Sheraton Lathe Model A

[ozcutter]

Hi,
I have a 9 inch Sheraton A (South Bend Copy) in use in Sydney.
Beat-up but usable.
Currently with the following problems (challenges):
- worn top slide dovetails,
- high friction leadscrew (gearbox),
- non-releasable finefeed clutch,
- tailslide below centre.
- carriage in finefeed provides measurable non-parallelism.
I am slowly getting through the problems but would welcome anyone else in the same situation in Sydney (or near) to swap stories, theories, possible actions and fixes.

john997(at)tpg.com.au

Happy machining,
John.

[weldsol]

Hi john in answer to some of your problems.
If it's a Southbend copy you should be able to adjust the gib strip in the top slide unless the dove tail in worn in the middle then you will have to get the scraper out.
Re high friction leadscrew is this with the table engaged ?
How much is the tail stock below centre ?
Re non parallel turning is the bed bolted down ? as you may have to jack the bed as per myford (I had to do this on the Southbend I had a few years back)

Paul

[dickdastardly40]

John,

I do't know if you wish to join another forum to find the answers ou seek, however if you don't mind you could give this one a go:

www.practicalmachinist.com/vb/forumdisplay.php?f=25

The Southbend section to which the link takes you is friendly to well posed questions and has a lot of users who have reconditioned southbends with all the experience you may need to assist. Photos are always appreciated to assist with fault diagnosis if you can post them.

Hope this is of some help.

Al

[ozcutter]

Paul,
Thank you for your kind comments.
It is the dovetails that are worn.
Correction will be grind/scrape - but beyond me at the moment.
I am enrolled in a fitting/machining certificate at the local college, so I will get there eventually.
The non-parallelism is something in the leadscrew (friction) or the carriage (bed) slides.
The problem is visible patterning that looks worse than the reality, it measures at something like 0.020mm (0.0008 inch").
First step is to dismantle/check/clean/fix the Norton style gearbox.
Second step is to remove the carriage from the bed and dismantle/check/clean/fix as appropriate.
Carriage dismantle probably needed to sort out the feed clutch.
I suspect I will eventually get to considering the bed ways themselves.
The tailstock is perhaps 0.25mm below centre.
This will be corrected by a grind/scrape to square on th bed then a height shim to suit.
Note that I have successfully made a 13mm sliiting saw arbor with a MT2 taper for use in the mill, so the lathe errors can be managed.

Tonight I was on Colchester at the college - a real eye-opener for stiffness, 2 mm carbide cut with blue chips at a great rate.

Machining is happiness,
John.

[kingsteam9]

Oz,

dunno if it's any immediate help but have a look at this site 'www.steammachine.com/hercus/' - whole series by chap who had various problems on his newly acquired Hercus lathe which is another Southbend clone - loads of useful photos on there - might glean something from it.

Robin

[ozcutter]

Al and Robin,
Thanks for the two great links.
I have applied for membership of the practical machinist board, but I fear my local ISP has rejected the authorising Email to my email address.
The same thing happened here at the Clearing House when I first applied for membership.
Problem fixed only by nominating my wife's email address at a different ISP.
I will follow up the Hercus site as it references places only 20 km from me.
My immediate task on the lathe is a simple post-style quick-change toolpost.
Already made one version with 30 mm post and cast-iron boring bar holders - perfect !
I am into the new 34 mm post and it was the parallelism of this that prompted my original post.
One of my planned QCTP tool holders will accept a South Bend style latern tool holder, tilted at 13 degrees so the mounted HSS 1/4 tool is horizontal.
The tilt is necessary to get sufficient height for the toolholder on the post, but the weirdness factor does intrigue me.

Happy cutting,
John.

[Noddy]

There's a big collection of preserved southbend threads covering re-scraping etc here:
www.armurerieduroi.com/pages/lathe_index.html

I can second Al on Practical Machinist. It is very helpful.

Keith

[ozcutter]

Hi,
For anyone interested, the photo below shows the finefeed clutch mechanism.
The jam-up was caused by one of the semi-circular 'ears' becoming misplaced from the centre control shaft.
Initial cause was the left-hand thread screw at the end of the control shaft retaining the hand-operated engagement knob coming loose.
The screw had been noted as loose before, tightened by hand, but generally not attended to.
Not too much damage to the clutch bits, and I hope a clean-up to get rid of bruising will get the clutch back into operation.
BUT - note the chipped tooth on the drive gear.
I will attempt to get a South Bend gear out of the US, but someone may recognise it as a part from a Boxford or similar.

s460.photobucket.com/albums/qq321/ozcutter/?action=view¤t=FinefeedClutchCompressed2Oct08.jpg

Still happy maching,
John.