Here are some pics of my new servomotors from
IMservice/Cadcamcadcam for my Sherline 2000... Also in the kit was three SV-500 servo drivers and cabling. I haven't found too much in this forum about these, so I'll post my comments on them.
First, I ordered these on a Friday, and recieved them Monday morning... The motors were packed well, and nothing was missing
After hooking it up properly, these are my initial thoughts on the kit:
These things are
fast, almost too fast a Sherline machine, without a lot of modification/maintenance to the mill. Fred recommends 40 inches-per-minute, but I've tried mine at up to 50IPM, and they do fine... the weak part is the Sherline 1/4"-20 leadscrews, they will actually bow under load... The brass leadscrew and backlash nuts develop backlash much faster than the stock 10-20IPM Sherline stepper motors do, which is OK, as long as you keep a few extra brass nuts on hand
Accuracy is great, I couldn't be happier with the repeatability, even without backlash compensation... The encoder resolution is somewhere around 0.0001" in 1x mode, and 4 times that in 4x mode, and will not miss a STEP/DIR command unless the PID values are not tuned correctly.
The system uses Globe motors and Agilent encoders, both of which are great stuff... I've checked the output of the encoders on an osilloscope, and they are near-perfect square waves, which is good for accuracy. The motors are geared down with a toothed belt, which is housed inside an extruded aluminum enclosure. The construction of the enclosure is questionable, it seems the holes on mine were drilled on a press with a bent spindle, as the holes are all triangular. I would think something of this nature would have been drilled on a milling machine, clamped down to the table. The rubber boots on both ends of the extruded aluminum are crap, I'll be machining some caps from aluminum, with a watertight gasket, so I can use flood coolant later....
The motors and drivers run very cool, not hot to the touch like my Linistepper setup (which required a 3-pound heatsink and a large fan)... Actually, I ended up buying the IMservice kit after my Linistepper drivers overheated, which isn't that hard considering how much power it is quiescently dissipating.
The only bad thing I can say about this kit, besides the gearbox construction, is that the documentation is terrible. It doesn't mention several important pieces of information needed to set the kit up to a program such as
Mach2/3, like steps-per-revolution, and how to interface the Enable/disable line... I will attribute this to the fact that the kit is
intended to be used with IMservice's proprietary software; however, I feel that it was a mistake to leave this stuff out, considering how superior Mach3Mill is to it.
That being said, it is an excellent system if you have the $700 to spend, especially since they are upgradable to a larger mill (I have already outgrown my Sherline), such as a homemade type, with
ballscrews and THK ways...
Here are some pictures of the first job with the new servos: More pictures to come, as I have a stack of projects lined up, waiting to be machined...
11-01-2005, 11:39 PM
Linear Mode
