1 Topic by blarz

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Topic: Z bar replacement

Hello I need some help with figuring out the steps per mm on a replacement z threaded rod.

I would like to use either a 5/16 24 threads per inch, OR a 1/4 28 threads per inch replacement. Also if possible what the correct steps for 1mm, 2mm and of course 3mm would be for each. I have seen some of the formulas out there but I do not see how it works for standard threaded rods. I have gone to the calculator but it seems a bit intimidating and I do not see either one of these rods on it.

Also if anyone has any idea where a 1/4 inch coupler could be found would also be greatly appreciated.

I wasn't going to originally replace the rod, BUT ever since replacing the standard wooden arm with the aluminum bed arm, my banding has gotten horribly noticeable. I have tried the slop nut, there seems to be no play that I can see, it has helped very minor with the banding. I have also placed the anti wiggle modification onto my printer that hasn't improved the situation much more then the slop nut has.

Thank You in advance.

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

2 Reply by wardjr

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Re: Z bar replacement

If you're going to replace the Z-rod why wouldn't you go metric m3 or m5?  This mod has been covered numerous times and implemented with great success by many users.  I am sure if you have a search you'll find all sorts of solutions.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

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3 Reply by blarz

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Re: Z bar replacement

M3, seems to small and thin to support the bed, much less to raise and lower it. No one around here has an m5 that isn't crap, most of them are bent or all chewed up from transport, the m3's have pretty much the same issue. For some odd reason the 1/4 and 5/16th  seem to be the nicest out of them all in my area. I have everything ready to roll on this mod, the only thing holding me back is the Steps per mm, or how to figure it out for standard sizes.

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

4 Reply by grob (edited by grob 2014-12-11 00:07:51)

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Re: Z bar replacement

Steps per mm for the z rod will be:
[motor steps per rev] * [microstepping] / [thread pitch]
where [thread pitch] = 25.4 / [TPI]

So at 16x microstepping:
UNC 5/16" 18tpi (stock) is 200 * 16 / (25.4 / 18) = 2267.716535....
UNF 5/16" 24tpi is 200 * 16 / (25.4 / 24) = 3023.622047...
UNF 1/4" 28tpi is 200 * 16 / (25.4 / 28) = 3527.559055....
M5x0.8 is 200 * 16 / 0.8 = 4000
M3x0.5 is 200 * 16 / 0.5 = 6400

This should show why metric is a lovely idea. You're in the US? Have you tried McMaster Carr? Other users in the us have had good experiences getting straight rods from them.

SD3. Mk2b + glass, heated enclosure, GT2 belts, direct drive y shaft, linear bearings, bowden-feed E3D v5 w/ 0.9° stepper
Smoothieboard via Octoprint on RPi

5 Reply by wardjr

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Re: Z bar replacement

grob wrote:

Steps per mm for the z rod will be:
[motor steps per rev] * [microstepping] / [thread pitch]
where [thread pitch] = 25.4 / [TPI]

So at 16x microstepping:
3/8" 16tpi is 200 * 16 / (25.4 / 16) = 2015.748032....
1/4" 28tpi is 200 * 16 / (25.4 / 16) = 3527.559055....
M5x0.8 is 200 * 16 / 0.8 = 4000
M3x0.5 is 200 * 16 / 0.5 = 6400

This should show why metric is a lovely idea. You're in the US? Have you tried McMaster Carr? Other users in the us have had good experiences getting straight rods from them.

+1

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

6 Reply by blarz

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Re: Z bar replacement

wardjr wrote:
grob wrote:

Steps per mm for the z rod will be:
[motor steps per rev] * [microstepping] / [thread pitch]
where [thread pitch] = 25.4 / [TPI]

So at 16x microstepping:

3/8" 16tpi is 200 * 16 / (25.4 / 16) = 2015.748032....
1/4" 28tpi is 200 * 16 / (25.4 / 16) = 3527.559055....

Ok how did you come up with 2 different steps per mm? The two above are identical....right???
So motor steps are the same for all which is 200 step per revolution of the motor correct?
Motor stepping is the distance it turns(16), correct?

