Thanks for having me and thanks in advance for any help given with my question.
So I’ve just bought a new Hardened Steel Extruder gear for the P1P, and started removing the old one but the bearing seems to be stuck on the old gear, and the Hardened Steel doesn’t have any, I’ve watched the videos and can see the bearing seem to have stayed in place and on the video so I’m wondering how can I remove them without damaging them as they seem pretty much welded on?
If you need to reuse the bearing, you may have a problem. The only way I can think of to try, that won’t risk damaging the bearing, is to freeze the assembly and hope the bearing will slide off once the coefficient of thermal expansion has done its job. Besides that, pulling or prying would be the only alternative. But to do that, you’ll have to apply force to the outer race, and that could damage the internal bearing raceway or even the balls. It looks like a pretty standard bearing, though. If BBL can’t send you one, they at least ought to be able to tell you the critical dimensions so you could order a replacement on-line.
Pry the bearing off, then. Even if you damage it, it’ll work good enough you should still be able to print, at least for a while before the damage degrades the bearing to the point it stops turning or gets really “sloppy”. Order a new one and swap that in once it shows up.
What you want to try and do is get something thin between the bearing and the gear it abuts, so that you’re prying on the inner race as much as possible.
Force applied to the outer race while the inner race is stuck is where the damage might be induced.
Do not use the freezer technique. What you want is to expand the bearing. Normally bearings are heated and the shaft cooled before installation to help them slip together. To remove heating tends to cause the bearing to expand more than the shaft and it comes off easier.
Prying the bearing off will often damage the bearing, but it is an option. If you feel any roughness after prying it off then you need a new bearing. That is not a special bearing so you can probably get a dozen for $10 on amazon.
Looking closely at the photo it looks like there is a good sized gap next to the bearing. If you can get a thin blade screwdriver (or something else) all the way in next to the inner bearing race and twist, then move to another position and repeat, you might slowly pry it off without damage.
Thanks yeah I’m still apprehensive to do any prying so I might try and figure out the dimension (depending on if support gets back to me) and will order some I think that might be best.
You can measure the bearing in place if you have a set of digital calipers. Bearings are defined by 3 measurements: ID - shaft diameter, OD and width. From the photo it looks like a standard permanently lubricated sealed bearing.
The most common bearing used for 3D printed projects is the 608 skateboard bearing, which is ID: 8mm, OD: 22mm Width: 7mm.
Based on the photo and a little guessing, that might be a 693 which is ID: 3mm OD: 8mm width: 4mm. Even if your measurements are just close, all the measurements are almost certainly a multiple of 1mm. (There are some very small bearings with ID: 1.5mm etc.)
As a funny aside, the DJI drones use 693 bearings.
I specifically didn’t suggest heat because the shaft is pressed in to a plastic gear. Heating it enough to get the bearing off may risk the plastic part.
My thinking was that cooling them 'em off enough, the stress from the different CoTEs will maybe cause the mated surfaces to creep, breaking the tight bond and allowing the bearing to be removed.
If you’re going to have to get the bearing off the shaft no matter what, doesn’t matter if you intend to replace vs. re-use. Jam a thin blade in the gap between the bearing and that metal gear and pry. It might just pop right off. If it comes off easy enough, you can reuse it. If not, you can use the replacement you ordered.
I have to agree with Julie, better off just buying a new bearing. From the video it doesn’t seem like those bearings are supposed to be that tight of a fit. I have a feeling that the amount of force required to remove the bearing without using a proper bearing is just going to ruin the bearing. Since the bearings are so cheap and you don’t need the old shaft/gear there’s really no need to spend a lot of time trying to remove the bearing. Better spent designing your next invention in CAD.
Honestly, if you filed a ticket you might get Bambu to send you some new bearings or at least tell you what the dimensions are supposed to be.
For anyone else reading this. If you want to change to the hardened extruder, the X1C extruder assembly is the same as the P1P, except has the hardened gears. The only thing you have to do is unscrew the control board (2 screws) and substitute for the P1P one.
Go to McMaster.com and look up bearings, the website will ask you different measurements and then tell you what bearing it is. You can then buy the bearing anywhere you want.
shame I wanted to print with it today, but oh well!
