Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Tevo Tarantula Single Motor Dual Z Axis

by NinjaCookie Jan 4, 2017
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are there any issues you know of with placing the motor off center? I have bracket for my display mounted on the top beam id rather not move if I don't need to

hey, any solution for those who have to place the motor upside down?

One of the fun things about following this thread is that I see everyone else has the same problem making any kind of attractive, rational wire bundling of the Tarantula! I built my Tarantula with a TON of mods I created before I opened the kit's box. I missed this one...


Hello, your project is great, and i'd gladly use it, but unfortunately my custom mods make it incompatible. Could you upload or provide me with models in step format, or maybe even prt (NX)? This way i'd be able to apply some modifications without building it from scratch. Thanks in advance.

hi, nice one. do you have a link for bying the correct lead screws? i tried ordering 2 times from amazon sellers, they always send the wrong pitch, like for ANET A8. so it's moving 4 times faster...

it must say "2mm lead" (or in this banggood case 2mm distance)


you can also adjust your fw to match it
if 4 times faster use this:

define Z_STEPS 400

and this for original

define Z_STEPS 1600

and if it is twice as fast

define Z_STEPS 800

u see where this is going

thank u very much, just what i was looking for!

Are there any adjustable Z endstop files that you recommend? I'm a bit lazy and like to do the adjusting with a single screw. However, all the files that I found are placed in positions where it either interferes with the lead screws or just isn't convenient. I suppose you just use the stock endstop placement as it works fine in this case but is quite a fuss to adjust; correct me if I'm wrong.

I recently printed and installed this modification and It is working beautifully. It really helps in keeping with head truly square while traveling side to side. Was very easy to print and quickly installed. The only downside was going through the step calibration for the Z axis, but in the end it was worth it. Thank you very much for the nice design work. FYI I printed all pieces as solid for added strength which also helped.

Single Motor Dual Z screws are worst than use one, right? i was ready to print this mod, but read that is possble to get a lot of Banding and wobble,is that right?

I'm not sure where you're getting that information but you're incorrect I'm afraid. Like anything, how careful you are putting it together, how good your sourced parts are etc. All play a part in accuracy. Some people just print it out, throw it together and are surprised quality is worse. With 2 screws, the opportunity for inaccuracies are doubled. This can be due to alignment, due to the lead screws not being perfect. I had this problem and used the Oldham couplers I link further down. Works for me and I get better, more accurate prints, and it has sorted all of the problems I had with the printer. If you are looking for a magic solution that requires no work, this isn't it. I made these files for me in the first instance, not the community, so it's completely up to you whether you use them.

Thanks friend, then will print it and test it :)

I think this design is great!!!
I had no issue at all to implement it

Only one minor point , which is the to corners limit the Z axis movement so , the total high is reduced of about 2-3 cm
Additionally , as I have a cooling fan mounted on the heating head, the Z axis motor is also a bit in the way, eating another couple of Cm for a total of around 5 Cm .
I have "partially " solved the issue by mounting the motor top side down , making a small adjustment to the central Z axis support. This has also the advantage that you do not have to invert the motor movement in the firmware

hey, any solution for those who have to place the motor upside down?

I made this but am now having bad z banding issues with my prints. I've searched but can't find any oldham couplers that fit with this design. Has anyone else experienced my issue when installing this mod?

To my knowledge this coupler will work. I based my own one from this. https://www.thingiverse.com/thing:2039498

Oldham coupler for TEVO Tarantula
Comments deleted.

In the first picture, I noticed that the z-motor has been placed from bottom to top instead of top-to-bottom as it originally was with a single axis, does this mean that the firmware should be updated as well to reverse the motor movement???

Yes this is the case. If you read the instructions in full, you will see that I say to specifically do it there.

well, it might be a good idea to make a bracket which may support the stepper to be placed from top to bottom so that we may not have to touch the firmware!

This has been done by another person, I don't have a link I am afraid. Changing the direction in the firmware is a very simple thing to do though, with lots of guides. Needs longer screws etc. To make a bracket like this work.

