need a gear made

[irishwoodsman]

It certainly has 72 teeth + one missing makes 73. I use to have a Sheldon like yours but it didn't have any gear issues so I have no idea what gearing it had.

I went out to my shop and went through my old manuals and came across manuals for Sheldon 10", 11" and 12" lathes.

I think this information may be helpful.




Charlie

The 2 pages show Sheldon gear numbers. I noticed that the picture showing the end gear train shows a gear number listed. Does the one with the broken tooth have a "K" number on it? Based on the numbers listed, I suspect the broken gear does not belong to the lathe.

was wondering if i could get a copy of that manual, i thought it was the same as mine but i pretty sure mine is newer, dont mind paying for it just let me know how much, going to do some more research on this lathe and i think i will try and cut a standard thread to see if cuts it right:thinking:

 

[CharlieW]

was wondering if i could get a copy of that manual, i thought it was the same as mine but i pretty sure mine is newer, dont mind paying for it just let me know how much, going to do some more research on this lathe and i think i will try and cut a standard thread to see if cuts it right:thinking:

This post has evolved and gone in different direstions.
It started out looking for a 72 tooth gear and then a 73 tooth gear. As I mentioned before, 73 teeth does not make sense in the gear train in order to get the standard US threads. I don't think I need to explain and try and cover the finer points of the gear train that turns a lead screw.

The end gear train does 2 things. One is to reverse the direction of the lead screw as it relates to spindle direction of rotation and 2, it sets the rotation ratio of the spindle RPM to the input RPM of the QC gear box. The end gears can be changed so as to change the input into the QC box such as transposing gears do for cutting metric threads. I have changed the gears on the gear train in order to acheive a thread that is not listed on the QC thread chart.

I don't have enough information to analyze the feeds on your current gear train. I will just say that I think that in order to get the lead screw to turn at the thread charts indicated feed rates, you would be well served to replace the gears in the feed train as indicated on the parts diagram.

PM me your email address and I will send you a PDF copy of the manual.

Charlie

 

[irishwoodsman]

This post has evolved and gone in different direstions.
It started out looking for a 72 tooth gear and then a 73 tooth gear. As I mentioned before, 73 teeth does not make sense in the gear train in order to get the standard US threads. I don't think I need to explain and try and cover the finer points of the gear train that turns a lead screw.

The end gear train does 2 things. One is to reverse the direction of the lead screw as it relates to spindle direction of rotation and 2, it sets the rotation ratio of the spindle RPM to the input RPM of the QC gear box. The end gears can be changed so as to change the input into the QC box such as transposing gears do for cutting metric threads. I have changed the gears on the gear train in order to acheive a thread that is not listed on the QC thread chart.

I don't have enough information to analyze the feeds on your current gear train. I will just say that I think that in order to get the lead screw to turn at the thread charts indicated feed rates, you would be well served to replace the gears in the feed train as indicated on the parts diagram.

PM me your email address and I will send you a PDF copy of the manual.

Charlie

irishwoodsman@sbcglobal.net i'm sorry for being a pest i did not want that to happen, ty for your info

 

[CharlieW]

irishwoodsman@sbcglobal.net i'm sorry for being a pest i did not want that to happen, ty for your info

I don't think you have been a pest and if I came across that way, I did not intend to. Sometimes it can be difficult to get to the root of the issue and as more information comes out the solution can change.

Charlie

 

[irishwoodsman]

In the third post it is noted that this is an IDLER gear.



It is also noted that it mounts on a sleeve on the banjo. It is therefor NOT a screw gear or a stud gear (Southbend terminology) As such it does not enter into the gear ratio. Only if it were either on the stud position or the screw position or if it were a compound gear would the number of teeth matter.

Its function is to primarily take up space so the rotary motion is translated to another point. It does, as you noted reverse direction. You will note, in the exploded view, there are two idler gears. They are called intermediate gears. So the direction of rotation is the same as though there were no gears in between the stud gear and the screw gear.

so what your saying is that any gear with the same pitch and pressure angle and diameter will work weather it has 73 teeth or 64 teeth, or can you tell me what i need the gear made too:biggrin: or is the 73 tooth gear i have now is fine if i had one made to it:biggrin:

 

[irishwoodsman]

I don't think you have been a pest and if I came across that way, I did not intend to. Sometimes it can be difficult to get to the root of the issue and as more information comes out the solution can change.

Charlie

i understand, its like trying to put a puzzle together and the guy in the garage has 2 of the pieces:biggrin: fixing to mill them so it fits his puzzle:biggrin:

 

[irishwoodsman]

i took the banjo off, the gear on the left had a 65 tooth with a 4-1/4 diameter, the center gear was 73 tooth with a 4-11/16 diameter, the gear on the gear box is 96 tooth with a diameter of 6-1/8, thought i would throw this into the puzzle to see if it made sincehew:

 

[irishwoodsman]

[quotw]so what your saying is that any gear with the same pitch and pressure angle and diameter will work weather it has 73 teeth or 64 teeth, or can you tell me what i need the gear made too or is the 73 tooth gear i have now is fine if i had one made to it

No not quite that.

While the 73 tooth gear does not enter into the overall reduction ratio once the holes are machined in the banjo a gear with that number of teat and that diameterial pitch is needed to fit the space allowed.

I was addressing the comment of 73 teeth not fitting into a "standard" gear ratio,

On my change gear 9" SB the banjo is slotted. I can use any ideler gear(s) that allows the gear train to engage the stud gear. On my QCGB Heavy 10, the banjo is like yours ond anly the correct diameter gear will work, not because of gear reduction but because of space.

ah ok, now when i took this 73 tooth off i noticed that it meshed with a gear just under the spindle and it meshed with a smaller gear that is on the gear box and the big gear box gear sits in front of it, if this makes any since:thinking: but only mesh with top gear if i pull up on bamdjo

 

[irishwoodsman]

kinda like they were filling a area they made a little sloppy since its only purpose was to make up the gap:biggrin:

 

[irishwoodsman]

well i put everything back together, to tired to do any more to night but i did run her in threading mode, i understand now how the threading dial works, onced engaged it stops moving but i did notice it will only ingage just a tad before or a tad after, it might be cause i'm trying to catch the wrong mark, but will fig that tomorrow while trying to cut a thread, to everyone who jumped into help thank you so much, this old dog is trying to learn a few things and have fun at it, will keep everyone posted how it goes. thanks a bunch:biggrin: