QUBD : [v2] Twoup Gantry replacement

by Tony_921, published

QUBD : [v2] Twoup Gantry replacement by Tony_921 Aug 2, 2015
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I have been so happy since I replaced the original gantry with this.


My TwoUwp got significantly reliable, and I have no fear for hours printing now. Also, the print quality improved, too.

This [v2] addresses the drawback on [v1], missing the range of motion about 1 inch from the original. The [v2] has about 12[mm] wider range of motion than [v1].

The [v2] still misses a few millimeter from the original design with the stock x-carriage (60[mm]). But once the x-carriage is upgraded to narrow versions, you actually gain wider !.

The followings are such examples. They are all 15[mm] narrower than the stock carriage.


Although I have tested this with only TwoUp, I'm also interested in the result or feedback from OneUp users, in which the range of motion is more important.


The "belt_clamp" is for the stock x-carriage users. No need to print if you already upgraded the x-carriage with built-in clamp such as http://www.thingiverse.com/thing:951718.

They are very flat design, which is subject to "warp" on printing. If you don't have a way to preheat the platform bed, start printing 0.1[mm] lower than your usual print, so that the 1st layer smeared with enough pressure to the printing bed. Or google "3d printing anti warping" to find a workaround which suits your setup.

Sandwich the LM8UU bearing, pulley belt, horizontal rods.

  • x_gantry_left_motor_front and x_gantry_left_motor_back

  • x_gantry_right_front and x_gantry_right_back


  • M3 x 8[mm] for the steppe motor right-top, right-bottom
  • M3 x 30[mm] for "z-axis_holder" (including the stepper motor hole at left-top)
  • M3 x 25[mm] screw and M3 nuts for the rest.

There were feedback from an OneUp user, that the pulley belt got lose with this gantry.(thank you, "zabazoom" !) One of the followings is recommended for OneUp users.

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Do I need to get LM8UU bearings or will the LM8LUU bearings that came with my TwoUp work?

You can use the stock LM8LUU. Additional LM8UU may provide further stability (just put next to the LM8LUU), but so far, I got enough stability only with LM8LUU.

I also didn't need a belt clamp, not sure what that was supposed to do

Works great. Not sure why, but my home position went from front left to front right, but it doesn't matter. I couldn't level my bed due to sagging but now I can get my bed leveled. The printer also looks much cleaner without all the bulk in the middle. The belt was very difficult to get on, but after its on it goes together easily.

Hello, I have just assembled my twoup with this setup. But now, there's much too much tension on my motor to move. I can barely move the extruder carriage by hand. Im not sure what to do at this point.

Are you using my modification on both ends ( Not like mine at right, and Stephan's at left ) ?

Otherwise, I'd think of 3 possibilities --- .

1) Remove the hotend holder to see if the timing belt works.
If it does, 1-a) check the horizontal bearing smooth, 1-b) check the 2 x-rods are parallel

2) Remove the timing belt to see if the x-stepper motor can rotate (either by hand, or manual g-code). If it doesn't, replace the motor.

3) If none of the above address the problem, probably it's due to the timing belt bearing. See if losing the 3/8 screw helps.

This is a nice design. I have been using it for a while and it's great.
I made a Z Endstop mount for it: https://www.thingiverse.com/thing:1291247

TwoUp One Up Z Endstop for Tony's gantry

Anyone else have prints with jagged/uneven edges after printing this. I don't know if it's related and I'm trying to narrow down the source of the issue. Otherwise, works great.

If you mean the jag on the vertical surface of the print, can you try this ? http://www.thingiverse.com/thing:962471

In my environment, it disappeared surprisingly.

QUBD : Bearing holder to prevent z-rod wobbling

What do I need to print? 1 of everything? My gantry just split in half, its held together with rubber bands. Please, I need to know quick. My printer is barely hanging in there D:

Yes, 1 pcs for each.


Thanks for the build, its rock solid. I have not gottent to the final parts as I'm putting together a second X gantry (just in case). What bowden setup do you use? Purchased or Printed?

This modification should work with the stock extruders. However, my Bowden style extruder is consist of the following items.

QUBD : Bowden style x-carriage with hot-end metal holder
QU-BD Extruder Modifications
by bdring
QUBD : Bowden extruder with the original drive gear with 3/8' thread push-in connector.

Much obliged, this is a much simpler setup than the one I had. I get the feeling this is the best upgrade as removing the weight from the x-gantry should help a lot with sag, print speed and quality.

The one thing I see missing from this is a fan mount. What do you do for fan?

I consider it's a separate work item. Look at the picture of this. (not the description or STL file, but just the picture) http://www.thingiverse.com/thing:1092420

QUBD TwoUp : x-gantry replacement ( trial narrow version )

Can you please upload the source files? I plan on modifying the right side to add another z screw.

For my OneUp I combined the left piece from this with the right piece from Steffan Berger's gantry http://www.thingiverse.com/thing:248059 and the stock belt was actually too tight! After replacing it with another belt (and doing the 3 zipties) I measure my X range at 71mm which was exactly what I had to start with, but not super slanty!