I didn't make this for the community, it is something I made for myself and chose to release. I chose to go the firmqar route, so that is the version shared. That's just what I thought best.

Comments deleted.

This is the best kit I have found to brace up and steady the Tevo Tarauntla 3D printer with out any mods.
Very nice job , Thanks

Hi, thanks for this desing, i im printed ricght now, but the file "9-LPA_Proto_TopBracket4Vonsy" seems to have a little bug, cause i ccan't open it, can u share it again... Thank u so much...

I don't recognise that file name I'm afraid. All files have been used many times, so I would say to try downloading again or check in another slicer.

Just wondering, would F608ZZ bearings work here, seems like they would be more suited to this then 608ZZ.

THey have a flange on one side is the only difference

Should work, although the depth of holes has been worked out for unflanged. Shouldn't make a difference, so if that is all you have, go ahead.

Oh no, i am in big trouble. I printed the top parts then i realized that the bottom parts lift the device by some milli meters....
But that does not work with the rest of my upgrades (dual Y axis).
Is there any chance that I can find a version of the bottom parts, that do not lift the device from the ground?

oh, sorry, i did not see the post of >>> limwenyao <<< he has the answer


ıt would be great if you could share the source files for further improvements!



This looks very nice!
I was wandering how I could acquire the source files for these so that I can make some modifications.


Comments deleted.

Nice design !
I planned to do this on my Anet A8 until I decided to upgrade it to AM8.

A small improvement idea : use a 40T pulley on the motor : this way, It will need the same torque as before, and you will increase by 2 the Z precision ! This will need a slightly longer belt, I haven't yet calculated it !

Hey, just wanted to say thanks for the design! I have everything working great so far, asides a few things (but it could be many possibilities).

Also with the Brackets that hold the x axis to the rod is very short for some reason, ive had to mount them on an angle until i can find a solution for it, but if you have a recommendation that would be awesome. Currently they have to be mounted on an angle for them to fit and not bend the z rod immensely. are you using an x mount that is slimmer than the stock tevo one?

Thanks again!

Why do you say it's more strain on the motor with 2 rods, rather than with 1?. With 1 rod, it lifts 100% of the weight. With 2 rods, each lifts 50% of the weight, meaning also 100% of the weight at the motor. Do you refer to the friction in the pulleys and belt?

Thanx for the files NC, I like this idea a lot and will let you know how I get on. Although I'm just getting going with my Tarantula I had already modded my extrusion rails before assembly by machining proper V slot faces in the relevant places. ( Had to re-drill some roller positions to suit ) But I always knew that a dual Z axis set-up would be a preference. I've ordered a second lead screw right this minute!
Cheers matey. :¬)

Hi Ninja and others, I think it's the best solution for dual Z-Axis, and I printed all parts but before I will assemble it I think I have no center base and Y Axis bases too. see figure below.
Please direct me to bases STL links.
Thank you.

I love the concept of this mod, and am doing it during the first build of my Tarantula (Upgrading from Anet A8). Where do you recommend putting the Z-stop? Where the factory says to install it makes it way too high for the extruder to meet the bed. Thanks!

You know, I have a Wilson II that would benefit from this - and luckily I have some of the leadscrew out the top. Do you have measurements for all the center to center of leadscrews and pulleys? I bet I could get this to work. Nice design!!

Hello NinjaCookie,

I really like this thing - but I have also the problem that in the file "Left_Z_Top_Bearing.STL" the hole for the bearing is smaller than in the other three parts.

I measured a diameter of 2,1 cm and the other three parts have 2,2 cm. Sanding is hard because the bearing does then not sit tight in the hole.
Can you please check and adapt the diameter and depth of the hole for the bearing in this STL-File. This would be very nice.

I printed all 4 parts with the same printer and the same setup.

