threaded rod question +software

Hi everyone. I bought a Prusa i3x kit a year or two ago and got it to work. however, the quality is not where it should be. I think that the problem is z wobble but am not sure. I am not sure because my first prints looked great. Now I am starting to see little shifted layers. I have tried printing slower and it hasn’t helped.
I can't seem to upload pictures from my computer. Sorry about that.

question 1- is this problem z-wobble?
question 2- do I need to buy new threaded rods to fix this problem?

I was doing some research and found that most of the threaded rods are ACME lead screws. People also say that lead screws are better.


question 3- is it possible for me to buy the ACME rods and nuts and swap them in exchange with my current threaded rods? They seem to be easier to find. Would this require a lot of work to get them to work? Would I need to get new firmware and/or recode the motors for the correct layer height? I am not sure what to do.

On a completely unrelated question, does anyone know of a software that can import images and convert them into step files? Let’s say I import a picture of a bird. Using the software, could I trace out the image, extrude it into a 3d model, and export it into a step file?

Thank you very much!

It does sound like Z wobble and since your printer is using threaded rod on your Z I am surprised you did not have the issue from day one.
Threaded rod is 100% wrong for this application. Threaded rod is designed to be a way to fix things so they don't move, not what its being used for here!
My printer came with a 3/8" threaded rod and it was my first fix to toss it...

I don't know where you are but amazon and www.aliexpress.com both have lots of suppliers for proper lead screw.
Issues you are likely to run into:

1) direction - lead screw is usually the opposite thread direction so you will have to change direction in your firmware. Thats usually quite easy if you know your firmware.
2) pitch, your likely to go for a 2mm pitch so you will have to change your steps for your z axis to properly calibrate.

you will need:
1) new lead screw of the same diameter and length as your current threaded rod.
2) new nut for the lead screw. These are often supplied with.

suggest:
[www.aliexpress.com]

I also changed my coupler for this one when I did it.
[www.thingiverse.com]

print a few and keep them as spares just encase. I broke one once and was down while I waited for a friend to print me one up

as far as the software question, I don't know

Alright! Thanks a lot for answering. I will order some lead screws and nuts soon. While I am pretty good at the mechanical aspect of 3d printing, I don't understand firmware and such. when my lead screws are installed, I will probably need some help figuring that out. Thanks again!

> Threaded rod is 100% wrong for this application
So this one will not produce good prints, it uses 5mm threaded rods.

Another question. How do you hook up a 2 pin cooling fan? My printer only has 3 pin fan ports. Would I have to use a 3 pin fan or is there a way around it?

All printers have a means of guiding the Z axis up and down vertically. If you are getting layer shift perhaps there is a problem with the guide system you have, binding of the carriage, loose belts, or acceleration rates are too high (not to be confused with feed rate) ? The rods could be bent, bearings loose, or frame members loose or bent, rods not perpendicular to the bed. Your couplings may not have the holes concentric with each other forcing the rod to move in an orbit.

Threaded rod is not a perfect means of power transmission but adequate for this job. Issue is straightness and if bent a lot, it could force your carriage over. Pitch variation leads to inaccuracy in height and a lack of parallelism of the axis.

Before spending any money I would remove your threaded rods and guide rods and roll them over the best flat surface your can find. If they are bent they will rise and fall as they roll across a flat surface. If you don't have one go to a local machine shop or engine rebuilder and I am sure they will spend the 20 seconds needed to roll them over a surface plate. They might straighten them for you if they are not busy. Tell them what they are for so they realize not to damage the crests of the thread. Anything over 0.015" bend on the threaded rod might give you a problem. Consider that the nut is loose and can accommodate some variation.

It is very difficult to straighten threaded rod with out damaging the crests of the thread. Make sure you find a source first just in case you damage the rod.

The guide rails should be perfect. Any variation shows up as print error. I used center-less ground hardened steel rod from Misumi that is 0.03mm/300mm straightness.

Use a machinists square to check the rods are perpendicular to bed. Make sure they are parallel to each other.

Don't assume your kit parts were made accurately or of quality materials for durability. Some holes may need re-drilling and different parts used. There are a lot of things to look at before changing the threaded rods.

Good luck.

"How do you hook up a 2 pin cooling fan?"

find the + & - pins

"I will order some lead screws and nuts soon"

you will need to change your settings for Default Axis Steps per Unit for the z axis (it is probably set to something like 4000 and needs to be nearer to 400)

My 3d printer only has 3pin fan ports. For a two pin fan to work, do I just solder the + and - to the + and - of the extension cable and leave the signal wire empty? There are no ports for two pin fans on my control board.

yes don't worry about the signal pin just leave it open.

as far as those that find threaded rod adequate, there are many cases where things can do a job. Making something work does not mean it will work properly.

