#MT47 

***READ ME*** ***Olivier's drawings are now available to purchase*** See my video description for more details - click SHOW MORE to expand the description. Updated 4 April 2022...... I managed to get the limit switch functioning correctly. I set $21=1 as suggested by John Smith and it works. I now have limit switches fixed to all 3 axis and the homing function works a treat. I decided to wire the switches as Normally Open (NO). On each axis I have switches on both ends, wired into the controller in parallel. I think there is an argument to wire them as Normally Closed (NC), but this will suffice for the moment. Cheers Andrew Original post...... I'm not sure why the software isn't taking action when limit switches close. Maybe it's a grbl setting? I think I might have to enable soft and hard limits? More research needed! These are the grbl settings in the controller: [14:08:47] [ $$ ] $0=10 ;Step pulse time, microseconds [14:08:47] [ $$ ] $1=255 ;Step idle delay, milliseconds [14:08:47] [ $$ ] $2=0 ;Step pulse invert, mask [14:08:47] [ $$ ] $3=0 ;Step direction invert, mask [14:08:47] [ $$ ] $4=1 ;Invert step enable pin, boolean [14:08:47] [ $$ ] $5=0 ;Invert limit pins, boolean [14:08:47] [ $$ ] $6=0 ;Invert probe pin, boolean [14:08:47] [ $$ ] $10=1 ;Status report options, mask [14:08:47] [ $$ ] $11=0.010 ;Junction deviation, millimeters [14:08:47] [ $$ ] $12=0.002 ;Arc tolerance, millimeters [14:08:47] [ $$ ] $13=0 ;Report in inches, boolean [14:08:47] [ $$ ] $20=0 ;Soft limits enable, boolean [14:08:47] [ $$ ] $21=0 ;Hard limits enable, boolean [14:08:47] [ $$ ] $22=0 ;Homing cycle enable, boolean [14:08:47] [ $$ ] $23=0 ;Homing direction invert, mask [14:08:47] [ $$ ] $24=25.000 ;Homing locate feed rate, mm/min [14:08:47] [ $$ ] $25=500.000 ;Homing search seek rate, mm/min [14:08:47] [ $$ ] $26=250 ;Homing switch debounce delay, milliseconds [14:08:47] [ $$ ] $27=1.000 ;Homing switch pull-off distance, millimeters [14:08:47] [ $$ ] $30=1000 ;Maximum spindle speed, RPM [14:08:47] [ $$ ] $31=0 ;Minimum spindle speed, RPM [14:08:47] [ $$ ] $32=0 ;Laser-mode enable, boolean [14:08:47] [ $$ ] $100=250.000 ;X-axis steps per millimeter [14:08:47] [ $$ ] $101=250.000 ;Y-axis steps per millimeter [14:08:47] [ $$ ] $102=250.000 ;Z-axis steps per millimeter [14:08:47] [ $$ ] $110=500.000 ;X-axis maximum rate, mm/min [14:08:47] [ $$ ] $111=500.000 ;Y-axis maximum rate, mm/min [14:08:47] [ $$ ] $112=500.000 ;Z-axis maximum rate, mm/min [14:08:47] [ $$ ] $120=10.000 ;X-axis acceleration, mm/sec^2 [14:08:47] [ $$ ] $121=10.000 ;Y-axis acceleration, mm/sec^2 [14:08:47] [ $$ ] $122=10.000 ;Z-axis acceleration, mm/sec^2 [14:08:47] [ $$ ] $130=200.000 ;X-axis maximum travel, millimeters [14:08:47] [ $$ ] $131=200.000 ;Y-axis maximum travel, millimeters [14:08:47] [ $$ ] $132=200.000 ;Z-axis maximum travel, millimeters

Many many years ago I was involved with a similar type of project on a Gilson robotic system. I still remember the feeling of triumph and the yell of success when the machine actually moved for the first time. Great work.

I enjoyed the video very much, especially your dialog detailing concerns, opinions, and and discussions with Olivier.

Well it's looking good, the real fun bit has begun.

Looking Great Andrew. Stay Warm. Regards from Australia.

Limit switches should be wired in series to normally closed. If a switch fails or the limit is reached the motors halt.

Wow, that's come together quickly! Well done, and thanks for another entertaining video. 👍

Thanks for the video Andrew. I’m sure you will get the switches figured out. Coming along great. Cheers

Really a great Job Andrew! Machining is Your home territory but electronics like this,.. no the same much. Watching Tour video, hearing Your calm voice, I take my hat off for You. Facing so much new, unknown, You're doing an incredible job. A novell of comments below.. Oh. Things look rather difficult to me, in my eyes. I've built a CNC based on ready mechanics and Arduino stuff and it works well but it remains to create a dust repelling housing.... Time 07:20. Well done Andrew! That is a point when young newbies make the firs mistake. Plus or minus..... Connecting them one way gives forward, the other way backwards. A bit of test and try quickly sorts that out. Best to do before a full mechanical installation. Time 08:20. Having this question as number one designing logic and harness for a lot of UK running ware house fork lifters You must use the close circuit as "clear to run". NO, normally open, should stop the movement. That way even a broken cable will stop the CNC. A connector vibrating and getting loose etc... Those micro switches look complicated and costly. There are such switches for solder connection, the cheapest, and also screw connections. 3D printed mounting devices possible for them as well. Time 10:00. Good mounting idea! I bought a ready made kit like that for my MF70 - CNC conversion. Time 10:10. On safe grounds..... Turning the studs to size... Time 12:14. Mounting them diagonally I got away with only 2, but of course, using all 4 will be even more rigid. Time 13:45. Well done, all according "to the book". I think about the green/yellow cable, the safe ground. I run all my power supplies without it...... Why? I don't have 3 pin mains outlets in the places I would need them. NOT RECOMMENDED AT ALL! But I do, knowing the surrounding danger.. Time 16:10. Plus or minus being right? Wellcome in the club! It never gets right the first time. Time 18:05. Tuning the movements in. Number of steps per resolution, ball screw TPI are the variables. The result is put into the setup constants. Time 18:50. End switch. Active low or active high, and connected to the right input.. Your way of testing is the best, and it is safe! In one way You have the same ability as James Bond, solving the impossible matters. Really well done! I really applaud Your work in the video!