Best regards,

Unfortunately the tolerance on one of the parts is slightly smaller. On most it is 0.5mm, on that particular part it is only 0.25. This should be enough however, although may require a little sanding. Given that your printer is quite far out of tolerance, I would recommend adjusting setting to make sure that your tolerances are better. Given that you are the first person to bring this up as a problem it does not appear to be widespread. I'm doing final tests on a new version so this will be legacy in a week or so.

You should note that people need to make sure they are buying a lead screw with a fitting pitch to their original one.
I only realized that after installing the top brackets which means I get a lot of Z wobble (the tension from the belt moves the screw a bit since there's not a second one to hold everything stable).

All-in-all I suggest putting a little extra money into a second motor although this is a cool idea.

I have dual extruder, no extra port for an extra motor

Thanks for your comment. I do mention about needing to check the threads. The tarantulas come with 2 different three pitches so I have not listed them here for that reason. This is something I designed and released to people with as much documentation as I could. I cannot be held responsible for people not checking compatibility of the parts they have fitted. You would get bad banding using this system with only 1 screw, and would strongly recommend against using it like this. Given that you do not have the system installed correctly, comparing it against a dual motor setup is hardly fair, and doesn't reflect the problems of such as a system.

I get what you mean and I didn't blame you or anything like this. Once I get the correct lead screw I will be able to see how well it works

I dont understand what holds the lead screw in place. Is it just the weight of the carriage that pulls it down?

The pulleys on the lead screw sit on top of the 608 bearings. Gravity does the rest. If there are any problems like z axis crashing into the build platform, they simply lift up so a nice safety mechanism.

I just made a quick remix that allows you to use the standard Z limit switch. https://www.thingiverse.com/thing:2563700

Tevo Tarantula Single Motor Dual Z Axis Lower Right Bracket for Mechanical Endstop
by eBoB_

hi, can you create a version where it is only attached to the vertical parts of the frame but not connected to the stuff at the bottom bottom?
I don't want to lift my device, it does not work with the other upgrades I have. also i dont see why the bottom parts need to be so huge.

limwenyao <<
limwenyao's post has the answer, sorry :D

Hi, I see you are improving your design. I recommend you to put radiuses where the bottom plates meet the perpendicular walls to help spread the stress as mine cracked at those places. My layer adhesion sucks, but even with good adhesion, this would be an improvement. I like your design, I am using it just as bottom brackets for untill the loop belt arrives.

Yes that's something I'm working on. Using SOLIDWORKS and sometimes it doesn't like putting radiuses on some surfaces, so making sure next version does. Thanks for the tips

FYI - if you want to keep a mechanical end stop just you can with this mod. All you have to do is remove the right angle aluminum bracket on the 2040 extrusion and cut part of the original acrylic mount so it clears part of the bottom mount. That's what I have done on mine and it works without any trouble.

Care to share a photo of exactly what you did?

Would this work equally well with thingirob's bottom brackets in stead of yours?
The underside of the lead screws would be floating in the air as in the original Tarantula setup.

Can I use Idler pulleys with teeth?

It is possible but in this case it is not required, the idlers are on the smooth side of the belt. There are arguements against using toothed idlers as they can cause issues when it comes to tensioning. Better people than me have argued this online.

Does that motor eat up some of the Z build height?

It does unfortunately. The next versions moves the motor so hoping to eliminate this as much as possible. I will also include an adaptor to reverse the motor mount if people prefer.

Will that not save some printable Z height if the motor is brought to the top like other people have done? (i.e. when the board stand off were used)

Yes it would, hence why I am planning to include it in the next version. Up to people to decide how they wish to orient then. For me personally I prefer the motor below due to an enclosure.

Great design. I've just finished printing top brackets. Left side bearing hole seems to require sanding to fit bearing in. Right side is fine.

The tolerances should be the same on both so could only put that down to printing differences. In all the versions I printed, some needed it, some didn't. Tolerances with 3d printers are always tough to crack.

I wish I had the foresight to see this issue before printing and installing all these parts, but I am now at a standstill. Where does the -Z limit switch get mounted?

