P3Steel Build Log (#09) – X-Axis

Parts Used For The X-Axis

Below are the main components used in the x-axis assembly. These are the hotend carriage, stepper and idler z-axis supports, x-axis tension block, stepper motor and various nuts, bolts and bearings used to connect them all. You can skip to the end of this post to see the time lapse of most of this assembly, or click here to watch it on my YouTube channel.

X-Axis Idler And Tension Block

First up was to set up the x-axis idler by adding in two M4 nuts into their printed slots. The Idler bearing is built in a similar way to the y-axis idler bearing; with two MF126 (flange) bearings, a couple of washers, an M5 bolt and M5 nylock nut. I think eventually I will replace the bolt, washer and nut with black versions – just to keep it looking sweet! The idler mount has two LMU88 bearings inserted into it in the main large hole. They should slot in with a little force if you widen the expansion gap a little. Slide them all the way in. The part has a notch half way down the slot so you will have to insert one each way.

X-Axis Stepper Mount

Behold… the only video time lapse I could find of three versions of each part printed?!!

Next up is the construction of the stepper motor mount on the x-axis. This is secured onto the stepper with three M3 bolts. Doing the same with two LMU88 bearings in to the large slot and that part is done – simples!

You will then need to add a GT belt gear – I went with the 20 tooth version, same as the the y-axis version. Slip it onto the motor shaft and tighten it up using the grubs screw. Before tightening it all the way, make sure it is aligned with the gap in the plastic part so the belt will run freely through, as per the image below:

On both parts (motor and idler) the LMU88 bearings are held in with friction. There are holes to allow retaining fasteners to be used to keep the bearings in place. For this I used mounting M5 5mm screws which have a flange washer of 7mm built in. These allow just enough to connect to the edge of the bearing, but not block the hole where the 8mm smooth rod will go. You could use M3 bolts and a washer, but these were a neat and tidy solution. I drilled and tapped the holes with an M3 tap first to reduce the chance of splitting. The plastic is thin at these sections. Toolson was clever enough to add in a small notch in the design which allow the washer to fit perfectly, and the bolt screws in beautifully.

At this time the z-axis stopper bracket is added to the stepper motor section, as seen above and below. It is secured with an M3 bolt and nut. There is also an M3 nut inserted into this part to secure the long M3 bolt with will eventually trigger the z-axis endstop. I’ll cover that in another post.

Now comes the step of adding the 8mm smooth rods to join the two end up.  These two will insert into the stepper end all the way till they cannot go further, it’s best to add them to this part first. Before adding I drilled out the holes of the part with an 8mm drill bit. It was surprising how much material was removed, and even after a little trial fit I still needed to sand and file the holes down. I suspect that was due to my printer setup – as I have recently been playing with “flow rate” and realised I am extruding way too much plastic which is causing all my tolerances to be too tight. Anyhow – once the holes are drilled, sanded and filed to perfect 8mm bores – insert the rods into the stepper end. and then move onto the idler end.

Here you can see how the idler end works, and how the Toolson Edition changes compared to a standard Prusa i3 model. The belt tension on an standard Prusa i3 pulls on the idler end and through the z-axis. Toolson’s version exposes the 8mm rods as per below image and then the idler tension block directs the belt tension force down these rods, rather than along the z-axis. Line up the rods so they are about flush with the end of the plastic part.

Below is a test setup of the belt and tension block, and how the M4 bolts line up with the ends of the 8mm smooth rods. To add more tension to the belt you would turn these bolts which would in turn pull out the tension block and tighten the belt.

BUT WAIT! Don’t think you’re done here – where’s the x-carriage?! If you’ve followed along blindly you printer is missing the x-carriage! If so – remove the idler part and move on to the next page as per below!!


10 comments on “P3Steel Build Log (#09) – X-Axis

  1. Nice one Steve! 🙂

    I’ll try to build up my x-axis this weekend.

    As always thank you for the very detailed and nice to read build log!

    Best regards, Anil

    • Thanks again Anil, and I will try to get the next step (Z-Axis) written up too!! Have not worked on the printer for some time, need to kick my own butt into gear!!


  2. Hello again!

    I have now probably printed all the parts i need for my setup.

    I had a question about the X axis tension block, did yours slide nicely into the “receiving” part?
    I spent some minutes just now going over the thing with a knife to get it somewhat in, and yes i did check the orientation of the little keyed things there, It just wouldnt fit!

    I wonder if my prints just came out weird, hmm.

    Anyways, should be receiving my frame and other stuff on friday (atleast lets hope so, you never know with ups :P)
    Gonna be just in time for weekend beer and assembly project \o/

    • Hi Akseli,

      Thanks for the comment and update! Glad to hear you have all your parts done! Regarding the fit of the parts. They will all need a little trim for parts to fit. The x-axis and tension block does need some filing and sanding. A good tight fit will work well – it took me a while to make mine fit well. Your 8mm rods will take some time to fit into the x-axis blocks!!

      Best of luck with your build – a great weekend (and beer!!!) project – keep me posted!


  3. Hello again, i keep spamming your comments section 😛

    I was able to get my printer working, but had some problems along the way.
    How long is the distance between the Z smooth rods on your frame?
    The X axis rods i got were 375mm long so too short, then i got some mild steel rod from a shop nearby and cut that to ~390mm according to some BOM i found on toolsons site, and even that was too small, if i have the ends of the rod flush with the x idler, its not gonna work, its atleast ~15mm too small.

    • Hi Akseli,

      No problem! The x-axis rods should be 375mm for the 2.01 frame, and 385mm for the 2.5 DXL frame. Mine were 385mm and fitted fine. Not sure what version your frame is though, so they should be 375 or 385mm. 390mm will be too long, but should not be too short certainly! Can’t measure the distance between the z-axis rods at the moment.

      When you have the rods flush with the x-axis idler part as per the images above, they should go into the motor part fine. They don’t go all the way in for me, but the motor part end is used to secure them in, and should be a tight fit. Even with 390mm rods, they should not be too short if they are wedged all the way in?

      When you are measuring the z-axis rods and test fitting the parts, were you using the holes in the frame for the z-axis threaded rods, not the smooth rods? Seems odd?


      • Hi,

        Yeah, might be that the orballo printings frame is bit different from the originals, on their website it does say that its compatible with the mk42 heatbed which is wider than a standard 200×200 bed which could be the problem. (Not too big of a problem, i do have a MK42 bed coming in soon :P)

        But yeah, I got the X axis rods completelly into the motor holder, so if im thinking right the idler end should be flush with the rods and everything should be good, but no, its visibly too short if i rest the whole thing on the Z motor mounts. just to confirm tho, smooth rods on the outside of the Z motor holders and threaded rods on the inside? I dont think you could even put them the wrong way around tho.

        • Hi Akseli,

          That’s correct, smooth rods go on the outside, threaded rod on the inside. I suspect your smooth rods on the x-axis are just in too far into the stepper motor plastic part.. As long as it works though!


          • What is the size of the heatbed used in the 2.5 frame

          • Hiya, thanks for the comment, sorry for the delay! The 2.5 frame uses the same bed mount of the standard prusa design, so the mounts are 200 x 200 mm. You can get any standard heated bed that fits any of the old Prusa models, and with the size of the “gap” of the frame, you can go bigger – I started with the MK3 bed (https://s.click.aliexpress.com/e/_A4h1cI) and I now have an Anycubic Ultrabase on mine at the moment which is 235mm x 235mm, but still has the same mounting hole sizes – that gives you a little extra X and Y. I believe you may be able to get a MK4 or above style bed which is 240mm in width, but that would be close to the bed frame!


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