Hello guys I am running into a serious problem with my CNC machine. I have a 1500 mm by 1500 mm work bee open build CNC router machine. I have two stepper motors on my y-axis. And though I am able to run G-Code on my machine. After about 10 to 15 minutes my y-axis stepper motors seem to be running at different speeds. One side of my y-axis opens up roughly about an inch and a half. Obviously this throws off my zero and my design is all out of whack. I stood by my machine this time to watch it closely and after about 15 minutes I realized that one of my y-axis motors made a grinding sound. at this point I noticed that something had gone array because the next move that it made was in the wrong direction. I know my code is solid because I've had someone from tech help me with that. It is obviously my setup, something is going wrong with my machine stepper motos/ cnc shield/ Arduino uno or drivers. Do you guys have any advice for me, some solution to a problem?
Classic symptom of a wiring issue. One of the 4 wires intermittently comes loose. docs:blackbox:faq-identify-motor-coils [OpenBuilds Documentation]
Nope, my bet is wiring, classic symptom of an intermittent loose connection/wire broken off inside insulation/terminal rattld loose/bad strip with insulation under the terminal etc. Definitely wiring related
side bet : one of those tiny stepper drivers is overheating. point fan at the drivers during a job to prove/disprove (-:
I am using jumpers on the six pins underneath the drivers. I have two jumpers on last two pairs of pins. I believe this is making my stepper 1/8th. Someone advised me to do this. Should I take them off? What is the purpose of a jumper under the driver?
your jumpers are correct, leave them alone. Peter is talking about wires, the wires from the drivers to the stepper motors. I am talking about heat. Those little drivers get hot, when they get too hot, they selfprotect by turning off. This causes lost steps. One of them (the Y you are having trouble with) may have a slightly higher currrent setting causing it to get hot first. quick test is to point a desk fan at the drivers and run a job. if after 30 minutes all is well then the problem is/was heat. If it still fails, look at wiring, but also you said and that is a symptom of 'getting stuck'. So check that all rails/belts/wheels/leadscrews are clean. Especially if it always failing in about the same area, that means there is a sticky spot around there. Did it grind during a rapid move or a slower cutting move? If you rapid from one end to the other a few times does it stay happy? if you run the job with no bit and the router off does it still fail? It sets the microstepping state. Microsteps are electronically generated steps between the magnet poles in the motor. Picture this: you make a motor from a nail through a shaft and 4 electromagnets. by powering magnet 1 the nail points at it, power magnet 2 the nail moves there, and so on. By powering 1 2 3 4 1 2 3 4 etc the motor turns steadily, but there will be vibration as the nail moves then settles to point at the next magnet. That is called 'full stepping' to '1x microsteps' or 'no microsteps' We can lessen the vibration by powering magnet 1, then 1 and 2, then 2, then 2 and 3, then 3, and so on. now the nail points at 1 then halfway between 1 and 2, then2, then between 2 and 3, then at 3 and so on. It is doing a 'half step'. It will take 8 steps to go all the way round. This is called '2x microsteps'. The motors you have will have 200 full steps per turn. Seems a lot but Despite this they can vibrate fiercely at some speeds, so we use microstepping drivers to smooth everything out. At the same time we get more resolution (smaller mm per step values). Downside is we lose torque as microsteps increase. So we want a balance between smoothness, resolution and power. 8x gives us that. So, no, don't change the jumpers (-:
I was going to bet against the CNC shield as well, but I got beat to it. There is a reason they cost less than $20. I had one when I first started. Ditched it after less than a month because it would overheat even with a large fan blowing on them. One motor would loose steps and everything would be off.
Yeah, I am seeing now that they are not as reliable as I had anticipated. If not the cnc shield, What equipment would you recommend I upgrade and purchase in place of the shield? Do I have to upgrade my Uno too? I am going to run my machine today and post my update later today.
