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PM1236 gears
- Thread starter ShawnR
- Start date
- Joined
- Dec 21, 2018
- Messages
- 2,143
Isn't there a gear chart on the left front of the lathe? It will show gear positions and selector lever positions and feed, cross feed rates. The same chart is in the manual. My PM1440HD will do all the common imperial threads in both course & fine by just changing the lever positions. The only exception is the very coarsest 4TPI. Metric requires one change gear to be run against the 120 tooth and one against the 127 tooth (127 x 2 =254) the standard relationship, imperial to metric (25.4mm to the inch) Before you start trying to cut threads, Go to Joe Pie's site. Excellent info there.
Use his method to simplify the process. Cut away from the head stock with an upside down tool and straight in plunge. No fiddling with the compound angle. For using thread wires only one wire is needed, not 3 as is typical. Follow his instructions.
Use his method to simplify the process. Cut away from the head stock with an upside down tool and straight in plunge. No fiddling with the compound angle. For using thread wires only one wire is needed, not 3 as is typical. Follow his instructions.
Hi @Larry$
Yes, there is a chart and it provides a limited number of threads. I have the PM1440GT and I think it is the same chart as your 1440HD. While the chart is useful, it is very incomplete in that it does not show all (many) of the TPI values generated by all of the lever positions, plus it provides very limited information about the change gears, but does actually require that you use a few of them in order to fill in the chart provided . In some cases you can get very close to the desired TPI value without changing gears if you use a non-chart listed gear box lever arrangement. That is part of the reason I built the Excel Workbook with multiple spread sheets (other lathes), which generates all TPI, mm/T, and feed rates for all possible combinations of levers and external gears. It also works for a number of other lathes and is generalized enough to allow one to modify it for virtually any lathe. Lastly, I found that the feed rate chart on the 1440GT, and most HM type lathes are either not very accurate or are actually wrong. While the workbook initially seems rather complex run it is actually very automated. You can simply choose a set of lever positions and gears and it gives you the values. Or you can run a macro and it will generate a complete list of all possibilities. For my 1440GT gear box along with the standard external gears there are thousands of TPI values possible. The workbook has a search function which allows one to not only search for an exact TPI out of the thousands possible, but also can find all TPI values that are close to the one desired by providing you with the gear/levers arrangements. In many cases you can find a non-common (odd ball) TPI value or an approximation to the desired value to a small fraction of a percent error.
You might want to give it a look. Its free on HM and there is a sheet that has written instructions on its features.
PS. Lathes with Norton gear boxes usually have a much better chart, but it is still incomplete wrt to the external gears.
PSS. My secondary motivation for writing the Workbook was that I wanted to learn more about how to write Macro commands.
Dave L.
Yes, there is a chart and it provides a limited number of threads. I have the PM1440GT and I think it is the same chart as your 1440HD. While the chart is useful, it is very incomplete in that it does not show all (many) of the TPI values generated by all of the lever positions, plus it provides very limited information about the change gears, but does actually require that you use a few of them in order to fill in the chart provided . In some cases you can get very close to the desired TPI value without changing gears if you use a non-chart listed gear box lever arrangement. That is part of the reason I built the Excel Workbook with multiple spread sheets (other lathes), which generates all TPI, mm/T, and feed rates for all possible combinations of levers and external gears. It also works for a number of other lathes and is generalized enough to allow one to modify it for virtually any lathe. Lastly, I found that the feed rate chart on the 1440GT, and most HM type lathes are either not very accurate or are actually wrong. While the workbook initially seems rather complex run it is actually very automated. You can simply choose a set of lever positions and gears and it gives you the values. Or you can run a macro and it will generate a complete list of all possibilities. For my 1440GT gear box along with the standard external gears there are thousands of TPI values possible. The workbook has a search function which allows one to not only search for an exact TPI out of the thousands possible, but also can find all TPI values that are close to the one desired by providing you with the gear/levers arrangements. In many cases you can find a non-common (odd ball) TPI value or an approximation to the desired value to a small fraction of a percent error.
You might want to give it a look. Its free on HM and there is a sheet that has written instructions on its features.
PS. Lathes with Norton gear boxes usually have a much better chart, but it is still incomplete wrt to the external gears.
PSS. My secondary motivation for writing the Workbook was that I wanted to learn more about how to write Macro commands.
Dave L.
