Just thought I’d ask,
Default current is 900ma, what’s the advantage of bumping it to 1000ma(1A), I have all my printed parts in petg so as far as heat I should be ok compared to pla.
So what advantage would I get with having higher current?
Slightly lower chance of skipping steps if you are pushing it too hard.
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Current = power.
Power = heat.
So heat is the major factor.
My parts are all PLA, and I run my LR3 X axis at either 1000mA or 1100mA depending on the profile. (I can change “on the fly” via gcode, so some cutting profiles run a higher current for the single X motor.) I don’t have heat problems, but this is a cooler climate.
The other place hest accumulates is at the stepper driver. Trinamic drivers will protect themselves by reducing current when they get hot, so you can actually create a worse problem by turning up the current.
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Ok so if I increased from 900ma to 1000ma to all my stepper motors, I would reduce getting skipped steps and have higher torque in return for increased heat to the stepper motor? But it will only use 1000ma if it requires it.?
We are in a cooler climate, average temp is 16c throughout the year, but summer we get the odd 40c day (approx 5 days across summer) with the average temp in summer in the mid 20s.
Based on my specs would you advise to go higher or would 1000ma be good and/or better then the 900ma?
If you have a cooling fan in the case where your board is, and heatsinks attached to your drivers, that can help to dissipate heat from the drivers.
There are some stickers that change color based on temperature that can help you know if your stepper motors are getting too hot. I think Ryan sells them in his online store. I have not purchased any, but I have thought recently about getting some.
If you have your feeds and speeds right (and sharp bit), that helps to guard against skipped steps.
No. It uses the same current if it is moving or not. At least until you’ve reached the limit of your power supply.
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Interesting. The external drivers deliver varying current.
Ok well my power supply is 24v 10A so I should have sufficient current for them to run.
So if the steppers are running at 1A regardless, instead of the 900ma. It just means I will have less skipped steps and a tad higher torque?
Yes, and the motors and drivers will get hotter.
Too hot on the motors and the plastic mounts will deform.
Too hot on the drivers and they will save themselves by dropping the current. You have to monitor the serial to see if they are doing that.
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Ok. How do I monitor them in serial? And what temp do the drivers drop out.?
My drivers have heatsink also 2x fans in the enclosure of the controller.
Motors mounts and all my parts are petg printed which have a glass transistion at 85c, and melting point at 260c so I think I should be ok there.
Ok so my stepper motors are hitting around 30c-35c. Doing a basic vcarve text.
My 2209 drivers were hitting 40c-44c.
That’s all running at currently 900ma.
What’s the max temp the 2209’s can get before going into “limp/safe current” mode.
Marlin will print something on the serial when they change. You can also send M122 and see a detailed report. OT stands for OT. iORC. There is a prewarnOT. It also prints something like, “OTprewarn, reducing current to 827mA”.
If you want to push it, add a fan that blows directly on them. They should stay cool until the motor mounts get soft.
This makes a huge difference. Passive cooling with heatsink and no fan is really not that good, and if the driver cuts out it is a real bummer.
I have dual fans in my enclosure, so i should be ok.
But at what temperature should the driver not exceed before going into OT.
I just want to keep monitoring the temps (with temp gun) just so I can see roughly its average and/or if I need additional cooling etc
I don’t know the number, but it doesn’t matter. The temp is on the die, not the value at the other end of the heatsink. And it won’t ever reach that temp, because it will drop the current before that.
You could do some experiments to keep cranking it up and monitor the serial until you see it drop. But how do you measure the temp inside the enclosure? And if it rises quickly, the temp in the enclosure or on the heat sinks will not have caught up to the die temp.
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