Prusa i3 Z-axis leadscrew with 4 holes copper nut (add belt tightener)

by 3DPW Oct 28, 2014
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I just wanted to ask, because these are quite high resolution files, I can't open them in solidworks to check the spacing between the linear and threaded rod to make sure it's the same distance as my machine, can you just confirm for me please what the distance between centers is?


I just printed this and tried (but failed) to install it as a replacement.

my machine's frame expected the distance between the rods to be 23mm (center to center) (and far-edge to far-edge 30mm (an easier measurement to make on my printer).

This piece (unfortunately) will not work for me, the rods should be 16mm center to center (22 edge to edge).

(notably, I have an i3 clone-- which isn't using the original prusa design... so it's my own fault)

This is follow the standard Prusa i3 design. I forgot the distance. Maybe you can print one and measure/test it physically. thanks!

Printed them today, came out really nice. Did you tap the screw holes for the leadscrew nuts? they seem a little small.

no need. make it smaller in purpose but tighter screw.

Just found out that your design wont work with a typical t8 leadscrew.
The pitch of the screw holes is too much!
Will just have to wait and see when my screws turn up

The design perfectly match to my part. Not sure what spec your got.

Well I've printed them anyway and got them installed, I'm waiting for my lead screws to turn up but I'm also trialling a single motor belt driven z axis because I don't think 2 motors is necessary.

I tapped the screw holes in the end, they were printed with 3 walls and were really tight and didn't fancy splitting them.

Also bought a T8 thread tap so I can make my own nuts to lock the leadscrew in place.

It's going to be an interesting build, lead screw z axis, single z motor, custom built hot end mount with Bowden driven extruder.

Thanks for these designs though, they work well.

Thank you and have a nice day!

Добрый день. Попробовал ПЛА без поддержки с 20% и 50% заполнения "X_Motor_Leadscrew_20140721.stl". С правой стороны ПЛА по горизонтали начал спадать. Это когда первое отверстие закончил и начал выводить горизонталь под второе отверстие. Может я не правильно что делаю в настройках SLIC-3. Температура экструдера 220-215. Bed 80-75. ПЛА 1,75 extrusion multiplier 0,95. Сопло 0,4 мм. Посоветуйте пожалуйста. Можно мне на почту [email protected]

Everything I can provide already here.

Спасибо. Буду пробовать PLA с заполнением 20% без поддержки.

И еще. Нужны ли поддержки при печати деталей?

No support is needed

Добрый день. Я начинающий. Не подскажите чем лучше печатать PLA или ABS? И какой % заполнения деталей?

Either PLA or ABS is ok. Wall thickness 1.2mm top/bottom 0.8 and infill 15~20%.

I was thinking you might have a suggestion as i am having a very hard time getting the lm8uu bearings into them.

I would suggest a round file, just don't take too much off!

well, the dimension is just meeting with the bearing size (no any tolerance design) so the printing quality is important. if you are using a cartesian XYZ type 3d printer then it will be difficult to achieve the printing quality requirement. we did print it a lot and ok to fit bearing. thanks for suggestion and will consider to add some tolerance for easier fitting.

Having trouble getting the bearings in, thought the design was for easy insertion of bearings?

yes of course. it fits lm8uu well

Any chance you could modify the screw for the idler bearing to 4mm?


I really appreciate the design! I plan to upgrade tonight or tomorrow!


I am sorry. This design is to fit our machine. :)

I was wondering if this design was tested before posting. I downloaded a different design, from another author that was not.

This design is not only tested but been using for many users already. What's the issue you have?

Like I said, I downloaded another design, printed it and when I looked at it it was obvious it had not been tried. I want to make sure that if I dis-assemble my machine that the new parts work. I will print them and take a look. I am not running a rework machine. I have a Hephestos. I am not questioning any ones ability.

Welcome to feedback. I am wondering which part is not working for you. This design is for Prusa i3 original and there are over 73+ users are using it already. Please let me know which area is not working in your machine. Maybe you assembled it in wrong way.

Just wondering ... Are you using this?

What are the dimensions for the 4 hole copper nut you are using?

~3mm Self-tapping screw

What bearing do you use for the idler?

625ZZ or any inner 5mm bearing meet requirement

can you share original source files please?
or email to me... [email protected]

Sorry I can't find the original file due to I reinstalled my computer. Hope I didn't lost it.

What leadscrews do you use? The ones with a diameter of 8mm, model THSL-300-8D?

Sorry! i don't know the model number but I check THSL-300-8D and it look exactly the same as mine. Yes inner diameter is 8mm for its leadscrew.

BTW, i like your design.

You're welcome :)

dcchi007, can you be able to make the smooth rod hole (the top and bottom) thicker?. Also, can you make the smooth rod hole bit bigger like 8.4mm?
Thank you

why do you need that?

Because when I was trying to fit the smooth rod, it broke and I can't use drill to make the hole bigger.

the smooth rods go through LM8UU not this print part directly. i don't quite understand you

print part holes for the smooth rod it's small and the rods don't go directly. So, on the print part there isn't enough layers on the smooth rod holes (the top and bottom).

Again, smooth rods go through LM8UU not the print part. I don't understand your problem. Actually this design has been using for many users. There is no problem with it.

The x idler cracked when i was fitting the rods. i know smooth rods go through LM8UU. check it here http://www.thingiverse.com/thing:536396

X Idler Leadscrew
by GOO2014

you are not sharing the picture. it is not pubic. i can't see it.

Done now, sorry.

When I was pushing the rod into the plastic part, plastic part cracked.

increase the infill %. i believe you are having a print quality issue not a part design issue.

I did infill 40%

where you bought the leadscrew with 4 holes

I bought it in Taiwan and it's made in China