- Joined
- Dec 18, 2022
- Messages
- 2,585
- Joined
- Dec 18, 2022
- Messages
- 2,585
Hi @verbotenwhisky
Sorry if my description did not indicate that the Workbook as at the link location. Glad you found them. The file that is the most complete, with the macros, is "TPI Many Lathes M421_1443.zip" The workbook that is not compressed does not have the macros in it.
I would appreciate any comments, thoughts, suggestions, criticisms, etc. about the workbook or even if you have been able to open the files or not. I do not seem to get a lot of feedback on it and it would be nice to have some. Please post them at the workbook string so that they are connected to that project. Along with other lathes, the workbook explicitly has a sheet for the PM 1440 and PM1340. I don't think I put a sheet in for the PM1236, but I am sure I can create one without too much trouble if that is the lathe you have.
By the way, for your interest and convenience, in the workbook, I also inserted a sheet that shows a TPI table that @jbolt posted and a conversion table that @davidpbest had posted.
Dave L.
Sorry if my description did not indicate that the Workbook as at the link location. Glad you found them. The file that is the most complete, with the macros, is "TPI Many Lathes M421_1443.zip" The workbook that is not compressed does not have the macros in it.
I would appreciate any comments, thoughts, suggestions, criticisms, etc. about the workbook or even if you have been able to open the files or not. I do not seem to get a lot of feedback on it and it would be nice to have some. Please post them at the workbook string so that they are connected to that project. Along with other lathes, the workbook explicitly has a sheet for the PM 1440 and PM1340. I don't think I put a sheet in for the PM1236, but I am sure I can create one without too much trouble if that is the lathe you have.
By the way, for your interest and convenience, in the workbook, I also inserted a sheet that shows a TPI table that @jbolt posted and a conversion table that @davidpbest had posted.
Dave L.
Hi @verbotenwhisky
From the photos at PM, the PM1236T looks like it is the same gear box as the PM1340. (So that workbook tab/sheet should work for you. I think you have the PM1236T.) However, the PM1236 is different from the PM1236T. The PM1236 maybe the same at the as the sheet tab I labeled uwMM1340LB-Lever... I just no longer recall for sure.
From the photos at PM, the PM1236T looks like it is the same gear box as the PM1340. (So that workbook tab/sheet should work for you. I think you have the PM1236T.) However, the PM1236 is different from the PM1236T. The PM1236 maybe the same at the as the sheet tab I labeled uwMM1340LB-Lever... I just no longer recall for sure.
- Joined
- Dec 18, 2022
- Messages
- 2,585
I am a bit confused. I am not for sure what a 1236M looks like, but it sounds like it does not have the Norton gear box. PM does not sell an M version do they? Did you get it else where? Can you post a URL for the 1236M manual or at least post pictures of the front panels and the TPI tables? (On the PM site if you look at the manual for the 1236T it says it is the same as the 1340GT).
I worked from my machine, the PM1440GT. I believe this is the same gears as some of the other PM1440xx models but I am not positive about all of them. The 1440E-LB has gear knobs rather than concentric levers, but it appears that they have a similar number of settings .... so I am guessing they are the same. One quick way to check, but not 100% trusted, is to simply compare the TPI tables labels in the two manuals of the two machines and decode which gear lever letter of the GT corresponds to which gear knob position number of the E-LB and then do the same for your 1236M. Anyway, if you machine is not the same, with your machine info I could probably do create a worksheet pretty easily... or work with you to do it.
The PM1236 (no extra letters) is probably does not seem to be exactly like any of the other machines, as it has knobs and it has rearranged them physically!!!
By the way, don't waste your time looking at the gear arrangements in parts diagrams. I have yet to find one of these pages that is correct or actually makes sense and they maybe be incomplete. I have come to the conclusion that the diagrams have not kept up with the machine changes as so many models exist.
Dave L.
- Joined
- Dec 18, 2022
- Messages
- 2,585
Mine is the PM1236, I have seen it with the M behind and without, I had assumed (bad idea) that it was like my PM940 mill where M is a gear driven and V is a VFD/variable speed unit. 4 knobs at the bottom of panel are the carriage drive selectors (shaft or lead screw selector and feed rate) top 2 levers are 9 speed shifters and you get a high/low by shifting the belt. My machine is very new and I am still figuring it out, I have used a lathe before but I am not an expert, I know more about the mill, this isn't my first mill but it is the first lathe I have actually owned. Your sheet is great information, with a little math I think I it will be very useful and I appreciate you sharing it.