Micron question

Hi guys I was wondering about microns. I see printers advertise as having 10 to 100 microns or 200 up to 500 microns. what would I want in a printer? what do microns actually affect? are 10 microns better than 100 or 250? I see that ultimaker has printers with an advertised 200-300 microns but I don't know or don't see a difference in the print photos I see online. thanks guys for your input

Microns are not a selling feature. They are a unit of measure. A micron is 1/ 1,000,000 th of a meter, equivalent to 1/1000 th of a millimeter.

Some manufacturers may specify resolution in the X and Y axes as "<20 um" etc. In that case smaller is better, though I don't think I'd trust the numbers - they are probably just using values calculated from the microstepping motor driver, the belt pitch and the drive pulley and not actually measuring anything. The real value is affected by the rigidity of the machine's frame, play in bearings, flex in guide rails, etc.

The other thing they may talk about in microns is print layer thickness. They may say they can print down to 50 um or so layer thickness, but again it is probably a calculated value, not measured. Thin layers like that are rarely used for anything but jewelry making because it takes forever to print anything of substantial size. Any printer can print in thicker layers, with 80% of the extruder nozzle diameter being considered a rule-of-thumb maximum. Thicker layers print faster but have more obvious horizontal banding.

What they don't usually talk about is precision and accuracy. Accuracy is getting the nozzle to go where it is supposed to, and precision is getting it to go to the same spot over and over. Precision affects things like layer registration and print surface quality. Accuracy includes things like getting a part that is designed to be 25mm long to be exactly 25 mm long when printed.

What would you want? I guess it depends on what you want to print. All the available printers and kits can print at the sort of resolution (based on the calculated values, at least) that most people would want/need. Typical printing is done at 100-300 um layer thickness to keep speed up without sacrificing too much quality.

wow extremely detailed and understandable response. thanks. also, Instead of using 1/16 stepper drives, I opted for 1/32 due to someone showing a vid of how silent and "more accurate" they were. have you found this to be true?

They may be quieter, but you'll lose some torque which may or may not matter, depending on your acceleration and jerk settings. With 200 step/rev motors, microstepping beyond 16:1 does not increase resolution.
I am running my X and Y axes at 64:1 microstepping to try to keep my NEMA-23 motor vibration under control. The X axis is eerily silent but the Y axis is still pretty noisy.

ah, so im assuming your running a 24v printer, ive looked for answers on what differences there are. doesn't seem like much except for more power. so nema 23s can give better res than the 17's?

In my printer, the X and Y axes run on 32V supplies powering DSP motor drivers. All axis motors in the machine are NEMA-23, the extruder motor is NEMA-17. The controller is a Smoothieboard running from a 12V supply. The bed heater has its own, dedicated 24V transformer with 117VAC switched by an SSR driven by the smoothieboard. You can see it here: [www.instructables.com]

200 step/rev motors all provide the same resolution, it doesn't matter if they are NEMA-14 or NEMA-34 size. I run DSP drivers because I can use higher microstepping ratios than the default 16:1 of the smoothieboard. Microstepping beyong 16:1 doesn't increase the resolution, it smooths the rotation of the motor and helps reduce vibration and noise, both of which are typically worse as motor size increases, and is particularly bad in the Y axis of my printer.

Operating the stepper motors at higher voltages keeps the torque up at higher step rates and maximizes torque at lower step rates. It is common to run stepper motors at 8-10X their rated voltage, as I am doing in the X and Y axes.

Hi, I just saw your last response, sadly I didn't have the notification on and have a few threads. anyways. what you just pointed out is a great point. also, I want to learn to relay and will do so to add a large heat bed which requires its own psu. my question is, when you say that its common to run steppes 8-10x more than normal voltage, does that mean that if they are rated at about 1.5 amps, then I should run them higher? Im still new to electric stuff but I plan on taking a electronics class this coming semester at college so I can be like you guys!

You set the driver to supply the current that the motor is rated for, or maybe a little less. The driver sends current through the motor in pulses that average to the value you set (the rated current for the motor).

Motor torque is mostly a function of current. The current and torque spec for a motor are based on the temperature rise that that current produces. If you exceed the rated current the motor will get very hot, possibly to the point of failure/destruction. You can run the current lower than spec and keep the temperature down, but you give up some torque. If the motor can provide more torque (at rated current) than needed, you can reduce the current. The only way to know how low you can run the current is to experiment a little. If you've got a printer kit, there's a good chance the motors are as small and cheap as possible so you may not be able to run them at reduced current.