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Ender 3 X & Y Axis Idler

by jwalbridge May 20, 2018
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What's the wide of idler pulley should I buy?

Width of the idler should be about 8mm to 8.5mm depending on the brand.

Comments deleted.

Thank you for posting this. I'm going to be making it soon. Just curious, have you noticed an improvement in print quality after applying this mod?

No problem. I cant say this will increase print quality. You could argue that crooked or slanted belts can throw off tolerances, but for me this is more of a 'wear and tear on your hardware' type of issue. Also, The belts rubbing against the aluminum extrusion can often be heard, like little clicks (if the teeth are catching), which was driving me crazy.

Thank you for this thing! Thumbs up to you!

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This is great, thanks for posting it. I made the earlier version with 4 tabs and one broke right away so I didn't use it. I will try the updated 2 tab version you made. That may work perfectly for me. While I was admiring it in place though, it occurred to me that you could put a mirrored part on the other side of the Y axis which has a hole in it instead. Then the current Y axis part could have a solid end which would slide into this mirrored part. It would look much like the X axis part here, except the hole would be offset in the other vertical direction (when installed). This might make for a more solid assembly, and would work on my setup which is mostly stock - I'm not sure what kind of clearance problems modified setups would have. I have plenty of space between my Y axis and stepper mount.

If I understand you correctly, this could apply to both the x and y axis. Hardest part would be making sure clearance holes line up when inserted into the mirrored side, aluminum extrusion slots. There are 2 screws there at Y axis (holding the stepper motor bracket in place) and 1 screw at X (securing the aluminum extrusion to the bracket with 3 wheels along the Z axis). You'd have to remove the Y stepper bracket, which is no problem. It would be a real pain to remove the screw for the X axis, though. Either way, this could serve as a heavier duty fully printed option that requires no additional hardware beyond the Idlers, and eliminates tiny features. I personally will be using the 2 pronged version, as even printed in PLA its working just fine on my machine.

Just wanted to let you know that your creation inspired me to try part design for the first time. After quite a bit of work being a noob, I was able to remix your part and create the two pieces I envisioned. They are working great in PLA. Thanks!

Yes exactly.

I did try the two pronged version. It works quite well, but it has bent just slightly on my setup. I made it with PLA, which isn't that strong, and I may be over-tightening the Y belt. The two prong version is very nice though and the print came out quite perfect.

Nice. Looks like the mirrored version works pretty well on the Y axis. What software are you using?

I used FreeCAD to remix it. I've never tried it before. I pretty much just took your 2prong part, mirrored it, and put a hole where the prong was. Then I took the original 2prong, deleted the tip, and added a new cylinder of pretty much the same size to extend it. After one test print, and slight size tweak, and a beefing up of the base around the prong, my v2 worked quite well. It is very sturdy in PLA, and doesn't flex to the side a little bit like it used to. That all sadly took me like 5 hours to do, but you gotta learn somehow.

5 Hours isn't bad for a functional part, regardless of its size. I mean, they are all the same size on the screen.

Thank you so much for this.

The end tabs on the "E3_X_Y_Axis_Idler_Bracket.stl" vertical piece are very brittle and break off too easily. Printing in ABS with 100% infill. Attempted this with two prints and they both lost their end tabs without difficulty.

I'm replacing the 4 pronged version with a more substantial 2 pronged version. I am unable to create the desired snap fit with a shaft that is solid from the base to the end. I'm getting good results with PLA 40% infill, 10 second minimun layer time, 10mm/s minimum print speed in the cooling section of Cura settings.

Just wanted to clarify that its the 4 small tabs at the end of the main shaft that are breaking off, and not the entire shaft from the base. If so, I could upload a version with only one split at the end (or just solid with only the lip). Unfortunately, I haven't touched ABS in years, and I am not set up to try and replicate the problem. I am using AIO Robotics PETG at 245C, 40%-50% ish infill, 0.35mm nozzle; parts are stupid strong.

Hi - I printed the modified X limit switch bracket, however the screw holes I think are too small. The M3 screws thread into the walls of the screw holes. If this was intended, this would be perfect. However, in this case, since it threads, it does not allow me to fully tighten the X stepper against the bracket. The original part is not threaded and the M3 screws are loose in it.

Printed it on a Prusa MK3 which has been calibrated to print a 20mm calicube at 19.98mm so I don't think it's a printer inaccuracy problem.

Would you be open to enlarging the holes a bit to allow M3 screws to be tightened against the stepper?

