I'm having great difficulty in getting my black box to run my home built CNC machine successfully. My machine is a Root3 Lite with a bed size of 280mm x 280mm, belt driven using 20 tooth pulleys and Using GT2 belts. I am trying to get the movement correct as it is moving double the distance it should - ie. 10mm move from OB Control give a physical move of the machine of 20mm. I have tried through the Serial Console to alter the belt to the correct type - which is available in the dropdown, and changing the microstepping from 1/8th to 1/16th - which would give me the same steps/mm but with half the distance travelled. Try as I might, it will not allow me change the setting using the OB Control software. Worse is the fact that I don't seem to be able to use alternative software (UGS, Pronterface, grblPanel etc) now that I have had to install the Ftdi drivers for OB Control! A big downside for me. I find the OB Control software less than intuitive to use - it almost seems that you don't wish your Black Box to be used with anything other than your machines or software. Don't get me wrong, I think the Black Box solution is a big advance on the cheaper alternatives inasmuch as everything seems to be catered for, limits - probes - doors etc. However, that being said, I did think this was worth the extra to avoid any hassle when it comes to setting everything up. I would like to be able to have a 'blank' custom machine avaiable with all the options available via dropdowns so we can choose what we want, rather than the 'set' configurations available via OB. This, in its turn wold make the Black Box a much more attactive proposition any kind of machine, especially those that do not require the Ftdi Drivers. The almost complete lack of instructions on the build and setup was something that would leave the average hobbiest completely lost - this only made worse by the fact that technical support in any meaningful way is practically totally absent. I have relied on youtube and hours of reading though hundreds of posts trying to find answers to what are the most basic of queries - in fact I still do not know what Stepper drivers I am using, and I have looked - everywhere I can think of. Apart from all that, this box seems to work OK if I now do designs at half size so that I can at least get it to cut something out. Can anyone out there put me straight on how exactly one amends a OB standard grbl setup to allow my machine to work correctly using the Black Box - or even better if someone knows if this box can be used (without the Ftdi Drivers) on more user freindly software. Would also like to know a lot more about the 'Brains' and 'Muscle' of this board.
Totally acceptable, just remember to hit RESET so the firmware boots up with the new setting -see github.com/gnea/grbl/wiki for any additional info Uhm, no that would not be it. Drivers just make the O/S talk to hardware - read What is a Device Driver? (; I think you simply forgot to Disconnect in CONTROL before trying one of the others. Only one application at a time can connect to a serialport. And no thats not CONTROL or the FTDI driver's fault, thats how Operating Systems work! On Windows, the serial port HANDLE must be obtained in exclusive mode. That means just 1 application can hold a serial port at time. So disconnect from one when you want to use another. Nope! It can work with any Grbl 1.1 compatible host! You do: The profiles just pre-populate the settings inputs with the values for our bundles. If you don't have our machines, simply scroll past it and use the form to fill in YOUR settings. If you do just make sure you set $4=1 - thats only one BlackBox cares about FTDI driver is just a USB to serial chip, used on thousands on boards, not just BlackBox. Without it you wont be able to connect to any of them. See FTDI Drivers Did you checkout https://docs.openbuilds.com Did you email http://support.openbuilds.com/support/home or post here on the forum with your issues? Usually replies come within minutes (; TB67S109s but who cares (; thats all taken care of for you Just set your correct steps per mm: 3 ways to do it Option 1: OpenBuilds CONTROL > Grbl settings tab > Scroll down to $100-102 and change the values in the textboxes, hit SAVE, then click Reset Option 2: Use the Serial console and standard Grbl Commands (See github.com/gnea/grbl/wiki) just dont forget to reset so they take effect Option 3: Use the Calibration Wizards in OpenBuilds CONTROL -> Tools and Wizards button at the top Shoot with questions, or peruse docs.openbuilds.com and also the files provided on BlackBox - click files and drawings tab near the top for the FULL schematic (; Scroll down and fill in your settings:
Understand a little better now, but still cannot set the motors stepping rates to how I would like them. Seems like there are no jumpers like most boards to set stepping rates? Am trying to get 1/16th stepping using GT2 2mm belt - but however I try (including resets) I always get 20mm movement when asking for only 10mm, I have to reduce the steps/mm to 40 to get the correct movement. Anything lower than 1/16th stepping makes the Y motors sound like a tractor pushing them. X & Z sound fine. Also never realised that OBControl stays 'live' hidden away from view on the taskbar even when closed, hence comments about inability with using alternatives to OB Control.
