Date   

Rust Retarding...

Gordon Smith <gsmith@...>
 

Well, I thought that I had taken enough precautions in storing my
lathe (wiping down with some oil and wrapping it up in a cloth), but
when I went out to look at it this weekend, taking those critical
measurements to make sure my lathe and bench will actually fit
through the door to my workshop, once again, parts were showing rust.

Is there a good way to prevent rust from appearing once you sand all
the metal down? I've heard a variety of common-sense approaches, but
they sometimes conflict. Right now, I'm toying between some fancy
finishes and pastes, continually respraying with maybe WD-40, and a
simpler approach of a spray-on lacquer finish that would presumeably
be more permanent.

-G-


Re: buyer beware!!

Jordan <jordan@...>
 

I thought that transposing gears were just a pair of compounded gears,
one of them being 127 teeth. The claimed achievable range of pitches
might be based on an assumption - that the whole set of change gears
are already with the lathe!

pjwizr_1999@yahoo.com wrote:


There seems to be a rash of these type things on ebay lately - the
advertising language says something that the product doesnt deliver.
looking at this one -- METRIC TRANSPOSING GEARS (ebay) Item #
1647456759 his item description says that -

" When your lathe is equipped with this set of metric transposing
gears you can cut right-hand and left-hand metric threads ranging
from 6 mm pitch to 0.20 mm pitch in addition to the regular English
pitches."

and there are not nearly enough gears in the set shown to do that, in
fact - you have to already have some of the english set to even use
these to cut just the metric threads. what they are is an add-on set.
the seller refused to even state how many were in the set - pictures
clearly show less than the number needed to do what the charts show.
he did finally put the second chart up after it was pointed out that
he had too few gears shown, and there are still not enough gears to
do what it says.


buyer beware!!

pjwizr_1999@...
 

There seems to be a rash of these type things on ebay lately - the
advertising language says something that the product doesnt deliver.
looking at this one -- METRIC TRANSPOSING GEARS (ebay) Item #
1647456759 his item description says that -

" When your lathe is equipped with this set of metric transposing
gears you can cut right-hand and left-hand metric threads ranging
from 6 mm pitch to 0.20 mm pitch in addition to the regular English
pitches."

and there are not nearly enough gears in the set shown to do that, in
fact - you have to already have some of the english set to even use
these to cut just the metric threads. what they are is an add-on set.
the seller refused to even state how many were in the set - pictures
clearly show less than the number needed to do what the charts show.
he did finally put the second chart up after it was pointed out that
he had too few gears shown, and there are still not enough gears to
do what it says.

be careful what you are bidding on - some folks just dont care how
they twist the language around and you might not get what the
advertising says you are getting.

chips ahoy!


FS: SB Heavy 10, Mesa, AZ

Marty Escarcega <escarcega@...>
 

For anyone interested, I have a South Bend Heavy 10 lathe. 4' bed.
Good condition. Pedestal style machine, double tumbler wide ratio
quick change gear box. 6" 3 Jaw chuck, lantern tool post. 5C
Collet closer, though its missing the handwheel for the drawbar,
everything else is there. 3 phase motor, can see the machine run.

$1250.00 and machine is located in Mesa, AZ just East of
Phoenix. Can provide a picture upon request.

Marty


Re: 3at collet set

Yasmiin Davis <yasmiin@...>
 

They will if you have a 3at adapter for the nose of the lathe.
 
Yasmiin

-----Original Message-----
From: mfutrell@... [mailto:mfutrell@...]
Sent: Sunday, October 14, 2001 11:12 AM
To: southbendlathe@...
Subject: [southbendlathe] 3at collet set

will the 3at collet set on e-bay #1649865685 fit the 9"
model a south bend lathe ?
thanks fer your help



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3at collet set

marvin
 

will the 3at collet set on e-bay #1649865685 fit the 9"
model a south bend lathe ?
thanks fer your help


Re: low-tech mandrels

Christopher C Stratton
 

Because my workpieces go down to 1/2" I'd really rather cut towards the
tailstock so that torque is being transmitted through the 1/2" uncut
stock rather than through the stock I've cut down.
Er, that should be because the workpieces go down to 1/4" diameter and
stay small for quite some distance. Also, I will need to rechuck since
the piece is longer than the lathe, and I'd rather do that on uncut
1/2" diameter stock.

