Anyone Have Trouble With Threading On 1340 Lathe

vogeldp

Registered
Registered
Joined
Jul 6, 2016
Messages
7
Hello,

Has anyone had threading problems with their 1340 lathe, such as wrong dial engagement information on the Legond plate or in the manual or incorrect dial gear, leadscrew, incorrect half nut etc. My lathe is made by the same mfg of the PM1340 Liang DEI of Taiwan but is their 1236GH model which in every way identical to the 1340 (same p/n's) . My issue is the engagement info is wrong or incorrect internal parts, according to the manual/dial legond plate to thread a 20 TPI I am to use any number 1-8 on the dial but I get a mess after threading (thread splitting). Upon further investigating I found if I use either 1,3,5,7 or 2,4,6,8 I get a perfect thread. I have checked all parts for correct dial tooth count (32), leadscrew TPI (8). I have had no luck with the company I bought the lathe from , they claim if I am now able to cut threads then use that method but I disagree, I would have to go through every thread TPI to verify the engagement process. Anyone have any suggestions of what may be going on.
 
It sounds like the lathe is threading correctly, and that the problem is with the threading dial chart. I have a Kent 1340 lathe, it has a threading dial labeled 1,3,5,7 with unlabeled hash marks in between that I interpret to be 2,4,6,8. For a 20 pitch thread the chart says to use 1-4. That does not mean 1 or 4, they have other choices the use the word "or". So it must mean 1 through 4. That does not make sense, and is also incorrect. I think they really mean I can use every second mark on the dial, which has eight marks, from the one I started on. I have not tested it to see if that is true, and just re-engage on the same number every time, which will work on any imperial thread with an imperial lead screw.
 
My PM1340GT also indicates 1-8, but then I do not use the threading dial since I do not disengage the 1/2 nut. I do not see it as a big issue, unless you cannot cut threads, just use the even or odd numbers. I do a light scribe pass on the first cut, so that would be a good point to check the engagement matching the threading dial. I will check later today on the 20 TPI setting.
 
I've not done all thread pitches on my 1340, but the ones I have done came out fine. I do mostly 16 tpi and above, and the chart in my manual says either 1-8 or 1-4. So I always use '1'. :)
 
Hi

To use any number on the thread dial the thread pitch has to be a multiple of 8.

Even pitch thread that are not multiple of 8 can use 1,3,5,7 or 2,4,6,8

Odd pitch opposite numbers.

Tim
 
Hi

To use any number on the thread dial the thread pitch has to be a multiple of 8.

Even pitch thread that are not multiple of 8 can use 1,3,5,7 or 2,4,6,8

Odd pitch opposite numbers.

Tim
That is correct, Tim. Unfortunately, at some point someone changed the numbering scheme of the threading dials on the Asian lathes and did not change the charts to match, and the mistake has evidently proliferated across all or most the Asian lathes. That is understandable because most of the people making them do not have English as their first language and likely do not know how to run a lathe...

Edit: I just checked the Grizzly 0782 manual and it appears to be wrong as well...
 
Last edited:
I know it is possible to use the "if it works use it" but that is not the correct use of this $4300.00 lathe. The seller of this machine had no issue charging full asking price without discounts so it is in my best interest to get what I paid for. Changing methods of doing a job just to fit the situation is not the way especially when the manual clearly states a certain way, I have a copy of the PM1340 manual and the method is the same 1-8 as in one through 8 just to clarify ( not 1 or 8 ). Thanks for the input.
 
I know it is possible to use the "if it works use it" but that is not the correct use of this $4300.00 lathe. The seller of this machine had no issue charging full asking price without discounts so it is in my best interest to get what I paid for. Changing methods of doing a job just to fit the situation is not the way especially when the manual clearly states a certain way, I have a copy of the PM1340 manual and the method is the same 1-8 as in one through 8 just to clarify ( not 1 or 8 ). Thanks for the input.
Well, I agree with you entirely, vogeldp, and I understand your concerns as well, but the reality is that you can fight with the seller to get the correct threading chart and manual instructions provided to you, good luck with that, try to get the seller to take the lathe back completely at his expense because of this issue, I wish you even better luck with that, or learn to use the lathe, understand the math behind what the threading dial does, and be glad you did not have to spend five to ten times your purchase price for a lathe that might not have these kinds of issues. Yes, they are no doubt imperfect lathes, and that is part and parcel of the relatively low price of acquiring one...
 
Well I did check the 20 pitch threading on the PM1340GT, and as long as I was on one of the numbers, it threaded just fine. I tried 1-8, and they all tracked the same. I will note that the half nut might be just slightly + or - of the number/line, so you always need to engage it at the same position relative to the line. You might check to see that you have the proper thread indicator/teeth, I have heard of them installing the metric threading dial on English machine. I believe the threading teeth is a multiple of 4 of your threading feed TPI (8 TPI would have 32 teeth, 10TPI would have 40 teeth). So worth checking. As mentioned earlier, I never use the threading indicator, since I never disengage the half-nut, but then my machine operates differently then the stock machine.

I think what Bob indicated is that all these machine have some issues, and some being fairly major. Sometimes things are correctable, other times you just have to live with it. They import these items from overseas and often you get what you get. The manuals are usually pretty useless, and there can be errors, that they just do not correct. At least you have a work around, I purchased a mill with metric feed screws and English dials, never could do manual work off of the dials and had to buy a DRO. The company did nothing, so it goes.
 
Alright, finally got it figured out why I was splitting the 20 TPI threading. This lathe is much more sensitive or non forgiving that my old South Bend 10K in that the Dial number must be exactly in line with the center of the rivet/marker any deviation before say even 1/32" and it's out of sync. My old South Bend 10K could be engaged anywhere close to the mark. 8 TPI leadscrews/32 tooth dial gears require more finesse. Thanks for your input. Case closed.
 
Back
Top