I have been running my LR2 with SKR Pro 1.2 for almost a year now, mainly without the endstop configuration. I have had no issues and can cut quite quickly. Typically I cut 20mm/s 6.5m DOC with a 1/4 dual flute straight end mill. Recently I converted to dual end stops and changed up the wiring. My main issue is the X axis seems to skip when its supposed to be holding on long straight cuts. First time cutting the part it started to travel left when cutting away from me. I updated the G code and dropped it to 15mm/s , then cut again. On cut 1 it travelled away and then started skipping and drifting to the left. I thought maybe I was getting interference with the router cable on the X axis cable, removed the router power cable and checked the connector of the X axis on the board. I re did the cut (shifting slightly right), this time it traveled to the end of the part and on the way back it started to swerve to the right.
Does the dual end stop configuration result in less holding power of the X axis?
Could it be that the bit is wearing out and I was just that close to the limit to have gotten away with it until now?
The SKR Pro should tell you what it’s using for current on the driver. IIRC, the V1 default is 900mA. You may have had it bumped up before, and after reflashing the dual endstop firmware, it may be reduced. Still, 900mA on a decent motor should be enough to hold position and not skip steps.
On the touch-screen it should be under Settings | Machine | Parameter | Driver Current, and should list driver currents for X, Y, Z, and E. Edit: Just checked my SKR Pro, and this is where it is, and default is 900mA
Another possibility is that your PSU may be browning out, and unable to supply the required current. Because you are now running 2 extra drivers for the dual endstop version, that will increase the current load. Assuming all 5 drivers are set to 900mA, that could be as much as 1.2A, for 4.5A total current just from the drivers. If you are using a PSU only capable of delivering 5A, including running itself and the LCD, that might be enough to make it choke.
Come to think of it, this is probably the more likely culprit.
As an interrim measure, on the LR2, you can probably try reducing motor current for Z and Y to 450mA, which will make the total PSU load the same, though this might just push the problem off to the Y axis or make Z skip steps trying to lift the gantry. At the very least, it’s a way to test if it’s the PSU limitation.
Dan is most likely right, but let me throw in 1) a loose grub screw on a pulley, and 2) an intermittent wiring issue…especially since you had to run new wires to the steppers for dual endstop wiring.
I agree on the underpowered psu. Check amps going to steppers and add them up. Figure 1.5 amps for board and display. If they are over your rating for your power supply something needs to give.
Also the steppers don’t need to be set the same you could turn down the dual y steppers a bit and turn up the x. If you have TCM drivers you can do this via gcode M906 otherwise use a screwdriver and multimeter.
That said you are moving pretty fast with a big bit so you may need the power. I run my 2209s at 1.2amps on 7amp supply and am using about 6.8 amps total max power.
It might not be a bad idea to up the specified PSU in the base specifications. With all the fancy stuff we slap onto our machines the extra power overhead might be worth it.
Yes it’s a TCM it’s up to you if you want to save it wit M500 or put it in your gcode for each job.
I’d play with it until you have the correct setting then M500.
Since you are using cnc.js you can just set it up as a macro. I have it built into my autohoming script along with default feed rates and material offsets.
Do you have any temperature concerns either with the driver or the motor?
I like your script idea and might ping you for more ideas for material offsets script once this is sorted. I still need to wrap my head around the full capabilities I now have with the dual endstops
I have 2 fans actively cooling the drivers which stay slightly warm to the touch. The steppers run warmer but not hot. They seem to get warmer when holding than when in motion. I do have a standby macro that drops them back to .9A when not cutting.
I’ve run it as high as 1.6A but I was worried about heat deforming the stepper mounts the drivers themselves have thermal protection that I set to 75% power.
So I made some adjustments. I increased x to 1.1 amps, it seemed to improve things but it still ended up jumping a bit. I noticed quite a bit of torque on the machine as it got in and out of grooves. I’m suspecting my cutter may be dull even though it’s not burning any wood.
When would the steppers see max current? I figured it was when they were in the hold position but when putting a multimeter inline with the main power supply I was only ready 1.5 amps with all steppers on.
with the other motors set at .9amps and my x at 1.1 that totals 4.7 amps without accounting for the board or a screen ( I’m not running a screen at the moment). Wouldn’t that make the stock 5amp power supply too weak even at factory settings? I guess the idea would be that not all motors would be maxed at the same time?
I seem to have had a successful cut when I switch to my 1/4 spiral cutter. I think the 1/4 straight flute was putting too much side loading on the machine and I never noticed it previously because I wasn’t doing long straight cuts. I am still going to get a bigger power supply though.
Am wonderign what your final fix was for this issue as I’m havign the same problem ATM.
I was told it might be wiring or perhaps drivers are overheating so I am installing a fan.
Running SKR Pro V1.2 Nema 17s cutting with a single flute straight end mill bit 4.5mm.
Wil change to a compression bit shortly.
Hahah I just posted in your problem post. The issue was the straight flute cutter. Once it got dull it would pull the machine sideways. Spiral cutters pull material up or down instead of sideways reducing the lateral loading on the machine. New spiral bit. No problem at all.
At one point I could actually see the gantry torque up and twist with the straight flute.
Increased holding current, driver fans and all that too but those items were not the issue
Hi ya Rob… haha OK will take a read & I really appreciate your input. Ryan mentioned that the end mill I was using looked really suspicious. I am a little confused though as it cuts really well for maybe 10min. and then suddenly goes crazy drifting away or what looks to me like its suddnely missing a few lines of data and then suddenly starts again.
