looking for a good 3d printer

[Ross77]

Also worth mentioning, do you really NEED a 32bit controller? I only use 32bit because my printers are driven by ballscrews and the steps per mm is higher than using belts, so performance wasnt great for me until i went 32bit. If you want to use ballscrews or build fast Delta Printer i would stick to Ramps or similar, Mega cheap and very easy to setup.

Im coming to that conclusion and may just get a cheap mega/ramps set up to start with while I learn. the belt drives I'm using are from a vinyl plotter and are geared so lookes like I will have plenty of resolution (20mm/200=0.1mm with no microstepping)

I do want to be able to print small high detailed parts tho.

Other than the fact that i can use a 1/32 mircostepping on the swappable boards is there any advantage of going with the soldered drives limited to 1/16th?

[magicniner]

Iis there any advantage of going with the soldered drives limited to 1/16th?

Yes, if something dies you get the pleasure of soldering to fix it ;-)

[AlexDoran]

If you want high resolution, you can still use TMC2100 stepper drivers, expensive compared to the more common drivers used on a RAMPS but can provide upto 1/256 microstepping iirc, operate almost silently too.

Thanks

Alex

EDIT: Although DRV8825's still provide excellent performance and resolution.

[m_c]

If you want high resolution, you can still use TMC2100 stepper drivers, expensive compared to the more common drivers used on a RAMPS but can provide upto 1/256 microstepping iirc, operate almost silently too.

Microstepping does not improve resolution. Due to stiction/friction in the system you can only guarantee positional accuracy to within 1 full step, regardless of the number of microsteps.
When microstepping, the simplest way to describe how the motor's rotor is being held, is opposing coils are pushing or pulling against each other and holding the rotor like it's being pushed/pulled by a couple springs. Then depending on the position of the rotor relative to the cogging, you've effectively got another spring trying to push the rotor either way. And that's before you allow for any stiction/friction affecting the forces.

The only real benefit microstepping has is it improves how smoothly a stepper motor rotates at low speed. Once you get above a certain speed, it has no benefit which is where good quality drives will gradually reduce output stepping to full step mode as motor speed increases. Good drives will also let you adjust the point at which that happens, as it helps avoid motor stalling due to resonance between the stepping speed, motor cogging, and load.

[AlexDoran]

So you are saying that if the transmission was provided by a ballscrew with a 16mm Pitch, at 1 to 1 stepping - that i would have the same resolution as if i was using 1/32 microstepping.

Thanks

Alex

[A_Camera]

So you are saying that if the transmission was provided by a ballscrew with a 16mm Pitch, at 1 to 1 stepping - that i would have the same resolution as if i was using 1/32 microstepping.

Thanks

Alex

1/256 microstepping sounds totally pointless. Even 1/32 sounds too much to my ears. I run my CNC with 1/10 microstepping and I think that's more than enough for both speed and smoothness.

As far as I know, there is no ball screw with 16mm pitch, unless it is very large in diameter. Even 10mm pitch is normally 20-25mm in diameter and is very heavy. Nothing you can run with NEMA17 motors, which are common in 3D printers. My CNC is using 1605 ball screws, which means it is 16mm in diameter and has 5mm pitch.

I think if I build a 3D printer I will use dual ball screws (probably 1004) on the Z with one NEMA23 and belt connecting the two screws. For X and Y I will use direct belt drive.

[AlexDoran]

1/256 microstepping sounds totally pointless. Even 1/32 sounds too much to my ears. I run my CNC with 1/10 microstepping and I think that's more than enough for both speed and smoothness.

As far as I know, there is no ball screw with 16mm pitch, unless it is very large in diameter. Even 10mm pitch is normally 20-25mm in diameter and is very heavy. Nothing you can run with NEMA17 motors, which are common in 3D printers. My CNC is using 1605 ball screws, which means it is 16mm in diameter and has 5mm pitch.

I think if I build a 3D printer I will use dual ball screws (probably 1004) on the Z with one NEMA23 and belt connecting the two screws. For X and Y I will use direct belt drive.

I'm sorry but you could not be further from the truth, 1/256 microstepping is widely used in the 3D Printing sector, mostly for improved quality and almost silent operation (Mainly with Delta Printers), you think people want to listen to their printer go for 40 hours when its in the next room, making a noise when you're trying to sleep? The needs for a 3D Printer are totally separate from a Router regardless of how similar they actually are.

Well my printer uses a SFU1616 ballscrew on both the X & Y and a SFU1204 on the Z Axis, the X Axis is driven by a 1/32 microstepped Nema17, DRV8825 driver.



A belt is fine for most applications, but if you printing engineering plastics where the Bed Temperature needs to be 120c+ you will soon see they stretch and deform from the heat, screws are also far more robust.

