Thread dial indicator.

[Suzuki4evr]

T

To get a more accurate reading with your caliper, open the caliper out and measure as many threads as possible. Then divide that length by the number of threads in your measurement. Be aware that the result does not have to be a round number, it could be 12.5mm for example.
I am no gear expert but to get the circumference of a 15T gear to match your lead screw just measure the length of 15 threads on the screw, then divide that number by pi (3.1416). For the 14T gear measure 14 threads on the screw. That will give you a ballpark diameter for the gear.
How did you determine that a 14 and 15 tooth gear is required?

Thanks for the info. I browsed around and found it on another machinist site,I think it was "practical machist". It was discussed there on wich gear to use for a metric leadscrew.

 

[Tozguy]

I found the diagram in the manual.This is the diagram out of the manual,but it does not say anywhere the leadscrew pitch or the size of the gear and other thingI do not understand is the clock section on when to engage the halfnut on wich number for wich pitch. Can you declare this maybe.

Normally a diagram like you have shown in post 22 is accompanied by a parts list that provides the specs on the part. Often the parts list is on the next page following the diagram. For the dial gear shown as part 01 in the diagram I would expect that the parts list would show the number of teeth. The chart shown mounted on the dial body would only work with a gear of that size.

 

[Suzuki4evr]

To get a more accurate reading with your caliper, open the caliper out and measure as many threads as possible. Then divide that length by the number of threads in your measurement. Be aware that the result does not have to be a round number, it could be 12.5mm for example.
I am no gear expert but to get the circumference of a 15T gear to match your lead screw just measure the length of 15 threads on the screw, then divide that number by pi (3.1416). For the 14T gear measure 14 threads on the screw. That will give you a ballpark diameter for the gear.
How did you determine that a 14 and 15 tooth gear is required?

The fully opened calliper method gave me 11.57mm and for the 15T gear OD I got around 54.75mm.

 

[Suzuki4evr]

Normally a diagram like you have shown in post 22 is accompanied by a parts list that provides the specs on the part. Often the parts list is on the next page following the diagram. For the dial gear shown as part 01 in the diagram I would expect that the parts list would show the number of teeth. The chart shown mounted on the dial body would only work with a gear of that size.

This is all that is on the next page.Sadly I don't see anything I need.

 

[Tozguy]

I can not even read the page but we tried

 

[Tozguy]

The fully opened calliper method gave me 11.57mm and for the 15T gear OD I got around 54.75mm.

How many threads were included in your measurement to arrive at a pitch of 11.57mm?
15 threads of a 11.57mm pitch should give around 173.55mm. Divide that by pi and the result is 55.24mm diameter gear. Close enough to your number but the 11.57 result still looks funny to me.

Trying to imagine what the gear teeth would look like....and figure that they must look something like these.

 

[Suzuki4evr]

Good Heavens but that is one ugly gear.Over the length of 220mm,I have 19 full threads

 

[Tozguy]

Thanks for the details. Never heard of a 11.57mm pitch. I'm stumped.
Sometimes it takes an ugly gear to mesh with an ugly lead screw.

If the diagram in post 22 above is to scale, which I think it must be, is there a way that you can scale the diameter of the gear from a known dimension to arrive at its diameter?

And I am starting to wonder why there was no thread dial that came with your lathe.

 

[Suzuki4evr]

Neither have I. I will have to do something,just don't know what yet. There is a tapped hole where it is supposed to fit so I guess there was one,just got lost somehow

 

[Tozguy]

On a big lathe like that maybe they did not need a thread dial and cut the threads all in one pass.
Seriously I hope that you can work something out.