Threading Set up question?

[ljbenjam]

View attachment Photos for posting.pdf

Well you folks help resolve the “Leather Belt Slipping - 2 inch” so I am back learning again. :biggrin:


The issue I have run into is trying to thread a simple “square threaded jack screw”. I thought I had followed the “distructions” in How to Cut Screw Threads on a Lathe – Bulletin 36A – 1936 and LATHE WORK For Beginners, both South Bend Publications I found on Google and another Web Site from England.

Not sure why I am getting 12 threads per inch versus the quick change plate, for 4 threads per inch. I have included pictures of plate, the setup on the machine. View attachment Photos for posting.pdf

The basic information of the lathe is Catalog 198G
Swing 16” with insert to raise to 24”
Bed Serial Number 170936

If I have not provided enough information to help troubleshoot the issue please let me know. But I am betting, this newbie, must be doing something that all the experience out there will recognize real fast.

(Still trying to figure out how to get get large photo files small enough for posting....) hope y'all can ope the PDF where I combined)

Larry

 

[talkingmonkey]

is there a back gear involved?

 

[OldMachinist]

Are you using the half nuts or the feed knob to engage the carriage?

 

[GK1918]

Maybe I have mis read the question, and I really cant see your plate. All I know is on mine, I have to
change the stud gear for anything under (Ithink) 7 TPI. Here is my plate notice at the top the stud
gear is different. sp click on photo to make it bigger

 

[swatson144]

View attachment 36592

Well you folks help resolve the “Leather Belt Slipping - 2 inch” so I am back learning again. :biggrin:


The issue I have run into is trying to thread a simple “square threaded jack screw”. I thought I had followed the “distructions” in How to Cut Screw Threads on a Lathe – Bulletin 36A – 1936 and LATHE WORK For Beginners, both South Bend Publications I found on Google and another Web Site from England.

I think those are usually "Acme threads"

Not sure why I am getting 12 threads per inch versus the quick change plate, for 4 threads per inch. I have included pictures of plate, the setup on the machine. View attachment 36592

Assuming you are engaging the 1/2 nuts (threading lever) and not the feed lever.

Exactly 3X finer than selected by QCG. I'd suspect someone has it setup for finer feed and has swapped positions of say a 40T and a 120T (30T - 90T) look for a pair of change gears (touching) with a 3/1 ratio swap the positions and give it a try. Make sure to leave plenty of room and have the lathe turning slow because 4TPI makes things happen surprisingly fast.

Steve

 

[ScrapMetal]

View attachment 36592The issue I have run into is trying to thread a simple “square threaded jack screw”.

Larry

Larry,

It would really help to see pics of your setup, including a pic of your feed/tpi table/plate.

If you are trying to turn something with a square thread I'd really like to see some pics of how you are coming along. I've got to cut some square threads in the very near future so it would be nice to have someone else as a guinea pig. :biggrin:

-Ron

 

[ljbenjam]

Attachment 36592

I am having hard time getting the pictures to post in a small enough size... They are attached it the link at the start of this Note..... I had to put them in word document them convert to PDF so it would be small enough. I’ll have to figure out how to make a big 3 meg file into one that can be posted…. Sorry folks.

I hope all can see the photos in the pdf attached.

Thanks for all your input so far, keep your thoughts coming.

Steve,

You made the comment about gears touching that in a three to one ratio. I assume you are referring to the Drive Train that is shown in the photos on the right hand column?

If you are referring to the drive train and not the QC Box, I will go down and count, because looking at the photos I think there may be a set there that may be easy to swap to try your idea.

Larry

 

[ljbenjam]

Oh forgot to respond to one of the questions.....

Yes I am using the half nuts to engage the drive screw....

Larry

 

[ScrapMetal]

Very nice pictures, big enough so I can see them. :biggrin: Looking at the settings it would seem to be in the proper configuration. :thinking:

Would almost have to be something with the gears I would think. Hopefully someone will offer a more intelligent and informed opinion.

-Ron

 

[swatson144]

Attachment 36592

Steve,

You made the comment about gears touching that in a three to one ratio. I assume you are referring to the Drive Train that is shown in the photos on the right hand column?

If you are referring to the drive train and not the QC Box, I will go down and count, because looking at the photos I think there may be a set there that may be easy to swap to try your idea.

Larry

Yep on the right hand panel. I'd suspect either the ones on the banjo or just up string. I am NOT knowledgeable on that lathe but it is my suspicion.

Later edit to add the NOT.

Steve