Replacing the Z-Axis motor UM2

[3d_rockstar 0]

Hello there,

 

I bought my Ultimaker 2 a few years ago and it prints very well. My Z-Axis motor is broken and I want to replace it with a modular on. Modular in changing the rod. I've read a lot of the rod clutches and they say that it is better to have a motor with fixed rod. I found on the igus website a motor with changeable rod (https://www.igus.de/product/1298), but would like to ask here if:

1. there are other suppliers too, that maybe have cheaper sets of replaceable rods and motor

2. What's for 3D printing the solution with the best accuracy (fixed, clutch or montable like that one from igus). Do someone have any experience?

 

My goal is to experiment with various rods (coater, different materials etc.) to get the best of the Z-Axis.

 

Thanks and regards

[3d_rockstar 0]

No ideas?

[SandervG 1,521]

Hello, 

 

I hope you don't mind, I've updated the title of your post to better describe your question. 

Have you also checked if esumi offers motors with a changeable rod? I hope you realise the modification you are considering is quite impactful on the motion system on an Ultimaker and it is not as easy as just replacing a belt by a rod. 

 

If I remember correctly, but I am not a mechanical engineer, a rod can be more precise but at the same time it requires a more precise assembly with less margins than what a belt is comfortable with. Adding multiple rods introduces multiple levels of complexity. A belt might be slightly less accurate but it is much more forgiving at the same time. So I am not sure if the investment would justify the marginal improvement. Did you feel like the Ultimaker 2 was not accurate enough? 

 

 

[3d_rockstar 0]

Hello SandervG ajd thank you for your reply.

I think i didn't explained my goal exactly enough.

I don't want to now which system is better if rod or belt fits better.

I want to replace the Z-Axis motor with build in rod with a modular Z-Axis motor with changeable rod. To experiment on the accuracy of the Z-Axis. All the other axis work fine. Therefore I think that the headline suggest another goal than mine 🙂

 

Kind regards

 

[SandervG 1,521]

My apologies, in that case I must have misunderstood your message. Hopefully this is better, otherwise let me know what it should be. 

[3d_rockstar 0]

That's the right headline. Thanks. Now I hope that someone has a solution for this ;)

[Torgeir 264]

Hi 3D_rockstar,

 

Go for the old type h-stepper with fixed rod, -but if you really want to change this, -the only type that match good enough for an UM2 is the Igus type.

 

The original step/unit for an UM2 is; X80.00 Y80.00 Z200 E282

To improve the resolution on the Z axis you just have to install a link on the 8/16 bit contact on the PCB, then the resolution is doubled to 400 step/unit for the Z axis.

As a result of this link, your bed will only rice half of fully up position, so you need to change the number of step/unit in the firmware.

By using Pronterface (or other method) and sending the following to the printer:

 

M92 Z400

M500

 

The first string M92 Z400 change motion step for Z to 400 Step/unit and the second string M500 store the changes to the firmware. (Note: A factory reset will restore to the original setting.)

 

This will improve the Z axe stepping much!

 

I've doubled my step/unit for all tree axis, and my printer is much improved.. 🙂

 

So my printer setting X / Y is now 160 step/unit and Z is 400 step/unit.

 

My resolution is for X/Y down to 6.25 uM (old 12.5 uM) and h down to 2.5 uM (old 5.0 uM).

 

The result is amazing and I've never been able to make as god print as I do now.

Also I can print overhang better due to this modification.

 

Good Luck

 

Torgeir

 

 

Edited July 5, 2020 by Torgeir
Changed to use the same term.

[3d_rockstar 0]

Hi Torgeri,

 

your explanation sounds really impressive. Do you have maybe a 3D Benchy before and after the axis mod?

Do you have more information on how to improve the resolution of the Ultimaker or 3D printer in general. For me it is really difficult to visualize the resolution. For example what is the maximum resolution you could reach with the Ultimaker 2 and how. Better pulleys, stronger belt, better stepper etc. And where does it ends? I don't want to discuss this in this thread, but if you can give me some information if someone has made a research about that it would be very interesting for me.

