Can anyone point me to possible sources for this critter?

Thanks,
DOC

On Nov 23, 10:33 am, wrote:
Can anyone point me to possible sources for this critter?

Thanks,
DOC


No idea where you can get such a gear. You could try to make one.

That's the hard and expensive way.

The smart way is to use a 63 tooth gear which is much cheaper to get,
I believe.

I worked out the arithmetic for use of such a gear some years ago and,
while the conversion is not exact, it is so close that the inaccuracy
would get lost in the accumulated tolerances of the lead screw and
gear train.

If you are interested in pursuing this let me know and I will dig out
my scribbles.

Wolfgang

On Fri, 23 Nov 2007 09:02:29 -0800 (PST), wrote:

On Nov 23, 10:33 am, wrote:
Can anyone point me to possible sources for this critter?

Thanks,
DOC


No idea where you can get such a gear. You could try to make one.

That's the hard and expensive way.

The smart way is to use a 63 tooth gear which is much cheaper to get,
I believe.

I worked out the arithmetic for use of such a gear some years ago and,
while the conversion is not exact, it is so close that the inaccuracy
would get lost in the accumulated tolerances of the lead screw and
gear train.


The inaccuracy is only 1 part in 127, but it is all in one direction. If
you are threading a long part it could be a problem.

I bought change gears from Scott Logan for my 10EE and modified to fit. I'm
sure you can do the same. I used a smaller gear set that is only off .02%
but he has the 127 also if that's what you want.

Loganact.com I think


Karl

On Fri, 23 Nov 2007 07:33:53 -0800 (PST), wrote:

Can anyone point me to possible sources for this critter?

Union Gear and Boston Gear both list 127T 16DP change gears. Ametric
shows 127T metric spur gears in modules 1, 1.5, 2, 2.5, and 3.

--
Ned Simmons

On Nov 23, 12:09 pm, _
wrote:
On Fri, 23 Nov 2007 09:02:29 -0800 (PST), wrote:
On Nov 23, 10:33 am, wrote:
Can anyone point me to possible sources for this critter?

Thanks,
DOC

No idea where you can get such a gear. You could try to make one.

That's the hard and expensive way.

The smart way is to use a 63 tooth gear which is much cheaper to get,
I believe.

I worked out the arithmetic for use of such a gear some years ago and,
while the conversion is not exact, it is so close that the inaccuracy
would get lost in the accumulated tolerances of the lead screw and
gear train.

The inaccuracy is only 1 part in 127, but it is all in one direction. If
you are threading a long part it could be a problem.


The error is MUCH smaller than 1 in 127, provided the proper gear
train is set up. There is more to it than a straight substitution
plus 1 to 2 ratio.

As I said, if there is interest I will dig out my calcs.

Wolfgang

On Fri, 23 Nov 2007 12:06:35 -0600, "Karl Townsend"
wrote:

I bought change gears from Scott Logan for my 10EE and modified to fit. I'm
sure you can do the same. I used a smaller gear set that is only off .02%
but he has the 127 also if that's what you want.

Loganact.com I think


Karl

47:37
Gerry :-)}
London, Canada

wrote:
Can anyone point me to possible sources for this critter?


Check out this Australian dealer's site, under "Hercus lathe parts" near
bottom of page. Hercus9 is close copy of SB9, pretty sure gears will fit.
http://www.moyles.com.au/

On Sat, 24 Nov 2007 15:59:41 +1100, Jordan
wrote:

wrote:
Can anyone point me to possible sources for this critter?


Check out this Australian dealer's site, under "Hercus lathe parts" near
bottom of page. Hercus9 is close copy of SB9, pretty sure gears will fit.
http://www.moyles.com.au/

the hercus is actually an exact clone of the southbend.

try the hercus website as well. the guys who now run hercus
engineering have nearly all the hercus spares.
steve will respond to an email query.

hercus btw are gear makers and light engineering now so making a gear
shouldnt be a problem.

Stealth Pilot

wrote in article
...
Can anyone point me to possible sources for this critter?

Thanks,
DOC



I just read an article in one of the metalworking magazines I receive (Home
Shop Machinist - November/December 2007) that shows the use of a 32DP
127-tooth gear that drives another 32DP gear. On the same shaft as the
driven gear is a standard 16DP gear that allows the rest of the gear train
to be setup with the lathe's usual 16DP gears.

This allows for a smaller diameter, 32DP, 127-tooth gear to be used where a
16DP, 127-tooth gear might not fit well.

wrote:
On Nov 23, 10:33 am, wrote:
Can anyone point me to possible sources for this critter?

Thanks,
DOC

http://www.gandmtools.co.uk/cat_leaf.php?id=120

These should work just fine. I bought a used one for a Boxford and it
worked.

-- - - - - - - - - - - - - - - - -
Bill Graves RKBA!

On Sat, 24 Nov 2007 09:55:02 -0600, * wrote:

wrote in article
...
Can anyone point me to possible sources for this critter?

Thanks,
DOC



I just read an article in one of the metalworking magazines I receive (Home
Shop Machinist - November/December 2007) that shows the use of a 32DP
127-tooth gear that drives another 32DP gear. On the same shaft as the
driven gear is a standard 16DP gear that allows the rest of the gear train
to be setup with the lathe's usual 16DP gears.

This allows for a smaller diameter, 32DP, 127-tooth gear to be used where a
16DP, 127-tooth gear might not fit well.

This is exactly the setup I have for a generic 7x10 - using the Sherline
127 and 50 tooth gears; the 7x10 gears have a different pitch, but keying
each of the Sherline gears to one of the 7x10 gears eliminates this
problem.

The Sherline gears were

a) available; and

b) relatively cheap.

wrote:
On Nov 23, 10:33 am, wrote:
Can anyone point me to possible sources for this critter?

Thanks,
DOC


No idea where you can get such a gear. You could try to make one.

That's the hard and expensive way.

The smart way is to use a 63 tooth gear which is much cheaper to get,
I believe.

I worked out the arithmetic for use of such a gear some years ago and,
while the conversion is not exact, it is so close that the inaccuracy
would get lost in the accumulated tolerances of the lead screw and
gear train.

If you are interested in pursuing this let me know and I will dig out
my scribbles.

Wolfgang

33/13 = 2.5385, -0.06% error
127/50 = 2.5400, 0% error
94/37 = 2.5405, 0.02% error
61/24 = 2.5417, 0.07% error

My Smithy, which is a brand that is world-renowned for quality* uses the
33/13 trick, and does OK.

0.06% error would require 1666 threads to be off by one; if being off by
1/20th a thread makes you bind up that's still 83 threads, or over four
inches for a 1/4-20 screw.

* I didn't say _good_ quality!

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html