I am using the SKR Pro with TCM2208 drivers. My build is for 49" x 97" using 1" x .1" Steel tubing. Initial movement tests were fine with everything moving the correct distance and direction.
However, once I attached the control box, struts, ATX power supply and router to the gantry, the z motors seem unable to lift the weight.
I’ve read a few similar threads here and am thinking that I have to increase the current to them since they lifted it when it was lighter.
I feel like I’m a non swimmer in deep water, being a full novice in Visual Studio Code, Platformio, Marlin, ESTLCam, and all things CNC: Phew!!! Steep learning curve! I’m doing a lot of struggling and thrashing around.
It would be a lifesaver if someone here could give me guidance on the best/easiest way to increase the current to my Z motors. Do I need to reconfigure and recompile Marlin? (I sure hope not since I found that very stressful) Can I use M906 or M907? and if so, how is that done? Maybe someone can point me to a tutorial?
I sure look forward to the day when this is all ‘old hat’…
Hello @Bob-Son-of-Battle! Have you already ruled out mechanical issues, ensured leadscrews are not binding and well lubed, are they aligned and lubed so cleanly/well that the gantry falls down under it’s own weight when not powered? What’s the supply voltage from your ATX measuring as?
M906 is for the tmc drivers. M122 will report the current setting. You don’t have to recompile the code to change that setting. It will reset on each not unless you save it with M500.
Which firmware are you using? We don’t have any for 2208s in the MarlinBuilder releases.
Hi @azab2c, thanks for your help.
ATX voltage output is 12.4.
Gantry leadscrews are well aligned and although the gantry does not fall on power off, a very light effort to turn the leadscrew by hand sends it down very easily. If I try to lift one end of the the gantry by turning the leadscrew manually, it is impossible unless I physically take the weight with my other arm.I have not lubed them since if they are operating with any ambient dust, any oil product will exacerbate binding IMHO. Not sure if WD40 Specialist Dry Lube will be the answer, or how it works with Brass on Stainless, so I suppose I will give it a try. If a simple and moderate increase in current doesn’t do the trick, I might opt for a 2-start leadscrew/nut rather than the 4-start that’s on there now and then adjust the steps on the motor. On a CNC, there’s really no need for rapid Z movement and a 2-start would reduce the load on the motor by 50%.
Whoa!! Maybe I have discovered the problem:
@Ryan Please confirm something I might be seeing as my problem… The pic of your leadscrews that you are selling appear to be 2-start… the link on Amazon takes me to a 4-start.
Since I live in Canada, and have Prime, and that seller offers them on Amazon.ca, I ordered the ones from Amazon due to the abhorent cross-border shipping costs… mine are definitely 4-start!
Hi @jeffeb3
So do I send these codes to the LR using Pronterface or such? And, I am mystified about the syntax: how do I identify z1 and z2, do I use digipot or??? Do I set up a laptop interface via USB cable? Cable into the TFT or into the SKR? So many questions :-/
Re firmware, I am using V1CNC_SkrPro_DualLR_2209-2.1.1 and have edited the configuration.h in the section for driver definitions to read 2208 instead of 2209
Yep. Some of them can be sent on the tft. But I mich prefer just connecting a computer to set it up.
Yes.
M906 Z800 I0
M906 Z800 I1
Would set them both to 800mA. That is how I read the doc.
The current should already be set pretty well then. Make sure it isn’t a wiring issue or a mechanical issue (as Asa suggested). Check the grub screws.
You are not using parts from my shop so I am not really sure. 2208’s I have never used and not sure how or what to set the current to. My Leadscrews Are 4 start 8mm/rev.
At this point you should include a full picture of your build and some closeups of each problem area.
I can’t stress enough of how valuable this community is. Thank you for your generous help Jeff.
I am currently just coming out from under a snowfall event that has prevented me travelling to my machine but maybe today. So I will take my laptop over, with a can of WD40 Specialist Dry Lube to see if that is a friction problem (Thanks @azab2c ) I’ll get everything re-connected and try the M122, then go from there. So, for clarity, when I hook up the laptop, do I plug the USB cable into the port on the SKR, or the port on the TFT?
Hi @azab2c, thanks for your help. I replied to your post yesterday but I must have screwed up somehow since it doesn’t appear here so:
ATX voltage checked at 12.4v
Alignment looks very good and I am using flex couplings to the stepper shaft so pretty sure binding is not an issue.
In power off mode: Gantry does not fall, leadscrews are easily spun with fingers in the downward direction but in order to manually turn them in the upward direction, I have to directly lift the gantry’s weight or I can only turn them by gripping the flex coupling, and even then, it’s difficult.
I hope to get to the machine today and I will take some WD40 Specialist Dry Lube and give the screws and nuts a shot to see if that helps.
Normally they should absolutely go down. Maybe you have a 2 start leadscrew?
If I get to the machine, I’ll take more photo’s. Thanks for your help
You could also grease the lead screw just for troubleshooting.
Some considerations with dry lube would be most are graphite based or moly based and are conductive.
Hey Travis
WD40 Specialist Dry Lube is aerosolized PTFE. What are your thoughts on that? I am VERY resistant to using any type of grease
Don’t we all use grease? I use Syncolube.
Ohh neat I am not very familiar with that stuff I do use ptfe lube for my fep film on my resin printer but that’s it.
It’s z lead screw did jam up on me one time and some lube was what got it going again.
Sorry I don’t have any better info for you but threads have a enormous amount of mechanical advantage.
Don’t know if this good/bad idea, but have been using Lithium grease https://www.amazon.com/gp/aw/d/B000CINVA6?psc=1&ref=ppx_pop_mob_b_asin_title, would prefer to use food grade silicone grease I normally use in faucets, but my tube in lost somewhere in the chaos garage that should probably be on a Hoarders episode.
Would appreciate some authoritative decree as to what we should be using.
Just recalled, during assembly, I ran into binding issue with the linear rails not being 100% parallel/aligned. Can briefly see me fighting XZ and YZ plates being sticky/stuck due to alignment issues here. I noticed the temporary 3D printed Strut is almost the right dimension to also serve as an alignment/spacer tool for this step.
Cheers!
I have a spare lead screw and some great coatings for work I could do some testing maybe as far as dry lubricant.
Imho I don’t see a little grease being a big deal I mean they should be wiped and re lubed once in a while.
As for the hoard garage I feel your pain lol. There is one thing I find that I can never get obsessed about and that’s organization.
I use lithium grease.
I bet the dry stuff would collect less dust. I have always heard you should use dry lube in dry environments (dry and dusty) and grease if it is in a wetter (or muddy) environments.
As long as it falls on its own, it is definitely lubricated enough.