Chris


Re: low-tech mandrels

Christopher C Stratton
 

<< --- One thing that is critical is that they always taper in the same
direction, or pulling the mandrel out of the drawn tube gets difficult. >>

Now we're getting to it. Some of your thoughts have been on target, some not.

What you want is a direct read out DRO for longitudinal feed, a direct read
out for cross feed, an electronic drive motor (stepper motor, servo motor, or
?) for cross feed, and a program (CNC ?) to drive the cross feed relative to
the known position of the longitudinal feed.

Set up the cut to run from the larger diameter to the smaller diameter. This
means if you have the large diameter next to the headstock make your
longitudinal traverse from left to right (obviously right to left if you're
willing to place the large diameter at the tailstock end). This will insure
that the cross feed will always take up any slack in the feed screw.

You don't need ball screws, you don't need zero back lash, you don't need
special thrust bearings. As long as the cross feed during the cut is inwards
the slack will be removed and the position is controlled by the direct read
out, the stepper motor, and the CNC program.
Anthony, for a larger diameter workpiece this idea would have merit.
It would load the spindle in a thrust direction for which it is not
really designed, but that shouldn't be a problem in a non-production
situation.

Because my workpieces go down to 1/2" I'd really rather cut towards the
tailstock so that torque is being transmitted through the 1/2" uncut
stock rather than through the stock I've cut down.

Linear encoders are nice in that they give you a reading independent
of screw backlash, however one does *not* want to try to close a servo
loop across one using a screw wish has lash - we have such a setup in
a precision slide at work which got contaminated with aluminum oxide
and developed a tiny bit (around .001") of backlash. In certain
circumastances, the servo loop will go into oscillation across the
lash, so I have to shut down that axis when I do high acceleration
moves with other axis that shake the whole machine (the base is
unfortunately welded steel tubing - it should have been a welded box
filled with sand or polymer concrete)

Anyway, feed always in the opposition to the cutting force is a good
principle - one on which almost every manual machine tool depends.

Chris


Re: low-tech mandrels

Paul R. Hvidston <p.hvidston@...>
 

And please remember to turn towards the headstock rather than towards the
tailstock whenever possible. The headstock (at least on older SBs) has a
thrust bearing only for a force towards the headstock. Additionally, turning
towards the tailstock puts additional force on the tailstock center. Dead
centers are generally more accurate, but prone to friction burning if not
monitored during machining. Turning towards the tailstock just adds to the
problem.

Cheers!

Paul R. Hvidston, N6MGN
ACKSYS Engineering
Upland, CA

----- Original Message -----
From: <anthrhodes@aol.com>
To: <southbendlathe@yahoogroups.com>
Sent: Saturday, October 13, 2001 7:54 PM
Subject: [southbendlathe] Re: low-tech mandrels


In a message dated Fri, 12 Oct 2001 10:14:53 -0400, Christopher C Stratton
writes:

<< --- One thing that is critical is that they always taper in the same
direction, or pulling the mandrel out of the drawn tube gets difficult. >>

Now we're getting to it. Some of your thoughts have been on target, some
not.

What you want is a direct read out DRO for longitudinal feed, a direct
read
out for cross feed, an electronic drive motor (stepper motor, servo motor,
or
?) for cross feed, and a program (CNC ?) to drive the cross feed relative
to
the known position of the longitudinal feed.

Set up the cut to run from the larger diameter to the smaller diameter.
This
means if you have the large diameter next to the headstock make your
longitudinal traverse from left to right (obviously right to left if
you're
willing to place the large diameter at the tailstock end). This will
insure
that the cross feed will always take up any slack in the feed screw.

You don't need ball screws, you don't need zero back lash, you don't need
special thrust bearings. As long as the cross feed during the cut is
inwards
the slack will be removed and the position is controlled by the direct
read
out, the stepper motor, and the CNC program.

Does this make sense to you?

Anthony


Re: low-tech mandrels

Anthony Rhodes
 

In a message dated Fri, 12 Oct 2001 10:14:53 -0400, Christopher C Stratton
writes:

<< --- One thing that is critical is that they always taper in the same
direction, or pulling the mandrel out of the drawn tube gets difficult. >>

Now we're getting to it. Some of your thoughts have been on target, some not.

