Component Testing and Box Wiring (Part 1)

Not long after I had the holes drilled in the enclosure for everything, I bolted everything down excitedly, wired up the power supply, plugged it in and... nothing. The LED would not light, and checks with a multimeter indicated that there was no DC power coming from the output terminals. After dissassembly of everything and using a different power cord with similar results, I opened up the power supply (brand was AGT, for 'Advanced German Technology', looks like a Meanwell clone). I didn't see anything obvious (busted capactitors, burned resistors, etc), so bolted it back together with no success. I will say that these switched power supplies are not simple for the non-electronics type, and I suspect troubleshooting would be a pain.

This was a little over a year from when I originally bought it, and sure enough, long past a return period (though it probably would have been more trouble than it was worse). I sucked it up and bought a new Mean Well branded supply off Ebay, and when it arrived, went straight to checking it with an old cord I had cut up for this purpose.

LED Lit! Success! A Working Power Supply!

My original plan was to reuse some of the D-Sub connectors and wiring that came with the machine, but I decided it was going to be a pain to get these rewired and I wanted to use shielded wiring for the motors to limit interference into the limit switch cables. I really liked the GX16 style connector (4-pin) that is available on many of the hobbyist CNC suppliers, but they often ran $4 to $6 per connector... to pricy for me. I found I could get 10 for a little over $10 on Ebay, so went ahead and order some up.

I decided to use five connectors on the control box, and five connectors on the machine. For each side they would be:

• X Stepper Motor (using bipolar wiring, so only four wires needed)
• Y Stepper Motor
• Z Stepper Motor
• Emergency Stop (this uses two wires, leaving two left over if I ever wanted to add spindle speed control)
• Limit Switches (common power, one line for each axis)

The only fuses I was reusing in the control box were the main fuse and the spindle fuse, so the remaining fuse holes were good spots for additional connectors. To go along with these three locations I added two more nearby. Unfortunately, the fuse holder cutouts were too small, so I had to enlarge them (the GX16 connectors require a through hole for an M16 thread, or a hair bigger than 5/8". I removed everything from the control box to avoid chips in the electronics and drilled them out with a step bit, which work very well in thin metal like this. Since this is not a tool I use often, I picked up the bit at Harbor Freight for cheap.

Step Bit Used To Drill Connector Holes

Connector Holes Drilled

 With that, the box was cleaned back up to get rid of any chips or shavings that wouldn't agree with the electronics, and reassembly began.

First up, putting the wiring back in. I wired from the incoming outlet to the existing switch, then to the main fuse (I will try to find a good way to document the wiring if someone requests it). From here, power was split between the 36V power supply, the 5V power supply, the case fan, which runs on 120VAC, and the spindle fuse. The spindle power runs through the existing solid state relay, then over into the spindle outlet to go to the machine. Wire colors for the AC portions follow US wiring colors, with yellow or green as ground, white as neutral, and black as hot. Don't forget to ground everything.

The open fork connectors below go to the main power supply. The unconnected spade terminals are for the 5VDC supply, and the ring terminals go to the ground point, which I attached right near where the 5VDC supply goes.

AC Power Distribution Wiring In Place

Rechecking the Power Supply Again

Stepper Drives In Place

Next update I will cover the rest of the wiring.

Enclosure and Power Supply For Spectralight Mill

With my new electronics in hand, I wanted to reuse the old enclosure for a few reasons. First, it was setup with proper plugs for the spindle, along with fuses and a fan in there already. It has graphics for 'spectraLIGHT' on the front. And lastly, turns out enclosures aren't particularly cheap, so best to reuse and save the cash.

I took out the old control board and the power supply, but kept the fuse holders and the solid state relay for the spindle. I then rough mapped out where I wanted the components: main power supply in the front corner, stepper drivers across the center, and the C10 breakout board at the back, positioned such that the port would attach right where the 'MACHINE' decal was, which got it close enough to center to have good wiring access.

Rough Layout of Enclosure Box

To get the DB25 (printer/parallel) port on the C10 board out the back, I had to increase the size of the existing cutout. A little Google searching led to these dimensions for a DB25 port from cabledepot.com:

DB25 Cutout Dimensions

I rigged this up on my mill and cut in the new port. This could easily be expanded with a Dremel tool or similar for those without a mill that has enough Z travel to fit the box.

Milling Enlarged DB25 Opening

After that was some CAD work to punch in new holes for the drives, power supply, and breakout board. I've attached the hole pattern in an image below in case someone wants to use this as a starting point. I stress this was based off rough measurements, and some adjustment was required, especially with the breakout board (had to slot the holes slightly to get it to fit, so please verify on your own. This fits the KL-4030 stepper drives pretty well (a little tight), such that the flats of the nut hit the sides so you do not need to get a wrench in there. All these holes were punched in on the mill as well.

Enclosure Hole Pattern

Link to the higher resolution .pdf: PDF of Bolt Pattern

The documentation on the C10 board from cnc4pc (see here) states that the board should always be powered up if the computer is, due to risk of interference causing unintended movement. Instead of having a separate power supply to worry about or running another cable from the PC, I wanted to run a small power supply off of the same power switch as the main, such that they both turned on at the same time. The C10 requires 5 VDC at 400 mA. I've had several Android phones over the years, so pulled out an old charger to see it fit the bill. Sure enough, most that I found give 5VDC at over 400 mA, so I busted one open to see if I could adopt it here.

Here's what I'm talking about. This is a different charger but I've lose the image of what the charger looked like originally. I suspect almost any cell phone charger will do, as long as it has enough output capacity. All the phones I've got have a USB output.

Phone Charger Similar To That Used For 5VDC Supply

To mount it, I grabbed a couple of Nylon spacers from Home Depot and tapped the ends for a 10-32 screw. I roughed up the other ends with some coarse sandpaper and then used JB Weld epoxy to attach them to the bottom of the board (I did a little research, didn't seem to be a standout solution for bonding Nylon. The JB Weld is working for me, but is probably pretty fragile, so I handled it with care. JB Weld is non conductive.). Not a lot of room there due to the components, so it didn't come out looking very fancy.

Spacers For 5V Power Supply

 

5VDC Power Supply Board With Spacers In Its Proposed Location

 I soldered on some wire to the two line power contacts with some quick contacts at the ends. On the charger I used, along with my others, the plug does not appear polarized, so I don't think you need to worry too much about figuring out which contact is hot and which is neutral.

5VDC Power Supply With Wires and Supports Attached

In the next post I'll talk about why it's important to try you equipment when you receive it.

First Parts Unboxed!

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.

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.

New Keling KL-4030, one each for the three axes.

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.

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.