Thanks

Alex

[m_c]

So you are saying that if the transmission was provided by a ballscrew with a 16mm Pitch, at 1 to 1 stepping - that i would have the same resolution as if i was using 1/32 microstepping.

Re-reading what I wrote, I should of used accuracy instead of resolution.
You can have as much resolution as you want, but you still can't guarantee accuracy. I'm aware 3D printers will have less stiction than a typical CNC, but the same problem will still be there. Apply a bit load to the screw, or even try twisting it by hand, and unless you have a system with next to zero friction, it won't return to the exact position.
However with a 3D printer, you should get good repeatability, as the load is pretty constant. It's not like a typical CNC machine where you'll have a cutter pushing/pulling things away from where you want them.

The best way to see how much accuracy you do, or don't gain, would be to fit a high resolution encoder to a stepper, and see how even the encoder pulses are compared with the pulse train at slow speed. Once things are moving inertia will help smooth things out, and drivers will typically reduce the output microstepping anyway.

It's a bit like those who say a 10'000 count servo on a directly driven 5mm pitch screw has a resolution of 5 microns. In reality a 10'000 line servo is only likely to hold position within 20 counts with a pretty good tune, so your realistic accuracy is 0.01mm.

It's worth mentioning, that more advanced microstepping drives, will still microstep the output, even if you are using full step input. Without microstepping the output, you get rough movement at low speed.

Sound is down to a mix of the switching frequency of the drive, and the sound of the motors physically moving/cogging. Get something that switches above 20KHz, you're not likely to hear any buzzing/humming, but you'll still get the noise from the motors above a few RPM (6RPM if my calculation is correct assuming a typical 200 step motor and a lower hearing frequency of 20Hz - to get 20 steps a second, you need 20*60 = 1200 steps per minute, divided by 200 steps/rev to give 6RPM)

[AlexDoran]

Re-reading what I wrote, I should of used accuracy instead of resolution.
You can have as much resolution as you want, but you still can't guarantee accuracy. I'm aware 3D printers will have less stiction than a typical CNC, but the same problem will still be there. Apply a bit load to the screw, or even try twisting it by hand, and unless you have a system with next to zero friction, it won't return to the exact position.
However with a 3D printer, you should get good repeatability, as the load is pretty constant. It's not like a typical CNC machine where you'll have a cutter pushing/pulling things away from where you want them.

The best way to see how much accuracy you do, or don't gain, would be to fit a high resolution encoder to a stepper, and see how even the encoder pulses are compared with the pulse train at slow speed. Once things are moving inertia will help smooth things out, and drivers will typically reduce the output microstepping anyway.

It's a bit like those who say a 10'000 count servo on a directly driven 5mm pitch screw has a resolution of 5 microns. In reality a 10'000 line servo is only likely to hold position within 20 counts with a pretty good tune, so your realistic accuracy is 0.01mm.

It's worth mentioning, that more advanced microstepping drives, will still microstep the output, even if you are using full step input. Without microstepping the output, you get rough movement at low speed.

Sound is down to a mix of the switching frequency of the drive, and the sound of the motors physically moving/cogging. Get something that switches above 20KHz, you're not likely to hear any buzzing/humming, but you'll still get the noise from the motors above a few RPM (6RPM if my calculation is correct assuming a typical 200 step motor and a lower hearing frequency of 20Hz - to get 20 steps a second, you need 20*60 = 1200 steps per minute, divided by 200 steps/rev to give 6RPM)

Now that makes perfect sense to me, thanks for explaining it i have learnt from your post, you obviously have a much higher understanding than me in general about the technology involved. I think the TMC2100 can take a 1/16 input, and re-pulse (is that even a word?) it to 1/256, but in a way that you still get the 1/16 resolution.

I believe the "Silent Mode" the TMC2100's provide is only really suitable for smaller printers / Delta Printers, and don't handle higher accelerations well, but just for context this is a good video.



Thanks

Alex

[A_Camera]

Now that makes perfect sense to me, thanks for explaining it i have learnt from your post, you obviously have a much higher understanding than me in general about the technology involved. I think the TMC2100 can take a 1/16 input, and re-pulse (is that even a word?) it to 1/256, but in a way that you still get the 1/16 resolution.

I believe the "Silent Mode" the TMC2100's provide is only really suitable for smaller printers / Delta Printers, and don't handle higher accelerations well, but just for context this is a good video.



Thanks

Alex

It's silent when it is hardly moving. No wonder it must run 40 hours to make anything... and when it is not in silent mode the high pitch noise is unbearable, at least for my ears. Also, didn't you just dismissed belt drive?? I can see a belt in that video and that is very common in 3D printers. I also don't think heat is a problem for the belt. You know that there are different qualities, don't you?