We default it to 1/8th because that gives users the absolute best performance That is also decribed in detail on the Documentation along with instruction for changing it (which we dont recommend. Stick to 1/8th and calculate steps per mm accordingly or use the tools provided) OpenBuilds BlackBox 4X Documentation Ps: the term is Microstepping. Stepping rate would be something different, thus initially confusing Probably more a case of incorrectly adjusted current. See OpenBuilds BlackBox 4X Documentation As the others sounds fine proving that it shouldnt. Or incorrectly wired. Dual motors? Use the Y2 slave axis for the second one Right click, quit on the system tray icon. It stays open to integrate with a variety of cam solutions in the works.
Sorry I dont understand? You can fit whatever belt you want as long as you have the correct pulleys...
In grbl settings there is a dropdown for steps/mm calculation, I can't select the correct belt and make it 'stick' - it always goes back to the GT3 belt.
Better description ok will check that for you. Of course you can still just type a steps per mm in, or use the Calibration tools under Wizards and Tools
GIF (animated) screen recording below: Works 100% for me man, just try again... (or post some more details, screenshots, screen recording etc) (or wait, are you thinking that when you click it again later it will show whatever you had last selected?! It wont its just a CALCULATOR to determine the steps per mm value for you! Each time you launch the calculator it will be on defaults. All it is is a utility to help you calculate your theorical steps per mm. Theres no reason to save what you have, all that matters is the "steps per mm" man, that DOES get saved to Grbl - none of these settings are stored on your PC it gets sent to Grbl and stored there, you can view them with "$$" - read the Grbl Wiki at github.com/gnea/grbl)
Yes, I can now understand that better, the options 'drop downs' being part of a calculator function - but at least I am now getting the right amount of movement that I should be expecting which is a great advance for me. Many thanks for that. On another front, you said earlier that you don't recommend changing the standard 1/8th stepping on the bottom of the board - is there any particular reason for this, or is it that you maybe wouldn't like people taking a soldering iron to the board? I only ask as my particular machine sounds like a tractor when making moves along the Y axis, due (I think) to the the low rate of steps/mm I am now using (40steps/mm). X and Z axis movements are almost silent in comparison with the Y - maybe because I have dual Y motors, the only axis on my machine that does have two steppers, and that's why it sounds so different. To be honest, and having thought about it while sitting writing this, it wouldnt be too difficult to bring the solder pads out to a seperate small board with header pins on where one could change the microstepping easily? Many thanks Peter for both your advice and patience - and I apologise for what could be construed as a somewhat abrasive opening to this saga from me. I just felt so disappointed having spent £150 on a product (which I had to assemble) with little other than a 90 mph video to follow by way of instructional material. And there were areas in which I really had to dig hard to find out how this thing could be made to meet my requirements. Once again, apologies for that. I now have a somewhat better understanding.... Kind regards...
Pleasure! No need for it on a CNC, higher microstepping lowers torque. On CNCs you want Torque. Microstepping is falsely believed to increase resolution (misinformation from the reprap community) but thats not true either. (Microstepping was invented to smooth our rough motion, but too much of a good thing causes torque loss and artifacts) Again, no reason too. Thousands of blackboxes purring along happily at 1/8th Well now you know where the forum is and were we reply really fast, so you should be good. Do yourself a favour though and go read all of github.com/gnea/grbl/wiki and docs.openbuilds.com Everything is nicely documented (including why 1/8th microstepping is best, its on docs.openbuilds.com under section 2.2.2: OpenBuilds BlackBox 4X Documentation
I have built a 5ft x 10ft (workable area) router table to v-groove 1/2" PP Plastic sheets. I am using a Blackbox and am very happy with it so far. I have gone into settings and under (select) machine and according to a video I watched I should be able to scroll down and find "custom" settings or something like that. For some reason "custom" is not an option that I can find. What am I doing wrong?