[motor steps per rev] * [microstepping] / ([thread pitch] / [microstepping]) =   Is this correct?

The thread count on the 5/16 is 24 threads per inch so wouldn't it be 200*16 / (24 / 16) = 2133.33333333333333


M5x0.8 is 200 * 16 / 0.8 = 4000
M3x0.5 is 200 * 16 / 0.5 = 6400

This should show why metric is a lovely idea. You're in the US? Have you tried McMaster Carr? Other users in the us have had good experiences getting straight rods from them.

+1

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

7 Reply by grob (edited by grob 2014-12-10 03:12:49)

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Re: Z bar replacement

blarz wrote:

Ok how did you come up with 2 different steps per mm? The two above are identical....right???
So motor steps are the same for all which is 200 step per revolution of the motor correct?
Motor stepping is the distance it turns(16), correct?
[motor steps per rev] * [microstepping] / ([thread pitch] / [microstepping]) =   Is this correct?
The thread count on the 5/16 is 24 threads per inch so wouldn't it be 200*16 / (24 / 16) = 2133.33333333333333

I typo'd the pitch in the formula: should have been different! Calculated value used the right number though. Edited and fixed, thanks.

The motors usually turn 200 full steps / rev (1.8 degrees / step).
Microstepping splits these up into, say 16 smaller steps, so it takes 200 * 16 = 3200 pulses to make the motor rotate once

Sorry, your substitution was not correct, should be:
[steps per mm] = [motor steps per rev] * [microstepping] / (25.4 / [TPI])
Note [TPI] is 'threads per inch'

I've added the 5/16" UNF (24 tpi) calculation to the previous post: 3023.622047... is your answer (also not nice)

SD3. Mk2b + glass, heated enclosure, GT2 belts, direct drive y shaft, linear bearings, bowden-feed E3D v5 w/ 0.9° stepper
Smoothieboard via Octoprint on RPi

8 Reply by blarz (edited by blarz 2014-12-10 19:42:09)

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Re: Z bar replacement

Ok 25.4 is the pitch of the threads then correct?



MM per inch....DOHT didn't even think of that....

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

9 Reply by wardjr

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Re: Z bar replacement

blarz wrote:

Ok 25.4 is the pitch of the threads then correct?

That's how many mm's in an inch.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

10 Reply by blarz

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Re: Z bar replacement

grob wrote:

I've added the 5/16" UNF (24 tpi) calculation to the previous post: 3023.622047... is your answer (also not nice)

I assume that you mean not nice because it doesn't break down into a nice even number? Will the stepper have an issue with this? Will this solve my banding issue? Or will it make it worse?

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

11 Reply by wardjr (edited by wardjr 2014-12-10 20:28:20)

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Re: Z bar replacement

grob wrote:

Steps per mm for the z rod will be:
[motor steps per rev] * [microstepping] / [thread pitch]
where [thread pitch] = 25.4 / [TPI]

So at 16x microstepping:
UNC 3/8" 16tpi (stock) is 200 * 16 / (25.4 / 16) = 2015.748032....
UNF 5/16" 24tpi is 200 * 16 / (25.4 / 24) = 3023.622047...
UNF 1/4" 28tpi is 200 * 16 / (25.4 / 28) = 3527.559055....
M5x0.8 is 200 * 16 / 0.8 = 4000
M3x0.5 is 200 * 16 / 0.5 = 6400

This should show why metric is a lovely idea. You're in the US? Have you tried McMaster Carr? Other users in the us have had good experiences getting straight rods from them.