For the Z-Axis mod:

Will it make a difference in a 3d printer in general if I choose one of the following 3 variations for the z-axis (because of the fact, that the resolution of a 3d printer isn't that kind of a CNC machine)

Variation 1: build in rod -> I think that's the best one for don't losing resolution

Variation 2: changeable rod like igus (is there a difference between the var1 beside the price 😉

Variation 3: connection of the stepper with the rod by a clutch (I think her I would lose resolution in general but I don't know if that matters in a Ultimaker where the resolution isn't that of a professional industry printer?

 

Cheers 3D_Rockstar

 

[Torgeir 264]

Hi 3D_rockstar,

 

First I’ll explain my interest in improving the mechanical tolerances.

As thermoplastics is very difficult to keep within a given tolerances, I wanted to keep all this other mechanical play at a minimum level. I’ve also tried to get read of as much weight as possible from the moving extruder and the gantry system. This is important in order to have as little resonance as possible, as this often give your print object some shadow/echo effect. This is a typical after rapid accelerating/decelerating movement of the extruder head.

Much of this problem is caused by the short belts stretching/flexing during heavy load during this process. This two short belts are the ones suffer due to the high torque that’s needed for this rapid movements. As I used a mechanical “belt gearing” 16:32 tooth pulleys on both X/Y axis, I’ve got higher resolution on those axes, as well I halved the torque on those two axis.

 

You can see how this was done here:

 

https://community.ultimaker.com/topic/31254-changing-an-um2-from-125-micron-to-625-micron-resolution-on-x-y-axes/?tab=comments#comment-257342

 

 

When it comes to the height axis Z, I’ve found that the pitch angle is important to leave as it is.

This is because G play an important role in keeping the level as steady as possible, if this angle is less steep it is much easier to have issues due to this. I would rather go for the Igus type and the choose a step motor with higher step rate per/rev. But here ofc., using same pitch as the original

Z-shaft.

 

I have not printed the 3Dbenchy after I did this modification, but I've one other from before and after mod. I've printed the last one yesterday.

An important note here, this two model is printed with the exact same gcode file from 2016!

 

The one on the right side is printed after modification.  Click on the picture to zoom in.

 

 

 

I've splited the pictures into two part, not as good as it is originally, but you can see the ringing

resonance after the /S (sss).. 🙂

 

 

Here is another picture of this flow test print of the eight step upward the speed increase.

If you zoom in you will see the reduction of the resonance.

The only issue after this mod is that the steppers X/Y now running at the double speed from before to keep same speed of printing as before. So the noise level is increased!

 

I'll see if I can find some references from others I've used to collect.

 

Regards

 

Torgeir

 

Edited, by some reason my pictures is much reduced in quality here...

Edited June 27, 2020 by Torgeir
New compressed pictures.

[3d_rockstar 0]

Hello Togeir,

 

your results are pretty impressive. I've read the other post, too and learned additionally stuff. Thank you.

 

When you tell about Igus, do you mean the stepper with the rod or only the rod? I think igus sells only the combination of both, so you can screw in the rod.

But what I don't understand is, is it necessary to buy the expensive igus solution or can I combine a normal stepper with a clutch?

 

My dream is to have the same stepper for x,y and z and to change the rod. But I don't now if I lose resolution by using the clutch.

[gr5 2,234]

@3d_rockstar - I'm not saying you diagnosed this wrong necessarily but usually the steppers never die.  So maybe your issue is with the stepper driver and not the stepper.  On the um2 you can't replace the stepper drivers but there is usually a spare that you can use (E1 connector) and then modify the firmware (pins.h).  Maybe this is too much information - instead you can connect the Z stepper to the X axis connector and see if it moves when you turn the printer on and home the X axis.

[3d_rockstar 0]

Hi gr5,

 

thank you for your ideas, your right. My stepper is still working, it's my rod that doesn't anymore. I made some experiments with by buildplate and bended my rod. Therefore I'm asking if it's possible to switch from a build in to a modular Z-System without loosing resolution.

 

[Torgeir 264]

Hi 3D_rockstar,

 

The best thing to do is just to get a new stepper of same type as used in the standard UM2.

Other alternatives will not improve your Z resolution very much.

Let me explain, it is not easy to just to swap the axes, this is because they operate with different shaft diameter vs pitch angle..

