I am in the middle of rebuilding a 5914 lathe. The main thing that I am doing is doing away with the intermediate drive. I already have bought a hitachi vfd for it. It came with an old brush single phase motor so I need to switch it out to a 3phase motor. Shouldn't it be a 3450 rpm? Thanks
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5914
- Thread starter KenL
- Start date
- Joined
- Feb 22, 2012
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- 924
I can check on my 4900 motor spec to see what it's running at. can't recall at the moment.
quick Q though - are you planning to bypass the intermediate drive all together including the quick-disconnect clutch mechanism? or keep that one in the loop?
quick Q though - are you planning to bypass the intermediate drive all together including the quick-disconnect clutch mechanism? or keep that one in the loop?
Purplev
Thanks for responding. Yes I have done away with all of the intermediate drive and hardware. According to my calculations a 1700 rpm motor would only give me a top spindle rpm of around 1150. The 3450 should top out at around 2150 rpm. I was just wondering if that is what others had come up with. Basically just trying to confirm that I was on the right track?
Thanks for responding. Yes I have done away with all of the intermediate drive and hardware. According to my calculations a 1700 rpm motor would only give me a top spindle rpm of around 1150. The 3450 should top out at around 2150 rpm. I was just wondering if that is what others had come up with. Basically just trying to confirm that I was on the right track?
- Joined
- Apr 20, 2011
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I just cant imagine using/needing 2000+ rpm. I'm still a bit of a noobie, but on the 2-3 lathes I've had, I have only ran one in the 1000-1200rpm range a few times to polish a shaft. I have a highly skilled machinist friend and Ive heard him go off on ever needing more than 12-1400rpm - like me, Ive seen him go to 10-1200rpm and polish a shaft
Also, since youve already got the Hitachi (good choice by the way) you can program it to run at a higher freq - say 75 - 90hz - and gain more rpm off the 1700 motor.
What are some uses for high rpm??
Also, since youve already got the Hitachi (good choice by the way) you can program it to run at a higher freq - say 75 - 90hz - and gain more rpm off the 1700 motor.
What are some uses for high rpm??
Hello Pacer
Please look at the picture.The end face was cut with carbide 1200 rpm and diameter is 100mm .As You can se surface finish about half way to center goes down.I did not dare go faster but speed is good for carbide .
Three phase motors can easily be VFDed to double speed.I use a six pole ie 950 rpm at 50 hertz and I tested it to 100 Hertz without problems.The question to Kenl is what is the biggest V belt disc on spindle and let us have a picture
Kind regards
Farfar
Please look at the picture.The end face was cut with carbide 1200 rpm and diameter is 100mm .As You can se surface finish about half way to center goes down.I did not dare go faster but speed is good for carbide .
Three phase motors can easily be VFDed to double speed.I use a six pole ie 950 rpm at 50 hertz and I tested it to 100 Hertz without problems.The question to Kenl is what is the biggest V belt disc on spindle and let us have a picture
Kind regards
Farfar
Ok the lathe form the factory was set up to be able to operate from 52rpm to 2000 rpm. Spindle speed not using back gears. In pre calculations a 1800 rpm motor running at that speed will not give you 2000 rpm using the pulley arrangement on the lathe. Which is 4 inch on drive motor and 6 inch on spindle shaft. Like I said I did away with variable drive shaft and pulleys. I would post pictures but having trouble with that on my iPad. Anyway after hooking up vfd and using it. Running the drive at 54hz. Which should give me 2000 rpm, I can't imagine ever needing that kind of rpms? Looks like 20 to 35 hz is where it would be ran most of the time.
So should I leave it alone or put a 1800 rpm motor on it so it would be ran at 40 to 60 hz? Which is the better hz to run at?
So should I leave it alone or put a 1800 rpm motor on it so it would be ran at 40 to 60 hz? Which is the better hz to run at?
I am NOT an electrician but if it was me I'd go find a 1750-1800 motor and put that on. Otherwise you're talking about long-term use of a motor at half the designed frequency. 3-phase motors can take a beating, but still that doesn't seem right. And you'll have some loss of hp. Having said that, I'm sure someone will jump in and say they ARE an electrician, and that they have wired their entire house to run off a 3-phase generator and a shop-made VFD that drops the hertz down to 20 (except when they want to dim the lights for the wife - then they turn the dial down to 10). This article talks about the effects of running a 60hz rated motor at 50:
http://www.motorsanddrives.com/cowern/motorterms25.html
good luck
Joe
http://www.motorsanddrives.com/cowern/motorterms25.html
good luck
Joe
- Joined
- Feb 22, 2012
- Messages
- 924
Generally speaking the motors run best at full speed (60hz for US current) as most of these motors use a fan to cool them down that is designed to run at full speed (1800rpm for a 1800rpm motor = 60hz on VFD). running it at lower Hz results in motor overheating is run for long periods of time and/or under load. depending on how much lower you are planning on running it would affect the long term longevity of the motor.
I personally run it using the belts for nominal speeds keeping the motor at 60Hz at all times unless I temporarily need an inbetween or a change of speed on the fly.
As for the motor - as long as you keep the same RPMs that the spindle is designed to support you can use any motor you choose to. Looking at the 5900 brochure it shows that the shipped motors with the lathes run at 1425rpm at 50hz making this a 1700rpm/1800rpm motor.
higher RPMs are good for working on small diameter aluminum, or when using carbide, for mass production, or to turn wood. not necessary, but nice to have if you can. If I were you I'd just figure out the RPMs I'd want to run (keeping it within the spindle max rpm capacity) and choose a motor/VFD combo that would supply that.
I personally run it using the belts for nominal speeds keeping the motor at 60Hz at all times unless I temporarily need an inbetween or a change of speed on the fly.
As for the motor - as long as you keep the same RPMs that the spindle is designed to support you can use any motor you choose to. Looking at the 5900 brochure it shows that the shipped motors with the lathes run at 1425rpm at 50hz making this a 1700rpm/1800rpm motor.
higher RPMs are good for working on small diameter aluminum, or when using carbide, for mass production, or to turn wood. not necessary, but nice to have if you can. If I were you I'd just figure out the RPMs I'd want to run (keeping it within the spindle max rpm capacity) and choose a motor/VFD combo that would supply that.
- Joined
- Apr 20, 2011
- Messages
- 430
I guess we all do it differently, I have 3 VFDs and I run the motors all across the range. I'll power tap or single point thread at 5hz or run a fly cutter at 10-15hz. I probably run them in the 30-40hz range the most, using the gear box or belts set in the mid ranges. Aside from getting the house current changed to 3ph, the VFD gives you all these other wonderful benefits.