Linear bearings for y carriage on the Mega


Goal is to provide more support to the bed, so I can move it a bit faster.

Currently a work in progress, but I’ll keep the updates coming. Thanks to @ant0ny for the design work.

New idler end printed in 26.5 hours:

New motor end printing:


That’s a sexy looking Y idler - I like it!


Here is the motor end printing, that’s a sexy piece of kit:


That look like it might be sticking better as well.

What brand filament is that… is it Cocoon Create Orange?


Definitely better, but started to come up a bit. The skirt helped, the 27 hour and counting print doesn’t help.

Not sure on the brand, just something moderately priced on eBay.


Sad Squid:

Happy Squid:


Coke can and 30cm ruler for scale:


Wow that is big… impressive… this will make such a difference to the stability of the bed.

Shame about the bit broken… too tight still?

Because it is split there just when you clamp it with the block to the frame, make sure they are parallel other wise you will have issues with the linear rail. Once it’s all together it’ll be fine and you could print replacement. If you want me to open the hole I can.


Despite the splits and not being mounted, it is rock solid, so it should definitely improve stability.

Edit: measured with a ruler, there is no deviation to parallel over the length (within a fraction of a mm). I’ll get the verniers onto it tomorrow, but I’ll need a straight edge too, as it is to wide.

I’ll get it on and see how the stability improves, will likely reprint sometime in the future, but I don’t see any urgency as I won’t be moving it much.

I am toying with dropping the second deck and just running heated beds straight on top of the tray, as the bilinneal levelling in rc8 is awesome.

Also trying to work out how to mark and drill the holes for the bearings, I don’t want to do a hack job (my normal m.o.) and stuff it up.


Ok cool.

With holes you don’t need to be super precise. They are M5 (mine are but check) so draw out the holes as best you can then drill the holes 5.5mm or even 6mm and it’s putting it together that you have to be sure you are not forcing the bearing or twisting the bearings on the axis.

Use washers and put all the bots in so the are just loose to just finger tight. slide the bed back and forth and each time you stop nip up a bolt and move around in a circle. one bolt on each bearing then to the next till they are all done… with the action of sliding the bed between each time you are tightening you are feeling for the resistance.

If you feel all of a sudden it gets tighter with one bolt… back the bolt out and you may see it’s pinching on the edge of the hole and screw action is forcing the plate. You may have to open that hole up… mark the side it’s tight take the plate off file it a bit and start again.

Once you have all the bolts tight… if you want to, you could back out one bolt from each block and loctite it in. Do one bolt per block and work your way around and checking it’s still running nice and you are done.

I should also mention the supported rail bearings should be treated like any other bearing and washed out and re lubed. I wash mine out with Isocol which is 99% Isopropyl you can get it at a chemist or supermarket. I grease my bearings with White Lithium Grease the best place to get this is the 99 Bike Shops in a green tube $6. Difference to other bearings on a 3D printer there is adjustment screws. Watch this short video and he talks about it.


Got the tray loosely fitted last night, feels very solid and smooth.

I need to move where I mounted the bearings on the motor end - I went as far to the edge of the tray as I could, this won’t hit the end stop, so I need to move it back a bit.


Quick vid of progress, looking good!


Looking much better on a print:


trying to use some of these linear bearings for my second wilson II i am printing. and the prints are so tight on the rails that i cannot get them on without splitting the plastic every which way. is there a setting or something that i might be missing?


All mine slightly split, which is a shame, but isn’t impacting strength.

I will reprint at sometime in the future, ant0ny offered to make the holes a bit bigger.


@dolanm9 Can you measure the size your print is turning out at the tightest point. Is it the round or the extrusion, or all over.

I’ll do a looser version. out of interest what size nozzle and what layer height do you pint?


Sounds like the there is very little tolerance in that part. I get the best tolerance accuracy with my machine printing outside walls first and reducing flow until actual walls are +0.02mm of the nozzle diameter.

Here’s a tutorial on measuring walls and setting flow.

In Simplify3D the outside walls first setting is called “Outline Direction” and it’s on the layer tab of the advanced settings. In Cura the setting is called “Outer before Inner Walls” and it’s under the Shell settings after being enabled in setting visibility.

Hope that helps you guys achieve better tolerances.


it appears that my printer seems to have lost some tuning for interior sizes sometime in the last month. pretty much all internal surfaces are about .25mm off. need to look at my settings and changes and figure out what i fiddled with that threw it off. will get back once i can say that the prints are accurate size wise.


My prints are tight I an told often but I do prefer it tight rather than loose. I print close to dimentionally accurate as possible because the majority of my work for customers is Proto typing.

Rockeys suggestion is a good one and I do change between inside and outside for different things.

I also just watch the flow of the filament from the nozzle and look at the way it’s being layed down and adjust the “Flow” in the setting on the go. As I have mentioned before the magnifying glass is an essential tool for seeing how things are printing… you can tweak all the setting in the world for a good print but in the end it’s the flow from the nozzle and the squish that matters.


Is there a good write up somewhere of exactly what you are looking for/what adjustments to make?