I noticed that Grob mentions that the stock rod is 3/8" 16tpi.
I do not believe this to be true, the stock rod on both of my SD3's is 5/16" 18tpi
He is correct in stating that it isn't nice so you end up using layer heights like
.2963mm instead of .3mm
.1976mm instead of .2mm
.09878mm instead of .1mm

At any rate the metric rod is the correct solution.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

12 Reply by wardjr

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Re: Z bar replacement

Back to your issue of banding are you sure it is being caused by the rod itself?  You mention that you switched to the aluminum platform.  If your issue is caused by the bed moving around you can reduce this some by tightening the (3) leveling bolts to squish the springs more.  Then adjust the z-height to make up for the now lower bed.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

13 Reply by blarz

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Re: Z bar replacement

wardjr wrote:

Back to your issue of banding are you sure it is being caused by the rod itself?  You mention that you switched to the aluminum platform.  If your issue is caused by the bed moving around you can reduce this some by tightening the (3) leveling bolts to squish the springs more.  Then adjust the z-height to make up for the now lower bed.

Honestly that's a good question, I used to have slight banding, then I changed from the wooden arm bed to the aluminum one. the banding got much worse. If I move the bed all the way down to the bottom it gets stuck, so the zrod has a slight bend in it, you can actually see it when you move the bed up and down. I have used the slop nut and it's tight as can be but it only removed a bit of the banding......My banding is such that the external sides of my prints could actually be used to size threads on bolts....The bigger the print the more worse it is.

Also I have the z wobble preventer on my printer with the slop nut  and it has made a small difference but the banding is still there.

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

14 Reply by jagowilson (edited by jagowilson 2014-12-10 20:32:08)

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Re: Z bar replacement

wardjr wrote:
grob wrote:

Steps per mm for the z rod will be:
[motor steps per rev] * [microstepping] / [thread pitch]
where [thread pitch] = 25.4 / [TPI]

So at 16x microstepping:
UNC 3/8" 16tpi (stock) is 200 * 16 / (25.4 / 16) = 2015.748032....
UNF 5/16" 24tpi is 200 * 16 / (25.4 / 24) = 3023.622047...
UNF 1/4" 28tpi is 200 * 16 / (25.4 / 28) = 3527.559055....
M5x0.8 is 200 * 16 / 0.8 = 4000
M3x0.5 is 200 * 16 / 0.5 = 6400

This should show why metric is a lovely idea. You're in the US? Have you tried McMaster Carr? Other users in the us have had good experiences getting straight rods from them.

I noticed that Grob mentions that the stock rod is 3/8" 16tpi.
I do not believe this to be true, the stock rod on both of my SD3's is 5/16" 18tpi
He is correct in stating that it isn't nice so you end up using layer heights like
.2963mm instead of .3mm
.1976mm instead of .2mm
.09878mm instead of .1mm

At any rate the metric rod is the correct solution.

The stock rod on mine fit a 5/16-18 well nut so I believe it is 18 tpi, right?

15 Reply by wardjr (edited by wardjr 2014-12-10 20:31:23)

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Re: Z bar replacement

You are right it is 5/16" 18tpi.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

16 Reply by justsomeguy

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Re: Z bar replacement

Check out the threadless ballscrew thread (just search for it).  This is the most accurate z mod I have tried and I have tried pretty much all of them.

17 Reply by blarz

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Re: Z bar replacement

justsomeguy wrote:

Check out the threadless ballscrew thread (just search for it).  This is the most accurate z mod I have tried and I have tried pretty much all of them.

At this point in time that's a bit above me....lol

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

18 Reply by blarz

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Re: Z bar replacement

wardjr wrote:

You are right it is 5/16" 18tpi.

According to the lady at the hardware store the regular thread is 18tpi, the fine thread is 24tpi and according to her you can even order a 36tpi 5/16 threaded rod. She told me that they're special order and that not one carries them anymore so that's why they're a bit pricey.

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

19 Reply by n2ri

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Re: Z bar replacement

what about fine thread 5mm?

Solidoodle 2 with Deluxe kit cover & glass bed with heater. and 2nd board SD2 used not 3rd and alum platform not installed yet still wood. also need cooling fan installed to board. use Repetier Host couple vers. Slic3r also have all free ware STL programs

20 Reply by grob (edited by grob 2014-12-11 00:08:35)

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Re: Z bar replacement

n2ri wrote:

what about fine thread 5mm?

M5x0.5mm (metric fine) is the same pitch as M3 so would take the sane steps-per-mm, but a fatter rod. Lesser availability of the rod and nuts would be the only drawback.

