PM 1340GT with Simgle Phase Power

MWCurl

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Guys

I am considering purchasing a 1340GT for my farm shop. I do not have 3 phase power at the shop. Therefore, I would prefer a lathe that uses single phase power. Does anyone cut threads with single phase machine? If so, what has been your experience? Any issues for me to consider?

Mike
 
Get a VFD and have no issue running a 3-phase unit on single phase. Also, AFAIK, a lathe's ability to thread has nothing to do with the power supply.
 
kb58

I appreciate your prompt response to my post. I am familiar with the VFD option ...... but it adds about $500 to the cost of the lathe. Also, I understand a VFD would allow a continuous control of RPMs ..... in addition to acting as a converter for the single phase voltage. However, I do not envision the need for the continuous speed control.

The reason I posed the question is because I saw one review that indicated that a 3-phase motor would cut a smoother thread than a 1-phase motor. This is based on the fact that 3-phase power produces a smoother current that 1-phase power. The comment stated that this difference in "smoothness" of current would be translated to cutting the threads. Although I understand this reasoning in theory, I question if it is an issue as a practical matter.

Therefore, I posed the question to persons who are cutting threads with 1-phase lathes.

Mike
 
Fair enough, and I've never threaded with a 3-phase lathe so I shouldn't handing out advice!
 
Practically speaking, no, not a major issue.
 
I own a PM 1440 GT single phase and I have no problems with threading
 
On the 1340 gt the slowest speed is very fast for a novice at single point threading. When you are learning the 25 to 60 rpm speed is where you will feel most comfortable. But... higher speeds usually produce better surface on the thread flanks. Like speeds of 150 rpm on up.Factors:
rigidity, type of tools, sharpness, type of metal, etc.
 
Thanks for your comments guys. Pacifica ..... I was a little concerned about the 1340GT’s slowest speed being 90 RPM for threading. However, I am currently taking a class at the local community college and we are threading at 80 RPM on a 1340 Standard Modern lathe. Hopefully I will make any “newbie” miatakes on it!
 
When i closed the shop,I took home some small machines ,and simply changed them over to single phase........They dont run as nice,but the do run ,and are usable for anything they were usable before.The only possible issue Im aware of is that single phase motors can be limited to so many starts per hour,due to heating.............but if you dont start big chucks at top speed ,this isnt an issue,and certainly not an issue with threading ,where motor starting loads are light.
 
Threading a coarse thread (say 3/4 - 10 tpi) up to a shoulder at 80 to 90 rpm would certainly give me some serous pucker factor! One of the guys at work does 4tpi at 120 rpm, to a shoulder - "no problem", on a full manual machine! I can't do that.

There are good work arounds (i.e. thread from the groove, going outward in reverse), thread into a groove of width that make you comfortable.

Higher end lathes will often have a better speed range. I have an 11" English toolroom lathe that has a speed range 30 - 2500 rpm in 12 steps. It is very nice for threading to a shoulder (especially since it allows speed change on the fly, without effecting the threading take off - since the gear changes are earlier in the drive train than the take off for threading).

My larger lathe has a speed range of 45 - 2000 rpm. I find it very rare that I ever use the top speed, but I use the 45 rpm quite often - and sometimes wished it was slower. I have long thought about changing the belt drive ratio (never quite gotten aroundtoit). Perhaps that would be an option for your machine? Do you really need such a high top speed (sacrifice a little and get a more useful bottom end)? Make your self a pair of two groove step pulleys?
 
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