TTS-10 Pro
Lightburn- 2.0.04
Computer- Early 2015 13" MacBook Pro running Monterey OS 12.7.6
TTS-10 Pro
Lightburn- 2.0.04
Computer- Early 2015 13" MacBook Pro running Monterey OS 12.7.6
I have had my TTS-10 Pro for about one year now and only recently when cutting quite a complicated 6” Treasure Trunk with miniature mitre joints and etched decoration I have noticed the x-axis stepper motor gets so hot that I can’t touch it for more than 4 or 5 seconds. It is still working as I would expect without problem. I don’t know if this is normal as I have never consciously checked it before as most of my previous work has simply been cutting 4.75mm MDF with very minimal etching done.
I have it in a home built enclosure with a 80mm computer fan as an exhaust fan to take care of the smoke.
The laser head moves quite freely when the machine is turned off, it will smoothly glide when the enclosure is tipped to about 45°.
Any advice would be gratefully received.
Too hot to touch is certainly too hot.
You can lower the motor current by adjusting this trim potentiometer on the motherboard.
Usually, turning counter-clockwise lowers the motor current. See if 1/4 turn is enough.
There’s also a firmware setting that controls how long the motor should be kept powered after a move command. It’s the $1 value. If this setting is at 255, it means the motor is always powered.
GRBL Docs $1 - Step idle delay, milliseconds
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If you can hold your finger on it that long, I doubt if it is reaching a dangereous heat level. If your finger does an immediate and violent retract, that is too hot for sure.
However, compare it to the Yaxis motor. If it is somewhat hotter than the Xaxis motor, then a current reduction suggested bu @Aaron.F is recommended.
Another possibility is that the Max Accel value ($120) may be set too high (1000 is typical). Compare it to $121, they should be the same unless you have dual axis motors on the Yaxis.
Hi Aaron,
Thanks for your reply & sorry for my delay… Christmas season!
Checked the $1 setting and found it to be set on 25 so I changed it to 255 as you suggested and then tried just a simple shape cutout without any etching. There doesn’t seem to be any improvement.
Interestingly however, now while the machine is running I can no longer manually move the carriage. This was a concern to me previously as I thought It should not move unless I had it turned off. Also now when moving using the move control buttons the laser can be positioned much more precisely when lining up target points in Print & Cut.
Also you mention a 1/4 turn counter-clockwise on the trim pot may help, in your photo I see two potentiometers arrowed, which one is the correct one to adjust?
Regards,
Peter
Hi Mike,
Thanks for your reply,
I had made a mistake with the Treasure Chest I designed & cut by orienting the layout so the X stepper motor was doing a lot of work back and forth but only doing a small amount of etching on each side of the work space. I’ve been told my tolerance of hot is abnormal. When I asked my wife to touch the motor she did the immediate retraction🤣. So I think the amount of heat was somewhere in between.
The $121 & $120 values are both set at 2500. And yes my machine does have two Y stepper motors and they only feel slightly warm on any job I do. Do you think changing only the X one to 1000 would help.
To a good approximation, stepper motors are constant-power devices. The current through their windings is what determines that power, so reducing the current by twiddling that potentiometer is what you want to do.
Reducing the current also reduces the motor torque, but backing it down from “scary hot” to “unpleasantly warm” shouldn’t have much effect.
I didn’t exactly suggest to set the $1 value to 255 
But as mentioned, that keeps the motors powered whenever the machine is turned on. This is why you feel the resistance that you described.
Keep it that way if you like, because as you noticed correctly, that helps with precise positioning and you don’t run the risk of the carriage being accidentally moved. (The controller does not know if you moved the head by hand, and would still think that it’s at the old location.)
Just remember that if the motors are constantly under current, they will also warm up when idle. It is therefore important to also reduce the current at the potentiometer.
You can move the powered motors by hand. You will feel the resistance of the motor. This decreases with lower holding current.
Looking at the picture, the X-Axis pot should be the left one:
Many thanks to everyone for your replies to my problem. I’m sorry for the slow replies however I have been juggling Christmas preps with my laser work.
I have reduced the trim pot down by 1/8th of a turn and now I can hold the motor for an extended period although it still uncomfortably hot but not scary hot. I measured the temp after an hour of work at etching speed at 46°C or 115°F. I had intended to put a heat sink and small fan on the case of the motor but gladly this won’t be necessary.
I also changed the $1 setting from 25 to 255, which although it had the effect of generating more heat, I found it to be much more accurate when I am moving the head to line up target points in Print & Cut. The X & Y motors are now locked in position while the machine is on but not working. I have also reduced the acceleration settings to 1000 as suggested.
Many thanks again, this forum is very helpful.
Merry Christmas and a safe New Year to you all.
Peter
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