 

Edited: The pitch used for the Z shaft calculation 2 deg. pitch and this is to be multiplied with the number of coils in “parallel” in the shaft. An UM2 have a 4 coil shaft. So pitch to be used is 8 mm.

 

Lets look at the shaft UM2 is using.

The shaft diameter is 8 mm with 8 mm pitch (I.E. the axis move 8 mm per rev 360 deg.)

Meaning we have 8 mm/200 step. Each full step is then 0.04 mm or 40 micron.

Standard setting for Z use 8 bit micro step.

So standard setting give; 8 mm/200/8=0.005 mm or 5 micron!

 

If you like to improve this, you can install a jumper to use 16 bit micro step.

With 16 bit setting; 8 mm/200/16=0.0025 mm or 2.5 micron.

 

By looking at this numbers one can understand why Ultimaker selected 8 bit..

 

The reason I’m using 16 bit on Z and X/Y geared by two, is simply because I’m mostly print very small parts and most of my parts could be printed with an UM2 Go..

However, printing with this setting is very interesting -but sure kind of experimental.

 

So, all in all, a small mechanical play will easily ruin this resolution by numbers..

 

But the very good thing here is that most of the resonance shadows in my printed model's is gone. 🙂

The above numbers is recalculated with correct pitch 8 mm/rev.

 

Thank you @gr5

 

Hope this help you.

 

Torgeir

Edited July 1, 2020 by Torgeir
Wrong pitch used in calculation.

[gr5 2,234]

@3d_rockstar -  Just to reduce confusion, when you say "rod" I think you mean "screw".  People seem to call that part the screw.  If you get an off brand screw there is a small chance you will have to get a nut also that goes with it.  But for the most part there aren't very many different versions.

 

@Torgeir - it's a triple helix screw and the pitch is 2mm, right?  So doesn't it move 6mm with each rotation?

 

@3d_rockstar - keep in mind you can buy this complete assembly (stepper and screw as one piece and with proper connector soldered on) from Ultimaker.  Not particularly expensive.  Contact igo3d.  Email them.  It's not shown on their website but they can get any part of any ultimaker for a reasonable price.

[Torgeir 264]

Hi there,

 

No triplex, but a standard one with 2 deg. pitch.

 

Regards

 

Torgeir

[Torgeir 264]

Hi gr5,

 

@gr5

You certainly made me thinking.. Those axis types have been using "multi coils" for years..

I wrongly used the pitch 2 deg, -but it should be multiplied by 4 as an UM2 use quad coils.

So the real pitch is 8 deg., to be used for such a calculation.

I'm going to correct the numbers to avoid confusion..

 

Thanks for your hint.

Regard

Torgeir

 

 

[3d_rockstar 0]

Hey guys,

I know that I can get spare parts from supplier in the internet. I would like to experiment with for example Teflon coated or normal trapezoidal thread (that's what I meant with rod) just do see if there is a difference. And before I buy for example a stepper with rod soldered I asked me if there is a Modular solution like igus only cheaper. I don't want to "repair" my printer, because I have 2 more at home .. I want to experiment with Modular z axis.

 

[Torgeir 264]

Hi 3d_rockstar,

 

Ok. I see, You may use a standard NEMA17 200 step/rev with a 5 mm shaft, just order with the same connector type installed.

You will need adapter(s) to match the connection between the stepper and the multi coil shaft types you want.

Also you may "offer" some space under the bed to make space for the adapter. With such a setup you might consider to use an upper bearing for support of this shaft..  I would use the "new" plastic nut as they have less friction and are very smooth in operation. (Yes, I'm using such a bearing and have 5 brass ones never used, grin.)

It is possible to adjust the stepper a little down for more space.

 

I'll think that Igus might be the best place for a good selection of various Z shafts and adapters that's needed.

 

Sure, there's chines shops that can deliver such stuff, but you never will be sure that the tolerances will bee good enough for your printer.

 

The firmware setting is very easy, so no problem there I'll think.

 

Anyway, good luck in hunting new parts.  🙂

 

Regards

 

Torgeir

 

Edited July 1, 2020 by Torgeir
Text error

[3d_rockstar 0]

Hey Torgeir,

thank you for your patience in explaining the topic. Then I will try the igus parts to play with my z-parameters.

 

Thank you so much.

3d_rockstar