Y axis idler broken

So this happened. My Y axis idler cracked.

I managed to print a replacement but when I started taking my printer apart I noticed these inserts…

What am I supposed to do, buy some inserts and a heat gun to melt them in? What type are they?

They are heat-set inserts. Usually installed with an el-cheapo soldering iron, since you don’t want to get plastic on your nice iron. :slight_smile:

You can probably use a hot iron to get them out and put them in the new printed part. About $5 at Harbor Freight if you have one nearby.

Yep. Take those out with a cheap iron and install them in the new part.

If you want to buy new inserts, here is the link for McMasters Carr
(these are what is used on the Taz 5 - not sure what you have)

Heat Set Inserts
3.8mm long
5mm diameter
3mm thread

Best regards,

You can also temporarily fix that cracked idler with plastruct plastic weld, model cement or acetone if you like.

I just looked at mine. Yep, cracked!
Thanks for posting this before mine became completely broken.
Printing a replacement now.

Thanks for the heads up!

I picked up a can of ABS Pipe cement at the Home Depot. It works very well.

Best regards,

Right, I’ve bought m3 inserts and a soldering iron. I’m going to try and fix it tonight.

Also wanted to ask, how do you guys tighten the belts? Just a plyer tightening that screw?

Haha, glad I helped!

We have a great guide up on our Ohai. You can find belt tightening in either the Damper Install or the Motor Replacement guides.

We hope this helps!

What layer/infill is the original part printed at?

85% abs printed with a 0.5mm nozzle and 0.35mm layer height.

I like an adjustable tensioner on both X and Y.

So I’ve melted in the inserts and installed the idler back on. It was a bit difficult, for some reason the new idler was slightly larger? And I had to push down on it quite hard to be able to put it in position to screw it back on the frame.

With the belt down I saw the perfect occasion to install the vibration dampener on the y motor.

The result is incredible, I cannot believe how quiet it is, it’s uncanny. I can watch TV at an acceptable volume now while I am printing haha.

I’ve started printing replacements for all the printed parts. Don’t want any surprises after dismantling my printer for the first time.

I noticed my Y idler was cracked as well. I acetone welded it back together so I could print a replacement part. He staked in some new M3 inserts and it looks beautiful (Mcmaster requires you to buy the inserts in packs of 100 so I’ll be using the heat stake method for a lot of my future screw designs).

I’ll be installing this tonight, hopefully, since my vibration damper should be arriving this afternoon. Pray I don’t run into any issues!

Bad fortune must have been following me because after I finished that part, I noticed my idler had broken in half. Luckily even though it was split in half, the screw and the bottom and the spring clamp at the top held the filament bearing in place long enough for me to get a replacement part printed.

I wanted to make you all aware the Lulzbot must have realized the original idler arm was underdesigned. The latest design is much beefier and I suggest you guys print a spare to have ready when your original breaks. It’s very very easy to replace. The bearing just pops in and out with a slight press fit and the idler pivots on a screw that’s held in with a washer and a nut.

Here is the link to the beefier (or if you’re a simpsons fan…embiggened) idler arm. I would print yourself a spare if you have time.



I’m going to check mine tonight. I just had my extruder idler arm break. It was odd to remove because the nut that is on the inside part of the idler arm started to spin in place as I tried to loosen the screw. I ultimately had to grab some pliers and break the remainder of the idler arm to free the screw & nut. Happily I have a TAZ 6 right next to the Mini so I was able to easily upgrade it with the new “beefier” idler arm and latch (from the Gladiola build.) My Mini is an Olive, I believe. The 8mm latch spring tension jig won’t obviously work on this new one:

My Y axis idler broke yesterday splitting at the layers.

The vertical bolt and nut was tightened very hard, likely stressing the part to split, so probably a matter of time. I temporarily glued it with Loctite super glue.

Looks like these are the inserts: https://www.lulzbot.com/store/parts/heat-set-insert-tapered-m3-05mm-internal-thread-38mm-l-x20

Is PETG ok for printing a new one?

Hey DougZ, if you need a beefy idler arm that will fit older model Mini screws, check here:


BTW, my Y-Axis idler on my Mini 1.03 Foxglove cracked too. Does the new beefier Y idler on the 1.04 Gladiola fit the older Minis? It looks like it will.

This same part broke in mine. I don’t know if it’s affecting my prints but I just used a bit of super glue to seal the crack. Does this crack mess up prints?