Threads and gear conversion chart

[tailoredpencompany]

The calculations are backwards, you need to do 32-120-40 on D4 and that should give you 50 TPI. The way you have the gears set up will speed up the leadscrew, you need to slow it down.

Thank you it worked! Finally! It worked everyone!

 

[Ischgl99]

Thank you it worked! Finally! It worked everyone! View attachment 424212

You’re welcome! Now, time to see these pens

 

[B2]

Hi everyone. I own the 1236t which uses the same gears as the 1340gt. I’m trying to cut sae 50 threads per inch for a project. It needs to be 50 but my machine only does 48 and 52 according to the manual. I was told by precision Matthew’s that there might be a conversion chart using our different gears to get different threads per inch outcomes that precision Matthew’s doesn’t list in their manual. Does anyone know where I might find that chart?

Hi,

Glad to see that you got the needed gear combination. However for the future if you want a complete spread sheet for all the possible TPI that you might ever need to make you might want to try out a spread sheet that I wrote to generate TPI for a lot of possible lathes. It also gives feed rates and x-feed rates in Imperial and Metric. If you want to explore you can easily add other gears than beyond the standard ones and then run the macro to get all the TPI available. It is posted here:

TPI Feeds X-Feeds: Generalized Excel file for your Lathe

TPI Feeds X-Feeds: Generalized Excel file for your Lathe Hi Folks, My PM1440GT lathe manual only showed a few of the possible threading values and it appeared to me that the Feed rates were incorrect. They were. Hence, I set about to figure out what all possible TPI could be achieved via...

www.hobby-machinist.com

In order to generate a list of all possible TPI etc you need to run the built-in macros. However, if you do not wish to run macros and you can tell me all of the external gears that you own, if different from those that came with the lathe I can run the spread sheet for you and generate a pdf table of all the possibilities. Otherwise, I will run the standard set of gears and attach a complete table for you (attached). I think the standard gears supplied are 127/120, 40, 32, and 30. Are there others? I will also run a macro that would sort the TPI in order.

There is a very large number of possible TPI, especially when you include the threads that can be made using the feel rates. There is also another macro that will search for a chosen TPI and then list them. Below is an example of a search output where two searches were done at 50.????? and 49.?????. (note there are some redundancies, but the total table has over 1600 results for the standard gears!) The center column titles tells you where the external gears are to be placed. For example, the top row, row #966 of the search yields 50 tpi exactly and says to put the 40t gear in contact with the gear box input and the 32t gear in contact with the spindle. The levers are in position 4 and D.

Regards,
Dave L.

 

[tailoredpencompany]

Hi,

Glad to see that you got the needed gear combination. However for the future if you want a complete spread sheet for all the possible TPI that you might ever need to make you might want to try out a spread sheet that I wrote to generate TPI for a lot of possible lathes. It also gives feed rates and x-feed rates in Imperial and Metric. If you want to explore you can easily add other gears than beyond the standard ones and then run the macro to get all the TPI available. It is posted here:

TPI Feeds X-Feeds: Generalized Excel file for your Lathe

TPI Feeds X-Feeds: Generalized Excel file for your Lathe Hi Folks, My PM1440GT lathe manual only showed a few of the possible threading values and it appeared to me that the Feed rates were incorrect. They were. Hence, I set about to figure out what all possible TPI could be achieved via...

www.hobby-machinist.com

In order to generate a list of all possible TPI etc you need to run the built-in macros. However, if you do not wish to run macros and you can tell me all of the external gears that you own, if different from those that came with the lathe I can run the spread sheet for you and generate a pdf table of all the possibilities. Otherwise, I will run the standard set of gears and attach a complete table for you (attached). I think the standard gears supplied are 127/120, 40, 32, and 30. Are there others? I will also run a macro that would sort the TPI in order.

There is a very large number of possible TPI, especially when you include the threads that can be made using the feel rates. There is also another macro that will search for a chosen TPI and then list them. Below is an example of a search output where two searches were done at 50.????? and 49.?????. (note there are some redundancies, but the total table has over 1600 results for the standard gears!) The center column titles tells you where the external gears are to be placed. For example, the top row, row #966 of the search yields 50 tpi exactly and says to put the 40t gear in contact with the gear box input and the 32t gear in contact with the spindle. The levers are in position 4 and D.

Regards,
Dave L.



View attachment 424653

Those are it for my machine. Two 40, one 32 and one 30. Thank you so much!

 

[B2]

Thank you. I am glad that my efforts in writting TPI spread sheet program, or the printout, is useful. One puts in all of this work to make a tool like the Excel program and it is nice to hear back that someone actually can use it!

Dave L.

 

[tailoredpencompany]

Thank you. I am glad that my efforts in writting TPI spread sheet program, or the printout, is useful. One puts in all of this work to make a tool like the Excel program and it is nice to hear back that someone actually can use it!

Dave L.

I’m sure that was a lot of work and effort and I hate when I do things for the community and get very little recognition. So I understand completely. I’ll be using this the rest of my life Dave! You really saved my hide!

 

[B2]

Just curious. Did you try out the macros? If so, any questions about them? They will come in very handy if you ever decide to add another external gear? There were really two motivations for making the spread sheet. One was to get all of the TPI for my 1440GT (thousands of them). The second was that I wanted to understand more about writing Excell Macros. They were sort of a mystery to me for years. Curiously, when on this journey I found that most of the lathes that have tables mounted on the lathes about feeds and x-feeds.... are wrong. The values some cases were wrong by 50%.