Make the rod straight and you may reach a level of performance you find acceptable sure.
Use the right part instead for a very low price and you can rule out many future issues and questions......

That said, still check your lead screw for straight before you install it

Edited 1 time(s). Last edit at 12/04/2017 07:23PM by JustSumGuy.

If you mean a part cooling fan, this is usually connected to the 2nd extruder heater output(if your board has one). and is controlled via the slicer software

Quote
obewan
If you mean a part cooling fan, this is usually connected to the 2nd extruder heater output(if your board has one). and is controlled via the slicer software

I think he is mostly concerned with the signal wire, this is used to report back to the interface the actual RPM the fan is doing.

Since most controllers just change the voltage of the fan to change the speed and don't have active monitoring of the speed that fan is doing, it is not relevant.

If you have an 8 bit controller you would not want to waste CPU cycles to monitor your fan speed and its just adjusted via a % of total voltage across +/- anyhow.

If you have a 32bit controller and you want precise control of your fan rpm, you can setup all the special programing so the controller would then vary the voltage to match a specific RPM setting.

Thanks for your replies. I bought some lead screws and they are due before the end of the week. I am going to be hooking up a radial part fan that has two wires.

Justsomeguy- Should I just shrink tube the signal wire to the other ones to keep it from flopping around? (not the leads, just the wire.)

Regarding the settings for the lead screws. Can I change the print settings in repiter host or do I have to dive into the firmware coding in order to get the layer height right? What am I looking for?

heatshrink the wire is a good idea, I would.

I am mostly a marlin user with an astro print server and slice with Cura3 I only played with repiter host for about 20 min and went a different way

have you used and g codes yet? There should be a place to send g codes directly to your printer in the repiter host.

Then you will have to use a calculator to determine the e-steps for your axis based on the changes.

look for the section "Steps per millimeter - leadscrew driven systems" here:
[www.prusaprinters.org]

fill it in and get your e-steps # to start with.
use your command line to setup your e-steps like so:
M92 Z2560.00
then save to eeprom with M500

now you need to fine tune, follow this guide.

[reprap.org]

remember when you get your M92 steps just right, use m500 to save it!

ttfn

Edited 1 time(s). Last edit at 12/05/2017 12:50PM by JustSumGuy.

These are the lead screws that I bought. Is the pitch the "lead of thread" or the "screw spacing"?

Specification:

Brand new

Material: stainless steel lead screw, copper nut

Screw diameter: approx. 8mm

Length: approx. 100mm/ 150mm/ 200mm/ 250mm /300mm /350mm/ 400mm /500mm/ 600mm

Screw spacing: approx. 2mm

Lead of thread: approx. 8mm

Range: 3D printer accessories, stepper motor

There are 100mm/ 150mm/ 200mm/ 250mm /300mm /350mm/ 400mm /500mm/ 600mm, there have same lead of thread(8mm) which is the distance of the nut to rotate a circle

Suitable for: industrial automation equipment, stepper motor rails; such as 3D printers; engraving machine; XYZ module; slider; lifts, etc


How do I find out what my driver microstepping is?

Edited 1 time(s). Last edit at 12/06/2017 11:14AM by printjunkie.

Quote
printjunkie
These are the lead screws that I bought. Is the pitch the "lead of thread" or the "screw spacing"?

Specification:

Brand new

Material: stainless steel lead screw, copper nut

Screw diameter: approx. 8mm

Length: approx. 100mm/ 150mm/ 200mm/ 250mm /300mm /350mm/ 400mm /500mm/ 600mm

Screw spacing: approx. 2mm

Lead of thread: approx. 8mm

Range: 3D printer accessories, stepper motor

There are 100mm/ 150mm/ 200mm/ 250mm /300mm /350mm/ 400mm /500mm/ 600mm, there have same lead of thread(8mm) which is the distance of the nut to rotate a circle

Suitable for: industrial automation equipment, stepper motor rails; such as 3D printers; engraving machine; XYZ module; slider; lifts, etc


How do I find out what my driver microstepping is?

chinglish is always fun I would be fairly certain that the pitch is 2mm and the diameter is 8mm from that.
pitch is the distance the nut will travel on the rod with a full turn of the rod.

Driver microstepping is a function of the electronics of your controller, what stepper drivers do you have?
Most common is the A4988 configured as 16 microsteps but some persons change them up and different controllers etc etc.

I take it from all this the printer is used so a photo of the controller would help me help you here

[reprap.org]

I did some research and if this is the original Prusa Mk3 then the threaded rod may have been 5mm and you have ordered 8mm to replace it....

if I am right you may have to print up some parts to make that change before you pull your printer apart!

check this out:
[www.3ders.org]

[www.thingiverse.com]

Edited 5 time(s). Last edit at 12/06/2017 11:40AM by JustSumGuy.

