Laos MainBoard (re) design for buildlog interface
first of all, congratulations for the project! So nice to find an open hardware project about laser cutters!
I'm an italian guy currently working on the idea of building my own laser cutter, based on the buildlog project / design (buildlog) , but I would like to use LaosLaser as controller, abandoning MACH3 / EMC2 and the parallel interface in favor of the LaosLaser software configuration. So I would like to make my own design of Laos Mainboard, which of course will be shared to the community, in order to have an alternative controller board for the buildlog cutter, laos compatible, with some more features available (for instance, adding a fan for additional cooling for the pololu drivers, using different connectors, and so on).
I compared the Laos MainBoard schematic (v04) and the buildlog Laser interface PCB (here) and in my opinion there should be no problems for driving a buildlog laser cutter with the laos mainboard, apart a little doubt. So the reasons why I'm writing this post are the following:
- 1) The "little doubt": I identified all the connections between the controller board and the laser cutter on both schematics, the only doubt I have is about the laser PSU. The buildlog board uses 4 pins + power (connector J4) for connecting to Laser PSU: Enable High, Enable Low, Water SW and Input (Power level): on the Laos board it seems I have to use J37 and J39 connectors (Laser EN / Laser PWM, Laser ON and Exhaust EN). But currently I don't know exactly which laser PSU I will buy (maybe this one - lightobject ) , so the question is: can the LaosBoard drive "any" laser PSU, or only certain kinds? Does the laos have enough & proper connections for acting as buildog's J4 connector?
- 2) Improvements! If anybody has any suggestion for a "v04b" version, they're well welcome! I was thinking about using screw connectors - at least for motors - adding the fan for the steppers as written before and as in buildlog board, and maybe of getting rid of the CANbus (to be honest I didn't get what it does :) ) if I need extra I/O pins for other things such as laserPSU control (see above). I also would like to have a spare UART, like for BT interface. Any thoughts about these ideas?
- 3) dimensions: are there any dimensionals constraints which are needed for the current LaosLaser use in the compatible machines, if I want to shape differently the controller board?
I think that's all for now, as soon as possible I'll post more details about the board design.
Thanks to anyone who can help, bye!
I think there is no reason at all to redesign our board if you want to use it with a buildlog machine. In fact, the buildlog machine was one of our "ideal machines" when we designed the board!
I would recommend you use our board, as it is. It is still very flexible. And all the features you mention are already in there, it's just that we didn't document them that well.
Some thing you might want to think about: Do you really want Pololu drivers? You can also use Gecko drivers or other (bigger) drivers that are cooled and stronger. Our board supports these as well. I would recommend that any time, if it fits your budget.
To answer your questions:
We use "laser on" and "laser pwm" at the moment. You can connect laser enable to your lid switch, so that if you open the lid, the laser goes off.
At the moment, we do not switch water or ventilation in software. But I know some people are working on an extension/relay board for that. Maybe you beat them to it, it's not very difficult. But simple on/off switches will also do.
There's a minor bug in the current mainboard which you need to fix with a solder joint. Other then that, the board fits our current needs. Screw connectors fit on the board already!
You can just use regular 5.08 spaced phoenix connectors.
The current size is simular to that of boards found in most chinese lasers. The board cannot be smaller then it is now, unless you limit the number of (big phoenix) connectors you can place on it.
I can send you a PCB, holding it in your hands might make it much easier to see if it fits your needs.
thanks so much for your reply: nice to hear that buildlog machine is in the "compatibility list" :) !
I know that laos board is flexible and (at least if I got everything correct) suits my needs, the idea to redesign it is just something fun for me, and hopefully useful for others.
I see where I'll get, at least it is a good way to fully understand the electronics behind the laser. In this moment I just made a placement of the components, using some different connectors as written in my first post, see the attached pdf. Of course ANY comment is welcome.
Regarding your reply:
- drivers: I would like to use polulu instead of geckos in order to keep the cost as low as possible. From what I saw there is a huge price difference between the 2. And buildlog's board uses them, so.. I'd like to try. Do you see any contraindication?
- ok for water / ventilation switch, thanks
- I saw the HW bug description, and as you can see from the placement pdf I changed the (intended to be used) connectors.
- for the dimensions currently my design (not definitive at all) is 139x99mm , which I think is my lower limit. Good to hear I can go a bit bigger if needed. One thing I took away from the board is the 4th stepper driver circuit, being useless to me / buildlog's design.
Just a note, and sorry for asking again but I didn't find anything about it: the CAN bus, what is it needed for? Is it in use in the current software?
Thanks also for offering to send the pcb, but right now I'm just thinkering about this... later I'll decide what to do, and if needed I'll buy the board from the webshop.
CAN is the industry standard's Swiss Army Knife, it can do anything from driving servo's to switch relays (for water and ventilation). We don't use it yet, but implementing CAN-attached servo motors is one of the things on the todo list. You could use it to switch water and ventilation, but there are many other ways to do that, too, so you could also decide not to have it on your board. Also the USB connector is not in use yet, but I think someone will one day write a USB-attached driver (we now use ethernet).