Upgrading my Delta to VFD

[Kathy Marshall]

After seeing Mike Heaney's post about upgrading his old Delta, I started thinking that would be a nice upgrade for my Delta 46-612.
I replaced the belts a month or two ago, and while it is working better it doesn't have the torque it had when I started turning and I can bog it down pretty easily. I think the problem is that the Reeves drive pulleys are a little out of sync and one belt is always looser than the other allowing some slippage. Anyway, I'd like to go digital and do away with the Reeves drive and maybe upgrade to 2hp.

I sent an email to Automation Direct looking for some recommendations on a motor and VFD and according to their response, using just the motor and a VFD I would lose alot of torque, especially at lower speeds. So what am I missing? Obviously several turners have made the upgrade and are happy with the results, and why would this be different than any of the newer lathes with electronic variable speeds? Do you use step pulleys to make 3 or 4 different speed ranges?

Here is their response:

Here is the technical support response to your inquiry:
----------------------------
Good afternoon,
Are you planning on doing away with the Reeves drive? You are aware you
will lose a great deal of power if you try to replace the Reeves drive with
a motor and VFD combination.
The Reeves drive gives you torque multiplication as it changes speed, and
keeps your power roughly the same.
The VFD only changes speed and your power would drop off rapidly as you
lower the speed ( your lathe couldn't make very heavy cuts at all, and
could quite easily stall).

Please think this over, and let me know if you want to continue with this.
Most lathe owners are unwilling to give up the performance of the machine
caused by using just a VFD.
-----------------------------

Also, can someone explain the difference between 1phase and 3phase? I have 110 into the shop (trailer), I could bring in 220 but that an expense I'd rather delay until I get a real shop built. Is there something I would need to do to convert my 110 single phase to 110 3 phase?

This is something I'd really like to do if I can be sure it would be an improvement. If I could end up with a more powerfull lathe, then I'd be happy with just the 12" swing until after I get a shop built (or win the lottery) and I could think about a new, bigger lathe.

Thanks!

[Dennis Ford]

The email response you got is technically correct, if you do away with the reeves drive, step pulleys would be a good idea.
I have helped do this on a couple of machines. One of them kept the reeves drive and added a VFD, he has the mechanical advantage of both but the reeves drive is noisy. The other turner did away with the reeves drive and added step pulleys (he has three ranges). I think the step pulleys are a better solution but they do add to the cost.
You don't have to worry about 1 phase vs 3 phase; the VFD converts the 1 phase that you have into 3 phase power.
There are VFDs available that use 110 volt input to power 220 3 phase motors but they are usually limited to 1 hp (this is what the second friend used). I will dig up the model numbers we put together if you are interested. With either 110 or 220 input, you still need a 3 phase motor wired for 220 volts.

[Dale Winburn]

Kathy,

I converted my old Rockwell/Delta to variable speed drive with the Automation Direct VFD and A 3 phase 1HP inverter duty motor. My power is 220 and I could go up to a 2HP motor with the VFD. My lathe had and still does have four step pulleys, this give me a wide range of power/speed base on what I'm doing. I do not use my Rockwell/Delta for large bowls, I have a separate bowl lathe, so I don't need a lot of torque.

I'm very happy with my conversion, it works great.

Good luck with your upgrade.

Dale Winburn

[Bob Bergstrom]

I turned for 15 years on a Delta 450 just like yours. I found that the 1/2 belt to be a weak spot when I was turn bigger bowls on the outboard side. That was on a 1hp. motor. To help with the slippage problem, I would spray the belt with belt dressing ( a sticky spray used for auto belts). After I moved up to a 3520b, I wished I hadn't done all the modifications that I did. The wide rib belts on the newer lathes make them run with no vibration. I would give a lot of thought to upgrading to a newer lathe rather than putting too much into the Delta

[Jerry Marcantel]

Kathy, there isn't any expense except the cost of a breaker to go from 110 to 220 volts. How long the run is from the breaker panel to your shop, what is the current wire size and do you have 3 wires should be your only concerns.
I have a Delta Milwakee that I have running with a 3 phase 2 hp motor with a Hitachi VFD. I made my own pullies,a 2" and 4" step, and the drive pulley is 2". The current set up is 2" drive pulley and the 4" spindle pulley = 1725 rpm, and I feel there is plenty of power at low speeds even though I haven't figured out how to program the VFD.
My other lathe is a Rockwell 46-450, with 3/4hp and a noisy Reeves drive that I have to always tighten something weekly. It'll be changed to VFD and a larger motor soon......Jerry (in Tucson)

[Dick Strauss]

Kathy,
I'm considering making the same mods to my Delta 1440 lathe (14" reeves drive).

You supply either 110V or 220V single phase and the VFD creates the three phase for you. Using 110V, you are pretty limited to 1hp via VFD as noted by others. Using a converted 220V/20A line, you should be able to power a 2hp/3ph motor.

Step pulleys are a good idea for increased torque and better speed ranges. At least 2-3 steps should help quite a bit! 3ph motors can be made to rotate 2x or more of their rated rpms (1740, 3560, etc) using a VFD but the motor bearing life is significantly reduced as speed goes above the nominal. With a 12" of lathe swing, this will be less of an issue if you don't add step pulleys because you'll be turning 11" and smaller pieces.

I've bought my VFD supplies from FactoryMation and have had good luck with their products.

Let me know if I can help from afar.

[Kathy Marshall]

Thanks guys!
I think I'm going to give it a try. Probably go with the 2hp in conjunction with the Reeves drive and think about switching over to step pulleys later on. One of my neighbors is an electrician and will help set me up with 220.

[Dick Strauss]

Kathy,
The reeves drives are specifically made for a given hp. If you up the hp, I suspect you will get lots of slippage and vibration (more than normal) because the springs won't hold well (maybe you have one of those better reeves drives found in the old Olivers and PMs). You might consider some Maska cast iron step pulleys. They make sizes to fit most most all bores (diameter of the motor and spindle shafts). These pulleys should be able to be pressed on and are not too expensive IMO (about $70+shipping for a pair of 3 step pulleys).
http://www.electricmotorsite.com/c/pul_step_a/A+Belt+Step+Pulleys.html

Whatever you do, don't use the cheap zinc Chicago step pulleys...they are not worth your time and money.

It's good to hear you've got a neighbor to help with the electrical change.

Take care,
Dick

[Bob Bergstrom]

Got to agree with Dick on the slippage. The springs in the reeves drive just won't squeeze the belt well enough to use the 2hp. available. Belts on a reeves drive don't rely on tension to drive the headstock, they are being pinched between the pulleys. The 2hp. may help in low end torque at low speeds but the more torque the more likely the slippage. When the reeves is at the slowest speed, the pulley diameter will be the smallest and with the smallest amount of belt contacted with the pulley.


Kathy,
The reeves drives are specifically made for a given hp. If you up the hp, I suspect you will get lots of slippage and vibration (more than normal) because the springs won't hold well (maybe you have one of those better reeves drives found in the old Olivers and PMs). You might consider some Maska cast iron step pulleys. They make sizes to fit most most all bores (diameter of the motor and spindle shafts). These pulleys should be able to be pressed on and are not too expensive IMO (about $70+shipping for a pair of 3 step pulleys).
http://www.electricmotorsite.com/c/pul_step_a/A+Belt+Step+Pulleys.html

Whatever you do, don't use the cheap zinc Chicago step pulleys...they are not worth your time and money.

It's good to hear you've got a neighbor to help with the electrical change.

Take care,
Dick