Need advice on Paxton/Patterson Sherline 5400 Mill with Microkinetics Controller
I recently picked up an older model Sherline 5400 CNC Mill at a local school auction (for what may or may not be a good price) and could use some advice on getting it up and running. According to the auction and the VHS training tapes that came with the CNC, it was sold to the school by Paxton/Patterson to train the kids on using a CNC machine and was used almost exclusively for milling jeweler's wax, acrylic, and other simple projects. However, the enclosure looks like the Microkinetics Desktop Mill (http://microkinetics.com/cncmill.htm) rather than the Paxton/Patterson version. The mill came with 83 oz-in steppers installed on the x and y axis, a 112 oz-in stepper on the z axis, a Microkinetics Mighty Drive controller, an ancient Pentium 266 computer with an Optidrive Plus PC card installed in it, and a few accessories, endmills, and textbook manuals.
From what I've read online and in this group, it appears that the Optidrive card is only compatible with the Microkinetics software and it looks like it's old enough hardware that it won't work with (or fit inside) the low profile Dell Optiplex 740 I was planning to use to control the machine (using either Mach3, EMC2/LinuxCNC, or some other CNC control software). I read in some previous posts that it's possible to rewire a DB25 cable to connect the Mighty Drive to a standard LPT port, but does this modification still allow for the limit switches to work or not?
My plan is to use the mill to machine materials like plastic, jeweler's wax, aluminum, brass, copper, printed circuit boards, and possibly mild steel, but I'm not sure if the stepper motors have enough torque to them. I know the ideal solution would be to just replace the stepper motors with something in at least the 150-300 oz-in range and the controller with a Gecko G540, but I'd like to see how well the machine performs as is before spending $600+ on new electronics.
So the ultimate question is whether the cable modification will work well enough to allow for me to use the machine with the current steppers and controller or do I save up the cash for either a G540 or something nearly as good, but cheaper? Also, how big of stepper motors can the Mighty Drive control?
Lastly, does anyone know where I can pick up a used rotary table that I can attach a stepper motor to for a decent price to add a 4th axis to the machine?
Any help you guys can give will be greatly appreciated.
- from http://www.cnczone.com/forums/benchtop_machines/19359-cncmill_paxton_patterson_workable.html
No, you want to leave the microkinetics pin 25 floating - as in your quoted text above. Hooking +5 straight to your port is generally a bad idea.
Let me write up a harness list for you:
PC DB 25 uKinetics DB 25
The PC parallel port itself is pretty simple. Pins 18-25 are all grounds. Pin 2-9 are output, pins 10,11,12,13,15 are input, pins 1,14,16,17 are either input or output. If you can get a good magnifying glass on the connector then you should be able to see the pin numbers.
You should have had something at least respond if not move before when you were messing with fkeybit and TurboCNC at the prompt. You may want to have an electronics type at your school set up a signal injector for TTL logic and verify that the stepper drives actually move when they're commanded to. It would be no fun to discover that they don't work after all this effort - IMHO things do tend to get set aside for a reason so this is a definite possibility...
And the complete pinout of the microkinetics:
1. Don't use a standard 25 pin to 25 pin cable: This is because the
OptiDriver is designed to connect to another MicroKinetics card (the
OptiStep) that isn't really necessary. Pin 25 on the driver card is +5V.
You'll ground that to your PC, blowing the 3A fuse in the power supply
(ask me how I know!!) If you can find an OptiStep card, you can use the
additional features it provides: things like limit switch inputs for the
axes. If all you want to do is turn on a stepper motor and move the
axis, it will work with just these pins.
2. To connect this controller to a conventional printer port for use
with TurboCNC the pinout is
MicroKinetics DB-25 Description and Pin # (note offset of 1 pin) to PC
1 MOTOR #1 DIRECTION to: LPT 2 Direction
2 MOTOR #1 CLOCK LPT 3 Step
3 MOTOR #2 DIRECTION LPT 4 Direction
4 MOTOR #2 CLOCK LPT 5 Step
5 MOTOR #3 DIRECTION LPT 6 Direction
6 MOTOR #3 CLOCK LPT 7 Step
7 MOTOR #4 DIRECTION
8 MOTOR #4 CLOCK
9 CURRENT 0
10 CURRENT 1
11 OUTPUT 1
12 OUTPUT 2
13 OUTPUT 3
14 MOTOR #1 NEG LIMIT INPUT
15 MOTOR #1 POS LIMIT INPUT
16 MOTOR #2 NEG LIMIT INPUT
17 MOTOR #2 POS LIMIT INPUT
18 MOTOR #3 NEG LIMIT INPUT
19 MOTOR #3 POS LIMIT INPUT
20 SHIELD INPUT
21 MOTOR #4 NEG LIMIT INPUT
22 MOTOR #4 POS LIMIT INPUT
23 EXTERNAL GND
24 OUTPUT 4
25 EXTERNAL +5 VOLTS DC
* * * * * * * *