Yeah, I could probably do that. The hole diameters are currently taken directly from the part provided in the Ender 3 Github. They might be M3 screw holes and not M3 Clearance holes? If you want to use the part you already printed (and have the necessary tools), try clearing it with a slightly larger drill bit at a slow speed.

If you're talking about this file off github, it seems to be 3.10mm. (https://github.com/Creality3DPrinting/Ender-3/blob/master/Ender-3%20Mechanical/Ender-3%20Parts/X%20limit%20switch%20bracket.SLDPRT)

I've also measured the original injection molded part with calipers and its ~3.15-3.18mm holes. So a bit bigger than the spec.
I measured the screw diameter of threads and its 2.97 to 2.99mm
I measured the actual printed part and I'm seeing 2.86 to 2.90 something. Which makes sense why the printed part threads in with force, but not through holes.
And, I opened your STL and it appears to be 3.10mm too!

So yeah, I think it's my issue not yours - I guess my printer is making the holes too small!

Been reading some threads - apparently for FDM printing one needs to oversize the holes a bit, rather than trying over and over to calibrate.


Would you be open to enlarge holes to say 3.30mm?

Either way, they could definitely be a little bigger. A standard M3 clearance hole is 3.4mm-3.5mm diameter. I'll see if I can get to it this weekend.

Hi, were you able to enlarge the holes in the X limit switch bracket? If you're too busy perhaps you can share the design/step files and I can take a swing at it?

Uploading it now. 3.5MM clearance holes, should do the trick.

Worked perfectly, thanks!!

Comments deleted.

Can you come up with a pulley mod for the X-axis?

See the reply below under TallDonkey

On my E3 the X-axis belt does make some contact with the aluminum extrusion on the stepper motor side. That is a pretty tight space to work in, maybe if the injection molded cover with the QR code is removed? I'll try to look into it when I have more free time, lots of overtime at work currently. I'm spending this Saturday modding one of the company printers, a CR-10 S4.

+1 to mindbender9's request! I think theres this one, but prefer to use a proper GT2 pulley idler. https://www.thingiverse.com/thing:2986187

Ender 3 X-rail Idler
by WhittM

You'll have to print a modified X limit switch bracket, but it looks like the GT2 hardware should fit. I need to test the snap fit for the part since I'm trying to eliminate screws and nuts to fit in this small space. See the attached images.

Awesome! Seems like that for the X limit, the snap fit is the only option, but for the Y, either the screws/nuts and the snap fit will work too, but the screw and nut would be stiffer/more preferable?

Metal Hardware should always be sturdier than FDM plastic. But these parts aren't under a terrible amount of stress for their shape and size (unless you over tighten your belts). Without proper layer adhesion I can see the snap fit part breaking at the base of the shaft that inserts into the idler. I'm using PETG at about 40% to 50% infill and the snap fit works just fine for X and Y.

Are two of these idlers needed or just one?

Just one in the back. If your Y belt is touching in the front, the existing bracket there should have enough play in it to be loosened, angled up slightly, and re tightened to clear the aluminum extrusion.

Very well done, works for me! Thank you

You're welcome. Things like the belts rubbing or the nozzle homing off the bed drive me nuts. I guess a 3D printer that didn't have to fix itself would be kind of boring though, right?

The nozzle is meant to home off the bed though. It's completely normal and there's nothing wrong with it.

It is normal (So is the pre-assembled lower frame being crooked and out of square). Is it really meant to be? I cant think of any reason for it. Why would you want any x and y coordinates to be off the print bed?

So the nozzle oozes and idles somewhere else than right at the bed after homing. It also allows you to add in a nozzle cleaning brush like http://www.thingiverse.com/thing:3012742 if you want to.
But you are right, X0 Y0 should be on the bed as it's part of the print volume. But with the Ender 3, it's advertised as 220x220, the bed is actually 235x235, and the movement you get is even larger. If you correctly set it up as a 220 x 220 (aka config it so that "width / 2 by height / 2 = nozzle exactly in the middle of the bed"), I ended up with home coordinates of X -6 Y -11 with the nozzle few mm off the bed, and X0 X0 is correctly 7.5mm in from the edge.

Ender 3 Hotend Brush Holder
by Kevlarr

Idling off the bed and oozing filament near the exposed control board fan seems to work great for most people. It just isn't for me. I am a fan of incorporating a cleaning sequence into the start g-code. I'm using a 10mm x 40mm strip of high temp Velcro in the front right corner of my build area. After auto-leveling, the nozzle zig-zags through the Velcro, purges along the front, then starts printing.

Without this idler the Y belt passes through the opening in the aluminum extrusion and will make contact on one side or the other. Attached is a picture of the idler that comes stock on the CR10.