My apologies, I have autolevelling so did not plan for the limit switch. It is something I am considering for the next version

For those interested in bottom mounts mounted by screws onto the 2020 and 2040 extrusions, I've made them here: https://www.thingiverse.com/thing:2504887

Bottom Bearing Mount for Tevo Tarantula Single Motor Dual Z Axis

Do you have the X axis motor mount plate design. From your pictures. Mine snapped from the screw holder being to tight up to it.

There are a bunch of designs on here to look at. Part of the reason I left them off my 3d model was because so many people have different variations. The designs I made work, but are a bit lousy, with too much flex in them. I am working on a simple 3 wheel design at the moment which I will update at some point. I suggest you look around and find what works for you.

I made this so you move the motor out of the way and do not need to change the motor settings in the firmware https://www.thingiverse.com/thing:2450016

motor mount
by XennoNL

This is a great simple idea. The whole mount being in the centre at all causes issues with cabling, bowden etc. so it's not idea. Have a version 2 in testing at the moment that fixes the issues of the first I hope.

Sorry to be smothering you like this but I am really holding on for the update any tentative timeline for the release?
Thanks and great work!

I am almost at the point of printing this one off so if you think you will be ready to release version 2 (3?) and it uses the same part list I will hold off. Any update?

i really like the look of this
i have now ordered most of the parts listed in the description

thanks for this

Just wondering would it be possible to change this to a gear setup? might solve the torque issue with single motor having to handle all the load

This is something I have considered, however I'm not a massive fan of small 3d printed gearing. Getting meshing to work well can be a problem. Would definitely be a good idea though if this can be fixed.

i have been using this mod for a while now. with good results. but there are some modifications needed to make it better.
1 maby you can think of a way to move the stepper motor out of the way maby with an extra bracket so you can mount it upside down? that way the teflon tube does not get tangled and you have extra printing hight.. maby incorporate the motor bracket into the top right bracket?

2 the top bracket need to be shorter because now the wheel guide plates hit the brackets on the top.. and block 20mm of printing realestate :)

thanks for this great design!

Thanks for the feedback. I'm testing version 2 at the moment which fixes these issues and reduces the need for supports. Plus integrates the tensioner mechanism as well. We'll have to see how it works.

how do you invert the motor firmware?

Hi, like the design. Was working on a similar one, but will be using this instead. Read the comments regarding the danger of binding due to misalignment of the bearings. Did a quick test of some chinese 608Z bearings I have. And I found they will allow enough angular misalignment that I think this shouldn't be a concern as long as the prints are dimensional correct. Or printed in the same orientation. Any chance of you publishing the cad files? I'd like to design a Y-carriage with a back plate that integrates the Z-nut mount. And having the cad files would make this easier.


Thanks for doing this awesome mod! A quick question – where can I get the STLs for the brackets you used to raise the y axis as shown in the center of image 3? I can't seem to find them in the Files section. Thank you :)

Thans a lot! iv made it, and realy love this mod all fets and woks great.(Модернизация прошла успешно, работает на ура, жесткость возросла в разы. вобщем рекомендую запариться)

Какое количество шагов в конфиге указано у вас, или подскажите как посчитать при комбинированом варианте ремень и ходовой винт?????

Is it possible move motor off the printing area to top to top rail because i have fanduct which need space on top so i cant print high prints because fanduct hit motor

Does it really work?

Yes, I have been using it on my printer for several months now. I am still making improvements to the design and hope to post an update when I have finished my work putting in a v6 and printed the parts again.

How much slack do I need to take out of the belt? I would like to run the motor with a 16-tooth gear and the lead screws with 60-tooth gears to get more precision out of the whole thing.

Given that arrangement I would say you would need a different length of belt. Would need to run the figures through my system, but I would expect you need something longer given the larger diameter gears on the lead screws. Saying that, I don't think you can get that much more precision out of the system given the moving build plate and the gantry. I'm not sure of the maths but the 20 gears given precision at least down to 50 microns. I doubt you will get more precision that that out of this printer.