Alright! My new lead screws have arrived! I haven't installed them yet (darn schoolwork) but I am ready. According to the part list, my control board is a GT2560+ 4 A4988. That is all that it says... In other news, I have printed a fan duct for my radial cooling fan. I haven't soldered my fan cables together yet either. (Can't blame school for that one...I am just plain lazy). Hopefully by tomorrow I will have the lead screws installed and try to have tinkered with the coding.

My printer uses 8mm threaded rods so hopefully no adapters are required.


EDIT- I installed the lead screws and used the 3d printed self centering couplers. The problem is that it wont go up. The motors "grind" and can't spin the shafts. It goes down just fine. What should I do? I haven't fixed the firmware yet and will be waiting to get this problem fixed first.

Edited 2 time(s). Last edit at 12/08/2017 02:17PM by printjunkie.

Its a prity sure bet the GT2560 will be set at 1/16th microsteping.

The important part of the leadscrews is
Lead of thread: approx. 8mm which leads me to believe they are 2mm spacing with 4 lead starts
so your steps/mm will come out at 400
this can be edited directly into the eeprom via repetier hosts eeprom editor

I have read what I believe is a lot of bad advice about what kind of lead screws to use. So this post starts with me putting my 2 cents in. It has been suggested to use a Z-Axis lead screw with the following specifications. Trapezoidal T8-8 as a newbie to the 3D Printer innovation went with the suggested.

The suggestion that this lead screw should be a must have purchase was a T8 Trapezoidal 2mm pitch 4 start, (8mm per turn pitch) 3D Printer Z-Axis Lead Screw. This lead screw has a thread form that is profiled with trapezoidal outlines. They are designed for high strength, ease of manufacture and are designed for high torque with its trapezoidal thread design. Making it perfectly suited for CNC machining.

This lead screw design with its 8mm shaft (4 start, 8mm per turn pitch) has one major flaw. Using the lead screw for over a year now, I find that the 8mm per turn pitch is highly wrong for the Z-Axis when using a Prusa style 3D Printer design. It seems that I am constantly crashing into the bed as the lead screws do not maintain its alignment very well. I find that if the Z-Axis is just aligned to perfection and the 3D Printer is turned off, and if you have a second 3D Printer sitting on the bench next to the first. This vibration can cause the 3D Printer to need to be re-aligned. Now this is just from the vibrations, causing the printers Z-Axis to spin unevenly downwards. Normally this may not be a problem though the Z-Axis on the Prusa i3 designed 3D Printers causes one of the Z-Axis lead screws to turn more than the other causing the Z-Axis to become out of alignment.

As I have two 3D Printers one was equipped with the T8 Trapezoidal 2mm pitch (4 start, 8mm per turn pitch) and the other is equipped with a T8 Trapezoidal 2mm pitch (single start, 2mm per turn pitch) lead screw. This is the lead screw that will be suggested by me from this date forward. It is identical to the T8-8 with only one difference. This lead screw has a T8-2 (single start, 2mm per turn pitch), and does not loose the position like the T8-8 (4 start, 8mm per turn pitch).

Take a T8 Trapezoidal 2mm pitch (4 start, 8mm per turn pitch) install the nut, turn vertically the nut will spin to the other end, What is this some kind of an expensive fidget by Adding the lead screw to a 3D Printer is just asking for alignment issues. And when any downward pressure is applied to the 3D Printer X-axis this will cause the Z-Axis rods to spin. If they would only spin equally this would be no problem, but this truly is not the case.

So Needing Lead Screws save yourself a major headache and buy this one T8-2 Trapezoidal (single start, 2mm per turn pitch) Lead Screw.

[youtu.be]

Edited 1 time(s). Last edit at 12/09/2017 09:57AM by Roberts_Clif.

I already got my lead screws. I only have one printer on it's own table. Will this be fine? I am really struggling with coding because I am a mechanical person. If someone could take the time to walk me through it, I would probably die of relief the firmware is in marlin. I read the comments about sending g code from repeiter host but am not sure when to send it. (By itself, during a print, ect.)


EDIT- Did the prusa calculator... going under the steps per millimeter- leadscrew driven systems. My answer is 1600. code should be M92 Z1600? Where do I put this in permanently? where do I look for the spot to put the code in marlin? What do I replace? Is it a m92 code? I am so new at this it's not even funny.

Sorry for the swamp of questions. I'm 'slightly' frusterated and perplexed.

Edited 1 time(s). Last edit at 12/09/2017 06:57PM by printjunkie.

