Clearpath & IPC5 vs everything else (for small mill)

[bbatarelo]

Hi all,

I have been looking to upgrade my existing low power steppers on mini mill that are behind 36V power supply and Gecko drives with something beefier and with closed loop. As price points I've been observing went up, suddenly servos caught my attention and after seeing Keith's post about officially supported Clearpath configurations and C86ACCP board, I became very interested in pursuing that path.
What I am really curious about is the power supply scheme. Basically Teknic says that even one IPC3 should be enough for 3-4 axes, and IPC5 for even more. I know that you can usually get away with less power then nominal because usually not all axes will be working crazy hard together at the same time, but IPC really seems (at first glance) like it's kind of undersized. On the other hand, servo's might be completely different story then steppers, maybe Teknic made something extraordinarily efficient, etc. so I'm interested in other people's experiences.
To be honest, having one compact power supply is really interesting to me especially since I will need to import to Europe all that stuff if I decide to go that route (vs Delta).
My milling machine is small and frictionless (size of BF20 or just a bit bigger), with head counterweight and nice linear guides. Tecknic tech says that I should be good with one IPC5 and 3X either CPM-SDSK-3421S-RLN or CPM-SDSK-3441S-RLN motors.
What are your experiences/advice?

Thanks.
Bruno

[Gary Campbell]

My experience has been, for the vast majority of cases, to follow the advice of the Teknic's engineers. They have not failed me yet.

[Richards]

I agree with Gary. Teknic gives good advice.

The IPC-5 is rated at 350W continuous, 900W peak. A fan can be attached to the power supply to keep it from overheating if the load is high.

The 3421S is listed at 227W continuous. The 3441S is listed at 251W continuous. If you look at the Teknic torque curves, you'll see how torque relates to watts. The hard part is not knowing how hard the motors will need to work in your machine. If all three axes are constantly moving and you're making heavy cuts at the highest possible speed for that cut, you're going to be pulling some serious amps. On the other hand, if the machine is lightly used, the motors will pull hardly any amps.

A stepper requires a lot of current at standstill and at low speeds (where it produces the most torque). Many stepper drives automatically reduce current to 50% or less if the motor is stopped. Reducing the current, reduces the holding torque, but it also reduces the heat. Many of us have touched a stepper that has been in standby for awhile. We remember well the blisters on our fingertips.

A servo works differently. At standstill, it only draws the current needed to hold the motor in place. If the motor's encoder starts to turn, the servo driver applies some current to the motor to hold position. The higher the force against the motor, the greater the current required at standstill. Using gas struts or counterweights on the Z-axis reduces the load on the Z-axis motor.

The bottom line about which power supply to use and whether you might even need two or three IPC-5 power supplies depends entirely on how hard you work your machine.

I have run three SDSK-3421P-RLN motors on my test bench from a single IPC-5 power supply. The power supply stayed at room temperature under those test bench conditions.

[bbatarelo]

This is most helpful and promising. Thank you both, Mike and Gary!
I'll analyse my costs and will probably go the Clearpath route. Worst case scenario is that I'll need additional IPC-5 eventually, if at all given the robustness of the machine I have.

Bruno

[Jason3]

The Teknic products are nice, and the support is quick and knowledgeable. I’d been using their Hudson servos for a number of years until I switched to Clearpath a couple of years (?) ago and have been very happy.

[ShawnM]

I have a Shop Sabre plasma table, 5x10, that has 4 Clearpath NEMA34 servos on it, Y axis has two motors. Mind you it’s a plasma cutter and doesn’t see high cutting loads but the machine is VERY ROBUST and very heavy for a plasma table. The gantry itself is crazy insane overbuilt and very heavy. The machine has one IPC5 driving all four motors at rapids up to 1200 IPM. I’ve never had any issues with power.

[RichMaple]

I have 2 IPC-5's on my 4-drive CNC gantry machine (with 4 nema 34 Clearpaths). I almost always see people using one of them and I think in 99% of cases that is probably fine if you look at the odds that ALL drives would be pulling max power at any one time for long enough to starve the power supply. That said, I wanted a nice clean system from the start without worrying about shoehorning in another power supply in the future or having to troubleshoot the need for another one in the first place. But go with what their engineers say and I'm sure you'll be fine