South Bend Heavy 10 - phase converter or single phase motor?

I just won an auction for a South Bend Heavy 10(long bed)with taper attachment and a lot of tooling. It has a 3 phase motor and I'm wondering the best route to go..install a single phase motor or use a converter.

First off I'm not a machinist but an automobile hot rodder with a Rockwell 11X48 lathe w/taper attachment that I use for basic auto related fabrication. Years ago I had one (Rockwell) with a phase converter but my current Rockwell has a 110v single phase motor. Don't remember the characteristics of the phase converted lathe.

What do you folks recommend phase converter or single phase motor? Is the Heavy 10 really more than I need.

Thanks

If you think you might acquire other three phase machine tools, go the rotary converter route.

If this is the only machine you'll own, then install a VFD.

Thanks....most likely will never utilize other 3 phase equipment.

Don't forget a static converter, relatively inexpensive and dead simple to install. Drawback being you'll lose approximately 1/3 hp.

Both options have advantages and disadvantages depending on your situation and usage. I have a SB 15" with a 220v single phase motor that I've owned for around 40 years. Recently, I picked up a SB 13" that had a 3 phase motor on it. For this one I bought a Teco FM50 VFD from FactoryMation (no shipping or tax for me in NY). I got the same VFD I had installed on my Bridgeport mill. It works fine on my mill.

I wired it up on the lathe and the motor that came on my 13" didn't like the VFD. It was an older motor and not VFD rated. My mill motor wasn't VFD rated either and most older motors will run find on VFDs but some will not.

Anyways, I ended up getting a new VFD rated motor for my 13" and I love the setup. I can run the frequency slow and not get motor overheating. This is very nice because I don't have to change the flat belt on the 4 step cone pulleys as often and I can tweak it during a cut to get chips to break, etc. which is very handy.

I'm a hobbyist but use my lathe a lot so I'm glad I went this route. Your mileage may vary depending on your situation and usage.

Good luck,
Ted

Zip said:

What do you folks recommend phase converter or single phase motor?

Click to expand...

If you swap the 3 phase motor for single phase you'll be giving up the ability to reverse the spindle while underway (with a single phase motor you have to first stop the motor and then reverse it). If you keep the 3 phase motor you can power it with a static phase converter, a rotary phase converter, or a VFD.

Another reason for me and the most important one is that these SB lathes are light machines and are susceptible to tool deflection due to cutting forces. Single phase motors suffer from velocity modulation issues under moderate load, where the armature speed will fluctuate within a given revolution. This is much reduced with a 3 phase motor because of the increased magnetic pole count within the motor. This velocity fluctuation will actually create a very slight herringbone pattern in a very fine finish cut when not in back gear. This drove me crazy for years before I finally figured out what was happening.

I would use a vfd. A lot more flexibility in speed changing.

If you want a single phase motor, I'll swap you even up for your 3 phase assuming the frame size is the same. (I have a single phase 120v heavy 10 and a shop with 3 phase power)