What version Marlin you need help with. I use Marlin 1.1.5

The Code you need to change is in Configuration.h

// Typical stepper motors have 200 steps per full step/rev = 1.8°/step, so 1/16 microstepping = STEPS_PER_REVOLUTION_E = 3200
// X-Y Axis 3200, / 20 tooth, / 2mm pitch = 200*16 / 20 / 2 = 80 :: (STEPS_PER_REVOLUTION_X / IDLER_TEETH_X / BELT_PITCH_X)
// Z Axis 3200, / 1.25mm pitch leadscrew = 200*16 /1.25 = 2560 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)
// Z Axis 3200, / 2mm pitch leadscrew = 200*16 /2 = 1600 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)
// E-Axia 3200, / (11mm Gear OD * pi) :: (STEPS_PER_REVOLUTION_E * EXTRUDER_GEAR_RATIO / (PINCH_WHEEL_DIAMETER * PI))
//
#define DEFAULT_AXIS_STEPS_PER_UNIT { 80, 80, 1600, 94.4962144 }

Specify what you have and Firmware you are using.
Post your Configuration.h file

To be sure that your Lead screw is if you rotate both lead screws one complete revelation nozzle should rise only 2mm.

Edited 3 time(s). Last edit at 12/09/2017 08:04PM by Roberts_Clif.

The prussa calculator does not take in to account the 4 starts, therefor gives you a result of 1600,which is fine if you do have a 'single start' lead screw(look at the end of the thread, see how many thread ends it has).
If it has 4 thread ends, then you need Z-steps/mm = 400
AS i said befor, repetier host has a eeprom editor in the config menu tab, you can change the value in eeprom from there.

I got it to work in repeiter host using m92 z400. Works great! However, it is only temporary. I have to type it in every time I turn it on. How do I save this permenantly? I also got my fans soldered together. They both get power. I will run some cooling fan tests later tonight. Thanks for the z400 answer. I was confused why z1600 wasn't working.

Ok.
Using RH,send a
M92 Z400

then send a

M500

This will store the new value into the eeprom (if eeprom is enabled in your firmware).

sorry I did not get back in here for a while, glad you got help and it worked out.

Did I read in there that the lead screw you ended up with has an 8mm travel per 360 degree turn?

I had believed it was a 2mm pitch....

Obewan has given you good info on how to save the M92 value via M500

I must say the lead screws were the best 15 bucks I have spent in a long time. Coupled with the cooling fan-woah!!!! The quality is incredible! The M500 gcode worked. I only have one more problem to fix. My cooling fans(both the 2 pin and the 3pin) get power and push air. I can't change the speed. The fan is plugged into the fan3 port on the board and runs no matter if the fan icon on rep is on or off. Both the 2 pin and the 3 pin fans (I only have one plugged in at a time; the other is a spare) don't change speed when I tell them to. So, other than that, I am over the moon with my printer. I am officially back into the love part in our love/hate relationship Thanks for all the help!

Quote
printjunkie
I must say the lead screws were the best 15 bucks I have spent in a long time. Coupled with the cooling fan-woah!!!! The quality is incredible! The M500 gcode worked. I only have one more problem to fix. My cooling fans(both the 2 pin and the 3pin) get power and push air. I can't change the speed. The fan is plugged into the fan3 port on the board and runs no matter if the fan icon on rep is on or off. Both the 2 pin and the 3 pin fans (I only have one plugged in at a time; the other is a spare) don't change speed when I tell them to. So, other than that, I am over the moon with my printer. I am officially back into the love part in our love/hate relationship Thanks for all the help!

a lot of controllers use the second hot end output for the controlled fan port.
if you look at this diagram you see the fan connected in between the hotbed and the hotend heater connections.

[www.makerfr.com]

Cant say exactly how your controller works tho....

I am kinda hoping it has a second hotend connection and thats where it should go...
My 8 bit controllers are MKS Gen 1.4 and they work the same way of connecting the fan to the 2nd hot end heater connector.

If you are wondering or if someone in the future comes across this and is trying to figure out dual hotends with print fans with Ramps or MKS Gen you have to get a little add on board that allows for dual fan control and make some adjustments to the Marlin firmware to make it all work.
Its called the RRD fan extender and plugs into the servo pins.

Edited 1 time(s). Last edit at 12/12/2017 11:27AM by JustSumGuy.

So the cooling fan plugs into what would normally be the 2nd extruder plug in?

On MOST 8 bit controllers, yes. Give it a try, it cant hurt your fan as the heater output is the same as your PSU puts into your controller and your fan I assume is the same voltage as your power supply right?

The hotend is just a PWM controlled psu connection where it can pass amperage high enough for a heater cartridge. Thus it controls a fan without breaking a sweat

Edited 1 time(s). Last edit at 12/13/2017 02:03PM by JustSumGuy.

How would I control the speed and turn it on and off from Rep? do I activate the 2nd extruder icon or do I run it on the fan symbol? I havent tried it yet; I'm just curious how I will control a fan from the extruder output.

This fan will be controlled via the slicer, you can set what layer the fan starts at and also vary the speed.