Both designs seem to have somewhat arcane interfaces, which may be fine for manual controls but are a pain for CNC interfacing. The KBWT unit analog input controls are at -100 VDC!
Hi Roger, I was going to defer to your superior electronics training & keep my mouth (keyboard) shut but I have to voice my opinion. I know my electronics knowledge is sadly lacking but I do read about this stuff & have been able to make my hacked-together stuff work pretty well. I just don’t want someone down the road to stumble onto this thread searching for spindle drive info, take your statement as gospel & go away misinformed.
I have never owned or used a KBWT-26 but just couldn’t believe that KB would make a drive has a “somewhat arcane interface” that is “a pain for CNC interfacing.” I took the trouble of Googling the drive’s manual & found the following:
“Signal Input: The drive can be operated with a 5 kΩ Main Speed Potentiometer (supplied), an isolated 0 – 5 Volt DC analog signal, or an isolated Pulse Width Modulated (PWM) signal from a microprocessor.” To me that doesn’t sound like a pain. Granted, one does have to observe the “isolated” instruction without fail. Don’t ask me how I know! “Note: If an isolated signal is not available, an optional signal isolator must be installed (KBSI-240D or equivalent).” I picked up 1 of these on ebay for $30 and solved my isolation problem.
As to the old school KB SCR drive’s propensity to “make the motor hot if the motor is not designed for them” both the minilathe’s drive & the treadmill motor’s MC-68 drive are both SCR types so the motors will be fine as far as heating is concerned.
I hope I don’t come across as argumentative; just trying to be factual. I was wrestling with the exact issues as the OP with my ORAC conversion a few years ago & the KBCC-125R was suggested to me and was an immediate revelation. When necessary, the lathe can be spinning a 6” 4-jaw at full chat in one direction, receive an M5 command & the KB quickly & smoothly brakes the motor to a stop, receives M4 command, relay clicks, motor reverses & smoothly accelerates to the set speed, all in a couple seconds. I had asked around and was struggling with relays & a big resistor trying to do it myself. When I stumbled onto the KB, the problem was solved & I was able to get onto the next thing on the list.
Granted, you fellows with solid electronics knowledge can design the circuitry needed to do the same thing using the OP’s MC-68 but I was just trying to provide an easier alternative.
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