The easiest upgrade (plug and play) is what Peter suggested above. On my CNC, I have an Arduino Uno wired to some DQ542MA stepper divers. They are high quality stepper drivers that can handle the amperage needed. OpenBuilds used to sell them but with the advent of the BlackBox, no longer seem to carry them. I assume because the BlackBox can handle the larger stepper motors. When I made my controller from the genuine Arduino Uno (It is the brains so for a few extra bucks I didn't want to risk Chinese knockoff quality) and 4 of the DQ542MA drivers, those 5 items cost about what a BlackBox costs, without the ease of connecting it. It took some time to come up with an enclosure and get the wiring right (Lead Screw Driven Ox Derivative (850x1500)). There are other external drivers that are less expensive, but I learned my lesson of going cheap with the CNC shield so I went with the higher quality and have had no issues in the 4 years I have been using them. The other option is to keep the shield, or better yet for a few dollars more than the knock-off, buy the GRBL 1.1 compatible version from Protoneer - the company that actually came up with that design - and get much better quality stepper sticks for the shield and provide it with really good cooling. For the lathe I am building I got the BlackBox. It was super simple to put together compared to my previous build. It probably saved me a day of work on the build.
I believe I will purchase a black box. Before I make my order. Does the black box come with a power supply or do I need my own? Also, what controller can I use to send my g code?
You do need a PSU: See 24V Meanwell Power Supply Bundle CONTROL Software: See OpenBuilds Software - FREE Software for CNC Control: OpenBuilds CONTROL and OpenBuilds CAM Documentation: See start [OpenBuilds Documentation] Videos: See https://www.youtube.com/user/OpenBuilds/videos
Follow up: Hello everyone, I found the problem/problems. What I did to find the problem: 1) checked all my stepper motor wires to find any loose wires. Found TWO loose wires one of which was on my Y axis. 2) checked the power on my potentiometers on my stepper drivers. After doing some research I found the the power is x2 and my drivers should not exceed 1.5 v, that means that the potentiometers should be set at 0.75v. so I changed them all at .75v 3) removed all jumpers for micro stepping. I was at 8 micro steps but I changed my drivers to half steps. It was a little rough at one step. Too much vibration, but at half steps. I didn't loose power (I achieved this by placing a jumper on mo1 on my cnc shield underneath my driver.) 4) I installed a small fan blowing right at my drivers. This is a small 5 volt fan that I bought for under $5 bucks. (Before the fan after ten minutes of operation the drivers would be hot to the touch. After the fan and power adjustments after running for an hour, there was no heat on my drivers. It is amazing how far a little wind goes.) 5) once I made all my wiring and power adjustments I moved to the program. Checked my settings on Arduino using Universal G-Code sender under $$ setting. 6) calibrated my steps per inch. $100-102. My settings have me about 50 steps 7) also changed my acceleration on my motors can't recall which $ setting this is but you can locate it if you look at the Grbl handbook online. My acceleration was set to 150. Which was too high because I was missing steps. So I reduced it to the factory setting 50. (I ran the machine and it did start a little slower but I could see the difference in smoothness, I could probably increase this but I am okay with the slower acceleration if this means the machine will run g code without missing steps.) changed my post processor in VCARVE from xcarve to GRBL in.. this didn't seem to change much, but reviews say that this is the best option for my current setup. 9) the RFI issue that I was having my hard limit switches being triggered without and contact to the limit switch. To solve this I pulled the spindle power cord out of the drag chain because it was running parallel to my stepper motor Cables and my limit switch cables. Bought a pack of ten fertile filters to reduce RFI places one on every cable on my cnc. Probably excessive, but precautionary. And put a hook in the ceiling and now have the spindle power cord suspended from the ceiling where it is not touching any of my other cables. This seemed to have solved my hard limit switch problem. There is still one issue I am having where my cut depts are not uniform. Someone did tell me to check the table my cnc is on and make sure it is perfectly level at all corners of the machine. I believe this may be the issue because my floor is far from level.