Don’t worry about custom. Scroll down and do your thing. Just make sure to set $4=1 or the drivers wont enable, and we recommend $1=255 just to avoid machine loosing position. Refer to github.com/gnea/grbl/wiki for all the documentation on Grbl Settings custom is currently not in the list (should be, will fix in a future version) but all it did was set $4=1 and $1=255. The rest was all up to you
It is requiring me to select a machine. Sounds like I can simply select any machine and then customize the settings. Thanks
You dont have to select a machine but you can, all the dropdown does is throw some default values down into the inputs
Okay, thanks. You and I are going to become best friends. Only kidding. I will do my homework before I bother you. Regards
Just did a search of forums for "enabling blackbox limit switches" and "limit switches" came back with zero on the first search and 1 relevant on the second. I must not be searching correctly because this happens to me a lot. I searched high and low for a function key in both "Control" and "G Code Generator' to enable the limit switches I have just installed on my X and Z axis to no avail. The diode lights up when triggered but no alarm and I can continue to jog after switch is activated. I sure don't want to bother you for every little thing like this so if you could be me better direction with my search for information I would appreciate it. Very frustrating when I do a search for a common issue like this and get zero hits. I feel like I am in the twilight zone. Thanks
Take a couple hours and read all of github.com/gnea/grbl/wiki - yes even the pages that seem irrelevant. Understanding Grbl is a key to understanding all this. All CONTROL and other hosts do, is interface with Grbl. Show you what it says, and send your files and commands to it. The rest is all up to grbl. So have a read through the wiki. In the Configuration pages you'll find into about Hard Limits. On the FAQ page theres a lengthy section about Homing etc Enabling switches is easy (Grbl settings, Limit Switches installed to the right of the machine selection. Or scroll down to $20s (couple related settings) but read the wiki to understand them too
Not sure if I should continue here or start a new thread but here is my update. Limit switches installed and functioning well on X and Z axis. Ordered more switches for Y. I am calibrating X and have gotten it pretty close. Here is my issue. I am finding just over .002 backlash when I change direction. That seems extreme to me. This is not a conventional build. 5ft X 10ft (usable) router table. I am using #25 roller chain instead of belt and pinion or rack and pinion. The chain is totally adjustable and tight as a guitar string. I have no binding or slop. I am using a nema 23 with a 47:1 gearbox to drive my X axis. When I jog the stepper it moves immediately but when I put a dial indicator on it shows my eyes are not as good as they use to be. I am also finding when I jog the axis back to zero after a 1" run it falls short by over .005. Not sure if I can fix this or need to change my drive system. Now is the time to make the change if I need to. I have big plans for this table. Thanks
Use dial indicator to check breakdown of mech components. Slop in chain over sprocket, sprocket to motor shaft, etc
Depending on the setup (type, price) of the reduction gear, 2-5 thou lash is probably to be expected. A wheel rocks on a worm (just look at machining rotary tables), inexpensive planetaries have some internal wiggle too. Higher-grade planetaries can get exremely low lash levels, but expect to pay low-mid three figures. Obviously for essentially-zero, you have to go to harmonic drive for high three figures (mid for used). You can get whatever lash level you want, but you'll pay accordingly. A simpler solution is to use a controller that allows for backlash compensation. Mach 3/4, LinuxCNC, whatever. You should still understand the entire grbl wiki before trying to use either of them, though. CNC is CNC.
Thanks Rob, After studying my setup I think you are correct. It may very well be in the gearbox. I can always switch to a Nema 23 without a gearbox but thought the gear reduction would help since this is such a large machine. 5ft X 10ft (usable) router table. I will be v-grooving 1/2" thick polypropylene sheets. After all of this I just found out yesterday that Mach 4 does work with the Blackbox I have purchased. I guess my obvious question is: Does the Openbuilds Controller have a backlash compensation function? I watched a Youtube where another software program had a simple function that basically allowed the computer figure out what the backlash is by using a digital dial indicator. I am thinking this type of function could also be useful in calibrating all of the axis. Your thoughts? Thanks again.
