looking for a good 3d printer

[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

[A_Camera]

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.

Quality is NOT improved if you are micro stepping a stepper motor at 1/256, that is a total misunderstanding. Also, you don't need to microstep at 1/256 to make it silent and even running, that largely depends on the quality of the driver, as well as the mechanical quality of the printer or router.

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.

OK, so I was wrong, there exists 1616 ball screws. Anyway, I don't think it is a good idea to use them because the 16mm pitch is just too much in my opinion. I would prefer something with MUCH less pitch.

[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?

[AlexDoran]

It was moving at 10mm/s because that is the loudest it is going to be causing the most vibrations, are you saying you preferred the noisier DRV8825 compared to the TMC2100?

You are completely missing the point, that video was only intended to display the noise difference between the two drivers, nothing else. Yes i did dismiss belt driven printers for specific applications, you dismissed Ballscrews for all 3D Printers but actually they are required for specific applications - as i stated before, if you are printing in materials such as Nylon or Polycarbonate, you need to have a bed temperature of 120c+, and almost certainly need the printer in an enclosure to maintain the correct ambient temperature.

Now if you try and print a large object, where the first layers are going to be printed very slowly, the toolhead and the belts connected to it would be exposed to high ambient temperatures from the Heatbed, these will cause standard rubber belts to distort, i've seen it happen. Maybe you could get some steel belts or whatever, but whats the point when ballscrews are so cheap and offer far superior performance.

Look im sorry, but go and do some research, LARGE 3D Printers, depending on their architecture, will print at an acceptable quality from 40 - 60mm/s. Now if im printing a full size object on my printer (400 x 400 x 400mm), at a high resoluton maybe 150 - 250microns it will take 40+ Hours, thats standard - not a big deal.

For just one example, check out this video, i have set it to start just before he tells you how long it took to print - Just under 100 Hours.



Thanks

Alex

[A_Camera]

It was moving at 10mm/s because that is the loudest it is going to be causing the most vibrations, are you saying you preferred the noisier DRV8825 compared to the TMC2100?

Of course I'd prefer a silent driver.

You are completely missing the point, that video was only intended to display the noise difference between the two drivers, nothing else.

OK.

Yes i did dismiss belt driven printers for specific applications, you dismissed Ballscrews for all 3D Printers

That's nonsense.

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.

Which part of that sentence was not clear? The only thing which is wrong there is that I meant 1204 ball screws. I also said that there are different quality of belts on the market, not necessary steel belts, but also not need to buy the cheapest rubber band, which of course will cause problems, not only because of heat but also stretching. Regardless of which I did NOT dismiss ball screws for 3D printers, I said thet I THINK I'd use belt (not said rubber belt!!!). Whatever will be is written in the starts right now. I will probably only use my CNC to start with and then decide if I want to build one at all, or if I just use my CNC for 3D printing occasionally. I will definitely not print large parts or parts which takes 40+ h to print.

... but actually they are required for specific applications - as i stated before, if you are printing in materials such as Nylon or Polycarbonate, you need to have a bed temperature of 120c+, and almost certainly need the printer in an enclosure to maintain the correct ambient temperature.

OK

Now if you try and print a large object, where the first layers are going to be printed very slowly, the toolhead and the belts connected to it would be exposed to high ambient temperatures from the Heatbed, these will cause standard rubber belts to distort, i've seen it happen. Maybe you could get some steel belts or whatever, but whats the point when ballscrews are so cheap and offer far superior performance.

Look im sorry, but go and do some research, LARGE 3D Printers, depending on their architecture, will print at an acceptable quality from 40 - 60mm/s. Now if im printing a full size object on my printer (400 x 400 x 400mm), at a high resoluton maybe 150 - 250microns it will take 40+ Hours, thats standard - not a big deal.

For just one example, check out this video, i have set it to start just before he tells you how long it took to print - Just under 100 Hours.


Thanks

Alex

I don't plan to start and industry... so it is not relevant for me and don't have time to watch, and I believe most DIY 3D printer builders/users never print anything that takes 100 hours and never use or build a LARGE 3D printer anyway.

[m_c]

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.

I've got to admit, people who claim microstepping increases accuracy, are one of my pet hates.

The term you're probably looking for is gearing or scaling. With modern drives, there's a lot of internal scaling going on. The input simply tells the drive the distance you want the motor to move, be that a 256th microstep, or a full step. The drive then takes that, and runs it through however many switching phases it takes to move to that position, which in itself will depend on the speed things are moving at, as once you increase speed, the benefits of microstepping diminish, so the number of switching phases is usually reduced to ensure maximum motor performance (often called morphing).