Yes, My v2 Is incompatible with Steffan's gantry, to enable wider print area. Print both right and left. Or try v1. Otherwise, another timing belt would be needed as you mentioned.

Thanks for sharing your design. I just had my gantry printed and I am about to start putting it together. Do you have any recommendation for a design of end stops that would work for this gantry? The ones I have are for the original Gantry and my big piece for X and Z does not fit anymore (Learning how to use the design software is next on my list, but I still don't know how to design my own). Thanks!

This would be my best bet for z-axis.

I don't know any designs for x-axis.

Simple Z-Axis Endstop holder V2 (OneUp/TwoUp)

Hey thanks for this. After printing a dozen 20mm cubes the first thing I did was to Start printing out replacement parts for the One-Up. Good thing as the tensioner spring lever was the first to brake, and the hot end mounting plate was the next to fail. Held em together with a couple of mini clamps as I printed out the rest of the parts to get the major design flaws changed. After looking at the few options I printed out your gantry replacement. First off nice job! It fit on the oneup bed and looked to be designed by someone who understands designing for 3d printing.

90% though the rebuild this week end and the gantry fit nicely. Using a modified X and with the bearings ends exposed I think I have gained a bit in X.

Now for the only problem with the Gantry. I have lost belt tension, I suspect that the bearing hole on the right might be a bit to the left. A Slot might be in order. Although thinking about it the motor might be shifted right a bit in your design also. I lost a lot of tension, right now I'm going to use the three zip-tie method of trying to tension it. Since this is my only printer I have to get it back to printing to get any replacement fixes made.:)

Thanks for the positive feedback. Being the QUBD printer owner, I never feel bored.

I designed this for my TwoUp printer whose timing belt is longer than OneUp. So, it's possible the two models have different tension. This is a kind of feedback I was looking for and appreciate.

If you can redesign the xgantry* for OneUp, it would be very beneficial for other OneUp users. I will update my description here to redirect to it for OneUp users.

Meanwhile I updated the instruction to warm this to OneUp users.

In TwoUp with modified x-carriage, the hotend can go beyond the building platform. So, I didn't have reason to take risk to lose the grip to the horizontal rods. But this may worth trying with OneUp.

Well I got the one-up back up and printing the gantry is working great. The 'ol three zip-tie trick worked for tensioning the belt. I had to shim the belt attachment with a piece of old credit card, but that tightened it up. I lost about 6mm in X travel, but some of that is from the remounting of the hot end and the non-symmetrical nature of it. Once I get the bed above the Y bearings I should gain about 8 or 9 mm, (for a net gain) I noticed that on the left rear v2 that a couple of more mm's might be gained by reducing the material on the right of far right upper and lower m3 tabs, matching what is on the left front. With the one-up every bit helps. As I was doing the rebuild a couple of thoughts occurred. 1.) using yer method on the top with a couple of cheep rod's in the horizontal gets rid of the card board on top. 2.) doing the same on the Y gantry loses the zip-ties holding it to the 6mm rods, lets me raise the bed, and maybe get rid of the hard stops on the belt wings. 3.) doing those to things lets me cut the base in half freeing the Z and Y sides and then it's a simple matter to just get longer rods to expand the x to something beyond the limitations of the present design. Since I have to rise the bed I may well try a Y gantry mod using your concept.

But the next issue I see a head of me is the Hot end, The extruder I printed out is a good design , but I used PLA, After hitting it with a IR thermometer the 136C I was seeing where the hot end meets the plastic is a good indication the it's gonna fail fast, So the next hunt is on for a replacement design. I saw your fix using the metal, but I'm not convinced about using a bowden(sp) to supply the filament. The simple goal is getting it to the point I can use it for the purpose it was obtained and not keep chasing design flaws.:)

Comments deleted.

just realized after I printed them, X gantry motor front is the wrong file for this gantry. It looks like it is a file from the previous version of this gantry. Could you please upload the right file?

They are correct files. The motor_front and motor_back have different width so that the stock carriage has the maxim travel length.

I am affraid I don't follow you. In this picture: https://drive.google.com/file/d/0BzzCAmvDHa0gRWpVU1lBekYzN2s/view?usp=sharing the back half is stacked on top of the front half. Wouldn't the extra length on the front half cause you to lose the benefits of this gantry over the first version (The two provided motor files have the same width)? Also the images for this thing show the gantry left front piece having a U shaped cut out in it. Could you please upload the file with this?

My apologies. You are right. The updated version was not the latest. I updated the latest one now, which I believe I used. I will print again this weekend to confirm.

The one uploaded 8/14 is the latest version, I confirmed. Sorry for the trouble.

Comments deleted.

Not much. See the instruction section.

I see you have the heated bed. How do you keep it from shaking violently/tipping? My printer tends to do this.

i screwed my printer down to a solid plywood board using "L brackets.

Masking tape :)