Does this work with the stock lead screw length(375mm)? Or do you really need a 400mm one?

how you mount z endstop i can't mounted it

You will need to use longer screws, and perhaps use a different setup. There are a number of the on here. My apologies, I use automatic leveling, so don't have a physical Z end stop anymore. I will have to consider this in the next version.

My printer is going to arrive in a few weeks and this will be one of the first things I will make.

P.S. Like your username

A very nice project

Are you going to publish the x-axis drawing suitable for the project

Hi, not sure what you mean? I have included the brackets to lift the X axis. There are a bunch of other X axis mods that will suit this.

I want to remix this for another printer can you tell me what the distance center to center of the lead screws so I can adjust the belt length required?

Yeah, no problem. Center to center of screws is 350mm.

how easy is it to print the bottom right and left brackets with the overhang that they have? i am not sure my printer would be capable of such a feat, but i really do like this design.

It needs supports unfortunately. I did have a version which didn't but was so much plastic wasted. I am working on a version that uses Pillow block bearings, so should avoid the problem of printing the brackets like this.

I am looking forward to seeing this new version. Do you have any time in mind when that one will be done? I am definitely going to use this design as it is one of the best I have seen yet. I have been wanting to convert to a duel z for quite a while and this looks like the one i am willing to try.

Sorry for not getting back to you. I'm still working on it at the moment, I've had the board of my printer die on me, so had to get a replacement. It's back up and running so will be printing my first set of test pieces this week. Hope to have an update by the end of the month.

Im curious if you already made any progress in the pillow block bearing design :). Im planning on buying some of them to create a dual Z on my Tevo

looking forward to it. I think I'm going to be buying the parts for the upgrade here pretty soon.

I just found this and it looks so much more stable than the other z axis I found on here. Now I just need a longer belt and some bearings (the other one uses those pillow blocks).

Thank you for this. I was going to start designing this myself.
As far as the bearing bottom and top, you could use Bore Diameter Mounted Bearings Ball Bearing Pillow Block (http://www.ebay.com.au/itm/Dia-8-10-15-17-20-25mm-Bore-Diameter-Mounted-Ball-Bearings-Pillow-Block-Great-/142140997733?var=&hash=item2118438065:m:mv7OnicwOF4mN2o4JfNCVeQ)
This would allow for slight misalignment.
Have a great day

There is NO DISCUSSION compared to two unsynchronized Z steppers which IS A DESIGN ERROR !
I did that 10 month ago for my Geetech Prusa (one of the first improvement) and put it recently here as it applies to any Z bed.
I did it in a simpler manner as I don't need idlers.
BUT YOU MUST NOT hold the lead screws at the bottom as it is unnecessary because it adds a constraint that that will require perfect alignment otherwise it will lead to binding.

At last common sense seems to reach the 3D printer hobbyist :)

BTW: The Tevo Black Widow uses the same setup as yours, you should mention it.

Thank you for your feedback. I agree that the 2 motor solution is not good, and within the confines of this printer, this is the best solution I could come up with for now.

I understand your point about alignment, and don't have any issues myself. I will update the description to suggest that if you have a problem with binding, then remove the bottom bearing. That should be sufficient.

Removing the bottom bearing with your current design will cause more issues. Where people (including my own printers) remove the bearing to negate any Z axis shaft wobble is when you have 2 Z motors and so the forces on the shaft are released but the shaft is supported by the motor and coupling... this is proven as a sound solution to the common problem of not stright leadscrews.

If you remove your bearing on your setup as you have it now the belt tension will try to push the bottom of the zaxis leadscrew in the opposite direction to the belt tension which in turn will cause all sorts of forces not wanted on the Xaxis.

MKSA's design will fail eventually (without bottom bearing) as it wears his bearing out but I would consider this an acceptable loss due to the cost etc but for people using his design idea with less mechanical knowledge will end up hitting issues which will take them a while to discover.

Tevo Black Widow is the same as yours in principle but in reality uses the Openbuils C-bean Actuator as the base for their Zaxis, which is a very robust system designed for systems up to 1m+ in each axis.


