Printable View
I recently purchased an Emco turn 242 from a local school. Everything seems to be in good condition on it. Im upgrading it to a newer control and electronics. Im curious about keeping the spindle motor if there is a way to control it with a VFD. Ill post a picture of the motor plate. I found some VFD's that claim they are for 11kw motors. 220v single phase in 380v 3 phase out. Has anyone seen motors of this size ran off single phase power with a VFD?
It is 4 speed motor. i would change it for new one. Connecting it with VFD can be possible, but not necessary. If (as I assume) it is brushed AC motor, frequency control wil not work properly with it. More probably U can control it with voltage, so U would need some programmable transformer.
That's quite a motor. I agree with steryd, I would replace the motor. 11KW is pretty large to run on single phase. I have a similar sized machine and it had a 7.5kW spindle motor/VFD that I replaced with a 7.5kW servo motor so I could have a full C axis. Since I replace the original spindle motor, I have not seen the load meter go over 29%, where the original motor used to run 60 to 110% load pretty consistently. The original spindle motor was rated at 5000 RPM, but the servo motor is only rated at 3000 RPM. In my case it's no problem because for my parts I never run over 2500 RPM. The torque curve on the servo motor is much better than the original motor.
I only have single phase, 240V power in my shop, but I run the lathe with a rotary phase converter.
Thank you all for the advice. Ill go ahead and replace the motor. I will probably go with a 7.5kw motor. Is there any benefit in going with a servo on the spindle if i dont need positional control? My turret doesn't have live tooling.
That is a tough call and a few weeks ago I would have said no. But after running the servo for a few weeks, I am much happier with the servo motor for general turning because of the torque characteristics. Much more low speed torque than the original Fanuc motor. The other interesting thing is the power usage went down a bit, but not enough to justify the servo on that basis alone. I will say that for my work I could have used a 5.5kW servo and would have plenty of power, I just didn't know it at the time.Quote:
Originally Posted by aaronky
The cost difference for quality equipment, if you are buying new, is not that different. Assuming 7.5kW, the servo system, including all needed cables is about $3300. A VFD is going to be in the $500 - $1500 range depending on specs, and a motor suitable for spindle use will be in the $2000 range.
In either case, I think you will need 3 phase power to run it.
Definitely for such power U would need 3 phase power. As for using servo as spindle I'm sceptic. Well selected motor and vector VFD will be cheaper and will do the same with low frequency torque. Anytime U can add rotary encoder for positioning and threading, and it will still be quite cheaper.
I ended up going with a 10hp and vfd. I found a Baldor motor local, brand new for 250$. Their company stocks spare motors and when they "expire" if they haven't been used they sell them at a discount.
I stripped the machine down and am in the process of putting it back together now. I have a very dumb question to ask. I didn't pay attention to the mounting arrangement of the cable chain when i tore it apart thinking it would be obvious. If someone has a similar lathe and would kindly post a pic I would appreciate it lol.
I tore the electrical cabinet off the machine and plan to mount all the new electronics in the control cabinet on the front of the machine. The original spindle encoder will work with my new electronics so I will retain it for threading. I haven't yet tackled the 8 pos tool changer. I'm saving the best for last. If anyone has any references for retrofitting a 8 pos turret or similar I could use it. Thank you guys for sharing your knowledge.
Well I've done a 10 position if that helps. Depends on the type of drive, locking mechanism, rotator, and your control software.Quote:
Originally Posted by aaronky
I am curious about the original motor from your machine. I also have a 242 and wanted to know if you have any original parts no longer needed after the retrofit that you’d be willing to sell.
I tried to Message you but I don’t think it went through.
Please let me know.
Also,
If you need pictures of anything for assembly I can post what I have. My machine is totally original and very unmolested so I am happy to help where I can.
Sent from my iPhone using Tapatalk
How is the retrofit going?
Did you get the machine fully working?