is probably
better. That said, if I was doing it for a hobby, I'd put on a three
phase motor and a brake. That's just me, and it reflects my experience
of working in machine shops for so long.
Cheers,
Eric

On my 13 - 40 lathe, from MSC, the motor shaft has a brake disk mounted on
it. Automotive type master cylinder is hosed to a set of calipers and the
whole affair is actuated by a long treadle, within easy reach of any area in
front of the lathe. IMO, your time would be better spent learning to cut
metric threads with a hand crank, etc., than fiddling around with trying to
contrive a brake. Frustrations less; rewards more! You will feel better
about your new machine if you perfect certain difficult procedures first
rather than trying to modify it.

Bob Swinney
wrote in message
roups.com...
Sounds like a very interesting modification. Do you have any pictures
or maybe a rough drawing of how the brake assembly is connected to the
gear train? If not, that's OK. Thanks for the detailed explanation of
the setup.

Doug

Point duly noted, Eric. Thanx.

Bob Swinney
"Eric R Snow" wrote in message
...
On Tue, 4 Oct 2005 15:08:49 -0500, "Robert Swinney"
wrote:

Bob,
Since I make my living on my machines I tend to see thing in a daily
use production mode. For just occasional use a hand crank is probably
better. That said, if I was doing it for a hobby, I'd put on a three
phase motor and a brake. That's just me, and it reflects my experience
of working in machine shops for so long.
Cheers,
Eric

On my 13 - 40 lathe, from MSC, the motor shaft has a brake disk mounted
on
it. Automotive type master cylinder is hosed to a set of calipers and the
whole affair is actuated by a long treadle, within easy reach of any area
in
front of the lathe. IMO, your time would be better spent learning to cut
metric threads with a hand crank, etc., than fiddling around with trying
to
contrive a brake. Frustrations less; rewards more! You will feel better
about your new machine if you perfect certain difficult procedures first
rather than trying to modify it.

Bob Swinney
wrote in message
groups.com...
Sounds like a very interesting modification. Do you have any pictures
or maybe a rough drawing of how the brake assembly is connected to the
gear train? If not, that's OK. Thanks for the detailed explanation of
the setup.

Doug