# Anyone Have Trouble With Threading On 1340 Lathe



## vogeldp (Aug 31, 2016)

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.


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## Bob Korves (Aug 31, 2016)

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.


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## mksj (Aug 31, 2016)

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.


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## wrmiller (Aug 31, 2016)

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'.


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## Fltenwheeler (Aug 31, 2016)

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


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## Bob Korves (Aug 31, 2016)

Fltenwheeler said:


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


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...


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## vogeldp (Aug 31, 2016)

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.


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## Bob Korves (Aug 31, 2016)

vogeldp said:


> 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...


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## mksj (Aug 31, 2016)

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.


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## vogeldp (Sep 2, 2016)

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.


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## Downunder Bob (Mar 13, 2017)

vogeldp said:


> 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.



Hi, I have just read your question re. screw cutting. And agree that it would be quite a disappointment to discover your new machine has a defective user manual. In following your post I gather that this sis not an uncommon problem.

However my interest is somewhat different, in your original question you state that your lathe, a PM 1340 is made by the same factory as the Liang Dei of Taiwan. You also say that your 1340 is the same as their 1236. I find this interesting because my lathe is the LD 1216 These are sold here in down under as LD brand machines. It should be the same machine only somewhat shorter bed. Sometimes it's uncomfortably short, but I wanted the largest swing I could get and I had a very short space to put it in so as with everything it is a compromise, I had been looking on this forum for a similar lathe so that I could read relevant comments but no one appeared to have an LD product.

However if you are certain that PM is made by Liang Dei then I have have the group that I need. Thank you. I had noticed that PM lathes looked remarkably similar to mine, but that doesn't mean they are the same. The other thing is that PM products do not appear to be available here in downunder. So there was no way to check.

Unfortunately it would seem that I might have the same problem as you, but as I haven't done any screwcutting yet I can't confirm it, but will be on the lookout for it. So far I am quite happy with my lathe, still getting use to it as I don't get a lot of shop time.

Bob.


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## qualitymachinetools (Mar 16, 2017)

He doesnt have a PM Lathe, it is a different brand, but I believe he got it figured out. I am guessing though, that if you are in Australia, your lathe is Metric so none of that would apply anyway, but I am not sure? Never thought of it, and just tried to look it up, and I can't figure out if you guys use Metric or Imperial?

But with the PM-1340GT, it has an 8 TPI Main Leadscrew, a 32T Thread Dial, there is absolutely no issue threading with the PM-1340GT .


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## Downunder Bob (Mar 17, 2017)

qualitymachinetools said:


> He doesnt have a PM Lathe, it is a different brand, but I believe he got it figured out. I am guessing though, that if you are in Australia, your lathe is Metric so none of that would apply anyway, but I am not sure? Never thought of it, and just tried to look it up, and I can't figure out if you guys use Metric or Imperial?
> 
> But with the PM-1340GT, it has an 8 TPI Main Leadscrew, a 32T Thread Dial, there is absolutely no issue threading with the PM-1340GT .



Hi, Many people here in Australia are also confused. We officially changed from imperial (british) system back in 1966 when we changed to a metric currency of dollars and cents. other measurements were progressively changed over the next ten years until all our weights and measures became metric. Having said that we still commonly use both the old british and the american imperial systems side by side with the metric system. 

I chose to order my lathe as an imperial machine so all lead screws and dials are calibrated in inches. The cross slide, compound and tailstock also have metric dials, so I can get all the TPI threads I want and also by using the 120x127 change wheel provided and the feed screw gearbox I can also get almost every metric thread that exists. A full imperial and metric chart is provided on the front of the headstock.

My query however is related to the similarity between the Liang Dei lathes and the PM lathes, it appears to me they are made in the same factory and to all intents and purposes, they are identical, can you confirm this? The reason I am asking is that as far as I can see I am the only member of this forum with an LD machine, and I am looking for similar machines to compare with and for picking up hints.

Bob.


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## bench (May 29, 2017)

Hi Bobshobby, Nice you have the same machine as mine. I have a LD1216GH. Mine is metric, has a three phase motor and runs on a VFD.


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## MarkM (May 29, 2017)

The Princess Matthews Lathes are a step up in Quality and can be used in a pro shop for day in and day out use having the gears Hardened and Precision ground which I know the Liang Dei doesn't as I am in the process of purchasing a Lathe and have inquired about this.  The Hardened gears for the Liang Dei start with there 1440 which Eason sells as the 1440e.  Which is in competition for me with the Pm 1340gt.  Both great lathes now I just need a deal on one of them.


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## pdentrem (May 29, 2017)

I ALWAYS use 1 for any thread. Avoids any and all confusion!
Pierre


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## Downunder Bob (May 29, 2017)

bench said:


> Hi Bobshobby, Nice you have the same machine as mine. I have a LD1216GH. Mine is metric, has a three phase motor and runs on a VFD.



Hi, Nice, you are the first person since I joined who has owned up to having a LD lathe, and the fact that yours is a LD1216 GH the same s mine is quite something. How do you like the 3ph motor and VFD. As I said I opted for the single ph and no VFD. Quite happy with my choice. I could have gone with 3 Ph, as I have 3 ph connected here, but just didn't think I would need it. how long have you had your lathe for and have you done much work with it yet? 

Bob.


