Back Gears Setscrew

[MikeMc]

The problem with the setscrew in the back gear spindle is written about often and I found out last week that some PO of my lathe over tightened it scoring the shaft so that to replace the bushings I'll have to groove one just to get it apart.
To keep me from doing the same one day when my mind is on other things I replaced that setscrew with a 1/8" panhead and was wondering if anyone else had done so on their lathe?
I plan on replacing the spindle pulley setscrew with a flathead screw but have to figure out how to hold it to turn the head down first.
Mike

 

[RJSakowski]

The problem with the setscrew in the back gear spindle is written about often and I found out last week that some PO of my lathe over tightened it scoring the shaft so that to replace the bushings I'll have to groove one just to get it apart.
To keep me from doing the same one day when my mind is on other things I replaced that setscrew with a 1/8" panhead and was wondering if anyone else had done so on their lathe?
I plan on replacing the spindle pulley setscrew with a flathead screw but have to figure out how to hold it to turn the head down first.
Mike

What appears to be a set screw on my 6" Sears/Atlas is actually a lube port plug. The back gear is meant to be free rotating held in place by the frame and spacers. The screw should not contact the shaft.

 

[wa5cab]

That is what he was explaining. As with the oil plug/set screw in the spindle cone pulley, sometimes PO's screwed them in too hard and gouged the spindles.

The 10F parts list does not list or show the screw but the later 12" list does. Perhaps some PO's, thinking that the screw was too short, deliberately installed a longer one.

 

[RJSakowski]

That is what he was explaining. As with the oil plug/set screw in the spindle cone pulley, sometimes PO's screwed them in too hard and gouged the spindles.

The 10F parts list does not list or show the screw but the later 12" list does. Perhaps some PO's, thinking that the screw was too short, deliberately installed a longer one.

I assumed that a PO had put a longer screw in. I believe that the 1/4" long r. h. screw in my back gear is OEM but I can see where someone would mistake it for a set screw. The Sears user manual makes no mention of the screw other than the parts list.

 

[RJSakowski]

I plan on replacing the spindle pulley setscrew with a flathead screw but have to figure out how to hold it to turn the head down first.
Mike

Mike, drill and tap a short length of round stock and mount your screw in that.

 

[Round in circles]

Going on with the lube part of the thread .
Can anyone tell me what the thread form & TPI that there is on the USA's Atlas lathes that have screw down grease cups caps to lube the head stock taper roller bearings .

I ask because I want to replicate the thread on mine on a reasonable quality steel bar to make an extending shoulder so I can then drill and tap the extender shoulder for it to take a metric grease nipple .

This will be my first attempt at thread cutting on the lathe for the grease cup thread on the extender , I have a metric grease nipple tap for the other thread .

Perhaps you'd also be kind enough to explain the breakdown of how you write the thread form and size details plus give the thread angle as I don't have a USA thread gauge .

 

[louosten]

Greetings;
I know what the back gears are supposed to be used for...but who really uses them and for what purpose?
Thanks in advance for responses,
Lou O.

 

[John Hasler]

Greetings;
I know what the back gears are supposed to be used for...but who really uses them and for what purpose?
Thanks in advance for responses,
Lou O.

I use them frequently on my Logan 400 to get lower speeds (which aren't slow enough, which is why I intend to convert to a DC motor some day soon).

 

[JimDawson]

Many many years ago when I had my Craftsman Commercial 12x36, it pretty much spent it's entire life cutting Inconel, so it lived in back gear. It was really not enough lathe to do what I was doing with it, and I pretty much wore it out in about 2 years. It did make me enough money to to buy a new 14x40 gearhead and a new Bridgeport clone so I can't complain.

 

[mattthemuppet2]

back gears = lower speeds without losing torque. Very useful for turning large objects (like chuck back plates) or perhaps work hardening steels where the surface speed would exceed what is recommended for the cutter. I wiped the nose off an HSS cutter in an instant truing up a 4in back plate at 800rpm - put it in back gear (100rpm for that pulley?) and it cut just fine. Also recommended for threading to a shoulder so that you have more time to open the half nuts before crashing the tool into the shoulder.

To be honest, if there's room and you have the skills/ tools I'd replace that screw with a knurled knob. You're supposed to oil the back gear pulley every time it's used and for me at least it would be way easier to have a tool free way of doing so.