Junior 9" change gear help.

C

Cleancut

Aluminum

Joined

Apr 23, 2018

• Jan 11, 2019

• #1

Hi guys,

These are the gears I have, does anyone know if I am missing any? I have never cut threads before, and just starting my first threading project. I need to cut a short section of 1/4" 20 TPI threads. The manual says use a 32 on the stud and 80 on the lead screw? Do I have that right?

most of the gears have three numbers, not sure what that means - guessing different combinations. if anyone can point out a good how to on change gears it would be very appreciated.

thanks in advance.

 

I

iwananew10K

Diamond

Joined

Sep 12, 2010

Location

moscow,ohio

• Jan 11, 2019

• #2

http://www.wswells.com/data/catalog/1931_Jr_Cat_No.22C/1931_Jr_Cat_No.22C.pdf

yup, 32 and 80

Ain't gonna be much fun without those backgears...you might want to unplug the lathe and turn the spindle by hand for a couple passes and finish with a die.

 

C

Cleancut

Aluminum

Joined

Apr 23, 2018

• Jan 11, 2019

• #3

thanks 10k...... I have the back gears, just not installed.

 

lazz

Stainless

Joined

Feb 12, 2012

Location

The warm desert of Phoenix Arizona

• Jan 12, 2019

• #4

Threading on a lathe is a difficult place to start your lathe experiences. Practice makes the experience much easier. Back gears are good for threading. They slow down the process ....

Some advice offered to me in the beginning was to buy a 3/4 plastic conduit and a find a 3/4 X 10 nut. Cut the conduit into 10" or 12" lengths. Use a center dead or live. Then start threading. Thread an inch, try the nut, cut off the thread and rinse and repeat.

This method will give you 50 to 75 attempts for about 3 bucks.

 

K

kitno455

Titanium

Joined

Jul 9, 2010

Location

Virginia, USA

• Jan 12, 2019

• #5

The 9Jr change gears have casting numbers like '9-32-80 T' for the 80 tooth gear. You basically ignore the first couple numbers.

You should have a pile of gears including 16, 18, 24, 30, 32, 32, 40, 44, 46, 48, 52, 56, 60, 64, 72, 80, 92, and an 18/81 compound. When threading, you do not use the 18 tooth portion of the compound gear, the screw gear contacts the 81 tooth side instead.

Something looks really weird about your current gear setup. I think perhaps the end of your spindle has been cut off flush with the drive gear, perhaps to allow really large stud gears to be installed.

allan

 

C

Cleancut

Aluminum

Joined

Apr 23, 2018

• Jan 12, 2019

• #6

kitno455 said:

The 9Jr change gears have casting numbers like '9-32-80 T' for the 80 tooth gear. You basically ignore the first couple numbers.

You should have a pile of gears including 16, 18, 24, 30, 32, 32, 40, 44, 46, 48, 52, 56, 60, 64, 72, 80, 92, and an 18/81 compound. When threading, you do not use the 18 tooth portion of the compound gear, the screw gear contacts the 81 tooth side instead.

Something looks really weird about your current gear setup. I think perhaps the end of your spindle has been cut off flush with the drive gear, perhaps to allow really large stud gears to be installed.

allan

Click to expand...

Hi Allan , thanks for the reply - I know you are the authority on the Jr's

Im not sure about the spindle being cut shorter? heres a pic, let me know what you think. the spindle goes all the way threw to the end of the gear.

also what is this large gear used for? has about 90-100 teeth and reads 9-42-J, is that the 92?

also, i have no threading dial unfortunately, but what threads can I cut without one? from what I understand as long as the TPI is divisible with the number of TPI on the lead-screw I should be able to engage and disengage the half nuts anywhere? maybe im way off? thanks again.

 

T

tommy1010

Stainless

Joined

Apr 21, 2010

Location

northeastern Pa, USA

• Jan 12, 2019

• #7

To the OP. Looking at your initial post pics and seeing the compound gear in your gear train, that will not cut 20 TPI. If you need to fill space to connect the stud gear and screw gear you do it with an idler not a compound. Those compounds and larger gears were for longitudinal cutting using the lead screw and half nuts. Somebody must have a chart off the back of a model B or C South bend showing thread arrangements. I had the metal tags but are all gone now that showed gear arrangements for threading and cutting.

 

K

kitno455

Titanium

Joined

Jul 9, 2010

Location

Virginia, USA

• Jan 13, 2019

• #8

Your spindle should protrude from the end of the gear around 1/2 to 3/4 inch, so it sticks out of the end gear cover. I don't think this makes much difference unless you want to install a spider or use an existing collet closer.

Yes, you can cut threads multiples of 8tpi and engage the half-nut anywhere. For all other pitches, you need a thread dial, or leave the halfnuts closed and reverse the lathe. You can make a substitute thread dial by putting a mark on the lathe bed to return the carriage to, and a mark on the screw gear that aligns with some feature of the lathe or a pointer attached to the table. When the mark lines up, and the carriage is on its mark, engage the half nuts.

allan

 

C

Cleancut

Aluminum

Joined

Apr 23, 2018

• Jan 13, 2019

• #9

Thanks for the info Allan. seems the most important gear i'm missing is a 32. anyone have one? with it i could at least make a couple good common threads.