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## Downunder Bob (May 29, 2017)

pdentrem said:


> I ALWAYS use 1 for any thread. Avoids any and all confusion!
> Pierre



Pierre, It's not foolproof, If you're cutting metric threads on an imperial lead screw, or imperial threads on a metric leadscrew it most likely will not work, Also other special situations can apply. much safer to leave half nuts engaged and run lathe backwards to begin next cut.

however in the acse of standard threads where the machine chart shows you can use various numbers it should be safe to do so, and much quicker


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## pdentrem (May 29, 2017)

If cutting threads on the opposite style lead screw than all bets are off of course. You have to leave the half nuts engaged unless you have made a Graham Meek threading clutch which is very high on my list!
Pierre


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## darkzero (May 29, 2017)

Or use the method posted in post #12 here: http://www.hobby-machinist.com/threads/cutting-metric-threads.22504/#post-199388


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## Bob Korves (May 29, 2017)

darkzero said:


> Or use the method posted in post #12 here: http://www.hobby-machinist.com/threads/cutting-metric-threads.22504/#post-199388


It is actually pretty easy to cut metric on an imperial machine (or vice versa) and disengage the half nuts long enough to pull out from the work and stop the motor.  Just put the half nuts back in when the number you had before comes around after you start the lathe again in reverse.  It is a MUCH safer method than others.  Another good approach is to cut on the back side of the work while cutting toward the tailstock.  With both techniques combined, it is child's play...


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## Downunder Bob (May 30, 2017)

Bob Korves said:


> It is actually pretty easy to cut metric on an imperial machine (or vice versa) and disengage the half nuts long enough to pull out from the work and stop the motor.  Just put the half nuts back in when the number you had before comes around after you start the lathe again in reverse.  It is a MUCH safer method than others.  Another good approach is to cut on the back side of the work while cutting toward the tailstock.  With both techniques combined, it is child's play...



Yes that should work, But I think I'd want further proof before trying it on a critical job. 

Like all child's play, it's bound to end up in a mess.


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## Bob Korves (May 30, 2017)

bobshobby said:


> Yes that should work, But I think I'd want further proof before trying it on a critical job.
> 
> Like all child's play, it's bound to end up in a mess.


Practice it on a piece of scrap until you become confident in the method.  That is what I did...  Don't take my word for it, prove it to yourself.


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## bench (May 30, 2017)

bobshobby said:


> Hi, Nice, you are the first person since I joined who has owned up to having a LD lathe, and the fact that yours is a LD1216 GH the same s mine is quite something. How do you like the 3ph motor and VFD. As I said I opted for the single ph and no VFD. Quite happy with my choice. I could have gone with 3 Ph, as I have 3 ph connected here, but just didn't think I would need it. how long have you had your lathe for and have you done much work with it yet?
> 
> Bob.



Hi,I owned the machine since last October and so far quite happy with it. I have no experience with a single phase motor so cannot say whether 3ph is better than 1ph, but running the machine on a VFD is quite convenient for its speed adjustability. I modified a few things. Crashed once the carriage at the tailstock end, and since then power feeding makes noise when the lathe is running at high rpm. Rather than fixing the QC gear box I added a DC motor to run the power feed shaft. It is very quiet and the feed speed can be adjusted continuously, in the middle of machining---a very convenient feature. Also added an extra rotary switch for the spindle, which ended up as my main switch for the spindle. To get a decent surface finish for a steel it seems I have to run the lathe at high rpm, above 1500, for a half inch stock using a carbide insert. I am not quite comfortable with the rpm. What is your typical high rpm?


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## darkzero (May 30, 2017)

bobshobby said:


> Yes that should work, But I think I'd want further proof before trying it on a critical job.
> 
> Like all child's play, it's bound to end up in a mess.



I've been using that method ever since I found out about it & never had an issue. It's the only way I do it for metric threads on my imperial lathe.


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## Downunder Bob (May 30, 2017)

bench said:


> Hi,I owned the machine since last October and so far quite happy with it. I have no experience with a single phase motor so cannot say whether 3ph is better than 1ph, but running the machine on a VFD is quite convenient for its speed adjustability. I modified a few things. Crashed once the carriage at the tailstock end, and since then power feeding makes noise when the lathe is running at high rpm. Rather than fixing the QC gear box I added a DC motor to run the power feed shaft. It is very quiet and the feed speed can be adjusted continuously, in the middle of machining---a very convenient feature. Also added an extra rotary switch for the spindle, which ended up as my main switch for the spindle. To get a decent surface finish for a steel it seems I have to run the lathe at high rpm, above 1500, for a half inch stock using a carbide insert. I am not quite comfortable with the rpm. What is your typical high rpm?



Mine is only a couple of months older than your's. Your not likely to notice much difference between single ph and 3 ph except you will have a little higher starting torque, and some say that 3 ph is smoother, I doubt if you would notice that. The real difference will be with the VFD. The ability to adjust the speed is useful, but I don't think it's worth the cost. I just use the gearbox, isn't that what its for. My top speed is 1500 rpm, and I've rarely used it. I mostly run around 600 to 900. Sure I would like a lower speed for difficult screwcutting. Continuously variable speed would be useful for facing large diameters, but other than that ?. Ok your dc drive is useful, but I suggest you fix the damage you might need it for screwcutting.. I haven't crashed a lathe since I was an apprentice about 55 years ago, but I guess there's always the next time.

Bob


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