Oh and I just forgot to add I like your design and I will build one of these soonish but most likely a remix with the ideas discussed but with a better mechanical approach in relation to removing the bottom bearing.

Yes removing the bearing can cause potential issues, but only under very high tension from my test. Why you would need to put this design through that I don't know. I'm currently reviewing it myself using pillow block bearings as mentioned previously. This would help with the alignment somewhat. I have looked at mksa's design and the parts for his I don't think would stand up to tension that well. I have followed the openbuilds actuators for some time and they basically all run one the same principle but with higher manufacturing tolerances. I'm still testing this, and have had mine working really nicely for a while now. I will be interested to see what you come up with regarding the bottom bearing.

Finally, my ordered parts have arrived. I had ordered both the regular bearing and the Pillow block as you and Milabar mentioned. ("I'm currently reviewing it myself using pillow block bearings"). Will you be uploading the STL that uses the pillow bearing or should I figure that one out by myself? I have all the parts as you mentioned. but a bit confused based on all the discussion. I feel its a good design and worth building...

Comments deleted.

Pillow blocks are good idea but maybe not needed as long as you have a way to align the top and bottom bearings.

If someone was to adopt a single bearing then the self aligning type bearing blocks cant be used on their own for the obvious reason.

As far as the argument for the tension it comes from 2 thoughts. 1 people who build and modify their printers are not all engineers and don't always have a feel for how tight to have their belts. So a safeguard. 2 Scale-ability: bigger and cheaper beds are hitting the market and the beauty of an open builds system is you can adapt. Then if you start to add duel extruders etc etc all add weight to the X axis and Z axis has to cope.

If I was to through a spanner in the works here... if you wanted a better linear Z axis with minimal "Z wobble" or "Z banding" then you would go with Z axis driven by Belt only and not leadscrew. The issue here though is when the motors are "off" there is nothing to hold the weight of the X axis up and it drops.

I just deleted repeated comments of mine... weird.

Thanks, I appreciate the comments. Given the nature of using a low cost 3d printer, aligning the top and bottom bearings isn't so easy. Like you say, most aren't engineers, so won't necessarily have items such as dial indicators to help them get the alignment just right. This is why I am looking at the pillow block route, given that I can forgo the big print of the brackets potentially, only needing the 1 add-on. I am also considering Thingirob's gimballed nut to help as well.

Understand the tension, however the main person I have made this for is me. The group wanted me to release this, so that's what I'm doing, but had never really planned to do so. Hence why X Carriage weight etc. are less of an issue for me.

For the best X axis, I would say dual ball screws are the way to go, not belts. But then there is the added expense. I think the dangers if a belt drive outweigh the benefits, mainly for novices though, especially when weight gets added.

Thanks, I appreciate the comments. Given the nature of using a low cost 3d printer, aligning the top and bottom bearings isn't so easy. Like you say, most aren't engineers, so won't necessarily have items such as dial indicators to help them get the alignment just right. This is why I am looking at the pillow block route, given that I can forgo the big print of the brackets potentially, only needing the 1 add-on. I am also considering Thingirob's gimballed nut to help as well.

Understand the tension, however the main person I have made this for is me. The group wanted me to release this, so that's what I'm doing, but had never really planned to do so. Hence why X Carriage weight etc. are less of an issue for me.

For the best X axis, I would say dual ball screws are the way to go, not belts. But then there is the added expense. I think the dangers if a belt drive outweigh the benefits, mainly for novices though, especially when weight gets added.

Yes I didn't mention ball screw mainly because of cost and also size there seems to be very little in smaller sizes. From what I have read belt driven Z axis gives very good results...not that I have seen it myself.

FYI someone pointed this at me yesterday while talking about your design... http://3dwrx.com/TrueUp/DIY/ some neat little ideas about the position of things and the clean lines. The idea about the z axis slide blocks is an obvious mistake... just use the openbuilds "plate and wheels" would make this pretty good.

Awesome. Thank you!!!