What you want is a direct read out DRO for longitudinal feed, a direct read
out for cross feed, an electronic drive motor (stepper motor, servo motor, or
?) for cross feed, and a program (CNC ?) to drive the cross feed relative to
the known position of the longitudinal feed.

Set up the cut to run from the larger diameter to the smaller diameter. This
means if you have the large diameter next to the headstock make your
longitudinal traverse from left to right (obviously right to left if you're
willing to place the large diameter at the tailstock end). This will insure
that the cross feed will always take up any slack in the feed screw.

You don't need ball screws, you don't need zero back lash, you don't need
special thrust bearings. As long as the cross feed during the cut is inwards
the slack will be removed and the position is controlled by the direct read
out, the stepper motor, and the CNC program.

Does this make sense to you?

Anthony
Berkeley, Calif.


WTB: Handwheel For Heavy 10" Draw tube

Marty Escarcega <escarcega@...>
 

Looking for a spare hand wheel for a Heavy 10 5C Drawtube. (has 3
bolts hole that bolt it to the hub) Would rather find good used one,
otherwise I'll make it.

Email me if you have one and price.
Thanks,
Marty


1937 SBL 9"x36" + Tooling Available

charliep@...
 

Lathe is B or C model shipped February 1937 to my dad, a professional
tool and instrument maker, for home use. Seems in excellent shape.
Three and four jaw chucks, turret tool post and tail stock, live
center, collets, knurling tool(s) tool bits, taps, dies, micrometers,
lots of other stuff I don't recognize. Located in Fort Lauderdale, FL

Please contact me via e-mail if interested. Al Babin and ilk need
not reply. cp


Re: backlash, what should it be?

JS. EARLY <j.w.early@...>
 

Matt
Is that all, mine has a half turn since I got it almost new in the late 60s.
It is worse now but does not keep it from doing very precise work if you
take the lash out before you start cutting.

JWE

----- Original Message -----
From: Matt Pierce <ml_roak@hotmail.com>
To: <southbendlathe@yahoogroups.com>
Sent: Saturday, October 13, 2001 12:13 AM
Subject: [southbendlathe] backlash, what should it be?


What should "normal" backlash be in an old lathe, according to the knobs
on
my lathe I'm getting about .030 (compound and cross-feed), is this good,
bad, indifferent, or does it even matter for someone who knows not what
they
are doing? :-)

"Cry 'Havoc!' and let slip the dogs of war,"

M.L. Roak
aka Matt Pierce in real life

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backlash, what should it be?

Matt Pierce <ml_roak@...>
 

What should "normal" backlash be in an old lathe, according to the knobs on
my lathe I'm getting about .030 (compound and cross-feed), is this good,
bad, indifferent, or does it even matter for someone who knows not what they
are doing? :-)

"Cry 'Havoc!' and let slip the dogs of war,"

M.L. Roak
aka Matt Pierce in real life


Re: backlash fixes etc.

gorvil
 

Delrin is a DuPont trade name for a plastic that is strong, wear
resistant, machineable, and very slippery. Check it out at this URL.

Glen Reeser




http://www.dupont.com/enggpolymers/english/products/delrin.html

--- In southbendlathe@y..., Larry Crebs <larrysbp2000@y...> wrote:
What is delrin?
I have
some Delrin rod
stock, so I may try the spring loaded anti-backlash
double nut system.

I'll post the results when I'm done.

Glen Reeser




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Re: Backlash Fixes: South Bend Lathe

Webb Wyman <lynnw@...>
 

Hi There,

I have been following the threads on "Backlash" with great interest. The
latest posting by Chris prodded me into responding. If there is play (or
"backlash" if you want) in the ball crank - graduated collar - bushing area,
there is a proper fix that does not require shims. I have included the SBL
sheet on fitting a new cross screw with the instructions as an attachment.
These instructions are just as pertinent to fixing a screw that has a worn
thrust shoulder on the screw and/or bushing.

