Tevo Tarantula Dual Z / Adjustable Z Limit Switch

by supasorn Mar 9, 2017
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For anyone who wants to print this mod, gt2 belt is not 610mm, you need at least670mm closed loop gt2 belt. Otherwise secondary z axis can not be mounted because it collides with bed.

I printed it and mounted everything and when i want to connect two z axis with gt2 belt it doesnt reach other one, and making two rods close together is impossible because motor side rods position is fixed and all you can do is play with second rods position. But there is not enough space to make second rod closer to main one because it touches heated bed when you want to make it closer enough to fit 610mm gt2 belt.

I couldnt find any gt2 belts longer than 610mm so i am going to make closed loop from regular one, when i finished i will measure length and write here.

Hello everyone, collect the printer
the top turned out a hairpin M5

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I want to use this setup but it's too close to the X bar to use a gimbal.... I'm trying to remix so the lead screws are at a stock distance but I'm new to fusion 360 so it's gonna take some time

I just added gimbals to mine. Try this: https://www.thingiverse.com/thing:3026029

BB gimbals for supasorn's dual-z

What is the size of that screw on flange bearing? Thanks

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?

Yes, they are. This 'upgrade' will cause z-banding/wobble.

do you need to invert motor in firmware? thankyou

Yes, you do :)

Are there any base brackets that are compatible with this?

Is there any trick to getting the lead screws aligned? I've done a couple of calibration cube prints, but there has been some z-banding. How tight should the timing belt be? I am looking forward to getting prints similar to the calibration cube in pictures on this design.

Unfortunately this 'upgrade' produces z-banding which is pretty much impossible to get rid of without big changes to the design, see here: https://www.evernote.com/shard/s211/sh/701c36c4-ddd5-4669-a482-953d8924c71d/1ef992988295487c

Do you think this would also make sense for a single Z setup?

Where can you download the marlin software and does the printer connect to windows 10.I had experienced some issue with connecting to my PC.

You can find the Marlin software here: https://github.com/JimBrown/MarlinTarantula

The printer can connect to Windows 10, but it's generally best to print from an SD card or a Raspberry Pi to avoid issues.

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hi friend

define ZAXIS_STEPS_PER_MM 3200

t8*2 pitch
soft ware
it's true?

Will the stock lead screw work for one side? Or do i need 2 400mm leads?

The stock should work.
However, do make sure to visually check the pitch. I bought lead screws with the exact same spec from two venders but the pitches differ by a tiny fraction of MM, even though both say 2mm pitch. One of them matches the stock, the other doesn't.

anyone know if its the 9mm belt or the 6mm?

thank you good sir, will post pics when i finish my build ;)

What size belt did you use?

Are there any bearing mounts that can hold the right side at the bottom for improved stability?

I tryed to modify the screw holes, but they seem to be 4mm already ?

There's a 4mm design in the fusion 360 file.
But depending on your printer setup, the x axis might hit the motor holder before the hot end touches the plate. This was the reason I went with the 3mm design to make it more compact. You might be able to use 4mm without this problem though.

I'm currently in the middle of remixing this and combining it with the thing on style braces. I am so glad you attached the fusion 360 file.

hello can I use the aluminum z motor brackets for the pillow bearings or do I have to print new ones? thanks

I had the same question. I ended up using 2 M3 bolts to mount the pillow bearing to the aluminum stepper mount. It has the mount diagonally in place of the stepper motor mount.
However the lower stepper motor mount required modification to account for the change. I extended it out about 9mm to be used with the stock bracket hardware, aluminum or acrylic. Additionally I made the T-nut area stronger and with 4mm wide holes (Originally it was ~3mm wide). I would not use my mod unless you have the aluminum upgrades.

i have a problem with this setup. I'm using Modular X carriage by Elzariant with tevo titan direct extruding and my Z endstop can't reach the screw xD The adapter for the endstop should be around 45mm tall.. oh what to do...

Same problem here.... u need longer belt and bigger idlers

for some reason I have to screw it most of the way inorder for it level properly. Yours in the image looks like its half way, did you remove the spacer on the y carriage?

I'm not sure what you meant. Which screw are you talking about?
I did not modify remove the spacer.

I mean the zadjustment scrrew. I dont know how you have you screw so high, I have to screw mine in almost all the way in order for it to level the bed. Did I build it wrong?

I see. I wouldn't worry about it. I think our heated beds are just at different heights due to how many turns we screw the four plate spring screws.

Hi, I just reassembled my printer but the Z axis is reversed- because I've turned the whole motor upside down, presumably! I am very bad with software but I've read that it's possible to fix this in hardware by changing some of the pins- has anyone done this and can you tell me which to swap?


In marlin/Configuration.h, toggle:
"#define INVERT_Z_DIR

What's the trick for getting the z-bolts perfectly straight? I am getting horrible banding now that it's on, coming from the single Z with oldham. I can reduce it a bit by not tightening the t-nuts/bolts to the X-axis, but the banding is still there... The bolts are perfectly straight when rolling across a flat surface.

Yes, this 'upgrade' produces noticeable z-banding/wobble and should be avoided. The problem is that the threaded rod is constrained at both ends, which causes even slight bends in the threaded rod (which are always present) to sway and flex both the rod and the printer frame. See here: https://www.evernote.com/shard/s211/sh/701c36c4-ddd5-4669-a482-953d8924c71d/1ef992988295487c

The resulting flex is usually in the 50 - 100 um range, which is not noticeable just by observing the rod or frame (and the rod will appear to be straight on inspection and rolling across a surface). But it will cause very noticeable and significant z-banding in prints.

