My Jet 1024 can do SAE and metric threading. It can do .75 mm pitch,
but not .7. But the M4 standard pitch is .7!

1. Why in the world wasn't this lathe designed to do .7? There's only 4
or 5 pitches that one needs 99% of the time and .7 is one of them. The
lathe will do about 20 different metric pitches, but not one that is
needed! Unless ...

2. Is .75 close enough?

Thanks,
Bob

..75 is not close enough, if your nut is longer than say 3x the pitch
you may start to bind or not fit correctly, even so it will cause
uneven wear and premature failure.

You can probably change the output of the gear box by using some quick
change gears (if any were supplied)

I'm not sure about your lathe, but every lath can be changed to putput
a different lead. Either by using a factor of the output or by using a
seperate set of gears.

one formula is (for change gears)

(mm pitch) x 5 x (TPI of leadscrew)
---------------------------------------------------
127

..7 x 5 x 6 (for example)
------------------------
127


7 x 30
--------------
10 x 127

28 30
---- x ------
40 127

Final gears would be

28 60
----- x --------
40 127

28 on stud driving the 40. the 40 is on the same shaft and keyed to
the 60, and the 127 would be on the leadscrew. If you need to change
the direction add idlers between the 60 and 127 gears

there is plenty of information in Moltrecht's books on modifying the
quick change gearbox output.

Good luck

-S

oh and the other thing you can do is use a die, much easier..



-S

Bob Engelhardt writes:

2. Is .75 close enough?

No.

Are you sure your documentation is correct? Maybe there is some gear combo
that you don't know about?

My Enco 1024 came with 4 or 5 change gears.
Does your lathe have those?

- -
Rex Burkheimer
WM Automotive
Fort Worth TX

Bob Engelhardt wrote:
My Jet 1024 can do SAE and metric threading. It can do .75 mm pitch,
but not .7. But the M4 standard pitch is .7!

1. Why in the world wasn't this lathe designed to do .7? There's only 4
or 5 pitches that one needs 99% of the time and .7 is one of them. The
lathe will do about 20 different metric pitches, but not one that is
needed! Unless ...

2. Is .75 close enough?

Thanks,
Bob

Richard J Kinch wrote:
Are you sure your documentation is correct? Maybe there is some gear combo
that you don't know about?

There is a sticker on the gear train cover with the pitches listed.
However, not all change gear combinations are shown, so I'm going to
fill in the blanks and see it there is something closer to .7. Thanks
for the idea. Bob

Rex B wrote:
My Enco 1024 came with 4 or 5 change gears.
Does your lathe have those?

The sticker with the pitches on it has 3 gear configurations using
combinations of 40, 32, and 30 tooth gears, plus the 120/127 combo.
None of the configurations show a .7 pitch. Does yours? If so, what
gears are used for it?

Thanks,
Bob

Bob
Looking through the docs I have, none show a .7

- -
Rex Burkheimer
WM Automotive
Fort Worth TX

Bob Engelhardt wrote:
Rex B wrote:

My Enco 1024 came with 4 or 5 change gears.
Does your lathe have those?


The sticker with the pitches on it has 3 gear configurations using
combinations of 40, 32, and 30 tooth gears, plus the 120/127 combo. None
of the configurations show a .7 pitch. Does yours? If so, what gears
are used for it?

Thanks,
Bob

It's possible that 36 tpi will work for .7mm.

..7 mm is 36.29 tpi that's less than 1% difference and I would think
that it should be good as long as the either the screw or nut is
fairly short. It might be close enough for common thread fit no matter
the length of thread, but I've never tried it.

Cheers,

Kelley

On Mon, 01 Aug 2005 21:18:13 -0400, Bob Engelhardt
wrote:

My Jet 1024 can do SAE and metric threading. It can do .75 mm pitch,
but not .7. But the M4 standard pitch is .7!

1. Why in the world wasn't this lathe designed to do .7? There's only 4
or 5 pitches that one needs 99% of the time and .7 is one of them. The
lathe will do about 20 different metric pitches, but not one that is
needed! Unless ...

2. Is .75 close enough?

Thanks,
Bob

I set up a spread sheet to calculate the pitches using all quick-change
gears (5 x 8), as well as all combinations of the gears in the feed
train. Jet had shown just the values that were even to 1/8's. E.g.,
..375, but not 1.6363. Also, Jet just used 3 of the 7 gear combinations.

I found a setting that gives a .703125 pitch. Over the course of 5
threads (normal(?) engagement), it would be off .016 mm. Close enough
for me.

That setting is: 30 tooth gear before the 127 & 32 tooth after. Quick
change on D1.

I'll post the table to the drop box once I get it formatted to something
other than an .xls file.

Bob

Bob - reckon you could email me the XLS file?

- -
Rex Burkheimer
WM Automotive
Fort Worth TX

Bob Engelhardt wrote:
I set up a spread sheet to calculate the pitches using all quick-change
gears (5 x 8), as well as all combinations of the gears in the feed
train. Jet had shown just the values that were even to 1/8's. E.g.,
.375, but not 1.6363. Also, Jet just used 3 of the 7 gear combinations.

I found a setting that gives a .703125 pitch. Over the course of 5
threads (normal(?) engagement), it would be off .016 mm. Close enough
for me.

That setting is: 30 tooth gear before the 127 & 32 tooth after. Quick
change on D1.

I'll post the table to the drop box once I get it formatted to something
other than an .xls file.

Bob

Bob Engelhardt wrote:

I set up a spread sheet to calculate the pitches using all quick-change
gears (5 x 8), as well as all combinations of the gears in the feed
train. ...

It's in the DropBox as "Jet1024gears.txt". I.e.,

http://www.metalworking.com/dropbox/Jet1024gears.txt

The original .xls is available by email.

Bob

How about posting the .xls as well? I have a small Atlas lathe, and I would
like to adapt your file for my gear set.

Joe

Bob Engelhardt wrote:

Bob Engelhardt wrote:

I set up a spread sheet to calculate the pitches using all quick-change
gears (5 x 8), as well as all combinations of the gears in the feed
train. ...

It's in the DropBox as "Jet1024gears.txt". I.e.,

http://www.metalworking.com/dropbox/Jet1024gears.txt

The original .xls is available by email.

Bob

Joe wrote:

How about posting the .xls as well? ...

The DropBox doesn't allow .xls's, because of the security risk (embedded
macros).

On Wed, 03 Aug 2005 10:13:01 -0400, Bob Engelhardt
wrote:

Joe wrote:

How about posting the .xls as well? ...

The DropBox doesn't allow .xls's, because of the security risk (embedded
macros).

You could zip it up, no?

- Mike -

Can you rename it with instruction to the user to change it back to an
XLS extension after downloading?

- -
Rex Burkheimer
WM Automotive
Fort Worth TX

Bob Engelhardt wrote:
Joe wrote:

How about posting the .xls as well? ...


The DropBox doesn't allow .xls's, because of the security risk (embedded
macros).

Mike Haaland wrote:
You could zip it up, no?

Yeeaah...

Rex B wrote:
Can you rename it with instruction to the user to change it back to an
XLS extension after downloading?

No, I won't hack the DropBox.

1. I will gladly email it to anyone.
2. It is not really general purpose - it would have to be patched for a
different lathe/gears.
3. If you're going to patch it you could probably write one from scratch
without much more work.

Bob