Also, 10,000 (or for imperial fans playing at home only 2267.716535) apologies for getting the stock rod size wrong. Totally 5/16" UNC. Haven't had it around in a while.... DUH.

SD3. Mk2b + glass, heated enclosure, GT2 belts, direct drive y shaft, linear bearings, bowden-feed E3D v5 w/ 0.9° stepper
Smoothieboard via Octoprint on RPi

21 Reply by n2ri

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Re: Z bar replacement

grob wrote:
n2ri wrote:

what about fine thread 5mm?

M5x0.5mm (metric fine) is the same pitch as M3 so would take the sane steps-per-mm, but a fatter rod. Lesser availability of the rod and nuts would be the only drawback.

Also, 10,000 (or for imperial fans playing at home only 2267.716535) apologies for getting the stock rod size wrong. Totally 5/16" UNC. Haven't had it around in a while.... DUH.


yep, Im saying its stronger support than 3mm, also more fine steps/layers than the non-threaded ball type setup posted above. I looked up that topic. not impressed with that style for ultra fine quality on layers as it only goes down to .15mm thin layers which is not even as low as slicer settings used. plus its very likely to be bumped/moved up or down rod mid print. so I do not think its a good use for 3D printing with consistent accuracy. maybe some other application.

3D printing has way finer tolerances required unless your just making bulky toys using 3mm filament and large nozzles/layers for fast medium quality prints not needing high resolution details or accuracy like most R&D etc need.

Solidoodle 2 with Deluxe kit cover & glass bed with heater. and 2nd board SD2 used not 3rd and alum platform not installed yet still wood. also need cooling fan installed to board. use Repetier Host couple vers. Slic3r also have all free ware STL programs

22 Reply by n2ri (edited by n2ri 2014-12-11 15:29:38)

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Re: Z bar replacement

justsomeguy wrote:

Check out the threadless ballscrew thread (just search for it).  This is the most accurate z mod I have tried and I have tried pretty much all of them.


this setup is not ideal for most 3D printing due to reasons posted in my last post above.

also we need to understand that while all these roller type bearing mods reduce friction etc. they also create several times more places for mechanical failure if even 1 ball or needle bearing ware down it magnifies the loss of tolerances on those build plains associated with said bearing. which is detrimental to 3D print quality goals.

Solidoodle 2 with Deluxe kit cover & glass bed with heater. and 2nd board SD2 used not 3rd and alum platform not installed yet still wood. also need cooling fan installed to board. use Repetier Host couple vers. Slic3r also have all free ware STL programs

23 Reply by wardjr

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Re: Z bar replacement

n2ri wrote:
justsomeguy wrote:

Check out the threadless ballscrew thread (just search for it).  This is the most accurate z mod I have tried and I have tried pretty much all of them.


this setup is not ideal for most 3D printing due to reasons posted in my last post above.

also we need to understand that while all these roller type bearing mods reduce friction etc. they also create several times more places for mechanical failure if even 1 ball or needle bearing ware down it magnifies the loss of tolerances on those build plains associated with said bearing. which is detrimental to 3D print quality goals.


Ummmm.... Never mind.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

wardjr's Website

24 Reply by justsomeguy

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Re: Z bar replacement

n2ri wrote:
justsomeguy wrote:

Check out the threadless ballscrew thread (just search for it).  This is the most accurate z mod I have tried and I have tried pretty much all of them.


this setup is not ideal for most 3D printing due to reasons posted in my last post above.

also we need to understand that while all these roller type bearing mods reduce friction etc. they also create several times more places for mechanical failure if even 1 ball or needle bearing ware down it magnifies the loss of tolerances on those build plains associated with said bearing. which is detrimental to 3D print quality goals.

While this may all be true in theory, the best prints to come out of my printer have been since I did this mod.  I'm just sharing my personal experience.  Is there anyone in this forum who tried the threadless ballscrew and went back?

25 Reply by justsomeguy

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Re: Z bar replacement

PS My minimum layer height is something slightly over .02 mm which is smaller than I will ever try to print with my Solidoodle.