This is really a very basic design mistake and the user who uploaded this 'upgrade' could have done well to first learn more about CNC/3D printer design beforehand.

I suppose your bolts refer to the lead screws. Sometimes rolling on a surface looks fine with a small bent. A somewhat better way to spot it is to let the stepper motor spin the rod. If they're not straight you can more easily spot it this way. I suggest you do this with a single rod setup first. One at a time.

Now suppose they're both really straight. One thing to check is whether both of them are parallel and perpendicular to the x axis (ground). First install the bottom bracket (motor), then the top making sure they are perfectly straight up. Then tightening the lead screw nut to the axis. The other lead screw that's not connected to the motor is a little tricky. First install the top, then raise the x axis to the very top and tighten the nut.

It'd be great if you can share your solution and findings once you've finally solved the problem! I'd love to hear.

I tried for 3 weeks to get this to work without issues, and I just couldn't do it. I leveled the entire printer, made sure it was perfectly level / square, Checked that the rods were perfectly parallel to each other / the printer. Every time I tightened the screws to where the lead screws connect to the X-Axis, the motor would have issues. Sometimes at the top, sometimes in the middle, sometimes at the bottom. I tried spacing them with washers, that didn't work, I tried solid couplers, those didn't work. I was able to get a few decent quality prints out of the whole thing if I loosened the x-axis connections up a little bit, but there were still occasional issues. Not to mention, with the pillow bearings at the top, getting tension across the system that wouldn't pull the lead screws was incredibly difficult.

I tried every single thing I could, but nothing worked. I did something new every day... I gave up and went back to the stock Z-motor position + Oldham, and everything is printing very good again.

Not sure what else I could have tried to make this work, but I just got tired of messing around with it.

I also cant make it work. The Z motor is clicking now since he needs to work harder. I tried to raise the driver voltage a bit but without any success it still clicking

i think youre not understand the concept off leveling there are two kinds of leveling one is to make everything leveld even the underground but wat must be leveld is the distance from hot end to the bed not the whole printer.put a standard peice of pater a4 under the hotend en if the papar gets a littel stuk when you rotate the bed levers youre nearbey do that several times around the bed keep cheking if you adjust one another will divide in the end you should be allright when al the corners are the same.hight then try to print something large not gthe whole thing but a few layers look at them isnt it allright adjust bed level screw on that site a little look at layers again after a few passes if its better adjus further if not turn to beginning en start the otherway.aroundgoud for al the bed leveling screws. alter not to much at one time small steps will bring you there.

Did you design the bed-level nuts? Can you share the design please?

Thumb wheel for bed leveling (Tevo Tarantula)

Does this working if print from pla without flexing and can you modify this for m4 screws

I bought a 696mm belt, but it looks shorter then the one in your pics, are you sure it's the right size?

It doesn't quite go all the way from edge to edge when installed. It looks like this: http://www.thingiverse.com/make:315727
Can you post a picture of your build?

Tevo Tarantula Dual Z / Adjustable Z Limit Switch

my bad, i tought it was going 'edge to edge'

it's like in the picture you linked

Hey! Nice upgrade!
Maybe a stupid question, but what size bore and od for the pulley?

Good catch! Bore is 8mm (same as your lead screw) and OD is 16mm. You can use any OD though, but take that into account when buying the loop belt.

Great work, very elegant and simple solution! I just remixed and published it for Anet A2. Am currently using it on A2 as single inverted Z, while I'm waiting for longer lead screws, pulleys and belt, works fine like this as well, much better than top mounted Z. No sag, no elephant foot. The only "issue" I have is that I feel the motor mount is a bit weak right now and if done in PLA, might crack if X bar is lifted with serious force. Probably not an issue once the top is fixed to the support bearings.

How well are you printing after this mod?

There is still some z wobble or it has been totally fixed?

I actually didn't have large z wobble even before this mod -- I didn't enable hop or auto bed level.
If your stock has some really bad wobble, try troubleshooting that first would be useful.

The mod makes it less sensitive to bad assembly, to bad calibration and makes z hob / auto bed (where z constantly moves) more robust. And you can theoretically print everything at higher speed as X axis doesn't wobble.

I, too, have very little z wobble.

But since I'm going to mod my X axis (steel pieces instead of acrylic, for 1,5Kg for total Z weight, with 150g of X moving mass) I'm in need of a stronger system that decrease the wobble even more

Hi, this looks very promising.
Could you adapt also a KP08 to this design. So I would have not to order the KFL08 :)
I've until now no experience with other CAD tools than OpenSCAD.


It's harder to design for KP08 so that there's a sliding slot for adjustment (otherwise need physical measurement), and the load will be on the screw which is less ideal.

You saw the desing errors of this machine but to get rid of them, you could improve and eliminate at the same time the risk of wobbling due to the coupling by adapting what I did to my Geetech. http://www.thingiverse.com/thing:1830451
Just put the motor at the top, one more pulley, no coupling, a new motor bracket, the belt tension being adjusted by moving the motor.

Prusa Z axis, so many problems yet one simple solution !

Thanks for the suggestion! Yours looks nice as well!
There are pros and cons to mounting a motor on top as well as aesthetic trade-off. I have thought of that solution, but prefer the inversed mount. Also it allows a unified unit with the adjustable z end stop.