@MaverickNH
This site charges for the manual. Do you have a pdf copy you could sent to me via private message? I don't want to pay just to see how the gears fit together.
Mean while I have made an attempt to add your file to my workbook. I had to make some assumptions. I do not know what your cross feed gears are and so do not know a cross feed rate. If you supply me with a table (or the manual) of feed values for gear settings I can usually figure this out. So I just assumed a number used in some other lathe models. I looked at the table of threads you supplied and assumed that the gears listed represented all of the gears that come with the lathe (and that you have). Secondly, I assumed the lathe does not have a separate "feed" bar so it cannot cut threads by feeding rather than by using the lead screw. In order to easily match the table with the gears I had to assume that the lead screw is 16TPI. If this is not correct and it is the more standard 8TPI of larger lathes then there must be a hidden 2x gear in the box somewhere. The best way to run the spread sheet is to allow any of your gears to be placed on any axle, so this assumes that the axles are all the same diameter etc. Because of the way the spread sheet is set up to be universal for a number of lathes it will compute cases where their might be the same gear size on two axles at the same time. You will just have to know that you do not have multiple gears of a size. Likewise without further knowledge it is impossible to know if a set of gears will actually fit together. The operator has to be smart this way. For example putting 80T gears on all of the A, B, C, D positions is most likely impossible. However, this would give you the same results as any single gear on all of the axles.
So I built the spread sheet and ran the macros for you. It is attached. You will find two unprotected tabs(sheets) AllTPI and SrchdTPI. The SrchdTPI provides a table of Imperial and Metric gear arrangements for the most standard threads and approximations to them. I set the approximations up so that you got at least one, but usually many, gear arrangements for the value being searched. I say the tabs are unprotected as they do not begin with the letters "uw" and so if you run the TPI generator macro then any tab that does not start with uw will be deleted so that a new AllTPI can be created cleanly. If you want to save these tabs just add the letters to be beginning of the tab name. However, if you late want to run the macros on the AllTPI list you will need to copy the saved tab contents into a tab/sheet by that name.... or just remove the uw from the one you protected.
Doing it this way the macro found 5329 possible gear arrangements, not counting any duplications. You may note that in the AllTPI list that some columns have letters in them like "S & T". You will find this twice, in columns S and T. The meaning of this is that you can put any gear in both of these axle positions and get the result. You just need to have two of any gear to do so.
You can also run the uwLMS4200_7x sheet manually. For example, click once at cell O30 you will find a pull down menu. Use the arrow to select one of the gear values listed and you will see that the results at various cells, E24-E28 for imperial threads and at X24-X28 for metric values. Of course some of these feed and x-feed entries will/may be meaningless or incorrect.
You will have to unzip the file. Then when it is opened in Excel you will need to enable the macros if your security is set that way. If you have never used macros you will need to enable or click on the Developer Tool bar entry at the top. If it does not show then you will have to enable it.
I suggest you open the AllTPI tab/sheet so that you can see it. Then run the macro called "HideAuto". This will hide some of the columns in the table/list/sheet which you do not use. There is also a Hide macro which lets you choose which columns you wish to hide.
By the way there were 6 gear arrangements to get to 80TPI. Of course some require multiple gears of the same value.
Let me know what you think. Also, I will be happy to try to answer any questions.
After you have looked at it and we have checked the x-feed rates out to our satisfaction I will prepare a final version and post it for everyone.
Dave L.