Well I did some more research and found out Openbuilds does not have a backlash function. I guess I am in the market for a powerful Nema 23 stepper. Any recommendations? Speed is not an issue for me. Accuracy and material removal is the key to this project. Thanks
Is there a list of Blackbox compatible programs. I searched the forums and found very little info on the subject. Better yet, what basic software seems to have the most happy users. I hate to switch out my stepper motors only to find out a free software program would allow me to do a backlash compensation peoceedure. Thanks
As it runs Grbl, ANY grbl compatible software will do List of more popular ones here though docs:software:overview [OpenBuilds Documentation] Software based compensation is a hot topic, some for, some against. I say build the machine right... Compensation is "cheaping out" and unreliable
BlackBox is an Arduino Uno, 4 stepper drivers, a relay or two and a bit of extra IO with some handy plugs all wrapped up in a pretty enclosure. It's worth the price for the specs vs buying separate components, but you have to know its use case and limitations as well. grbl is a motion control firmware that, primarily, runs on Arduino Uno. It requires a PC host to drip feed it G-code because the microcontroller doesn't have the capacity to manage its look-ahead queue whilst also processing it. It has many missing features that ideologically are devolved to the host PC software ("sender"). Whether a specific sender has any particular set of features or not is up to the person who writes it. Peter has a specific set of design ideals for OpenBuilds CONTROL, primarily simplification for new users which is what OpenBuilds is all about. I use bCNC for more power and control, as do several other people here. There are a few other options too. I don't think any of them have backlash compensation, though, because that's better happening at the acceleration-planning level, which can take into account the system's maximum pulse speed (the backlash comp adjustment has to happen at a much higher speed than a regular motion in order to stay synchronised with the other axes) and other variables to yank the machine into place as necessary, independent of what the G-code is telling it to do. That's typically the domain of high-speed stepgens occurring in higher-grade PC-based control software where the processor or (in some cases, including one of mine) an external dedicated FPGA chip is doing even higher-speed independent processing without the GUI/network/IO overhead of the PC OS. I assume Mach3/4 have some kind of backlash comp, maybe in the plugins, I'm not sure- the ecosystem always seems like kind of a mess, so I generally avoid looking at it. LinuxCNC provides very simple backlash comp, you plug it right into the wizard when you're setting up and calibrating the machine. All you technically need is a cheap parallel breakout board (and a parallel port, of course) to use LinuxCNC at its most basic- you could wire the drivers in the Muscle side of the BlackBox right into the board and start controlling it directly from the PC. Drivers just need step, direction and enable (sometimes) signals. That's it. That said, Peter's right about building the lash out of the machine- to an extent. Every mechanical system has lash in it, in order to function. No matter how expensive the gear mechanism is, it'll have some element of lash in it. That's what you need to take out in software- and even expensive CNC mills with high-end controllers like Fanuc and Heidenhein have backlash comp. The point is to mechanically reduce it to a point where software adjustment isn't going to cause problems. I don't really understand the project though, so I can't offer much specific advice on more powerful steppers other than "just get a NEMA 34".
Wow, thanks for all of your time. As far as my project, I am v-grooving (not all the way through) 1/2" thick polypropylene sheets (4ft X 8ft), heating the remaining material that was not removed during the v-grooving and forming the sheets into a somewhat rectangular shape over a wooden mold. Pretty simple and after rethinking this project I should have built a manual router table with jigs to hold my tolerances. What I am doing is not rocket science but each bend MUST be exact and repeatable CNC seemed like the way to go. I had no idea I needed to learn so much to do something so simple. Since all of my machining for this project will be straight lines I am thinking backlash may not be so much of an issue if I simply travel in one direction to the next cut without backing up. My X axis can simply run off the material before returning to it's original starting point so backlash won't matter. I am truly mystified that backlash isn't a consideration in everything CNC except maybe some laboratory grade machines but it is what it is. Thanks again for your time. BTW I am a fellow veteran. Regards Larry
