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Lead screw gears

Mogens

Plastic
Joined
Jul 22, 2007
Location
Gadsden, AL
Hi,

Lathe info SN 14287RKX16

R= 10 in swing
K= Quick change gear
X= Special

I have one set of gears from the spindle to the lead screw gear box

Stud gear 40 tooth
Idler 80 toot
Lead screw/gearbox input: 56 tooth

When I want to cut imperial threads, say 18 TPI I have to set the levers in the 6 TPI position (3x6=18) setting to get the correct spindle to lead screw ratio.

Does anyone have a chart or some other information that shows what stud gear or lead gear I need to get the normal standard ratio so the gear box numbers will match the actual speed.

Thanks
 
If it is a wide range gearbox, which I think it is, then the stud gear should be a 40 tooth for all the threads on the index plate. The 56 tooth should be on the gearbox, with the 80 tooth as the idler.
That set up should work, as long as you are using the half-nuts...:scratchchin:
Ted
 
Stud gears and transmission

I dont know if the gear box matches the gears.

The label on the gear box shows that the stud gear should be a 40 tooth like it is. I hope the attached photos will help on the understanding.

Thanks :-)
 

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Yep sounds like the apron gearing ratio is near 3 to 1, so it would seem you are not cutting threads using the half nut lever (and lead screw) and instead are using the longitudinal feed on the apron

Put the feed selector in the middle of its three holes and then you can engage the half nuts and actually cut some threads
 
Put a mark(line) with a sharpie on your spindle near the chuck or even right on the chuck. Mark the lead screw with a sharpie mark where it exits the gearbox. Select 8 TPI on the gearbox. Turn the chuck one complete turn by hand and the leadscrew should turn one complete turn also. If it does everything is ready to use the lathe for threading. If not you got a problem.
 
Yep had the lever in the wrong (up) position and was using the half nuts. I did not know that, learning everyday :-) Thanks for your help
 
(" Model B Change Gear Setup

Probably a bit off topic, but for sure, Mogems got some really great answers from brilliant folks on this thread.

But I rescued a 9" Model B late last year and have been restoring it over these pandemic months. As I'm usually prone to do,
I take a boatload of photos before, during and after I disassemble a machine for transport for future reference. Unfortunately,
my computer crashed and along with it, all those photos. But fortunately, I had the computer backed up using Carbonite.
So a new computer is on order, but I won't get until mid-January. So I have no real reference for how the gear train was
set up before I took it apart. I do own a Model A, but I think the set-up is quite different when a QCGB is in the mix.

I was going to mention to Mogems (or anyone) that there are plenty of images on-line that show gear trains on various machines. I noticed
that some have single banjo yokes and some have the double yokes, depending on size and type of machine. If a gear was mounted on a bolt shaft,
I kept it on that bolt (I have two). But I'm just not certain about the rest of the gears and will have to figure it out, which I will
eventually.

I do have the metal plaque that was mounted on the machine that shows the different configurations for specific TPI, and is same as
the one printed in HTRL manual.

PMc
(Yeah, I messed up the thread title)

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