IH mill motor upgrade

[Randall]

I am thinking of upgrading my motor to the higher rpm leeson like Aaron reccomends. Has anyone else done this upgrade and what were the results.
Randy

[ViperTX]

doesn't the IH mill have a gearhead? Will the gearhead handle the additonal RPM?

[Randall]

On the IH site he gives reccomendations if you want the higher rpm and listt the motors. He maked a point to say the gears are hardened for this reason so I assume the gears will handle or he wouldn't make the recomendation.
Randy

[ChrisJ]

Randy,

I have a Leeson 2HP 3425 RPM motor. I haven't mounted it yet, but the shaft was cut to the D80 specs and the motor will mount on the head without any complications. The Leeson metric motors with the B5 flange make it a direct swap except for the shaft needing to be turned down and cut to length.

I will assume that you have plans on running this motor from a VFD since this Leeson motor only comes in 3 phase. If this is correct than I have some thoughts that you may want to consider.
You can only turndown the speed of the motor to approximately 25% of nameplate (860 RPM) before you risk overheating. If you want to reduce the speed further you will need to utilize the gears in the head. A 3425 RPM motor running at 50% speed (30 Hz) will give you half the torque on this motor. So, at 2HP at 3425 RPM you have 6 ft-lbs of torque and at 1712 RPM you will have 3 ft-lbs of torque. Depending on the type of machining you are going to do, this may or may not affect you. I personally do not like this tradeoff.
You can however run the motor at full speed through the VFD and use the gears to reduce the spindle to 1700 RPM without any loss in torque. This is not as nice as using the program, like Mach2/3 to set the spindle speed though. Now you have a manual operation that you have to remember to do.

Another alternative where you will loose less torque on the bottom end is to purchase a 1700 RPM Leeson motor. Leeson rates the metric motors up to 90hz. This will give you a top end of 2550 RPM. You sacrifice 1000 RPM but you maintain all 6 ft-lbs of torque at the 1700 RPM.

Or you can purchase a 3 HP motor at 3425 RPM and you will get 9 ft-lbs of torque at nameplate and 4.5 ft-lbs at 1712 RPM. I believe Aaron put a 3 HP motor on his recent retrofit.

My personal favorite is a constant torque, TENV motor, such as a Marathon Blackmax or a Leeson Speedmaster. Baldor makes one as well. Both are constant torque motors from 0 to 1800 RPM. Plus the manufacturer rates these motor to a maximum speed of 5200 RPM. In this scenario a 2 HP motor will give 6 ft-lbs of torque from 0 to 1800 RPM and from 1800 to 3600, the torque linearly decrease from 6 to 3 ft-lbs. In this arrangement you are loosing torque on an increase in speed and not on a decrease in speed. The only catch is that the maximum size motor that will fit on the IH mill is a 2 HP. The 2 HP motor has a 145 TC frame. Anything bigger than this is just too big. Plus the other disadvantage is that this motor will not fit on the head without some ingenuity. It will need a custome made adapter plate and will need a shaft coupler of some sort to adapt the motor shaft to the head. Also this motor would want to be controlled by a sensorless vector VFD and not just a standard VFD. This is required to simulate the constant torque as the motor decreases in speed. Or you can purchase this motor with an encoder and drive the motor with a Vector VFD. The sensorless drive maintains the motor's constant torque by preprogramming the VFD to the motor specs., where the vector drive actually uses the encoder feedback to maintain constant torque at the motor.

Just some things for you to consider before you take the plunge.

Chris

[Randall]

Chris
Jeez lots of info. I think I will go with the 3hp motor and VFD. And if I have to use the gears occasionally. I know this voids warrenty and may come back to bite me, but my main goal is to machine aluminium now.
I appreciate your input and help. Have you cnc'd your mill yet?
Randy

[CNCadmin]

I'm considering using a Wood router @ 30,000 RPM, and remount it to a dedicated mount and remove the existing milling head.

[ChrisJ]

Still working on it. :frown: Summer came and so did my progress.

Installed a pool for the kids. Working on extending the deck to the pool, etc. My wife and I thought only the kids were going to enjoy the pool. With the heat we have been getting all summer long, both of us enjoy it as much as the kids.

Can't wait till the cold weather hits. May be then I can finish up my conversion.

I have plans for machining 316SS (hope the machine can take it), so the higher torque at the lower RPMs is more attractive to me. Maybe I will find another use for the 2HP Leeson I have.

I hope the motor serves you well.

Regards,
Chris

[Randall]

Chris
welll hopefully there will be a break in temps.
CNCadmin
I would love to see your results and pictues, what a great cnc router. a 2 in machine.
Randy

[ChrisJ]

Hi Paul,

And I thought Aaron was hacking his machine apart by converting the head to belt drive, and here you are replacing the head altogether.
Once these machines are converted to CNC, there are so many features not being utilized, they go to waste. Don't need a quill, don't need to rotate the head, don't need the original lead screws and nuts, if converted to belt drive, don't need any of the gears.......
Time for a new generation of bench top mills for the purpose of being CNC'ed.

Chris

[CNCadmin]

Yep I agree, it's a waste of many besides, have to just to upgrade and modify.

[Randall]

As I metioned before I purchased the 3hp Motor from leeson but juct realized that to go to a 5hp VFD I would need a 3 phase supply. I ordered the 3hp VFD from automation direct so I wont have the headroom that Aaron mentions.
Randy

[baldusi]

I was told that if I did the CNC conversion I could use a straight Servo for the motor. In a machine lika Haas of Fanuc, this allow not only to program the spindle but to thread with a tap or even a single point. My big problem is that I don't know how to interface this to mach3 and or LinuxCNC. Any ideas?