If one lacks access to a second lathe, the repairs can be accomplished on
the lathe under repair. For example if one is repairing the cross feed
screw, one removes the cross feed screw assembly (ball crank, collar,
bushing and screw) from the cross slide. Then one tightens the gib screws
on the cross feed slide to lock it in place. Then one can swing the
compound to "zero" or straight in and use the compound as the cross feed.
One doesn't need power feeds for this repair. After the cross feed screw is
repaired and replaced (and the gib screws are readjusted), the same
procedure can be performed on the compound screw assembly.

End play in the ball crank - collar - bushing assembly is common on these
lathes if they have any time on them. It is often confused with "backlash"
in the screw - nut fit and is easily fixed.

I hope this information is helpful. God Bless America!
- Blue Chips -
Webb


Re: backlash fixes etc.

Christopher C Stratton
 

First let me mention one thing I found on the 9" lathe last night. I
was getting endplay in the crossfeed screw bearing no matter how tight
I turned the nut in the hand crank. Turns out the micrometer collar
was slightly too short and the 5/16" bored crank was bottoming out on
the shoulder to the 3/8" bore of the collar. A simply brass shim
washer (between collar and crank) fixed that.

i think that we are all eluding to the fact that SOME backlash is
acceptable as long as its CONSISTENT for the length of screw travel.
that way the accuracy is maintained.
It depends on your goal. For a manual machine, this is true - some
backlash is okay, while consistency is paramount. For a computerized
machine the opposite is actually the case - backlash is very bad (for
some types of cuts) but consistency is not paramount as it can be
compensated in software. Of course it's hard to make a tight screw
that isn't a consistent pitch.

we are assuming that the screw
is ok, and only the nut is worn out. not true. consider that your
lead screw is worn more near the headstock than at bracket end. i
think someone pointed out this example.
I am in favor of replacing the screw, as long as I can find new stock
that is as good as the original. This is partly as I'd rather
carefully pack up the original components in a safe place and run my
experiments (fit altering, polymer casting, etc) on easily replaced
generic screw stock.

can anyone definitely state what the thread is on the screw?
i would assume that it is standard acme. is it some weird pitch like
and odd number? (i admit, i havn't gone out to measure mine, and i
know my screw is worn so i wouldn't trust my screw as the standard)
On the 9" south bend the screw is 10 tpi. I thought it was 3/8"
diameter, but it may be 7/16". I think I might try to fit 1/2-10 as a
replacement. (The 13" is 5/8-8). We're assuming it is acme - one
reason for replacing both screw and nut.

i think scott pointed out converting to a ball screw is propably best
for accuracy. he might be right, and i don't want to seem like i am
second guessing his expertise. however, consider that ball screws
don;t have enough friction to resist turning of not held in place
with some sort shaft lock or stepper motor power. this could be a
issue when using the compound off of the apron drive. also, i don't
think that manufacturing a ball screw retrofit is as easy as it might
seem as i think that the ball screws and maybe the nuts are hardened.
i will eat my words later talking about machining 4130 futher on...
I have a 5/8-5 double nut left hand ballscrew (about $200 for the set)
partially fit to my 13" lathe. I had to mill out the channel in the
carriage a little bit, using a ball nose mill to keep everything nice
and round to avoid creating stress risers. If anyone else attempts
this, be smarter that I was and put round stock under the V ways to
set it on the mill table... (I tried to shim it level off the flat
surfaces) I'm making a new screw-in bearing sleeve so I just remove
the entire screw, sleeve, collar and handwheel assembly intact (can't
get it apart anyway) and replace it with the ballscrew based one set
up for a cog belt pulley instead of a handwheel.

with fixes like moglice and babbit wearing surfaces i sounds like its
almost too much trouble. not only in material cost, but the time and
detours you would need to take to do the job completely. and what do
you do if the fix doesn;t hold? you are only taking out play in the
nut. you are not fixing the wear in the screw. and you are using a
potentially worn screw as the mold for both and makeing that defect
the reference surface for the entire screw.
There is one thing I think that would make using moglice in
conjunction with a new screw easier than using a new nut. This is
machining the top of the nut to fit into the hole in the slide. For
the block the ballscrew fits into on the big lathe, I finally put the
old screw in a 5c block holder on the mill table and indicated the nut
boss. Then I switched to an appropriate collet holding a piece of bar
single pointed with the same threads 15/16-whatever threads as on the
outside of the ballnut and screwed the block that would become the nut
mount onto that. Programed the mill to circular mill the boss - one
might be able to do it on a manual machine with a boring head having a
cutter turned in rather than out.

