Alright, so the project is getting into full swing (or at least as full as I can find free time to work it, which isn't much). I'm trying to order the parts that I have confirmed I'll use, along with finishing up the mechanical design of a new anti-backlash saddle and designing a total of three electronics boards for the add-on features.
Now to the more exciting part. I've got the major electronics in a few days back. These include new stepper motors, drives, and a breakout board from Keling (now Automation Technologies), and a cheap switching power supply off Amazon (appears to be the same Chinese made power supply that everyone stocks).
I went with two new 185 in-oz 8 wire NEMA 23 steppers for the X and Y axis and a 270 in-oz 4 wire NEMA 23 stepper for the Z. From what limited info I've been able to find on the stock steppers, they appear to be in the range of 100 in-oz (bipolar). Sherline supplies 120 in-oz steppers (unipolars) with their factory kit, so I figured these guys should give me what I need and some room to spare. The Z-axis is always the one that drags due to lifting the weight of the motor and head, so the extra power here should help as well. The motors from Keling were very well priced, look good, and spin smoothly (far more smoothly by hand than the stock motors, which makes we wonder if the stock ones were less than 200 steps/rev). Can't wait to put them to use.
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New steppers from Keling. These came very well packed. |
Since the original electronics looks like they utilized the first integrated circuits ever created, I decided to upgrade, both to have something that I had some documentation (and know what motor specifications they could run), and to get some features such as microstepping and idle current reduction. The Keling KL-4030s got me all that for a good price (I originally was very interested in Keling's new digital drives, but alas, am on a budget). The drives have gotten good reviews (as has many of Keling's items) and look easy to wire up.
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New Keling KL-4030, one each for the three axes. |
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The not so modern motor controller they will be replacing... |
The last item from Automation Technologies/Keling was the C10 breakout board, which actually comes from CNC4PC. Research indicates it's a cheap and effective solution for getting the parallel port signals to the drives, with inputs and outputs to spare. Exactly what I need. No pictures just yet; I'm waiting to unwrap the packing until I'm ready to use it. I should be able to get my home switches, E-stop, reed switch (enclosure open switch), and spindle control signal through this guy.
My intent is to use the stock cables to get from the control box to the mill, which use D-sub connectors at the box interface (one DB9, one DB15). These are only partially filled with pins, but I was pleasantly surprised to cut away some of teh cable insulation and find the missing wires cut off just past the connector. With some addition D-Sub pins, I'll be able to make use of all the wires (all of which I think I'll need). Unfortunently, the connectors on the box are part of the main board I'm replacing, so I'll need to get new ones before I can use any of the new toys.
The final item to get up and running will be a 5V power supply for the breakout board. If you buy a kit from Keling, they give you a wall wart power supply to use. I wanted a solution tied to the main power supply for two reasons: one, to prevent having yet another cord and another connector to hook up, and two, to ensure the BOB is always powered when the stepper drives have power (there was a word of caution in the BOB manual about how an unpowered board could cause erroneous signals to get to the drives and cause unwanted behavior). I'm trying to finish up a simple power supply board to use (for an upcoming post).
Last item I got was a 36V/9.7A power supply from a seller off Amazon. Looks the same as the Keling one, only cheaper. Should provide all the power I need for both the steppers (3A max. per phase, but won't pull the full amount to my understanding), the breakout board (500 mA), and whatever other small add-ons I've got. Even though the mill currently has a nice unregulated power supply, it appears to be putting out something in the range of 40-48 volts, above what the KL-4030 drives are good for. While I considered upgrading the drives to something that could handle the voltage, it was actually cheaper to get this new power supply, and it'll let me save the transformer and rectifier for another project down the road.
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Cheapo power supply. |
Here's the rundown on the purchases thus far (and the hit to the budget).
Next up is to finish the electrical design so that parts can get ordered and the new motors can be put into action.