Hi there Andrew. Another interesting episode. It might well reignite my lapsed interest in cnc. I converted a small Proxxon mini mill to cnc a few years ago but despite learning g code and successfully getting the machine to run I found that I missed engineering by hand. CNC wasn’t for me. Anyhow good luck and my wife says thanks for the return of “ hi there” at the beginning. 👏👏👍😀 Andrew

Great project, good information on the controller and software, I have been keen on making something similar but not sure on what controller/software/motors etc to use. You have given me the confidence to use the same equipment. Now you will just have to get your head round the fact the table doesn’t move, it is in fact the tool that moves! At least that’s how you view it when programming CNC. All the best James

Morning Andrew, cold and windy but bright sunshine here in New England this morning. Hot coffee tastes good. Limit switches have to stop the motor when contact is made but be open to move the motor in the opposite direction to jog off the limit switch. Must be something in the software to accomplish this. Other than that I had a fellow in the New England Model Engineering Society help me set up my Bridgeport NC tape drive, no circular interpolation to a full CNC with Gecko drivers and Flashcut software. I have everything necessary to make it three axis but have never gotten around to it. Cheers Dick B. USA

Thanks for sharing 👍

Hi Andrew, for me building the CNC was easier than setting up all the software. I looks like you are figuring it out. I ended up spending almost as much for caming software and Mach3 as I did for the machine it self. Good luck Rich

Evening Andrew, Im still enjoying watching alll the vids on your channel, but all the electrics side is way above me. But nevertheless I still enjoy the clever bits immensely , I loved the one you did for the electronic controller for gear cutting on the rotary table. Anyways im waffling but keep on keeping on its grand stuff. Cheers Buzz

Andrew if you look at your limit switches closely you will see C. NC NO, these relate to the switch terminals below the lettering and mean C Common. NO. Normally open. NC Normally Closed. Normally means in the unswitched rest position. So if you need contacts that are Normally open you need the left and centre contacts .

Impressive set up. The electronics are beyond me so I cant offer help with the switches. One suggestion I do have is to isolate the steel components from the aluminium as far as possible. Plastic washers will do the job and maybe paint inside the holes. If you leave the two materials raw and in contact you will get electrolytic corrosion at the joints.

Andrew, on industrial CNC systems the axis has two switches at each end of the travel, one is for over travel and the other is its home position. the home position is the first switch that is made and and the second switch is if you've exceeded travel, when you first start up the machine it doesn't know where it is but you can manually move the axis, you have to run a routine to allow the control to find home on all axis and the machine then works all of its coordinates from those known positions, I've not worked on systems like yours but maybe that is your issue.

Those spring type stepper connectors have a tendency to break. I prefer the 2 piece lovejoy spider type.

Where can I find information on building the black box controller?

This maybe isn't the problem you are having here, but when a controller homes it will allow you to reverse or else it would just be stuck with the switch on. You would usually wire a limit switch up to be normally closed so if the wires break you don't get a nasty crash it just refuses to move.

I've been very happy with my GRBL controller connected to a Raspberry Pi, but if you're not comfortable with setting up Linux the initial learning curb might be an issue.

I love the idea of these units, even though I went down the Mach3, separate stepper driver route. It all works fine but having to run an XP computer for my router & another for my mill is a pain as they take up a lot of room!!! My only concern with switching over to one of these all in one units is exactly what makes them so easy, everything is inside! If a stepper driver dies on my system, I throw a 30 quid driver away. If one of the drivers dies in this type of setup, you throw away a 200 quid box, or is there a way around that?

Hello Andrew, More good progress... I was wondering has Olivier got his machine up and running? also the Ooznest guys do seem to have some nice products and from what I understand are nice to work with. See you on the next one. Take care. Paul,,

Could you be using the left or right switch i'd try reversing the direction .

Once again a quality production Andrew. I seem to remember a while back you mentioned a drill doctor or similar , can I ask which model you got and what your experience is ?

Hi Andrew Do you use Windows and what version to run the BlackBox. Thanks

👍👍👍👍👍

Why didn't you buy the blackbox interface. No laptop req'd

Have you tried $21 hard limit enable.

the limit switch has 3 wires, maybe it has to be earthed to work properly. eg connected ti the frame

You calibrate using a dial indicator and an accurately measured 1,2,3 block or calibrated block. You can send me an email and I can point you in the right direction for calibrating the axis. As for the limit switches not triggering the drivers to stop you may need to look into the driver settings.

I really do winder what people are going to do with all these cnc engravers