Constrasting with moglice, I think one could machine a sleeve that fit
the apron with an oversize bore in about the right place for the
screw. Assemble it with some clay or something to dam around the
screw. Take the carriage off the lathe, set it upside down on the
workbench and inject moglice through the hole that I think I remember
is present in the middle of the carriage.

the spring loaded pair of nuts is a good idea. the spring force is an
issue.
Springs work best with a low friction nut material... moglice is
supposed to be lower friction than bronze.

from green bay: a 4130 or 1018 acme threaded rod 2G, lead
error of less than 0.001 /inch in "standard" sizes (0.25-16 up to
0.75-6/8/10/12) is anywhere from $3-$7 per foot. a round ampco or sae
bronze acme nut roughly 1" long is around $20 for the matching
sizes.
I'd get 2C class screw from Mcmaster, but otherwise agree. Bruce at
moglice said stainless screws are often better made than the carbon
steel ones... I would be the alloy steel ones are pretty good, too.
I've turned ballscrews with carbide - acme screws are deeper but
I would guess still do able.

Chris


Re: low-tech mandrels

Christopher C Stratton <stratton@...>
 

Chris is using these very fine mandrels for drawing thin brass parts for
French Horns.
So I ask a dumb question here. How critical is this long taper from one
inch to the next?
Since you will be hardening these anyway, won't there be minute changes in
your work-piece?
I imagine you will want to go back and finish the mandrels afterwards. Have
you already tried the
low-tech approach of long taper-jigging and then finishing with gages and
bluing? It is time-consuming
but accurate. How many mandrels do you need?
I believe the Carpenter Steel Co. is still in business. If you can find
their book on tool steel,
it may be a big help towards selecting a good A/H.Just some thoughts.
regards, Ron
Hi Ron,

I believe I would be rather happy if I could hold a tolerance of +/-
.001 on the diameter of the finished mandrels for now. One thing that
is critical is that they always taper in the same direction, or
pulling the mandrel out of the drawn tube gets difficult. I am not
hardening them - at the moment I'm experimenting with the musical
qualities of various tapers, so I don't need to use the mandrels that
many times - and I have no way to heat something that long evenly.
Someday I might build a long pipe burner for annealing brass tubing,
and might try that with air hardening steel.

As the 'master' for these tapers is simply a spreadsheet, there
isn't really anything to compare them against with bluing, and they
don't need to be that accurate anyway.

Just for comparison, my previous method of making these was to stick
and inch of rod out of the chuck, machine a stairstep or two (in
several passes) approximating the taper, then rechuck with another
inch sticking out. Every once in a while I'd grab a file and smooth
out the stairsteps... It worked in the 1830's and still works today,
but tools made accurately in this fashion are expensive, wheras I'd
like to find a way to make them cheaply enough to permit
design experimentation.

Chris


low-tech mandrels

Ina Ron Lippard Renaissance Reproductions <renrepro@...>
 

Chris is using these very fine mandrels for drawing thin brass parts for French Horns.
So I ask a dumb question here. How critical is this long taper from one inch to the next?
Since you will be hardening these anyway, won't there be minute changes in your work-piece?
I imagine you will want to go back and finish the mandrels afterwards. Have you already tried the
low-tech approach of long taper-jigging and then finishing with gages and bluing? It is time-consuming
but accurate. How many mandrels do you need?
I believe the Carpenter Steel Co. is still in business. If you can find their book on tool steel,
it may be a big help towards selecting a good A/H.Just some thoughts.
regards, Ron


Re: rubber backlash

Jordan <jordan@...>
 

No way we can possibly approve of this, however successful. It's just
not
"engineering" enough!
(just kidding)

jackie.blake@telus.net wrote:


I made a small 3/4" pulley and attached itjust slightly below the
compound, then used a length of surgical tubing to fasten across to
my arm on my taper attachment. My back lash problem is over . I have
it so only enough pressure is applied to stop the backlash and not
create undo friction on cross feed. Cost: $1.50

103041 - 103060 of 104873