LightObject Z Table for the K40/EBAY Chinese lasers.
Editors Note: This ztable doesn’t actually fit in my particular Chinese laser, it is too tall… I’m seeing if they have shorter threaded rods available. my lasers gantry is about 93mm to clear, ztable is 105mm. le sigh….
Note 2: see bottom for updates.
I Picked up a motorised Z table from light objects for my Chinese cheapo laser cutter, it’d make it a lot more useful.
Of course first time I saw it, I didn’t pick It up and it was out of stock the next day, so a few months later I saw them back again and ordered one, arrived a few days later. First thing I noticed no instructions, but simple enough. A week or so later I got an email from them saying there might be a cable missing, I wasn’t sure it was meant to come with one but either way, they sent it out and got it a few days later, so good service there.
Of course I thought I had stepper drivers around, but didn’t so I went back to LO and bought the M415 driver. So put it together and waited for them to arrive.
After hooking up the motors and stepper to my frequency generator, I got nada, the motor wasn’t holding , stepping , buzzing or anything..
I probed the motor wires with an ohm meter and they were open circuit, so I prodded the pins on the motor and found the two coils, the cable was wired incorrectly.
I fed the info back to lightobject, who are a super nice place to deal with, just had to move two wires on the connector from position 1, to 2 and from 6 to 5.
I used the M415 driver, tried out a few speeds from 1khz to 16khz to see what gave the best results, 6khz seemed fine (16 steps) I also set the current of off/on/off or 1.05A measuring the power draw on my PSU it was about 0.4A which the datasheet for the motors its mean to be claim, the driver manual notes that the current on the coils might be less than you set, and it reduces the current by about 60% when idle. Though these might be different motors, they are not getting hot.
The Electronic Goldmine had a sale on miniswitches, I want to type mini microswitches, but that seems wrong, Stock # 61690B so I picked up a 100 or so they’re right angled pcb thru hole mount lever style, I wanted them for various things like cnc limit switches, so I’ll add them to this and see what happens
So then I needed something to drive it , poked through my dev board boxes and found a Cypress CY8CKIT-042 (as well as a stepper motor driver! ). It’s the PSOC4 Pioneer board
I did a quick test app
These are the pins I used.
If either of the switches are pressed, the table goes up and down, the limit switches will stop the current direction, but allow it to go the other way.
I set the PWM to period 32/16 count , that gave me just about 6khz
The pins I choose make the RGB LED on the board change colour when up/.down is selected
Pulse is wired to PUL on the m415 and Dir to DIR, common ground.
I could use the capsense to do a slider for the speed it moves at, but I think a fast/slow button set is easier.
Now all I have to do is mount the limit switches, and thenfit it into the laser
Remove the old bed is just four screws
and then remove these posts (and all the gunk)
One of the four posts on the z table gets in the way of the smoke extractor. so I removed the post, we’ll see what the effect of that is.
I haven’t decided how best to install it yet. I’ll update when I do.
The CY8CKIT is about $25, so instead I decided to make it for about $2
Decided to try to redo one of the old cylon boards to see if I can make a mini controller. The ATTIN2313A is a pretty neat chip. I modded my cylon to look like this, its got extra ports too. its about 2.6cm x 2.6cm
and a short while later (This is actually a rougher version I recut it)
With some rubout (potatocam)
Momentary pushes ( all my black ones were not working correctly, so I used two red) one easy way to wire up the limits is to use a microswitch with NC connections, normally closed vs NO normally open. Wire the limit in series with the switch, so when its engaged the control button won’t be able to close the circuit, so you can only use the down one.
The downside to doing that way, rather than using the microprocessors inputs is that its harder to override if for some reason you need too, but if you’ve got limited IO space, and makes the wiring simpler, plus don’t really have to worry about noise/debounce.
Mounted onto the driver. since it’s a double sided board and I only cut one side, the blue kynar is doing ground, I couldn’t route it single but I might drop one of the io’s and add a ground on the rear pins. The cap is 1uF 0805 it won’t work properly without this
And there we have it, now to mount it in the laser, the tedious part!
The wiring is really simple.
Two phases to the motor, 24Vish to the motor driver, common ground, 5V to the opto and the controller board. The switches are common ground, then to the controller board, pins 2 and 3, pulse and dir to the controller, 8 and 9.
Making the table shorter
The threaded rod is M6 x 1.0 pitch. So now I need a lathe, any excuse to buy tools right? So I did !
I figured I’d need some better measuring tools as I go along, so thread per inch measuring tool (doesn’t do metric aye aye aye ) mitutoyo gauges with SPC , very nice.
Since I also had gift cards lying around on amazon from bitcoin, I thought what the hell and bought one of those teen tiny lathes, its exactly what you’d expect it to be. I’m still deciding which real lathe to actually buy.
took the table apart
Marked the aluminium posts and cut them with a hacksaw, about 1 cm, to fit my laser.
Then I marked the area to remove from the threaded rods, hacksawed them down.
On one of these the brass gear was loose, so I popped it off and filled it with thread locker then put it back on , that held it.
Next measured how much to remove for the bearings, I used the brass parts as a marker.
Then I squared off the aluminium posts and drilled holes in the middle.
Now to see if it clears the gantry
I found it easier to remove the side bars while it was in the machine to get the threaded rods into the bearings
Poking around the laser for power, we need 18-24V, and 5V for the CPU.
This switch on the right has 5V, but if it’s a moshi board, there is an easier place.
This white connector with the four green, and red/black wires coming off the power supply, its marked 24V G 5V L , so that’s all we need.
The other side plugs into the moshi driver board.
Moshi marked it so bottom is gnd, 24v, 5v, L, I tapped into those by removing the pins and soldering to them. just pressing a pointed thing into the teeth and gently removing it. Solder the wires and then push the tooth out a little and snap it back in.
Next I drilled a couple of holes for the up/down switches.
And that’s more or less it, plugged in the stepper and tested it, all good.
I don’t have any tap/die sets so I didn’t tap the posts , and I wanted to keep the original setup, plus again more excuses to buy more tools.
Made sure it was all working before I started bolting it all down.
Laser is almost running again, the pump I bought from lowes to replace the original chinese one fell apart so have to fix that now.
I might make a change to the software so if you press up, hold it then press down it’ll go faster (or slower),, and vice a versa.